Replace most uses of gpr_asprintf() with absl calls.

src/core/ext/filters/client_channel/http_connect_handshaker.cc

@@ -22,6 +22,8 @@
 
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/slice_buffer.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
@@ -241,11 +243,10 @@ void HttpConnectHandshaker::OnReadDone(void* arg, grpc_error* error) {
   // Make sure we got a 2xx response.
   if (handshaker->http_response_.status < 200 ||
       handshaker->http_response_.status >= 300) {
-    char* msg;
-    gpr_asprintf(&msg, "HTTP proxy returned response code %d",
-                 handshaker->http_response_.status);
-    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
+    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("HTTP proxy returned response code ",
+                     handshaker->http_response_.status)
+            .c_str());
     handshaker->HandshakeFailedLocked(error);
     goto done;
   }

src/core/ext/filters/client_channel/http_proxy.cc

@@ -23,6 +23,8 @@
 #include <stdbool.h>
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
@@ -176,13 +178,13 @@ class HttpProxyMapper : public ProxyMapperInterface {
       /* Use base64 encoding for user credentials as stated in RFC 7617 */
       char* encoded_user_cred =
           grpc_base64_encode(user_cred, strlen(user_cred), 0, 0);
-      char* header;
-      gpr_asprintf(&header, "Proxy-Authorization:Basic %s", encoded_user_cred);
+      std::string header =
+          absl::StrCat("Proxy-Authorization:Basic ", encoded_user_cred);
       gpr_free(encoded_user_cred);
       args_to_add[1] = grpc_channel_arg_string_create(
-          (char*)GRPC_ARG_HTTP_CONNECT_HEADERS, header);
+          const_cast<char*>(GRPC_ARG_HTTP_CONNECT_HEADERS),
+          const_cast<char*>(header.c_str()));
       *new_args = grpc_channel_args_copy_and_add(args, args_to_add, 2);
-      gpr_free(header);
     } else {
       *new_args = grpc_channel_args_copy_and_add(args, args_to_add, 1);
     }

src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc

@@ -65,6 +65,7 @@
 #include <string.h>
 
 #include "absl/container/inlined_vector.h"
+#include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
 #include "absl/strings/str_join.h"
 
@@ -547,12 +548,10 @@ ServerAddressList GrpcLb::Serverlist::GetServerAddressList(
       memcpy(lb_token, server.load_balance_token, lb_token_length);
       lb_token[lb_token_length] = '\0';
     } else {
-      char* uri = grpc_sockaddr_to_uri(&addr);
       gpr_log(GPR_INFO,
               "Missing LB token for backend address '%s'. The empty token will "
               "be used instead",
-              uri);
-      gpr_free(uri);
+              grpc_sockaddr_to_uri(&addr).c_str());
       lb_token[0] = '\0';
     }
     // Add address.
@@ -1458,11 +1457,10 @@ void GrpcLb::ProcessAddressesAndChannelArgsLocked(
       balancer_addresses, response_generator_.get(), &args);
   // Create balancer channel if needed.
   if (lb_channel_ == nullptr) {
-    char* uri_str;
-    gpr_asprintf(&uri_str, "fake:///%s", server_name_);
-    lb_channel_ = CreateGrpclbBalancerChannel(uri_str, *lb_channel_args);
+    std::string uri_str = absl::StrCat("fake:///", server_name_);
+    lb_channel_ =
+        CreateGrpclbBalancerChannel(uri_str.c_str(), *lb_channel_args);
     GPR_ASSERT(lb_channel_ != nullptr);
-    gpr_free(uri_str);
   }
   // Propagate updates to the LB channel (pick_first) through the fake
   // resolver.

src/core/ext/filters/client_channel/lb_policy/subchannel_list.h

@@ -390,23 +390,21 @@ SubchannelList<SubchannelListType, SubchannelDataType>::SubchannelList(
     if (subchannel == nullptr) {
       // Subchannel could not be created.
       if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) {
-        char* address_uri = grpc_sockaddr_to_uri(&addresses[i].address());
         gpr_log(GPR_INFO,
                 "[%s %p] could not create subchannel for address uri %s, "
                 "ignoring",
-                tracer_->name(), policy_, address_uri);
-        gpr_free(address_uri);
+                tracer_->name(), policy_,
+                grpc_sockaddr_to_uri(&addresses[i].address()).c_str());
       }
       continue;
     }
     if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) {
-      char* address_uri = grpc_sockaddr_to_uri(&addresses[i].address());
       gpr_log(GPR_INFO,
               "[%s %p] subchannel list %p index %" PRIuPTR
               ": Created subchannel %p for address uri %s",
               tracer_->name(), policy_, this, subchannels_.size(),
-              subchannel.get(), address_uri);
-      gpr_free(address_uri);
+              subchannel.get(),
+              grpc_sockaddr_to_uri(&addresses[i].address()).c_str());
     }
     subchannels_.emplace_back(this, addresses[i], std::move(subchannel));
   }

src/core/ext/filters/client_channel/lb_policy_registry.cc

@@ -23,6 +23,7 @@
 #include <string.h>
 
 #include "absl/container/inlined_vector.h"
+#include "absl/strings/str_format.h"
 
 #include "src/core/lib/gpr/string.h"
 
@@ -168,11 +169,9 @@ LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(const Json& json,
   LoadBalancingPolicyFactory* factory =
       g_state->GetLoadBalancingPolicyFactory(policy->first.c_str());
   if (factory == nullptr) {
-    char* msg;
-    gpr_asprintf(&msg, "Factory not found for policy \"%s\"",
-                 policy->first.c_str());
-    *error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
+    *error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrFormat("Factory not found for policy \"%s\"", policy->first)
+            .c_str());
     return nullptr;
   }
   // Parse load balancing config via factory.

src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.cc

@@ -23,6 +23,8 @@
 #include <ares.h>
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
+
 #include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h"
 
 #include <grpc/support/alloc.h>
@@ -155,11 +157,10 @@ grpc_error* grpc_ares_ev_driver_create_locked(
   grpc_ares_test_only_inject_config((*ev_driver)->channel);
   GRPC_CARES_TRACE_LOG("request:%p grpc_ares_ev_driver_create_locked", request);
   if (status != ARES_SUCCESS) {
-    char* err_msg;
-    gpr_asprintf(&err_msg, "Failed to init ares channel. C-ares error: %s",
-                 ares_strerror(status));
-    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(err_msg);
-    gpr_free(err_msg);
+    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Failed to init ares channel. C-ares error: ",
+                     ares_strerror(status))
+            .c_str());
     gpr_free(*ev_driver);
     return err;
   }

src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_libuv.cc

@@ -20,6 +20,8 @@
 #include "src/core/lib/iomgr/port.h"
 #if GRPC_ARES == 1 && defined(GRPC_UV)
 
+#include "absl/strings/str_format.h"
+
 #include <ares.h>
 #include <uv.h>
 
@@ -43,15 +45,14 @@ class GrpcPolledFdLibuv : public GrpcPolledFd {
  public:
   GrpcPolledFdLibuv(ares_socket_t as,
                     std::shared_ptr<WorkSerializer> work_serializer)
-      : as_(as), work_serializer_(std::move(work_serializer)) {
-    gpr_asprintf(&name_, "c-ares socket: %" PRIdPTR, (intptr_t)as);
+      : name_(absl::StrFormat("c-ares socket: %" PRIdPTR, (intptr_t)as)),
+        as_(as),
+        work_serializer_(std::move(work_serializer)) {
     handle_ = new uv_poll_t();
     uv_poll_init_socket(uv_default_loop(), handle_, as);
     handle_->data = this;
   }
 
-  ~GrpcPolledFdLibuv() { gpr_free(name_); }
-
   void RegisterForOnReadableLocked(grpc_closure* read_closure) override {
     GPR_ASSERT(read_closure_ == nullptr);
     GPR_ASSERT((poll_events_ & UV_READABLE) == 0);
@@ -98,9 +99,10 @@ class GrpcPolledFdLibuv : public GrpcPolledFd {
 
   ares_socket_t GetWrappedAresSocketLocked() override { return as_; }
 
-  const char* GetName() override { return name_; }
+  const char* GetName() override { return name_.c_str(); }
 
-  char* name_;
+  // TODO(apolcyn): Data members should be private.
+  std::string name_;
   ares_socket_t as_;
   uv_poll_t* handle_;
   grpc_closure* read_closure_ = nullptr;

src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_posix.cc

@@ -24,6 +24,8 @@
 #include <string.h>
 #include <sys/ioctl.h>
 
+#include "absl/strings/str_cat.h"
+
 #include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver.h"
 
 #include <grpc/support/alloc.h>
@@ -41,15 +43,13 @@ namespace grpc_core {
 class GrpcPolledFdPosix : public GrpcPolledFd {
  public:
   GrpcPolledFdPosix(ares_socket_t as, grpc_pollset_set* driver_pollset_set)
-      : as_(as) {
-    gpr_asprintf(&name_, "c-ares fd: %d", (int)as);
-    fd_ = grpc_fd_create((int)as, name_, false);
+      : name_(absl::StrCat("c-ares fd: ", (int)as)), as_(as) {
+    fd_ = grpc_fd_create((int)as, name_.c_str(), false);
     driver_pollset_set_ = driver_pollset_set;
     grpc_pollset_set_add_fd(driver_pollset_set_, fd_);
   }
 
   ~GrpcPolledFdPosix() {
-    gpr_free(name_);
     grpc_pollset_set_del_fd(driver_pollset_set_, fd_);
     /* c-ares library will close the fd inside grpc_fd. This fd may be picked up
        immediately by another thread, and should not be closed by the following
@@ -78,9 +78,10 @@ class GrpcPolledFdPosix : public GrpcPolledFd {
 
   ares_socket_t GetWrappedAresSocketLocked() override { return as_; }
 
-  const char* GetName() override { return name_; }
+  const char* GetName() override { return name_.c_str(); }
 
-  char* name_;
+ private:
+  std::string name_;
   ares_socket_t as_;
   grpc_fd* fd_;
   grpc_pollset_set* driver_pollset_set_;

src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_ev_driver_windows.cc

@@ -20,6 +20,8 @@
 #include "src/core/lib/iomgr/port.h"
 #if GRPC_ARES == 1 && defined(GRPC_WINDOWS_SOCKET_ARES_EV_DRIVER)
 
+#include "absl/strings/str_format.h"
+
 #include <ares.h>
 
 #include <grpc/support/alloc.h>
@@ -100,14 +102,14 @@ class GrpcPolledFdWindows {
   GrpcPolledFdWindows(ares_socket_t as,
                       std::shared_ptr<WorkSerializer> work_serializer,
                       int address_family, int socket_type)
-      : work_serializer_(std::move(work_serializer)),
+      : name_(absl::StrFormat("c-ares socket: %" PRIdPTR, as)),
+        work_serializer_(std::move(work_serializer)),
         read_buf_(grpc_empty_slice()),
         write_buf_(grpc_empty_slice()),
         tcp_write_state_(WRITE_IDLE),
         gotten_into_driver_list_(false),
         address_family_(address_family),
         socket_type_(socket_type) {
-    gpr_asprintf(&name_, "c-ares socket: %" PRIdPTR, as);
     // Closure Initialization
     GRPC_CLOSURE_INIT(&outer_read_closure_,
                       &GrpcPolledFdWindows::OnIocpReadable, this,
@@ -118,7 +120,7 @@ class GrpcPolledFdWindows {
     GRPC_CLOSURE_INIT(&on_tcp_connect_locked_,
                       &GrpcPolledFdWindows::OnTcpConnect, this,
                       grpc_schedule_on_exec_ctx);
-    winsocket_ = grpc_winsocket_create(as, name_);
+    winsocket_ = grpc_winsocket_create(as, name_.c_str());
   }
 
   ~GrpcPolledFdWindows() {
@@ -127,7 +129,6 @@ class GrpcPolledFdWindows {
     GPR_ASSERT(read_closure_ == nullptr);
     GPR_ASSERT(write_closure_ == nullptr);
     grpc_winsocket_destroy(winsocket_);
-    gpr_free(name_);
   }
 
   void ScheduleAndNullReadClosure(grpc_error* error) {
@@ -260,7 +261,7 @@ class GrpcPolledFdWindows {
     return grpc_winsocket_wrapped_socket(winsocket_);
   }
 
-  const char* GetName() { return name_; }
+  const char* GetName() { return name_.c_str(); }
 
   ares_ssize_t RecvFrom(WSAErrorContext* wsa_error_ctx, void* data,
                         ares_socket_t data_len, int flags,
@@ -657,6 +658,7 @@ class GrpcPolledFdWindows {
   bool gotten_into_driver_list() const { return gotten_into_driver_list_; }
   void set_gotten_into_driver_list() { gotten_into_driver_list_ = true; }
 
+ private:
   std::shared_ptr<WorkSerializer> work_serializer_;
   char recv_from_source_addr_[200];
   ares_socklen_t recv_from_source_addr_len_;
@@ -670,7 +672,7 @@ class GrpcPolledFdWindows {
   grpc_winsocket* winsocket_;
   // tcp_write_state_ is only used on TCP GrpcPolledFds
   WriteState tcp_write_state_;
-  char* name_ = nullptr;
+  std::string name_;
   bool gotten_into_driver_list_;
   int address_family_;
   int socket_type_;

src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.cc

@@ -27,6 +27,8 @@
 #include <sys/types.h>
 
 #include "absl/container/inlined_vector.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
 
 #include <ares.h>
 #include <grpc/support/alloc.h>
@@ -277,15 +279,12 @@ static void on_hostbyname_done_locked(void* arg, int status, int /*timeouts*/,
       }
     }
   } else {
-    char* error_msg;
-    gpr_asprintf(&error_msg,
-                 "C-ares status is not ARES_SUCCESS "
-                 "qtype=%s name=%s is_balancer=%d: %s",
-                 hr->qtype, hr->host, hr->is_balancer, ares_strerror(status));
+    std::string error_msg = absl::StrFormat(
+        "C-ares status is not ARES_SUCCESS qtype=%s name=%s is_balancer=%d: %s",
+        hr->qtype, hr->host, hr->is_balancer, ares_strerror(status));
     GRPC_CARES_TRACE_LOG("request:%p on_hostbyname_done_locked: %s", r,
-                         error_msg);
-    grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg);
-    gpr_free(error_msg);
+                         error_msg.c_str());
+    grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg.c_str());
     r->error = grpc_error_add_child(error, r->error);
   }
   destroy_hostbyname_request_locked(hr);
@@ -326,15 +325,12 @@ static void on_srv_query_done_locked(void* arg, int status, int /*timeouts*/,
       ares_free_data(reply);
     }
   } else {
-    char* error_msg;
-    gpr_asprintf(&error_msg,
-                 "C-ares status is not ARES_SUCCESS "
-                 "qtype=SRV name=%s: %s",
-                 q->name().c_str(), ares_strerror(status));
+    std::string error_msg = absl::StrFormat(
+        "C-ares status is not ARES_SUCCESS qtype=SRV name=%s: %s", q->name(),
+        ares_strerror(status));
     GRPC_CARES_TRACE_LOG("request:%p on_srv_query_done_locked: %s", r,
-                         error_msg);
-    grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg);
-    gpr_free(error_msg);
+                         error_msg.c_str());
+    grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg.c_str());
     r->error = grpc_error_add_child(error, r->error);
   }
   delete q;
@@ -344,8 +340,8 @@ static const char g_service_config_attribute_prefix[] = "grpc_config=";
 
 static void on_txt_done_locked(void* arg, int status, int /*timeouts*/,
                                unsigned char* buf, int len) {
-  char* error_msg;
   GrpcAresQuery* q = static_cast<GrpcAresQuery*>(arg);
+  std::unique_ptr<GrpcAresQuery> query_deleter(q);
   grpc_ares_request* r = q->parent_request();
   const size_t prefix_len = sizeof(g_service_config_attribute_prefix) - 1;
   struct ares_txt_ext* result = nullptr;
@@ -386,18 +382,15 @@ static void on_txt_done_locked(void* arg, int status, int /*timeouts*/,
   }
   // Clean up.
   ares_free_data(reply);
-  goto done;
+  return;
 fail:
-  gpr_asprintf(&error_msg,
-               "C-ares status is not ARES_SUCCESS "
-               "qtype=TXT name=%s: %s",
-               q->name().c_str(), ares_strerror(status));
-  error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg);
-  GRPC_CARES_TRACE_LOG("request:%p on_txt_done_locked %s", r, error_msg);
-  gpr_free(error_msg);
+  std::string error_msg =
+      absl::StrFormat("C-ares status is not ARES_SUCCESS qtype=TXT name=%s: %s",
+                      q->name(), ares_strerror(status));
+  error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg.c_str());
+  GRPC_CARES_TRACE_LOG("request:%p on_txt_done_locked %s", r,
+                       error_msg.c_str());
   r->error = grpc_error_add_child(error, r->error);
-done:
-  delete q;
 }
 
 void grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
@@ -459,11 +452,10 @@ void grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
     }
     int status = ares_set_servers_ports(*channel, &r->dns_server_addr);
     if (status != ARES_SUCCESS) {
-      char* error_msg;
-      gpr_asprintf(&error_msg, "C-ares status is not ARES_SUCCESS: %s",
-                   ares_strerror(status));
-      error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg);
-      gpr_free(error_msg);
+      error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrCat("C-ares status is not ARES_SUCCESS: ",
+                       ares_strerror(status))
+              .c_str());
       goto error_cleanup;
     }
   }
@@ -482,20 +474,16 @@ void grpc_dns_lookup_ares_continue_after_check_localhost_and_ip_literals_locked(
                      hr);
   if (r->balancer_addresses_out != nullptr) {
     /* Query the SRV record */
-    char* service_name;
-    gpr_asprintf(&service_name, "_grpclb._tcp.%s", host.c_str());
+    std::string service_name = absl::StrCat("_grpclb._tcp.", host);
     GrpcAresQuery* srv_query = new GrpcAresQuery(r, service_name);
-    ares_query(*channel, service_name, ns_c_in, ns_t_srv,
+    ares_query(*channel, service_name.c_str(), ns_c_in, ns_t_srv,
                on_srv_query_done_locked, srv_query);
-    gpr_free(service_name);
   }
   if (r->service_config_json_out != nullptr) {
-    char* config_name;
-    gpr_asprintf(&config_name, "_grpc_config.%s", host.c_str());
+    std::string config_name = absl::StrCat("_grpc_config.", host);
     GrpcAresQuery* txt_query = new GrpcAresQuery(r, config_name);
-    ares_search(*channel, config_name, ns_c_in, ns_t_txt, on_txt_done_locked,
-                txt_query);
-    gpr_free(config_name);
+    ares_search(*channel, config_name.c_str(), ns_c_in, ns_t_txt,
+                on_txt_done_locked, txt_query);
   }
   grpc_ares_ev_driver_start_locked(r->ev_driver);
   grpc_ares_request_unref_locked(r);
@@ -709,12 +697,9 @@ void (*grpc_cancel_ares_request_locked)(grpc_ares_request* r) =
 grpc_error* grpc_ares_init(void) {
   int status = ares_library_init(ARES_LIB_INIT_ALL);
   if (status != ARES_SUCCESS) {
-    char* error_msg;
-    gpr_asprintf(&error_msg, "ares_library_init failed: %s",
-                 ares_strerror(status));
-    grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg);
-    gpr_free(error_msg);
-    return error;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("ares_library_init failed: ", ares_strerror(status))
+            .c_str());
   }
   return GRPC_ERROR_NONE;
 }

src/core/ext/filters/client_channel/resolver_registry.cc

@@ -23,6 +23,7 @@
 #include <string.h>
 
 #include "absl/container/inlined_vector.h"
+#include "absl/strings/str_cat.h"
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
@@ -65,22 +66,22 @@ class RegistryState {
   // If \a default_prefix_ needs to be prepended, sets \a canonical_target
   // to the canonical target string.
   ResolverFactory* FindResolverFactory(const char* target, grpc_uri** uri,
-                                       char** canonical_target) const {
+                                       std::string* canonical_target) const {
     GPR_ASSERT(uri != nullptr);
     *uri = grpc_uri_parse(target, 1);
     ResolverFactory* factory =
         *uri == nullptr ? nullptr : LookupResolverFactory((*uri)->scheme);
     if (factory == nullptr) {
       grpc_uri_destroy(*uri);
-      gpr_asprintf(canonical_target, "%s%s", default_prefix_.get(), target);
-      *uri = grpc_uri_parse(*canonical_target, 1);
+      *canonical_target = absl::StrCat(default_prefix_.get(), target);
+      *uri = grpc_uri_parse(canonical_target->c_str(), 1);
       factory =
           *uri == nullptr ? nullptr : LookupResolverFactory((*uri)->scheme);
       if (factory == nullptr) {
         grpc_uri_destroy(grpc_uri_parse(target, 0));
-        grpc_uri_destroy(grpc_uri_parse(*canonical_target, 0));
+        grpc_uri_destroy(grpc_uri_parse(canonical_target->c_str(), 0));
         gpr_log(GPR_ERROR, "don't know how to resolve '%s' or '%s'", target,
-                *canonical_target);
+                canonical_target->c_str());
       }
     }
     return factory;
@@ -136,12 +137,11 @@ ResolverFactory* ResolverRegistry::LookupResolverFactory(const char* scheme) {
 
 bool ResolverRegistry::IsValidTarget(const char* target) {
   grpc_uri* uri = nullptr;
-  char* canonical_target = nullptr;
+  std::string canonical_target;
   ResolverFactory* factory =
       g_state->FindResolverFactory(target, &uri, &canonical_target);
   bool result = factory == nullptr ? false : factory->IsValidUri(uri);
   grpc_uri_destroy(uri);
-  gpr_free(canonical_target);
   return result;
 }
 
@@ -152,7 +152,7 @@ OrphanablePtr<Resolver> ResolverRegistry::CreateResolver(
     std::unique_ptr<Resolver::ResultHandler> result_handler) {
   GPR_ASSERT(g_state != nullptr);
   grpc_uri* uri = nullptr;
-  char* canonical_target = nullptr;
+  std::string canonical_target;
   ResolverFactory* factory =
       g_state->FindResolverFactory(target, &uri, &canonical_target);
   ResolverArgs resolver_args;
@@ -165,7 +165,6 @@ OrphanablePtr<Resolver> ResolverRegistry::CreateResolver(
       factory == nullptr ? nullptr
                          : factory->CreateResolver(std::move(resolver_args));
   grpc_uri_destroy(uri);
-  gpr_free(canonical_target);
   return resolver;
 }
 
@@ -173,13 +172,12 @@ grpc_core::UniquePtr<char> ResolverRegistry::GetDefaultAuthority(
     const char* target) {
   GPR_ASSERT(g_state != nullptr);
   grpc_uri* uri = nullptr;
-  char* canonical_target = nullptr;
+  std::string canonical_target;
   ResolverFactory* factory =
       g_state->FindResolverFactory(target, &uri, &canonical_target);
   grpc_core::UniquePtr<char> authority =
       factory == nullptr ? nullptr : factory->GetDefaultAuthority(uri);
   grpc_uri_destroy(uri);
-  gpr_free(canonical_target);
   return authority;
 }
 
@@ -187,11 +185,12 @@ grpc_core::UniquePtr<char> ResolverRegistry::AddDefaultPrefixIfNeeded(
     const char* target) {
   GPR_ASSERT(g_state != nullptr);
   grpc_uri* uri = nullptr;
-  char* canonical_target = nullptr;
+  std::string canonical_target;
   g_state->FindResolverFactory(target, &uri, &canonical_target);
   grpc_uri_destroy(uri);
-  return grpc_core::UniquePtr<char>(
-      canonical_target == nullptr ? gpr_strdup(target) : canonical_target);
+  return grpc_core::UniquePtr<char>(canonical_target.empty()
+                                        ? gpr_strdup(target)
+                                        : gpr_strdup(canonical_target.c_str()));
 }
 
 }  // namespace grpc_core

src/core/ext/filters/client_channel/resolver_result_parsing.cc

@@ -24,6 +24,7 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
 #include "absl/types/optional.h"
 
 #include <grpc/support/alloc.h>
@@ -353,13 +354,11 @@ ClientChannelServiceConfigParser::ParseGlobalParams(const Json& json,
         error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
             "field:loadBalancingPolicy error:Unknown lb policy"));
       } else if (requires_config) {
-        char* error_msg;
-        gpr_asprintf(&error_msg,
-                     "field:loadBalancingPolicy error:%s requires a config. "
-                     "Please use loadBalancingConfig instead.",
-                     lb_policy_name.c_str());
-        error_list.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg));
-        gpr_free(error_msg);
+        error_list.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+            absl::StrCat("field:loadBalancingPolicy error:", lb_policy_name,
+                         " requires a config. Please use loadBalancingConfig "
+                         "instead.")
+                .c_str()));
       }
     }
   }

src/core/ext/filters/client_channel/subchannel.cc

@@ -872,7 +872,7 @@ grpc_arg Subchannel::CreateSubchannelAddressArg(
     const grpc_resolved_address* addr) {
   return grpc_channel_arg_string_create(
       (char*)GRPC_ARG_SUBCHANNEL_ADDRESS,
-      addr->len > 0 ? grpc_sockaddr_to_uri(addr) : gpr_strdup(""));
+      gpr_strdup(addr->len > 0 ? grpc_sockaddr_to_uri(addr).c_str() : ""));
 }
 
 const char* Subchannel::GetUriFromSubchannelAddressArg(

src/core/ext/filters/client_channel/xds/xds_bootstrap.cc

@@ -23,12 +23,11 @@
 #include <errno.h>
 #include <stdlib.h>
 
+#include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
 #include "absl/strings/str_join.h"
 #include "absl/strings/string_view.h"
 
-#include <grpc/support/string_util.h>
-
 #include "src/core/lib/gpr/env.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/iomgr/load_file.h"
@@ -98,11 +97,9 @@ std::unique_ptr<XdsBootstrap> XdsBootstrap::ReadFromFile(XdsClient* client,
   Json json = Json::Parse(contents_str_view, error);
   grpc_slice_unref_internal(contents);
   if (*error != GRPC_ERROR_NONE) {
-    char* msg;
-    gpr_asprintf(&msg, "Failed to parse bootstrap file %s", path.get());
-    grpc_error* error_out =
-        GRPC_ERROR_CREATE_REFERENCING_FROM_COPIED_STRING(msg, error, 1);
-    gpr_free(msg);
+    grpc_error* error_out = GRPC_ERROR_CREATE_REFERENCING_FROM_COPIED_STRING(
+        absl::StrCat("Failed to parse bootstrap file ", path.get()).c_str(),
+        error, 1);
     GRPC_ERROR_UNREF(*error);
     *error = error_out;
     return nullptr;
@@ -154,10 +151,8 @@ grpc_error* XdsBootstrap::ParseXdsServerList(Json* json) {
   for (size_t i = 0; i < json->mutable_array()->size(); ++i) {
     Json& child = json->mutable_array()->at(i);
     if (child.type() != Json::Type::OBJECT) {
-      char* msg;
-      gpr_asprintf(&msg, "array element %" PRIuPTR " is not an object", i);
-      error_list.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg));
-      gpr_free(msg);
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrCat("array element ", i, " is not an object").c_str()));
     } else {
       grpc_error* parse_error = ParseXdsServer(&child, i);
       if (parse_error != GRPC_ERROR_NONE) error_list.push_back(parse_error);
@@ -194,10 +189,8 @@ grpc_error* XdsBootstrap::ParseXdsServer(Json* json, size_t idx) {
   // Can't use GRPC_ERROR_CREATE_FROM_VECTOR() here, because the error
   // string is not static in this case.
   if (error_list.empty()) return GRPC_ERROR_NONE;
-  char* msg;
-  gpr_asprintf(&msg, "errors parsing index %" PRIuPTR, idx);
-  grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-  gpr_free(msg);
+  grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+      absl::StrCat("errors parsing index ", idx).c_str());
   for (size_t i = 0; i < error_list.size(); ++i) {
     error = grpc_error_add_child(error, error_list[i]);
   }
@@ -210,10 +203,8 @@ grpc_error* XdsBootstrap::ParseChannelCredsArray(Json* json,
   for (size_t i = 0; i < json->mutable_array()->size(); ++i) {
     Json& child = json->mutable_array()->at(i);
     if (child.type() != Json::Type::OBJECT) {
-      char* msg;
-      gpr_asprintf(&msg, "array element %" PRIuPTR " is not an object", i);
-      error_list.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg));
-      gpr_free(msg);
+      error_list.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrCat("array element ", i, " is not an object").c_str()));
     } else {
       grpc_error* parse_error = ParseChannelCreds(&child, i, server);
       if (parse_error != GRPC_ERROR_NONE) error_list.push_back(parse_error);
@@ -252,10 +243,8 @@ grpc_error* XdsBootstrap::ParseChannelCreds(Json* json, size_t idx,
   // Can't use GRPC_ERROR_CREATE_FROM_VECTOR() here, because the error
   // string is not static in this case.
   if (error_list.empty()) return GRPC_ERROR_NONE;
-  char* msg;
-  gpr_asprintf(&msg, "errors parsing index %" PRIuPTR, idx);
-  grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-  gpr_free(msg);
+  grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+      absl::StrCat("errors parsing index ", idx).c_str());
   for (size_t i = 0; i < error_list.size(); ++i) {
     error = grpc_error_add_child(error, error_list[i]);
   }

src/core/ext/filters/client_channel/xds/xds_client.cc

@@ -30,7 +30,6 @@
 #include <grpc/byte_buffer_reader.h>
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 
 #include "src/core/ext/filters/client_channel/client_channel.h"
@@ -180,13 +179,11 @@ class XdsClient::ChannelState::AdsCallState
     void OnTimerLocked(grpc_error* error) {
       if (error == GRPC_ERROR_NONE && timer_pending_) {
         timer_pending_ = false;
-        char* msg;
-        gpr_asprintf(
-            &msg,
-            "timeout obtaining resource {type=%s name=%s} from xds server",
-            type_url_.c_str(), name_.c_str());
-        grpc_error* watcher_error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-        gpr_free(msg);
+        grpc_error* watcher_error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+            absl::StrFormat(
+                "timeout obtaining resource {type=%s name=%s} from xds server",
+                type_url_, name_)
+                .c_str());
         if (GRPC_TRACE_FLAG_ENABLED(grpc_xds_client_trace)) {
           gpr_log(GPR_INFO, "[xds_client %p] %s", ads_calld_->xds_client(),
                   grpc_error_string(watcher_error));
@@ -1092,8 +1089,8 @@ void XdsClient::ChannelState::AdsCallState::AcceptEdsUpdate(
                   "[xds_client %p] Priority %" PRIuPTR ", locality %" PRIuPTR
                   " %s has weight %d, contains %" PRIuPTR " server addresses",
                   xds_client(), priority, locality_count,
-                  locality.name->AsHumanReadableString(), locality.lb_weight,
-                  locality.serverlist.size());
+                  locality.name->AsHumanReadableString().c_str(),
+                  locality.lb_weight, locality.serverlist.size());
           for (size_t i = 0; i < locality.serverlist.size(); ++i) {
             std::string ipport = grpc_sockaddr_to_string(
                 &locality.serverlist[i].address(), false);
@@ -1101,7 +1098,8 @@ void XdsClient::ChannelState::AdsCallState::AcceptEdsUpdate(
                     "[xds_client %p] Priority %" PRIuPTR ", locality %" PRIuPTR
                     " %s, server address %" PRIuPTR ": %s",
                     xds_client(), priority, locality_count,
-                    locality.name->AsHumanReadableString(), i, ipport.c_str());
+                    locality.name->AsHumanReadableString().c_str(), i,
+                    ipport.c_str());
           }
           ++locality_count;
         }

src/core/ext/filters/client_channel/xds/xds_client_stats.h

@@ -24,10 +24,10 @@
 #include <map>
 #include <string>
 
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
 #include "absl/strings/string_view.h"
 
-#include <grpc/support/string_util.h>
-
 #include "src/core/lib/gprpp/atomic.h"
 #include "src/core/lib/gprpp/memory.h"
 #include "src/core/lib/gprpp/ref_counted.h"
@@ -80,21 +80,20 @@ class XdsLocalityName : public RefCounted<XdsLocalityName> {
   const std::string& zone() const { return zone_; }
   const std::string& sub_zone() const { return sub_zone_; }
 
-  const char* AsHumanReadableString() {
-    if (human_readable_string_ == nullptr) {
-      char* tmp;
-      gpr_asprintf(&tmp, "{region=\"%s\", zone=\"%s\", sub_zone=\"%s\"}",
-                   region_.c_str(), zone_.c_str(), sub_zone_.c_str());
-      human_readable_string_.reset(tmp);
+  const std::string& AsHumanReadableString() {
+    if (human_readable_string_.empty()) {
+      human_readable_string_ =
+          absl::StrFormat("{region=\"%s\", zone=\"%s\", sub_zone=\"%s\"}",
+                          region_, zone_, sub_zone_);
     }
-    return human_readable_string_.get();
+    return human_readable_string_;
   }
 
  private:
   std::string region_;
   std::string zone_;
   std::string sub_zone_;
-  UniquePtr<char> human_readable_string_;
+  std::string human_readable_string_;
 };
 
 // Drop stats for an xds cluster.

src/core/ext/filters/http/client/http_client_filter.cc

@@ -23,12 +23,12 @@
 #include <string>
 #include <vector>
 
+#include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
 #include "absl/strings/str_join.h"
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/filters/http/client/http_client_filter.h"
 #include "src/core/lib/gpr/string.h"
@@ -121,8 +121,8 @@ static grpc_error* client_filter_incoming_metadata(grpc_metadata_batch* b) {
     } else {
       char* val = grpc_dump_slice(GRPC_MDVALUE(b->idx.named.status->md),
                                   GPR_DUMP_ASCII);
-      char* msg;
-      gpr_asprintf(&msg, "Received http2 header with status: %s", val);
+      std::string msg =
+          absl::StrCat("Received http2 header with status: ", val);
       grpc_error* e = grpc_error_set_str(
           grpc_error_set_int(
               grpc_error_set_str(
@@ -131,9 +131,9 @@ static grpc_error* client_filter_incoming_metadata(grpc_metadata_batch* b) {
                   GRPC_ERROR_STR_VALUE, grpc_slice_from_copied_string(val)),
               GRPC_ERROR_INT_GRPC_STATUS,
               grpc_http2_status_to_grpc_status(atoi(val))),
-          GRPC_ERROR_STR_GRPC_MESSAGE, grpc_slice_from_copied_string(msg));
+          GRPC_ERROR_STR_GRPC_MESSAGE,
+          grpc_slice_from_cpp_string(std::move(msg)));
       gpr_free(val);
-      gpr_free(msg);
       return e;
     }
   }

src/core/ext/filters/http/message_compress/message_decompress_filter.cc

@@ -23,11 +23,12 @@
 #include <assert.h>
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/compression.h>
 #include <grpc/slice_buffer.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "absl/strings/str_format.h"
 #include "src/core/ext/filters/message_size/message_size_filter.h"
@@ -258,14 +259,12 @@ void CallData::FinishRecvMessage() {
   grpc_slice_buffer_init(&decompressed_slices);
   if (grpc_msg_decompress(algorithm_, &recv_slices_, &decompressed_slices) ==
       0) {
-    char* msg;
-    gpr_asprintf(
-        &msg,
-        "Unexpected error decompressing data for algorithm with enum value %d",
-        algorithm_);
     GPR_DEBUG_ASSERT(error_ == GRPC_ERROR_NONE);
-    error_ = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
+    error_ = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Unexpected error decompressing data for algorithm with "
+                     "enum value ",
+                     algorithm_)
+            .c_str());
     grpc_slice_buffer_destroy_internal(&decompressed_slices);
   } else {
     uint32_t recv_flags =

src/core/ext/filters/load_reporting/server_load_reporting_filter.cc

@@ -20,11 +20,14 @@
 
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <grpc/grpc_security.h>
 #include <grpc/slice.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.h"
 #include "src/core/ext/filters/client_channel/parse_address.h"
@@ -121,8 +124,7 @@ void ServerLoadReportingCallData::StartTransportStreamOpBatch(
   grpc_call_next_op(elem, op->op());
 }
 
-void ServerLoadReportingCallData::GetCensusSafeClientIpString(
-    char** client_ip_string, size_t* size) {
+std::string ServerLoadReportingCallData::GetCensusSafeClientIpString() {
   // Find the client URI string.
   const char* client_uri_str =
       reinterpret_cast<const char*>(gpr_atm_acq_load(peer_string_));
@@ -130,9 +132,7 @@ void ServerLoadReportingCallData::GetCensusSafeClientIpString(
     gpr_log(GPR_ERROR,
             "Unable to extract client URI string (peer string) from gRPC "
             "metadata.");
-    *client_ip_string = nullptr;
-    *size = 0;
-    return;
+    return "";
   }
   // Parse the client URI string into grpc_uri.
   grpc_uri* client_uri = grpc_uri_parse(client_uri_str, true);
@@ -140,9 +140,7 @@ void ServerLoadReportingCallData::GetCensusSafeClientIpString(
     gpr_log(GPR_ERROR,
             "Unable to parse the client URI string (peer string) to a client "
             "URI.");
-    *client_ip_string = nullptr;
-    *size = 0;
-    return;
+    return "";
   }
   // Parse the client URI into grpc_resolved_address.
   grpc_resolved_address resolved_address;
@@ -151,26 +149,23 @@ void ServerLoadReportingCallData::GetCensusSafeClientIpString(
   if (!success) {
     gpr_log(GPR_ERROR,
             "Unable to parse client URI into a grpc_resolved_address.");
-    *client_ip_string = nullptr;
-    *size = 0;
-    return;
+    return "";
   }
   // Convert the socket address in the grpc_resolved_address into a hex string
   // according to the address family.
   grpc_sockaddr* addr = reinterpret_cast<grpc_sockaddr*>(resolved_address.addr);
   if (addr->sa_family == GRPC_AF_INET) {
     grpc_sockaddr_in* addr4 = reinterpret_cast<grpc_sockaddr_in*>(addr);
-    gpr_asprintf(client_ip_string, "%08x", grpc_ntohl(addr4->sin_addr.s_addr));
-    *size = 8;
+    return absl::StrFormat("%08x", grpc_ntohl(addr4->sin_addr.s_addr));
   } else if (addr->sa_family == GRPC_AF_INET6) {
     grpc_sockaddr_in6* addr6 = reinterpret_cast<grpc_sockaddr_in6*>(addr);
-    *client_ip_string = static_cast<char*>(gpr_malloc(32 + 1));
+    std::string client_ip;
+    client_ip.reserve(32);
     uint32_t* addr6_next_long = reinterpret_cast<uint32_t*>(&addr6->sin6_addr);
     for (size_t i = 0; i < 4; ++i) {
-      snprintf(*client_ip_string + 8 * i, 8 + 1, "%08x",
-               grpc_ntohl(*addr6_next_long++));
+      absl::StrAppendFormat(&client_ip, "%08x", grpc_ntohl(*addr6_next_long++));
     }
-    *size = 32;
+    return client_ip;
   } else {
     GPR_UNREACHABLE_CODE();
   }
@@ -178,31 +173,28 @@ void ServerLoadReportingCallData::GetCensusSafeClientIpString(
 
 void ServerLoadReportingCallData::StoreClientIpAndLrToken(const char* lr_token,
                                                           size_t lr_token_len) {
-  char* client_ip;
-  size_t client_ip_len;
-  GetCensusSafeClientIpString(&client_ip, &client_ip_len);
+  std::string client_ip = GetCensusSafeClientIpString();
   client_ip_and_lr_token_len_ =
-      kLengthPrefixSize + client_ip_len + lr_token_len;
+      kLengthPrefixSize + client_ip.size() + lr_token_len;
   client_ip_and_lr_token_ = static_cast<char*>(
       gpr_zalloc(client_ip_and_lr_token_len_ * sizeof(char)));
   char* cur_pos = client_ip_and_lr_token_;
   // Store the IP length prefix.
-  if (client_ip_len == 0) {
+  if (client_ip.size() == 0) {
     strncpy(cur_pos, kEmptyAddressLengthString, kLengthPrefixSize);
-  } else if (client_ip_len == 8) {
+  } else if (client_ip.size() == 8) {
     strncpy(cur_pos, kEncodedIpv4AddressLengthString, kLengthPrefixSize);
-  } else if (client_ip_len == 32) {
+  } else if (client_ip.size() == 32) {
     strncpy(cur_pos, kEncodedIpv6AddressLengthString, kLengthPrefixSize);
   } else {
     GPR_UNREACHABLE_CODE();
   }
   cur_pos += kLengthPrefixSize;
   // Store the IP.
-  if (client_ip_len != 0) {
-    strncpy(cur_pos, client_ip, client_ip_len);
+  if (!client_ip.empty()) {
+    strncpy(cur_pos, client_ip.c_str(), client_ip.size());
   }
-  gpr_free(client_ip);
-  cur_pos += client_ip_len;
+  cur_pos += client_ip.size();
   // Store the LR token.
   if (lr_token_len != 0) {
     strncpy(cur_pos, lr_token, lr_token_len);

src/core/ext/filters/load_reporting/server_load_reporting_filter.h

@@ -21,6 +21,8 @@
 
 #include <grpc/support/port_platform.h>
 
+#include <string>
+
 #include "src/core/lib/channel/channel_stack.h"
 #include "src/cpp/common/channel_filter.h"
 
@@ -54,9 +56,8 @@ class ServerLoadReportingCallData : public CallData {
 
  private:
   // From the peer_string_ in calld, extracts the client IP string (owned by
-  // caller), e.g., "01020a0b". Upon failure, set the output pointer to null and
-  // size to zero.
-  void GetCensusSafeClientIpString(char** client_ip_string, size_t* size);
+  // caller), e.g., "01020a0b". Upon failure, returns empty string.
+  std::string GetCensusSafeClientIpString();
 
   // Concatenates the client IP address and the load reporting token, then
   // stores the result into the call data.

src/core/ext/filters/message_size/message_size_filter.cc

@@ -21,10 +21,11 @@
 #include <limits.h>
 #include <string.h>
 
+#include "absl/strings/str_format.h"
+
 #include <grpc/impl/codegen/grpc_types.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/filters/client_channel/service_config.h"
 #include "src/core/ext/filters/client_channel/service_config_call_data.h"
@@ -198,17 +199,16 @@ static void recv_message_ready(void* user_data, grpc_error* error) {
   if (*calld->recv_message != nullptr && calld->limits.max_recv_size >= 0 &&
       (*calld->recv_message)->length() >
           static_cast<size_t>(calld->limits.max_recv_size)) {
-    char* message_string;
-    gpr_asprintf(&message_string,
-                 "Received message larger than max (%u vs. %d)",
-                 (*calld->recv_message)->length(), calld->limits.max_recv_size);
     grpc_error* new_error = grpc_error_set_int(
-        GRPC_ERROR_CREATE_FROM_COPIED_STRING(message_string),
+        GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+            absl::StrFormat("Received message larger than max (%u vs. %d)",
+                            (*calld->recv_message)->length(),
+                            calld->limits.max_recv_size)
+                .c_str()),
         GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_RESOURCE_EXHAUSTED);
     error = grpc_error_add_child(GRPC_ERROR_REF(error), new_error);
     GRPC_ERROR_UNREF(calld->error);
     calld->error = GRPC_ERROR_REF(error);
-    gpr_free(message_string);
   } else {
     GRPC_ERROR_REF(error);
   }
@@ -258,17 +258,17 @@ static void message_size_start_transport_stream_op_batch(
   if (op->send_message && calld->limits.max_send_size >= 0 &&
       op->payload->send_message.send_message->length() >
           static_cast<size_t>(calld->limits.max_send_size)) {
-    char* message_string;
-    gpr_asprintf(&message_string, "Sent message larger than max (%u vs. %d)",
-                 op->payload->send_message.send_message->length(),
-                 calld->limits.max_send_size);
     grpc_transport_stream_op_batch_finish_with_failure(
         op,
-        grpc_error_set_int(GRPC_ERROR_CREATE_FROM_COPIED_STRING(message_string),
-                           GRPC_ERROR_INT_GRPC_STATUS,
-                           GRPC_STATUS_RESOURCE_EXHAUSTED),
+        grpc_error_set_int(
+            GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+                absl::StrFormat(
+                    "Sent message larger than max (%u vs. %d)",
+                    op->payload->send_message.send_message->length(),
+                    calld->limits.max_send_size)
+                    .c_str()),
+            GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_RESOURCE_EXHAUSTED),
         calld->call_combiner);
-    gpr_free(message_string);
     return;
   }
   // Inject callback for receiving a message.

src/core/ext/transport/chttp2/server/chttp2_server.cc

@@ -24,15 +24,15 @@
 #include <limits.h>
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+
 #include <grpc/grpc.h>
 #include <grpc/impl/codegen/grpc_types.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 
-#include "absl/strings/str_format.h"
-
 #include "src/core/ext/filters/http/server/http_server_filter.h"
 #include "src/core/ext/transport/chttp2/transport/chttp2_transport.h"
 #include "src/core/ext/transport/chttp2/transport/internal.h"

src/core/ext/transport/chttp2/server/insecure/server_chttp2_posix.cc

@@ -24,8 +24,9 @@
 
 #ifdef GPR_SUPPORT_CHANNELS_FROM_FD
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/transport/chttp2/transport/chttp2_transport.h"
 #include "src/core/lib/channel/channel_args.h"
@@ -40,14 +41,11 @@ void grpc_server_add_insecure_channel_from_fd(grpc_server* server,
   GPR_ASSERT(reserved == nullptr);
 
   grpc_core::ExecCtx exec_ctx;
-  char* name;
-  gpr_asprintf(&name, "fd:%d", fd);
 
+  std::string name = absl::StrCat("fd:", fd);
   grpc_endpoint* server_endpoint =
-      grpc_tcp_create(grpc_fd_create(fd, name, true),
-                      grpc_server_get_channel_args(server), name);
-
-  gpr_free(name);
+      grpc_tcp_create(grpc_fd_create(fd, name.c_str(), true),
+                      grpc_server_get_channel_args(server), name.c_str());
 
   const grpc_channel_args* server_args = grpc_server_get_channel_args(server);
   grpc_transport* transport = grpc_create_chttp2_transport(

src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.cc

@@ -22,9 +22,10 @@
 
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/transport/chttp2/server/chttp2_server.h"
 
@@ -56,12 +57,10 @@ int grpc_server_add_secure_http2_port(grpc_server* server, const char* addr,
   }
   sc = creds->create_security_connector();
   if (sc == nullptr) {
-    char* msg;
-    gpr_asprintf(&msg,
-                 "Unable to create secure server with credentials of type %s.",
-                 creds->type());
-    err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
+    err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Unable to create secure server with credentials of type ",
+                     creds->type())
+            .c_str());
     goto done;
   }
   // Create channel args.

src/core/ext/transport/chttp2/transport/flow_control.cc

@@ -25,9 +25,12 @@
 #include <math.h>
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/transport/chttp2/transport/internal.h"
 #include "src/core/lib/gpr/string.h"
@@ -43,27 +46,23 @@ static constexpr const int kTracePadding = 30;
 static constexpr const uint32_t kMaxWindowUpdateSize = (1u << 31) - 1;
 
 static char* fmt_int64_diff_str(int64_t old_val, int64_t new_val) {
-  char* str;
+  std::string str;
   if (old_val != new_val) {
-    gpr_asprintf(&str, "%" PRId64 " -> %" PRId64 "", old_val, new_val);
+    str = absl::StrFormat("%" PRId64 " -> %" PRId64 "", old_val, new_val);
   } else {
-    gpr_asprintf(&str, "%" PRId64 "", old_val);
+    str = absl::StrFormat("%" PRId64 "", old_val);
   }
-  char* str_lp = gpr_leftpad(str, ' ', kTracePadding);
-  gpr_free(str);
-  return str_lp;
+  return gpr_leftpad(str.c_str(), ' ', kTracePadding);
 }
 
 static char* fmt_uint32_diff_str(uint32_t old_val, uint32_t new_val) {
-  char* str;
+  std::string str;
   if (old_val != new_val) {
-    gpr_asprintf(&str, "%" PRIu32 " -> %" PRIu32 "", old_val, new_val);
+    str = absl::StrFormat("%" PRIu32 " -> %" PRIu32 "", old_val, new_val);
   } else {
-    gpr_asprintf(&str, "%" PRIu32 "", old_val);
+    str = absl::StrFormat("%" PRIu32 "", old_val);
   }
-  char* str_lp = gpr_leftpad(str, ' ', kTracePadding);
-  gpr_free(str);
-  return str_lp;
+  return gpr_leftpad(str.c_str(), ' ', kTracePadding);
 }
 }  // namespace
 
@@ -204,13 +203,11 @@ uint32_t TransportFlowControl::MaybeSendUpdate(bool writing_anyway) {
 grpc_error* TransportFlowControl::ValidateRecvData(
     int64_t incoming_frame_size) {
   if (incoming_frame_size > announced_window_) {
-    char* msg;
-    gpr_asprintf(&msg,
-                 "frame of size %" PRId64 " overflows local window of %" PRId64,
-                 incoming_frame_size, announced_window_);
-    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return err;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrFormat("frame of size %" PRId64
+                        " overflows local window of %" PRId64,
+                        incoming_frame_size, announced_window_)
+            .c_str());
   }
   return GRPC_ERROR_NONE;
 }
@@ -248,13 +245,11 @@ grpc_error* StreamFlowControl::RecvData(int64_t incoming_frame_size) {
               "See (for example) https://github.com/netty/netty/issues/6520.",
               incoming_frame_size, acked_stream_window, sent_stream_window);
     } else {
-      char* msg;
-      gpr_asprintf(
-          &msg, "frame of size %" PRId64 " overflows local window of %" PRId64,
-          incoming_frame_size, acked_stream_window);
-      grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-      gpr_free(msg);
-      return err;
+      return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrFormat("frame of size %" PRId64
+                          " overflows local window of %" PRId64,
+                          incoming_frame_size, acked_stream_window)
+              .c_str());
     }
   }
 

src/core/ext/transport/chttp2/transport/frame_data.cc

@@ -22,9 +22,10 @@
 
 #include <string.h>
 
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include "src/core/ext/transport/chttp2/transport/internal.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gprpp/memory.h"
@@ -44,13 +45,10 @@ grpc_error* grpc_chttp2_data_parser_begin_frame(
     grpc_chttp2_data_parser* /*parser*/, uint8_t flags, uint32_t stream_id,
     grpc_chttp2_stream* s) {
   if (flags & ~GRPC_CHTTP2_DATA_FLAG_END_STREAM) {
-    char* msg;
-    gpr_asprintf(&msg, "unsupported data flags: 0x%02x", flags);
-    grpc_error* err = grpc_error_set_int(
-        GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg), GRPC_ERROR_INT_STREAM_ID,
-        static_cast<intptr_t>(stream_id));
-    gpr_free(msg);
-    return err;
+    return grpc_error_set_int(
+        GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+            absl::StrFormat("unsupported data flags: 0x%02x", flags).c_str()),
+        GRPC_ERROR_INT_STREAM_ID, static_cast<intptr_t>(stream_id));
   }
 
   if (flags & GRPC_CHTTP2_DATA_FLAG_END_STREAM) {
@@ -130,12 +128,11 @@ grpc_error* grpc_deframe_unprocessed_incoming_frames(
             p->is_frame_compressed = true; /* GPR_TRUE */
             break;
           default:
-            char* msg;
-            gpr_asprintf(&msg, "Bad GRPC frame type 0x%02x", p->frame_type);
-            p->error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
+            p->error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+                absl::StrFormat("Bad GRPC frame type 0x%02x", p->frame_type)
+                    .c_str());
             p->error = grpc_error_set_int(p->error, GRPC_ERROR_INT_STREAM_ID,
                                           static_cast<intptr_t>(s->id));
-            gpr_free(msg);
             p->error = grpc_error_set_str(
                 p->error, GRPC_ERROR_STR_RAW_BYTES,
                 grpc_slice_from_moved_string(grpc_core::UniquePtr<char>(

src/core/ext/transport/chttp2/transport/frame_goaway.cc

@@ -23,9 +23,10 @@
 
 #include <string.h>
 
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 void grpc_chttp2_goaway_parser_init(grpc_chttp2_goaway_parser* p) {
   p->debug_data = nullptr;
@@ -39,11 +40,8 @@ grpc_error* grpc_chttp2_goaway_parser_begin_frame(grpc_chttp2_goaway_parser* p,
                                                   uint32_t length,
                                                   uint8_t /*flags*/) {
   if (length < 8) {
-    char* msg;
-    gpr_asprintf(&msg, "goaway frame too short (%d bytes)", length);
-    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return err;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrFormat("goaway frame too short (%d bytes)", length).c_str());
   }
 
   gpr_free(p->debug_data);

src/core/ext/transport/chttp2/transport/frame_ping.cc

@@ -23,9 +23,10 @@
 
 #include <string.h>
 
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 static bool g_disable_ping_ack = false;
 
@@ -58,11 +59,9 @@ grpc_error* grpc_chttp2_ping_parser_begin_frame(grpc_chttp2_ping_parser* parser,
                                                 uint32_t length,
                                                 uint8_t flags) {
   if (flags & 0xfe || length != 8) {
-    char* msg;
-    gpr_asprintf(&msg, "invalid ping: length=%d, flags=%02x", length, flags);
-    grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return error;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrFormat("invalid ping: length=%d, flags=%02x", length, flags)
+            .c_str());
   }
   parser->byte = 0;
   parser->is_ack = flags;

src/core/ext/transport/chttp2/transport/frame_rst_stream.cc

@@ -21,9 +21,11 @@
 #include "src/core/ext/transport/chttp2/transport/frame_rst_stream.h"
 #include "src/core/ext/transport/chttp2/transport/internal.h"
 
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/transport/chttp2/transport/frame.h"
 #include "src/core/lib/gprpp/memory.h"
@@ -69,12 +71,10 @@ void grpc_chttp2_add_rst_stream_to_next_write(
 grpc_error* grpc_chttp2_rst_stream_parser_begin_frame(
     grpc_chttp2_rst_stream_parser* parser, uint32_t length, uint8_t flags) {
   if (length != 4) {
-    char* msg;
-    gpr_asprintf(&msg, "invalid rst_stream: length=%d, flags=%02x", length,
-                 flags);
-    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return err;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrFormat("invalid rst_stream: length=%d, flags=%02x", length,
+                        flags)
+            .c_str());
   }
   parser->byte = 0;
   return GRPC_ERROR_NONE;
@@ -106,13 +106,12 @@ grpc_error* grpc_chttp2_rst_stream_parser_parse(void* parser,
                       ((static_cast<uint32_t>(p->reason_bytes[3])));
     grpc_error* error = GRPC_ERROR_NONE;
     if (reason != GRPC_HTTP2_NO_ERROR || s->metadata_buffer[1].size == 0) {
-      char* message;
-      gpr_asprintf(&message, "Received RST_STREAM with error code %d", reason);
       error = grpc_error_set_int(
-          grpc_error_set_str(GRPC_ERROR_CREATE_FROM_STATIC_STRING("RST_STREAM"),
-                             GRPC_ERROR_STR_GRPC_MESSAGE,
-                             grpc_slice_from_moved_string(
-                                 grpc_core::UniquePtr<char>(message))),
+          grpc_error_set_str(
+              GRPC_ERROR_CREATE_FROM_STATIC_STRING("RST_STREAM"),
+              GRPC_ERROR_STR_GRPC_MESSAGE,
+              grpc_slice_from_cpp_string(absl::StrCat(
+                  "Received RST_STREAM with error code ", reason))),
           GRPC_ERROR_INT_HTTP2_ERROR, static_cast<intptr_t>(reason));
     }
     grpc_chttp2_mark_stream_closed(t, s, true, true, error);

src/core/ext/transport/chttp2/transport/frame_settings.cc

@@ -23,9 +23,10 @@
 
 #include <string.h>
 
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/transport/chttp2/transport/chttp2_transport.h"
 #include "src/core/ext/transport/chttp2/transport/frame.h"
@@ -117,7 +118,6 @@ grpc_error* grpc_chttp2_settings_parser_parse(void* p, grpc_chttp2_transport* t,
       static_cast<grpc_chttp2_settings_parser*>(p);
   const uint8_t* cur = GRPC_SLICE_START_PTR(slice);
   const uint8_t* end = GRPC_SLICE_END_PTR(slice);
-  char* msg;
   grpc_chttp2_setting_id id;
 
   if (parser->is_ack) {
@@ -208,11 +208,10 @@ grpc_error* grpc_chttp2_settings_parser_parse(void* p, grpc_chttp2_transport* t,
                     t->last_new_stream_id, sp->error_value,
                     grpc_slice_from_static_string("HTTP2 settings error"),
                     &t->qbuf);
-                gpr_asprintf(&msg, "invalid value %u passed for %s",
-                             parser->value, sp->name);
-                grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-                gpr_free(msg);
-                return err;
+                return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+                    absl::StrFormat("invalid value %u passed for %s",
+                                    parser->value, sp->name)
+                        .c_str());
             }
           }
           if (id == GRPC_CHTTP2_SETTINGS_INITIAL_WINDOW_SIZE &&

src/core/ext/transport/chttp2/transport/frame_window_update.cc

@@ -21,9 +21,11 @@
 #include "src/core/ext/transport/chttp2/transport/frame_window_update.h"
 #include "src/core/ext/transport/chttp2/transport/internal.h"
 
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 grpc_slice grpc_chttp2_window_update_create(
     uint32_t id, uint32_t window_update, grpc_transport_one_way_stats* stats) {
@@ -54,12 +56,10 @@ grpc_slice grpc_chttp2_window_update_create(
 grpc_error* grpc_chttp2_window_update_parser_begin_frame(
     grpc_chttp2_window_update_parser* parser, uint32_t length, uint8_t flags) {
   if (flags || length != 4) {
-    char* msg;
-    gpr_asprintf(&msg, "invalid window update: length=%d, flags=%02x", length,
-                 flags);
-    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return err;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrFormat("invalid window update: length=%d, flags=%02x", length,
+                        flags)
+            .c_str());
   }
   parser->byte = 0;
   parser->amount = 0;
@@ -91,11 +91,8 @@ grpc_error* grpc_chttp2_window_update_parser_parse(void* parser,
     // top bit is reserved and must be ignored.
     uint32_t received_update = p->amount & 0x7fffffffu;
     if (received_update == 0) {
-      char* msg;
-      gpr_asprintf(&msg, "invalid window update bytes: %d", p->amount);
-      grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-      gpr_free(msg);
-      return err;
+      return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrCat("invalid window update bytes: ", p->amount).c_str());
     }
     GPR_ASSERT(is_last);
 

src/core/ext/transport/chttp2/transport/hpack_parser.cc

@@ -25,9 +25,11 @@
 #include <stddef.h>
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/transport/chttp2/transport/bin_encoder.h"
 #include "src/core/lib/debug/stats.h"
@@ -1087,10 +1089,8 @@ static grpc_error* still_parse_error(grpc_chttp2_hpack_parser* p,
 static grpc_error* parse_illegal_op(grpc_chttp2_hpack_parser* p,
                                     const uint8_t* cur, const uint8_t* end) {
   GPR_ASSERT(cur != end);
-  char* msg;
-  gpr_asprintf(&msg, "Illegal hpack op code %d", *cur);
-  grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-  gpr_free(msg);
+  grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+      absl::StrCat("Illegal hpack op code ", *cur).c_str());
   return parse_error(p, cur, end, err);
 }
 
@@ -1173,7 +1173,6 @@ static grpc_error* parse_value4(grpc_chttp2_hpack_parser* p, const uint8_t* cur,
   uint8_t c;
   uint32_t cur_value;
   uint32_t add_value;
-  char* msg;
 
   if (cur == end) {
     p->state = parse_value4;
@@ -1200,12 +1199,12 @@ static grpc_error* parse_value4(grpc_chttp2_hpack_parser* p, const uint8_t* cur,
   }
 
 error:
-  gpr_asprintf(&msg,
-               "integer overflow in hpack integer decoding: have 0x%08x, "
-               "got byte 0x%02x on byte 5",
-               *p->parsing.value, *cur);
-  grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-  gpr_free(msg);
+  grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+      absl::StrFormat(
+          "integer overflow in hpack integer decoding: have 0x%08x, "
+          "got byte 0x%02x on byte 5",
+          *p->parsing.value, *cur)
+          .c_str());
   return parse_error(p, cur, end, err);
 }
 
@@ -1227,13 +1226,12 @@ static grpc_error* parse_value5up(grpc_chttp2_hpack_parser* p,
     return parse_next(p, cur + 1, end);
   }
 
-  char* msg;
-  gpr_asprintf(&msg,
-               "integer overflow in hpack integer decoding: have 0x%08x, "
-               "got byte 0x%02x sometime after byte 5",
-               *p->parsing.value, *cur);
-  grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-  gpr_free(msg);
+  grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+      absl::StrFormat(
+          "integer overflow in hpack integer decoding: have 0x%08x, "
+          "got byte 0x%02x sometime after byte 5",
+          *p->parsing.value, *cur)
+          .c_str());
   return parse_error(p, cur, end, err);
 }
 
@@ -1389,11 +1387,10 @@ static grpc_error* finish_str(grpc_chttp2_hpack_parser* p, const uint8_t* cur,
     case B64_BYTE2:
       bits = p->base64_buffer;
       if (bits & 0xffff) {
-        char* msg;
-        gpr_asprintf(&msg, "trailing bits in base64 encoding: 0x%04x",
-                     bits & 0xffff);
-        grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-        gpr_free(msg);
+        grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+            absl::StrFormat("trailing bits in base64 encoding: 0x%04x",
+                            bits & 0xffff)
+                .c_str());
         return parse_error(p, cur, end, err);
       }
       decoded[0] = static_cast<uint8_t>(bits >> 16);
@@ -1402,11 +1399,10 @@ static grpc_error* finish_str(grpc_chttp2_hpack_parser* p, const uint8_t* cur,
     case B64_BYTE3:
       bits = p->base64_buffer;
       if (bits & 0xff) {
-        char* msg;
-        gpr_asprintf(&msg, "trailing bits in base64 encoding: 0x%02x",
-                     bits & 0xff);
-        grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-        gpr_free(msg);
+        grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+            absl::StrFormat("trailing bits in base64 encoding: 0x%02x",
+                            bits & 0xff)
+                .c_str());
         return parse_error(p, cur, end, err);
       }
       decoded[0] = static_cast<uint8_t>(bits >> 16);

src/core/ext/transport/chttp2/transport/hpack_table.cc

@@ -23,9 +23,10 @@
 #include <assert.h>
 #include <string.h>
 
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/debug/trace.h"
 #include "src/core/lib/gpr/murmur_hash.h"
@@ -119,13 +120,11 @@ grpc_error* grpc_chttp2_hptbl_set_current_table_size(grpc_chttp2_hptbl* tbl,
     return GRPC_ERROR_NONE;
   }
   if (bytes > tbl->max_bytes) {
-    char* msg;
-    gpr_asprintf(&msg,
-                 "Attempt to make hpack table %d bytes when max is %d bytes",
-                 bytes, tbl->max_bytes);
-    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return err;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrFormat(
+            "Attempt to make hpack table %d bytes when max is %d bytes", bytes,
+            tbl->max_bytes)
+            .c_str());
   }
   if (GRPC_TRACE_FLAG_ENABLED(grpc_http_trace)) {
     gpr_log(GPR_INFO, "Update hpack parser table size to %d", bytes);
@@ -153,15 +152,12 @@ grpc_error* grpc_chttp2_hptbl_add(grpc_chttp2_hptbl* tbl, grpc_mdelem md) {
                       GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD;
 
   if (tbl->current_table_bytes > tbl->max_bytes) {
-    char* msg;
-    gpr_asprintf(
-        &msg,
-        "HPACK max table size reduced to %d but not reflected by hpack "
-        "stream (still at %d)",
-        tbl->max_bytes, tbl->current_table_bytes);
-    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return err;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrFormat(
+            "HPACK max table size reduced to %d but not reflected by hpack "
+            "stream (still at %d)",
+            tbl->max_bytes, tbl->current_table_bytes)
+            .c_str());
   }
 
   /* we can't add elements bigger than the max table size */

src/core/ext/transport/chttp2/transport/parsing.cc

@@ -22,9 +22,11 @@
 
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/profiling/timers.h"
 #include "src/core/lib/slice/slice_string_helpers.h"
@@ -85,18 +87,15 @@ grpc_error* grpc_chttp2_perform_read(grpc_chttp2_transport* t,
     case GRPC_DTS_CLIENT_PREFIX_23:
       while (cur != end && t->deframe_state != GRPC_DTS_FH_0) {
         if (*cur != GRPC_CHTTP2_CLIENT_CONNECT_STRING[t->deframe_state]) {
-          char* msg;
-          gpr_asprintf(
-              &msg,
-              "Connect string mismatch: expected '%c' (%d) got '%c' (%d) "
-              "at byte %d",
-              GRPC_CHTTP2_CLIENT_CONNECT_STRING[t->deframe_state],
-              static_cast<int>(static_cast<uint8_t>(
-                  GRPC_CHTTP2_CLIENT_CONNECT_STRING[t->deframe_state])),
-              *cur, static_cast<int>(*cur), t->deframe_state);
-          err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-          gpr_free(msg);
-          return err;
+          return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+              absl::StrFormat(
+                  "Connect string mismatch: expected '%c' (%d) got '%c' (%d) "
+                  "at byte %d",
+                  GRPC_CHTTP2_CLIENT_CONNECT_STRING[t->deframe_state],
+                  static_cast<int>(static_cast<uint8_t>(
+                      GRPC_CHTTP2_CLIENT_CONNECT_STRING[t->deframe_state])),
+                  *cur, static_cast<int>(*cur), t->deframe_state)
+                  .c_str());
         }
         ++cur;
         t->deframe_state = static_cast<grpc_chttp2_deframe_transport_state>(
@@ -194,14 +193,12 @@ grpc_error* grpc_chttp2_perform_read(grpc_chttp2_transport* t,
                  t->incoming_frame_size >
                      t->settings[GRPC_ACKED_SETTINGS]
                                 [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE]) {
-        char* msg;
-        gpr_asprintf(&msg, "Frame size %d is larger than max frame size %d",
-                     t->incoming_frame_size,
-                     t->settings[GRPC_ACKED_SETTINGS]
-                                [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE]);
-        err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-        gpr_free(msg);
-        return err;
+        return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+            absl::StrFormat("Frame size %d is larger than max frame size %d",
+                            t->incoming_frame_size,
+                            t->settings[GRPC_ACKED_SETTINGS]
+                                       [GRPC_CHTTP2_SETTINGS_MAX_FRAME_SIZE])
+                .c_str());
       }
       if (++cur == end) {
         return GRPC_ERROR_NONE;
@@ -255,34 +252,27 @@ grpc_error* grpc_chttp2_perform_read(grpc_chttp2_transport* t,
 static grpc_error* init_frame_parser(grpc_chttp2_transport* t) {
   if (t->is_first_frame &&
       t->incoming_frame_type != GRPC_CHTTP2_FRAME_SETTINGS) {
-    char* msg;
-    gpr_asprintf(
-        &msg, "Expected SETTINGS frame as the first frame, got frame type %d",
-        t->incoming_frame_type);
-    grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return err;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat(
+            "Expected SETTINGS frame as the first frame, got frame type ",
+            t->incoming_frame_type)
+            .c_str());
   }
   t->is_first_frame = false;
   if (t->expect_continuation_stream_id != 0) {
     if (t->incoming_frame_type != GRPC_CHTTP2_FRAME_CONTINUATION) {
-      char* msg;
-      gpr_asprintf(&msg, "Expected CONTINUATION frame, got frame type %02x",
-                   t->incoming_frame_type);
-      grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-      gpr_free(msg);
-      return err;
+      return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrFormat("Expected CONTINUATION frame, got frame type %02x",
+                          t->incoming_frame_type)
+              .c_str());
     }
     if (t->expect_continuation_stream_id != t->incoming_stream_id) {
-      char* msg;
-      gpr_asprintf(
-          &msg,
-          "Expected CONTINUATION frame for grpc_chttp2_stream %08x, got "
-          "grpc_chttp2_stream %08x",
-          t->expect_continuation_stream_id, t->incoming_stream_id);
-      grpc_error* err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-      gpr_free(msg);
-      return err;
+      return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrFormat(
+              "Expected CONTINUATION frame for grpc_chttp2_stream %08x, got "
+              "grpc_chttp2_stream %08x",
+              t->expect_continuation_stream_id, t->incoming_stream_id)
+              .c_str());
     }
     return init_header_frame_parser(t, 1);
   }

src/core/ext/transport/cronet/transport/cronet_transport.cc

@@ -20,10 +20,13 @@
 
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+
 #include <grpc/slice_buffer.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/transport/chttp2/transport/bin_decoder.h"
 #include "src/core/ext/transport/chttp2/transport/bin_encoder.h"
@@ -728,7 +731,7 @@ static void create_grpc_frame(grpc_slice_buffer* write_slice_buffer,
  Convert metadata in a format that Cronet can consume
 */
 static void convert_metadata_to_cronet_headers(
-    grpc_metadata_batch* metadata, const char* host, char** pp_url,
+    grpc_metadata_batch* metadata, const char* host, std::string* pp_url,
     bidirectional_stream_header** pp_headers, size_t* p_num_headers,
     const char** method) {
   grpc_linked_mdelem* curr = metadata->list.head;
@@ -789,7 +792,7 @@ static void convert_metadata_to_cronet_headers(
     }
     if (grpc_slice_eq_static_interned(GRPC_MDKEY(mdelem), GRPC_MDSTR_PATH)) {
       /* Create URL by appending :path value to the hostname */
-      gpr_asprintf(pp_url, "https://%s%s", host, value);
+      *pp_url = absl::StrCat("https://", host, value);
       gpr_free(key);
       gpr_free(value);
       continue;
@@ -1051,7 +1054,7 @@ static enum e_op_result execute_stream_op(struct op_and_state* oas) {
       bidirectional_stream_disable_auto_flush(s->cbs, true);
       bidirectional_stream_delay_request_headers_until_flush(s->cbs, true);
     }
-    char* url = nullptr;
+    std::string url;
     const char* method = "POST";
     s->header_array.headers = nullptr;
     convert_metadata_to_cronet_headers(
@@ -1059,11 +1062,10 @@ static enum e_op_result execute_stream_op(struct op_and_state* oas) {
         t->host, &url, &s->header_array.headers, &s->header_array.count,
         &method);
     s->header_array.capacity = s->header_array.count;
-    CRONET_LOG(GPR_DEBUG, "bidirectional_stream_start(%p, %s)", s->cbs, url);
-    bidirectional_stream_start(s->cbs, url, 0, method, &s->header_array, false);
-    if (url) {
-      gpr_free(url);
-    }
+    CRONET_LOG(GPR_DEBUG, "bidirectional_stream_start(%p, %s)", s->cbs,
+               url.c_str());
+    bidirectional_stream_start(s->cbs, url.c_str(), 0, method, &s->header_array,
+                               false);
     unsigned int header_index;
     for (header_index = 0; header_index < s->header_array.count;
          header_index++) {

src/core/lib/channel/channel_trace.cc

@@ -146,14 +146,12 @@ const char* severity_string(ChannelTrace::Severity severity) {
 
 Json ChannelTrace::TraceEvent::RenderTraceEvent() const {
   char* description = grpc_slice_to_c_string(data_);
-  char* ts_str = gpr_format_timespec(timestamp_);
   Json::Object object = {
       {"description", description},
       {"severity", severity_string(severity_)},
-      {"timestamp", ts_str},
+      {"timestamp", gpr_format_timespec(timestamp_)},
   };
   gpr_free(description);
-  gpr_free(ts_str);
   if (referenced_entity_ != nullptr) {
     const bool is_channel =
         (referenced_entity_->type() == BaseNode::EntityType::kTopLevelChannel ||
@@ -171,11 +169,9 @@ Json ChannelTrace::RenderJson() const {
   if (max_event_memory_ == 0) {
     return Json();  // JSON null
   }
-  char* ts_str = gpr_format_timespec(time_created_);
   Json::Object object = {
-      {"creationTimestamp", ts_str},
+      {"creationTimestamp", gpr_format_timespec(time_created_)},
   };
-  gpr_free(ts_str);
   if (num_events_logged_ > 0) {
     object["numEventsLogged"] = std::to_string(num_events_logged_);
   }

src/core/lib/channel/channelz.cc

@@ -156,9 +156,7 @@ void CallCountingHelper::PopulateCallCounts(Json::Object* object) {
     gpr_timespec ts = gpr_convert_clock_type(
         gpr_cycle_counter_to_time(data.last_call_started_cycle),
         GPR_CLOCK_REALTIME);
-    char* ts_str = gpr_format_timespec(ts);
-    (*object)["lastCallStartedTimestamp"] = ts_str;
-    gpr_free(ts_str);
+    (*object)["lastCallStartedTimestamp"] = gpr_format_timespec(ts);
   }
   if (data.calls_succeeded != 0) {
     (*object)["callsSucceeded"] = std::to_string(data.calls_succeeded);
@@ -456,9 +454,7 @@ Json SocketNode::RenderJson() {
       ts = gpr_convert_clock_type(
           gpr_cycle_counter_to_time(last_local_stream_created_cycle),
           GPR_CLOCK_REALTIME);
-      char* ts_str = gpr_format_timespec(ts);
-      data["lastLocalStreamCreatedTimestamp"] = ts_str;
-      gpr_free(ts_str);
+      data["lastLocalStreamCreatedTimestamp"] = gpr_format_timespec(ts);
     }
     gpr_cycle_counter last_remote_stream_created_cycle =
         last_remote_stream_created_cycle_.Load(MemoryOrder::RELAXED);
@@ -466,9 +462,7 @@ Json SocketNode::RenderJson() {
       ts = gpr_convert_clock_type(
           gpr_cycle_counter_to_time(last_remote_stream_created_cycle),
           GPR_CLOCK_REALTIME);
-      char* ts_str = gpr_format_timespec(ts);
-      data["lastRemoteStreamCreatedTimestamp"] = ts_str;
-      gpr_free(ts_str);
+      data["lastRemoteStreamCreatedTimestamp"] = gpr_format_timespec(ts);
     }
   }
   int64_t streams_succeeded = streams_succeeded_.Load(MemoryOrder::RELAXED);
@@ -486,9 +480,7 @@ Json SocketNode::RenderJson() {
         gpr_cycle_counter_to_time(
             last_message_sent_cycle_.Load(MemoryOrder::RELAXED)),
         GPR_CLOCK_REALTIME);
-    char* ts_str = gpr_format_timespec(ts);
-    data["lastMessageSentTimestamp"] = ts_str;
-    gpr_free(ts_str);
+    data["lastMessageSentTimestamp"] = gpr_format_timespec(ts);
   }
   int64_t messages_received = messages_received_.Load(MemoryOrder::RELAXED);
   if (messages_received != 0) {
@@ -497,9 +489,7 @@ Json SocketNode::RenderJson() {
         gpr_cycle_counter_to_time(
             last_message_received_cycle_.Load(MemoryOrder::RELAXED)),
         GPR_CLOCK_REALTIME);
-    char* ts_str = gpr_format_timespec(ts);
-    data["lastMessageReceivedTimestamp"] = ts_str;
-    gpr_free(ts_str);
+    data["lastMessageReceivedTimestamp"] = gpr_format_timespec(ts);
   }
   int64_t keepalives_sent = keepalives_sent_.Load(MemoryOrder::RELAXED);
   if (keepalives_sent != 0) {

src/core/lib/gpr/log_linux.cc

@@ -30,7 +30,6 @@
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 #include <inttypes.h>
 #include <stdarg.h>
@@ -39,6 +38,8 @@
 #include <sys/syscall.h>
 #include <time.h>
 #include <unistd.h>
+#include <string>
+#include "absl/strings/str_format.h"
 
 static long sys_gettid(void) { return syscall(__NR_gettid); }
 
@@ -63,7 +64,6 @@ void gpr_log(const char* file, int line, gpr_log_severity severity,
 
 void gpr_default_log(gpr_log_func_args* args) {
   const char* final_slash;
-  char* prefix;
   const char* display_file;
   char time_buffer[64];
   time_t timer;
@@ -86,12 +86,10 @@ void gpr_default_log(gpr_log_func_args* args) {
     strcpy(time_buffer, "error:strftime");
   }
 
-  gpr_asprintf(&prefix, "%s%s.%09" PRId32 " %7ld %s:%d]",
-               gpr_log_severity_string(args->severity), time_buffer,
-               now.tv_nsec, tid, display_file, args->line);
-
-  fprintf(stderr, "%-60s %s\n", prefix, args->message);
-  gpr_free(prefix);
+  std::string prefix = absl::StrFormat(
+      "%s%s.%09" PRId32 " %7ld %s:%d]", gpr_log_severity_string(args->severity),
+      time_buffer, now.tv_nsec, tid, display_file, args->line);
+  fprintf(stderr, "%-60s %s\n", prefix.c_str(), args->message);
 }
 
 #endif /* GPR_LINUX_LOG */

src/core/lib/gpr/log_posix.cc

@@ -22,7 +22,6 @@
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 #include <inttypes.h>
 #include <pthread.h>
@@ -30,6 +29,8 @@
 #include <stdio.h>
 #include <string.h>
 #include <time.h>
+#include <string>
+#include "absl/strings/str_format.h"
 
 static intptr_t sys_gettid(void) { return (intptr_t)pthread_self(); }
 
@@ -83,13 +84,10 @@ void gpr_default_log(gpr_log_func_args* args) {
     strcpy(time_buffer, "error:strftime");
   }
 
-  char* prefix;
-  gpr_asprintf(&prefix, "%s%s.%09d %7" PRIdPTR " %s:%d]",
-               gpr_log_severity_string(args->severity), time_buffer,
-               (int)(now.tv_nsec), sys_gettid(), display_file, args->line);
-
-  fprintf(stderr, "%-70s %s\n", prefix, args->message);
-  gpr_free(prefix);
+  std::string prefix = absl::StrFormat(
+      "%s%s.%09d %7" PRIdPTR " %s:%d]", gpr_log_severity_string(args->severity),
+      time_buffer, (int)(now.tv_nsec), sys_gettid(), display_file, args->line);
+  fprintf(stderr, "%-70s %s\n", prefix.c_str(), args->message);
 }
 
 #endif /* defined(GPR_POSIX_LOG) */

src/core/lib/gpr/string.cc

@@ -28,6 +28,8 @@
 #include <string.h>
 #include <time.h>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
@@ -50,12 +52,7 @@ char* gpr_strdup(const char* src) {
   return dst;
 }
 
-struct dump_out {
-  size_t capacity;
-  size_t length;
-  char* data;
-};
-char* gpr_format_timespec(gpr_timespec tm) {
+std::string gpr_format_timespec(gpr_timespec tm) {
   char time_buffer[35];
   char ns_buffer[11];  // '.' + 9 digits of precision
   struct tm* tm_info = localtime((const time_t*)&tm.tv_sec);
@@ -76,11 +73,15 @@ char* gpr_format_timespec(gpr_timespec tm) {
       break;
     }
   }
-  char* full_time_str;
-  gpr_asprintf(&full_time_str, "%s%sZ", time_buffer, ns_buffer);
-  return full_time_str;
+  return absl::StrCat(time_buffer, ns_buffer, "Z");
 }
 
+struct dump_out {
+  size_t capacity;
+  size_t length;
+  char* data;
+};
+
 static dump_out dump_out_create(void) {
   dump_out r = {0, 0, nullptr};
   return r;

src/core/lib/gpr/string.h

@@ -26,6 +26,8 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+#include <string>
+
 /* String utility functions */
 
 /* Flags for gpr_dump function. */
@@ -88,13 +90,13 @@ char* gpr_strjoin_sep(const char** strs, size_t nstrs, const char* sep,
 void gpr_string_split(const char* input, const char* sep, char*** strs,
                       size_t* nstrs);
 
-/* Returns an allocated string that represents tm according to RFC-3339, and,
+/* Returns a string that represents tm according to RFC-3339, and,
    more specifically, follows:
    https://developers.google.com/protocol-buffers/docs/proto3#json
 
    Uses RFC 3339, where generated output will always be Z-normalized and uses
    0, 3, 6 or 9 fractional digits. */
-char* gpr_format_timespec(gpr_timespec);
+std::string gpr_format_timespec(gpr_timespec);
 
 /** Case insensitive string comparison... return <0 if lower(a)<lower(b), ==0 if
     lower(a)==lower(b), >0 if lower(a)>lower(b) */

src/core/lib/gprpp/global_config_env.cc

@@ -30,6 +30,10 @@
 #include <ctype.h>
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 namespace grpc_core {
 
 namespace {
@@ -42,12 +46,10 @@ GlobalConfigEnvErrorFunctionType g_global_config_env_error_func =
     DefaultGlobalConfigEnvErrorFunction;
 
 void LogParsingError(const char* name, const char* value) {
-  char* error_message;
-  gpr_asprintf(&error_message,
-               "Illegal value '%s' specified for environment variable '%s'",
-               value, name);
-  (*g_global_config_env_error_func)(error_message);
-  gpr_free(error_message);
+  std::string error_message = absl::StrFormat(
+      "Illegal value '%s' specified for environment variable '%s'", value,
+      name);
+  (*g_global_config_env_error_func)(error_message.c_str());
 }
 
 }  // namespace

src/core/lib/http/httpcli.cc

@@ -22,6 +22,10 @@
 
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
@@ -112,11 +116,11 @@ static void append_error(internal_request* req, grpc_error* error) {
         GRPC_ERROR_CREATE_FROM_STATIC_STRING("Failed HTTP/1 client request");
   }
   grpc_resolved_address* addr = &req->addresses->addrs[req->next_address - 1];
-  grpc_core::UniquePtr<char> addr_text(grpc_sockaddr_to_uri(addr));
+  std::string addr_text = grpc_sockaddr_to_uri(addr);
   req->overall_error = grpc_error_add_child(
       req->overall_error,
       grpc_error_set_str(error, GRPC_ERROR_STR_TARGET_ADDRESS,
-                         grpc_slice_from_moved_string(std::move(addr_text))));
+                         grpc_slice_from_cpp_string(std::move(addr_text))));
 }
 
 static void do_read(internal_request* req) {
@@ -266,15 +270,14 @@ void grpc_httpcli_get(grpc_httpcli_context* context,
                       grpc_resource_quota* resource_quota,
                       const grpc_httpcli_request* request, grpc_millis deadline,
                       grpc_closure* on_done, grpc_httpcli_response* response) {
-  char* name;
   if (g_get_override && g_get_override(request, deadline, on_done, response)) {
     return;
   }
-  gpr_asprintf(&name, "HTTP:GET:%s:%s", request->host, request->http.path);
+  std::string name =
+      absl::StrFormat("HTTP:GET:%s:%s", request->host, request->http.path);
   internal_request_begin(context, pollent, resource_quota, request, deadline,
-                         on_done, response, name,
+                         on_done, response, name.c_str(),
                          grpc_httpcli_format_get_request(request));
-  gpr_free(name);
 }
 
 void grpc_httpcli_post(grpc_httpcli_context* context,
@@ -284,16 +287,16 @@ void grpc_httpcli_post(grpc_httpcli_context* context,
                        const char* body_bytes, size_t body_size,
                        grpc_millis deadline, grpc_closure* on_done,
                        grpc_httpcli_response* response) {
-  char* name;
   if (g_post_override && g_post_override(request, body_bytes, body_size,
                                          deadline, on_done, response)) {
     return;
   }
-  gpr_asprintf(&name, "HTTP:POST:%s:%s", request->host, request->http.path);
+  std::string name =
+      absl::StrFormat("HTTP:POST:%s:%s", request->host, request->http.path);
   internal_request_begin(
       context, pollent, resource_quota, request, deadline, on_done, response,
-      name, grpc_httpcli_format_post_request(request, body_bytes, body_size));
-  gpr_free(name);
+      name.c_str(),
+      grpc_httpcli_format_post_request(request, body_bytes, body_size));
 }
 
 void grpc_httpcli_set_override(grpc_httpcli_get_override get,

src/core/lib/http/httpcli_security_connector.cc

@@ -22,6 +22,7 @@
 
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 
 #include <grpc/support/alloc.h>
@@ -95,11 +96,10 @@ class grpc_httpcli_ssl_channel_security_connector final
     /* Check the peer name. */
     if (secure_peer_name_ != nullptr &&
         !tsi_ssl_peer_matches_name(&peer, secure_peer_name_)) {
-      char* msg;
-      gpr_asprintf(&msg, "Peer name %s is not in peer certificate",
-                   secure_peer_name_);
-      error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-      gpr_free(msg);
+      error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrCat("Peer name ", secure_peer_name_,
+                       " is not in peer certificate")
+              .c_str());
     }
     grpc_core::ExecCtx::Run(DEBUG_LOCATION, on_peer_checked, error);
     tsi_peer_destruct(&peer);

src/core/lib/iomgr/endpoint_pair_posix.cc

@@ -32,9 +32,12 @@
 #include <sys/socket.h>
 #include <sys/types.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/iomgr/tcp_posix.h"
 
@@ -53,19 +56,16 @@ grpc_endpoint_pair grpc_iomgr_create_endpoint_pair(const char* name,
                                                    grpc_channel_args* args) {
   int sv[2];
   grpc_endpoint_pair p;
-  char* final_name;
   create_sockets(sv);
 
   grpc_core::ExecCtx exec_ctx;
 
-  gpr_asprintf(&final_name, "%s:client", name);
-  p.client = grpc_tcp_create(grpc_fd_create(sv[1], final_name, false), args,
-                             "socketpair-server");
-  gpr_free(final_name);
-  gpr_asprintf(&final_name, "%s:server", name);
-  p.server = grpc_tcp_create(grpc_fd_create(sv[0], final_name, false), args,
-                             "socketpair-client");
-  gpr_free(final_name);
+  std::string final_name = absl::StrCat(name, ":client");
+  p.client = grpc_tcp_create(grpc_fd_create(sv[1], final_name.c_str(), false),
+                             args, "socketpair-server");
+  final_name = absl::StrCat(name, ":server");
+  p.server = grpc_tcp_create(grpc_fd_create(sv[0], final_name.c_str(), false),
+                             args, "socketpair-client");
 
   return p;
 }

src/core/lib/iomgr/error_cfstream.cc

@@ -19,10 +19,13 @@
 #include <grpc/support/port_platform.h>
 
 #ifdef GRPC_CFSTREAM
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <CoreFoundation/CoreFoundation.h>
 
 #include <grpc/support/alloc.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/iomgr/error.h"
 
@@ -33,7 +36,6 @@ grpc_error* grpc_error_create_from_cferror(const char* file, int line,
   CFErrorRef error = static_cast<CFErrorRef>(arg);
   char buf_domain[MAX_ERROR_DESCRIPTION];
   char buf_desc[MAX_ERROR_DESCRIPTION];
-  char* error_msg;
   CFErrorDomain domain = CFErrorGetDomain((error));
   CFIndex code = CFErrorGetCode((error));
   CFStringRef desc = CFErrorCopyDescription((error));
@@ -41,12 +43,11 @@ grpc_error* grpc_error_create_from_cferror(const char* file, int line,
                      kCFStringEncodingUTF8);
   CFStringGetCString(desc, buf_desc, MAX_ERROR_DESCRIPTION,
                      kCFStringEncodingUTF8);
-  gpr_asprintf(&error_msg, "%s (error domain:%s, code:%ld, description:%s)",
-               custom_desc, buf_domain, code, buf_desc);
+  std::string error_msg =
+      absl::StrFormat("%s (error domain:%s, code:%ld, description:%s)",
+                      custom_desc, buf_domain, code, buf_desc);
   CFRelease(desc);
-  grpc_error* return_error = grpc_error_create(
-      file, line, grpc_slice_from_copied_string(error_msg), NULL, 0);
-  gpr_free(error_msg);
-  return return_error;
+  return grpc_error_create(
+      file, line, grpc_slice_from_copied_string(error_msg.c_str()), NULL, 0);
 }
 #endif /* GRPC_CFSTREAM */

src/core/lib/iomgr/ev_epoll1_linux.cc

@@ -38,14 +38,15 @@
 #include <sys/socket.h>
 #include <unistd.h>
 
+#include <string>
 #include <vector>
 
+#include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
 #include "absl/strings/str_join.h"
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/cpu.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/debug/stats.h"
 #include "src/core/lib/gpr/string.h"
@@ -351,16 +352,14 @@ static grpc_fd* fd_create(int fd, const char* name, bool track_err) {
 
   new_fd->freelist_next = nullptr;
 
-  char* fd_name;
-  gpr_asprintf(&fd_name, "%s fd=%d", name, fd);
-  grpc_iomgr_register_object(&new_fd->iomgr_object, fd_name);
+  std::string fd_name = absl::StrCat(name, " fd=", fd);
+  grpc_iomgr_register_object(&new_fd->iomgr_object, fd_name.c_str());
   fork_fd_list_add_grpc_fd(new_fd);
 #ifndef NDEBUG
   if (GRPC_TRACE_FLAG_ENABLED(grpc_trace_fd_refcount)) {
-    gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, new_fd, fd_name);
+    gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, new_fd, fd_name.c_str());
   }
 #endif
-  gpr_free(fd_name);
 
   struct epoll_event ev;
   ev.events = static_cast<uint32_t>(EPOLLIN | EPOLLOUT | EPOLLET);

src/core/lib/iomgr/ev_epollex_linux.cc

@@ -38,10 +38,14 @@
 #include <sys/syscall.h>
 #include <unistd.h>
 
-#include <grpc/support/alloc.h>
-#include <grpc/support/string_util.h>
+#include <string>
 
 #include "absl/container/inlined_vector.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+
+#include <grpc/support/alloc.h>
+
 #include "src/core/lib/debug/stats.h"
 #include "src/core/lib/gpr/spinlock.h"
 #include "src/core/lib/gpr/tls.h"
@@ -124,11 +128,10 @@ static const char* pollable_type_string(pollable_type t) {
   return "<invalid>";
 }
 
-static char* pollable_desc(pollable* p) {
-  char* out;
-  gpr_asprintf(&out, "type=%s epfd=%d wakeup=%d", pollable_type_string(p->type),
-               p->epfd, p->wakeup.read_fd);
-  return out;
+static std::string pollable_desc(pollable* p) {
+  return absl::StrFormat("type=%s epfd=%d wakeup=%d",
+                         pollable_type_string(p->type), p->epfd,
+                         p->wakeup.read_fd);
 }
 
 /// Shared empty pollable - used by pollset to poll on until the first fd is
@@ -170,15 +173,13 @@ struct grpc_fd {
     write_closure.InitEvent();
     error_closure.InitEvent();
 
-    char* fd_name;
-    gpr_asprintf(&fd_name, "%s fd=%d", name, fd);
-    grpc_iomgr_register_object(&iomgr_object, fd_name);
+    std::string fd_name = absl::StrCat(name, " fd=", fd);
+    grpc_iomgr_register_object(&iomgr_object, fd_name.c_str());
 #ifndef NDEBUG
     if (GRPC_TRACE_FLAG_ENABLED(grpc_trace_fd_refcount)) {
-      gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, this, fd_name);
+      gpr_log(GPR_DEBUG, "FD %d %p create %s", fd, this, fd_name.c_str());
     }
 #endif
-    gpr_free(fd_name);
   }
 
   // This is really the dtor, but the poller threads waking up from
@@ -934,9 +935,8 @@ static grpc_error* pollable_epoll(pollable* p, grpc_millis deadline) {
   int timeout = poll_deadline_to_millis_timeout(deadline);
 
   if (GRPC_TRACE_FLAG_ENABLED(grpc_polling_trace)) {
-    char* desc = pollable_desc(p);
-    gpr_log(GPR_INFO, "POLLABLE:%p[%s] poll for %dms", p, desc, timeout);
-    gpr_free(desc);
+    gpr_log(GPR_INFO, "POLLABLE:%p[%s] poll for %dms", p,
+            pollable_desc(p).c_str(), timeout);
   }
 
   if (timeout != 0) {

src/core/lib/iomgr/ev_poll_posix.cc

@@ -32,9 +32,12 @@
 #include <sys/socket.h>
 #include <unistd.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/debug/stats.h"
 #include "src/core/lib/gpr/murmur_hash.h"
@@ -381,10 +384,8 @@ static grpc_fd* fd_create(int fd, const char* name, bool track_err) {
   r->released = 0;
   gpr_atm_no_barrier_store(&r->pollhup, 0);
 
-  char* name2;
-  gpr_asprintf(&name2, "%s fd=%d", name, fd);
-  grpc_iomgr_register_object(&r->iomgr_object, name2);
-  gpr_free(name2);
+  std::string name2 = absl::StrCat(name, " fd=", fd);
+  grpc_iomgr_register_object(&r->iomgr_object, name2.c_str());
   fork_fd_list_add_grpc_fd(r);
   return r;
 }

src/core/lib/iomgr/resolve_address_custom.cc

@@ -18,22 +18,24 @@
 
 #include <grpc/support/port_platform.h>
 
-#include "src/core/lib/iomgr/port.h"
+#include "src/core/lib/iomgr/resolve_address_custom.h"
 
-#include <grpc/support/alloc.h>
-#include <grpc/support/string_util.h>
+#include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
+#include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gpr/useful.h"
 #include "src/core/lib/gprpp/host_port.h"
-
 #include "src/core/lib/iomgr/iomgr_custom.h"
-#include "src/core/lib/iomgr/resolve_address_custom.h"
+#include "src/core/lib/iomgr/port.h"
 #include "src/core/lib/iomgr/sockaddr_utils.h"
 
-#include <string.h>
-
 struct grpc_custom_resolver {
   grpc_closure* on_done = nullptr;
   grpc_resolved_addresses** addresses = nullptr;
@@ -88,23 +90,16 @@ static grpc_error* try_split_host_port(const char* name,
                                        const char* default_port,
                                        std::string* host, std::string* port) {
   /* parse name, splitting it into host and port parts */
-  grpc_error* error;
   grpc_core::SplitHostPort(name, host, port);
   if (host->empty()) {
-    char* msg;
-    gpr_asprintf(&msg, "unparseable host:port: '%s'", name);
-    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return error;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrFormat("unparseable host:port: '%s'", name).c_str());
   }
   if (port->empty()) {
     // TODO(murgatroid99): add tests for this case
     if (default_port == nullptr) {
-      char* msg;
-      gpr_asprintf(&msg, "no port in name '%s'", name);
-      error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-      gpr_free(msg);
-      return error;
+      return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrFormat("no port in name '%s'", name).c_str());
     }
     *port = default_port;
   }

src/core/lib/iomgr/resolve_address_windows.cc

@@ -29,6 +29,10 @@
 #include <string.h>
 #include <sys/types.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/log_windows.h>
@@ -65,18 +69,14 @@ static grpc_error* windows_blocking_resolve_address(
   std::string port;
   grpc_core::SplitHostPort(name, &host, &port);
   if (host.empty()) {
-    char* msg;
-    gpr_asprintf(&msg, "unparseable host:port: '%s'", name);
-    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
+    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrFormat("unparseable host:port: '%s'", name).c_str());
     goto done;
   }
   if (port.empty()) {
     if (default_port == NULL) {
-      char* msg;
-      gpr_asprintf(&msg, "no port in name '%s'", name);
-      error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-      gpr_free(msg);
+      error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrFormat("no port in name '%s'", name).c_str());
       goto done;
     }
     port = default_port;

src/core/lib/iomgr/resource_quota.cc

@@ -25,10 +25,13 @@
 #include <stdint.h>
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+
 #include <grpc/slice_buffer.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/gpr/useful.h"
 #include "src/core/lib/iomgr/combiner.h"
@@ -118,7 +121,7 @@ struct grpc_resource_user {
   grpc_resource_user_link links[GRPC_RULIST_COUNT];
 
   /* The name of this resource user, for debugging/tracing */
-  char* name;
+  std::string name;
 };
 
 struct grpc_resource_quota {
@@ -181,7 +184,7 @@ struct grpc_resource_quota {
   /* Roots of all resource user lists */
   grpc_resource_user* roots[GRPC_RULIST_COUNT];
 
-  char* name;
+  std::string name;
 };
 
 static void ru_unref_by(grpc_resource_user* resource_user, gpr_atm amount);
@@ -349,13 +352,13 @@ static bool rq_alloc(grpc_resource_quota* resource_quota) {
         gpr_log(GPR_INFO,
                 "RQ %s %s: grant alloc %" PRId64
                 " bytes; rq_free_pool -> %" PRId64,
-                resource_quota->name, resource_user->name, amt,
+                resource_quota->name.c_str(), resource_user->name.c_str(), amt,
                 resource_quota->free_pool);
       }
     } else if (GRPC_TRACE_FLAG_ENABLED(grpc_resource_quota_trace) &&
                resource_user->free_pool >= 0) {
       gpr_log(GPR_INFO, "RQ %s %s: discard already satisfied alloc request",
-              resource_quota->name, resource_user->name);
+              resource_quota->name.c_str(), resource_user->name.c_str());
     }
     if (resource_user->free_pool >= 0) {
       resource_user->allocating = false;
@@ -388,7 +391,7 @@ static bool rq_reclaim_from_per_user_free_pool(
         gpr_log(GPR_INFO,
                 "RQ %s %s: reclaim_from_per_user_free_pool %" PRId64
                 " bytes; rq_free_pool -> %" PRId64,
-                resource_quota->name, resource_user->name, amt,
+                resource_quota->name.c_str(), resource_user->name.c_str(), amt,
                 resource_quota->free_pool);
       }
       gpr_mu_unlock(&resource_user->mu);
@@ -398,7 +401,7 @@ static bool rq_reclaim_from_per_user_free_pool(
         gpr_log(GPR_INFO,
                 "RQ %s %s: failed to reclaim_from_per_user_free_pool; "
                 "free_pool = %" PRId64 "; rq_free_pool = %" PRId64,
-                resource_quota->name, resource_user->name,
+                resource_quota->name.c_str(), resource_user->name.c_str(),
                 resource_user->free_pool, resource_quota->free_pool);
       }
       gpr_mu_unlock(&resource_user->mu);
@@ -415,8 +418,9 @@ static bool rq_reclaim(grpc_resource_quota* resource_quota, bool destructive) {
   grpc_resource_user* resource_user = rulist_pop_head(resource_quota, list);
   if (resource_user == nullptr) return false;
   if (GRPC_TRACE_FLAG_ENABLED(grpc_resource_quota_trace)) {
-    gpr_log(GPR_INFO, "RQ %s %s: initiate %s reclamation", resource_quota->name,
-            resource_user->name, destructive ? "destructive" : "benign");
+    gpr_log(GPR_INFO, "RQ %s %s: initiate %s reclamation",
+            resource_quota->name.c_str(), resource_user->name.c_str(),
+            destructive ? "destructive" : "benign");
   }
   resource_quota->reclaiming = true;
   grpc_resource_quota_ref_internal(resource_quota);
@@ -585,8 +589,7 @@ static void ru_destroy(void* ru, grpc_error* /*error*/) {
   }
   grpc_resource_quota_unref_internal(resource_user->resource_quota);
   gpr_mu_destroy(&resource_user->mu);
-  gpr_free(resource_user->name);
-  gpr_free(resource_user);
+  delete resource_user;
 }
 
 static void ru_alloc_slices(
@@ -640,8 +643,7 @@ static void rq_reclamation_done(void* rq, grpc_error* /*error*/) {
 
 /* Public API */
 grpc_resource_quota* grpc_resource_quota_create(const char* name) {
-  grpc_resource_quota* resource_quota =
-      static_cast<grpc_resource_quota*>(gpr_malloc(sizeof(*resource_quota)));
+  grpc_resource_quota* resource_quota = new grpc_resource_quota;
   gpr_ref_init(&resource_quota->refs, 1);
   resource_quota->combiner = grpc_combiner_create();
   resource_quota->free_pool = INT64_MAX;
@@ -655,10 +657,10 @@ grpc_resource_quota* grpc_resource_quota_create(const char* name) {
   resource_quota->reclaiming = false;
   gpr_atm_no_barrier_store(&resource_quota->memory_usage_estimation, 0);
   if (name != nullptr) {
-    resource_quota->name = gpr_strdup(name);
+    resource_quota->name = name;
   } else {
-    gpr_asprintf(&resource_quota->name, "anonymous_pool_%" PRIxPTR,
-                 (intptr_t)resource_quota);
+    resource_quota->name =
+        absl::StrCat("anonymous_pool_", (intptr_t)resource_quota);
   }
   GRPC_CLOSURE_INIT(&resource_quota->rq_step_closure, rq_step, resource_quota,
                     nullptr);
@@ -675,9 +677,8 @@ void grpc_resource_quota_unref_internal(grpc_resource_quota* resource_quota) {
     // No outstanding thread quota
     GPR_ASSERT(resource_quota->num_threads_allocated == 0);
     GRPC_COMBINER_UNREF(resource_quota->combiner, "resource_quota");
-    gpr_free(resource_quota->name);
     gpr_mu_destroy(&resource_quota->thread_count_mu);
-    gpr_free(resource_quota);
+    delete resource_quota;
   }
 }
 
@@ -774,8 +775,7 @@ const grpc_arg_pointer_vtable* grpc_resource_quota_arg_vtable(void) {
 
 grpc_resource_user* grpc_resource_user_create(
     grpc_resource_quota* resource_quota, const char* name) {
-  grpc_resource_user* resource_user =
-      static_cast<grpc_resource_user*>(gpr_malloc(sizeof(*resource_user)));
+  grpc_resource_user* resource_user = new grpc_resource_user;
   resource_user->resource_quota =
       grpc_resource_quota_ref_internal(resource_quota);
   GRPC_CLOSURE_INIT(&resource_user->allocate_closure, &ru_allocate,
@@ -805,10 +805,10 @@ grpc_resource_user* grpc_resource_user_create(
     resource_user->links[i].next = resource_user->links[i].prev = nullptr;
   }
   if (name != nullptr) {
-    resource_user->name = gpr_strdup(name);
+    resource_user->name = name;
   } else {
-    gpr_asprintf(&resource_user->name, "anonymous_resource_user_%" PRIxPTR,
-                 (intptr_t)resource_user);
+    resource_user->name =
+        absl::StrCat("anonymous_resource_user_", (intptr_t)resource_user);
   }
   return resource_user;
 }
@@ -890,8 +890,8 @@ static bool resource_user_alloc_locked(grpc_resource_user* resource_user,
   resource_user->free_pool -= static_cast<int64_t>(size);
   if (GRPC_TRACE_FLAG_ENABLED(grpc_resource_quota_trace)) {
     gpr_log(GPR_INFO, "RQ %s %s: alloc %" PRIdPTR "; free_pool -> %" PRId64,
-            resource_user->resource_quota->name, resource_user->name, size,
-            resource_user->free_pool);
+            resource_user->resource_quota->name.c_str(),
+            resource_user->name.c_str(), size, resource_user->free_pool);
   }
   if (GPR_LIKELY(resource_user->free_pool >= 0)) return true;
   // Slow path: We need to wait for the free pool to refill.
@@ -951,8 +951,8 @@ void grpc_resource_user_free(grpc_resource_user* resource_user, size_t size) {
   resource_user->free_pool += static_cast<int64_t>(size);
   if (GRPC_TRACE_FLAG_ENABLED(grpc_resource_quota_trace)) {
     gpr_log(GPR_INFO, "RQ %s %s: free %" PRIdPTR "; free_pool -> %" PRId64,
-            resource_user->resource_quota->name, resource_user->name, size,
-            resource_user->free_pool);
+            resource_user->resource_quota->name.c_str(),
+            resource_user->name.c_str(), size, resource_user->free_pool);
   }
   bool is_bigger_than_zero = resource_user->free_pool > 0;
   if (is_bigger_than_zero && was_zero_or_negative &&
@@ -977,7 +977,8 @@ void grpc_resource_user_post_reclaimer(grpc_resource_user* resource_user,
 void grpc_resource_user_finish_reclamation(grpc_resource_user* resource_user) {
   if (GRPC_TRACE_FLAG_ENABLED(grpc_resource_quota_trace)) {
     gpr_log(GPR_INFO, "RQ %s %s: reclamation complete",
-            resource_user->resource_quota->name, resource_user->name);
+            resource_user->resource_quota->name.c_str(),
+            resource_user->name.c_str());
   }
   resource_user->resource_quota->combiner->Run(
       &resource_user->resource_quota->rq_reclamation_done_closure,

src/core/lib/iomgr/sockaddr_utils.cc

@@ -24,11 +24,13 @@
 #include <inttypes.h>
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gprpp/host_port.h"
@@ -212,8 +214,8 @@ void grpc_string_to_sockaddr(grpc_resolved_address* out, char* addr, int port) {
   grpc_sockaddr_set_port(out, port);
 }
 
-char* grpc_sockaddr_to_uri(const grpc_resolved_address* resolved_addr) {
-  if (resolved_addr->len == 0) return nullptr;
+std::string grpc_sockaddr_to_uri(const grpc_resolved_address* resolved_addr) {
+  if (resolved_addr->len == 0) return "";
   grpc_resolved_address addr_normalized;
   if (grpc_sockaddr_is_v4mapped(resolved_addr, &addr_normalized)) {
     resolved_addr = &addr_normalized;
@@ -224,9 +226,9 @@ char* grpc_sockaddr_to_uri(const grpc_resolved_address* resolved_addr) {
   }
   std::string path =
       grpc_sockaddr_to_string(resolved_addr, false /* normalize */);
-  char* uri_str = nullptr;
+  std::string uri_str;
   if (scheme != nullptr) {
-    gpr_asprintf(&uri_str, "%s:%s", scheme, path.c_str());
+    uri_str = absl::StrCat(scheme, ":", path);
   }
   return uri_str;
 }

src/core/lib/iomgr/sockaddr_utils.h

@@ -69,7 +69,7 @@ std::string grpc_sockaddr_to_string(const grpc_resolved_address* addr,
 void grpc_string_to_sockaddr(grpc_resolved_address* out, char* addr, int port);
 
 /* Returns the URI string corresponding to \a addr */
-char* grpc_sockaddr_to_uri(const grpc_resolved_address* addr);
+std::string grpc_sockaddr_to_uri(const grpc_resolved_address* addr);
 
 /* Returns the URI scheme corresponding to \a addr */
 const char* grpc_sockaddr_get_uri_scheme(const grpc_resolved_address* addr);

src/core/lib/iomgr/socket_windows.cc

@@ -27,10 +27,11 @@
 // must be included after winsock2.h
 #include <mswsock.h>
 
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/log_windows.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/iomgr/iocp_windows.h"
 #include "src/core/lib/iomgr/iomgr_internal.h"
@@ -42,14 +43,12 @@
 static DWORD s_wsa_socket_flags;
 
 grpc_winsocket* grpc_winsocket_create(SOCKET socket, const char* name) {
-  char* final_name;
   grpc_winsocket* r = (grpc_winsocket*)gpr_malloc(sizeof(grpc_winsocket));
   memset(r, 0, sizeof(grpc_winsocket));
   r->socket = socket;
   gpr_mu_init(&r->state_mu);
-  gpr_asprintf(&final_name, "%s:socket=0x%p", name, r);
-  grpc_iomgr_register_object(&r->iomgr_object, final_name);
-  gpr_free(final_name);
+  grpc_iomgr_register_object(
+      &r->iomgr_object, absl::StrFormat("%s:socket=0x%p", name, r).c_str());
   grpc_iocp_add_socket(r);
   return r;
 }

src/core/lib/iomgr/tcp_client_cfstream.cc

@@ -46,7 +46,7 @@
 
 extern grpc_core::TraceFlag grpc_tcp_trace;
 
-typedef struct CFStreamConnect {
+struct CFStreamConnect {
   gpr_mu mu;
   gpr_refcount refcount;
 
@@ -65,9 +65,9 @@ typedef struct CFStreamConnect {
   grpc_closure* closure;
   grpc_endpoint** endpoint;
   int refs;
-  char* addr_name;
+  std::string addr_name;
   grpc_resource_quota* resource_quota;
-} CFStreamConnect;
+};
 
 static void CFStreamConnectCleanup(CFStreamConnect* connect) {
   grpc_resource_quota_unref_internal(connect->resource_quota);
@@ -75,8 +75,7 @@ static void CFStreamConnectCleanup(CFStreamConnect* connect) {
   CFRelease(connect->read_stream);
   CFRelease(connect->write_stream);
   gpr_mu_destroy(&connect->mu);
-  gpr_free(connect->addr_name);
-  gpr_free(connect);
+  delete connect;
 }
 
 static void OnAlarm(void* arg, grpc_error* error) {
@@ -130,8 +129,9 @@ static void OnOpen(void* arg, grpc_error* error) {
       }
       if (error == GRPC_ERROR_NONE) {
         *endpoint = grpc_cfstream_endpoint_create(
-            connect->read_stream, connect->write_stream, connect->addr_name,
-            connect->resource_quota, connect->stream_handle);
+            connect->read_stream, connect->write_stream,
+            connect->addr_name.c_str(), connect->resource_quota,
+            connect->stream_handle);
       }
     } else {
       GRPC_ERROR_REF(error);
@@ -157,9 +157,7 @@ static void CFStreamClientConnect(grpc_closure* closure, grpc_endpoint** ep,
                                   const grpc_channel_args* channel_args,
                                   const grpc_resolved_address* resolved_addr,
                                   grpc_millis deadline) {
-  CFStreamConnect* connect;
-
-  connect = (CFStreamConnect*)gpr_zalloc(sizeof(CFStreamConnect));
+  CFStreamConnect* connect = new CFStreamConnect();
   connect->closure = closure;
   connect->endpoint = ep;
   connect->addr_name = grpc_sockaddr_to_uri(resolved_addr);
@@ -170,7 +168,7 @@ static void CFStreamClientConnect(grpc_closure* closure, grpc_endpoint** ep,
 
   if (grpc_tcp_trace.enabled()) {
     gpr_log(GPR_DEBUG, "CLIENT_CONNECT: %p, %s: asynchronously connecting",
-            connect, connect->addr_name);
+            connect, connect->addr_name.c_str());
   }
 
   grpc_resource_quota* resource_quota = grpc_resource_quota_create(NULL);

src/core/lib/iomgr/tcp_client_custom.cc

@@ -42,15 +42,14 @@ struct grpc_custom_tcp_connect {
   grpc_closure* closure;
   grpc_endpoint** endpoint;
   int refs;
-  char* addr_name;
+  std::string addr_name;
   grpc_resource_quota* resource_quota;
 };
 
 static void custom_tcp_connect_cleanup(grpc_custom_tcp_connect* connect) {
   grpc_custom_socket* socket = connect->socket;
   grpc_resource_quota_unref_internal(connect->resource_quota);
-  gpr_free(connect->addr_name);
-  gpr_free(connect);
+  delete connect;
   socket->refs--;
   if (socket->refs == 0) {
     grpc_custom_socket_vtable->destroy(socket);
@@ -67,7 +66,7 @@ static void on_alarm(void* acp, grpc_error* error) {
   if (GRPC_TRACE_FLAG_ENABLED(grpc_tcp_trace)) {
     const char* str = grpc_error_string(error);
     gpr_log(GPR_INFO, "CLIENT_CONNECT: %s: on_alarm: error=%s",
-            connect->addr_name, str);
+            connect->addr_name.c_str(), str);
   }
   if (error == GRPC_ERROR_NONE) {
     /* error == NONE implies that the timer ran out, and wasn't cancelled. If
@@ -89,7 +88,7 @@ static void custom_connect_callback_internal(grpc_custom_socket* socket,
   grpc_timer_cancel(&connect->alarm);
   if (error == GRPC_ERROR_NONE) {
     *connect->endpoint = custom_tcp_endpoint_create(
-        socket, connect->resource_quota, connect->addr_name);
+        socket, connect->resource_quota, connect->addr_name.c_str());
   }
   done = (--connect->refs == 0);
   if (done) {
@@ -120,7 +119,6 @@ static void tcp_connect(grpc_closure* closure, grpc_endpoint** ep,
   GRPC_CUSTOM_IOMGR_ASSERT_SAME_THREAD();
   (void)channel_args;
   (void)interested_parties;
-  grpc_custom_tcp_connect* connect;
   grpc_resource_quota* resource_quota = grpc_resource_quota_create(nullptr);
   if (channel_args != nullptr) {
     for (size_t i = 0; i < channel_args->num_args; i++) {
@@ -135,8 +133,7 @@ static void tcp_connect(grpc_closure* closure, grpc_endpoint** ep,
       (grpc_custom_socket*)gpr_malloc(sizeof(grpc_custom_socket));
   socket->refs = 2;
   grpc_custom_socket_vtable->init(socket, GRPC_AF_UNSPEC);
-  connect =
-      (grpc_custom_tcp_connect*)gpr_malloc(sizeof(grpc_custom_tcp_connect));
+  grpc_custom_tcp_connect* connect = new grpc_custom_tcp_connect();
   connect->closure = closure;
   connect->endpoint = ep;
   connect->addr_name = grpc_sockaddr_to_uri(resolved_addr);
@@ -149,7 +146,7 @@ static void tcp_connect(grpc_closure* closure, grpc_endpoint** ep,
 
   if (GRPC_TRACE_FLAG_ENABLED(grpc_tcp_trace)) {
     gpr_log(GPR_INFO, "CLIENT_CONNECT: %p %s: asynchronously connecting",
-            socket, connect->addr_name);
+            socket, connect->addr_name.c_str());
   }
 
   GRPC_CLOSURE_INIT(&connect->on_alarm, on_alarm, socket,

src/core/lib/iomgr/tcp_client_posix.cc

@@ -29,9 +29,10 @@
 #include <string.h>
 #include <unistd.h>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 
 #include "src/core/lib/channel/channel_args.h"
@@ -57,11 +58,12 @@ struct async_connect {
   int refs;
   grpc_closure write_closure;
   grpc_pollset_set* interested_parties;
-  char* addr_str;
+  std::string addr_str;
   grpc_endpoint** ep;
   grpc_closure* closure;
   grpc_channel_args* channel_args;
 };
+
 static grpc_error* prepare_socket(const grpc_resolved_address* addr, int fd,
                                   const grpc_channel_args* channel_args) {
   grpc_error* err = GRPC_ERROR_NONE;
@@ -102,8 +104,8 @@ static void tc_on_alarm(void* acp, grpc_error* error) {
   async_connect* ac = static_cast<async_connect*>(acp);
   if (GRPC_TRACE_FLAG_ENABLED(grpc_tcp_trace)) {
     const char* str = grpc_error_string(error);
-    gpr_log(GPR_INFO, "CLIENT_CONNECT: %s: on_alarm: error=%s", ac->addr_str,
-            str);
+    gpr_log(GPR_INFO, "CLIENT_CONNECT: %s: on_alarm: error=%s",
+            ac->addr_str.c_str(), str);
   }
   gpr_mu_lock(&ac->mu);
   if (ac->fd != nullptr) {
@@ -114,9 +116,8 @@ static void tc_on_alarm(void* acp, grpc_error* error) {
   gpr_mu_unlock(&ac->mu);
   if (done) {
     gpr_mu_destroy(&ac->mu);
-    gpr_free(ac->addr_str);
     grpc_channel_args_destroy(ac->channel_args);
-    gpr_free(ac);
+    delete ac;
   }
 }
 
@@ -139,8 +140,8 @@ static void on_writable(void* acp, grpc_error* error) {
 
   if (GRPC_TRACE_FLAG_ENABLED(grpc_tcp_trace)) {
     const char* str = grpc_error_string(error);
-    gpr_log(GPR_INFO, "CLIENT_CONNECT: %s: on_writable: error=%s", ac->addr_str,
-            str);
+    gpr_log(GPR_INFO, "CLIENT_CONNECT: %s: on_writable: error=%s",
+            ac->addr_str.c_str(), str);
   }
 
   gpr_mu_lock(&ac->mu);
@@ -172,7 +173,8 @@ static void on_writable(void* acp, grpc_error* error) {
   switch (so_error) {
     case 0:
       grpc_pollset_set_del_fd(ac->interested_parties, fd);
-      *ep = grpc_tcp_client_create_from_fd(fd, ac->channel_args, ac->addr_str);
+      *ep = grpc_tcp_client_create_from_fd(fd, ac->channel_args,
+                                           ac->addr_str.c_str());
       fd = nullptr;
       break;
     case ENOBUFS:
@@ -214,19 +216,17 @@ finish:
   done = (--ac->refs == 0);
   // Create a copy of the data from "ac" to be accessed after the unlock, as
   // "ac" and its contents may be deallocated by the time they are read.
-  const grpc_slice addr_str_slice = grpc_slice_from_copied_string(ac->addr_str);
+  const grpc_slice addr_str_slice = grpc_slice_from_cpp_string(ac->addr_str);
   gpr_mu_unlock(&ac->mu);
   if (error != GRPC_ERROR_NONE) {
-    char* error_descr;
     grpc_slice str;
     bool ret = grpc_error_get_str(error, GRPC_ERROR_STR_DESCRIPTION, &str);
     GPR_ASSERT(ret);
-    char* desc = grpc_slice_to_c_string(str);
-    gpr_asprintf(&error_descr, "Failed to connect to remote host: %s", desc);
-    error = grpc_error_set_str(error, GRPC_ERROR_STR_DESCRIPTION,
-                               grpc_slice_from_copied_string(error_descr));
-    gpr_free(error_descr);
-    gpr_free(desc);
+    std::string description = absl::StrCat("Failed to connect to remote host: ",
+                                           grpc_core::StringViewFromSlice(str));
+    error =
+        grpc_error_set_str(error, GRPC_ERROR_STR_DESCRIPTION,
+                           grpc_slice_from_cpp_string(std::move(description)));
     error = grpc_error_set_str(error, GRPC_ERROR_STR_TARGET_ADDRESS,
                                addr_str_slice /* takes ownership */);
   } else {
@@ -236,9 +236,8 @@ finish:
     // This is safe even outside the lock, because "done", the sentinel, is
     // populated *inside* the lock.
     gpr_mu_destroy(&ac->mu);
-    gpr_free(ac->addr_str);
     grpc_channel_args_destroy(ac->channel_args);
-    gpr_free(ac);
+    delete ac;
   }
   grpc_core::ExecCtx::Run(DEBUG_LOCATION, closure, error);
 }
@@ -279,33 +278,25 @@ void grpc_tcp_client_create_from_prepared_fd(
     const grpc_channel_args* channel_args, const grpc_resolved_address* addr,
     grpc_millis deadline, grpc_endpoint** ep) {
   int err;
-  async_connect* ac;
   do {
     err = connect(fd, reinterpret_cast<const grpc_sockaddr*>(addr->addr),
                   addr->len);
   } while (err < 0 && errno == EINTR);
 
-  char* name;
-  char* addr_str;
-  addr_str = grpc_sockaddr_to_uri(addr);
-  gpr_asprintf(&name, "tcp-client:%s", addr_str);
-  grpc_fd* fdobj = grpc_fd_create(fd, name, true);
-  gpr_free(name);
-  gpr_free(addr_str);
+  std::string name = absl::StrCat("tcp-client:", grpc_sockaddr_to_uri(addr));
+  grpc_fd* fdobj = grpc_fd_create(fd, name.c_str(), true);
 
   if (err >= 0) {
-    char* addr_str = grpc_sockaddr_to_uri(addr);
-    *ep = grpc_tcp_client_create_from_fd(fdobj, channel_args, addr_str);
-    gpr_free(addr_str);
+    *ep = grpc_tcp_client_create_from_fd(fdobj, channel_args,
+                                         grpc_sockaddr_to_uri(addr).c_str());
     grpc_core::ExecCtx::Run(DEBUG_LOCATION, closure, GRPC_ERROR_NONE);
     return;
   }
   if (errno != EWOULDBLOCK && errno != EINPROGRESS) {
     grpc_error* error = GRPC_OS_ERROR(errno, "connect");
-    char* addr_str = grpc_sockaddr_to_uri(addr);
-    error = grpc_error_set_str(error, GRPC_ERROR_STR_TARGET_ADDRESS,
-                               grpc_slice_from_copied_string(addr_str));
-    gpr_free(addr_str);
+    error = grpc_error_set_str(
+        error, GRPC_ERROR_STR_TARGET_ADDRESS,
+        grpc_slice_from_cpp_string(grpc_sockaddr_to_uri(addr)));
     grpc_fd_orphan(fdobj, nullptr, nullptr, "tcp_client_connect_error");
     grpc_core::ExecCtx::Run(DEBUG_LOCATION, closure, error);
     return;
@@ -313,7 +304,7 @@ void grpc_tcp_client_create_from_prepared_fd(
 
   grpc_pollset_set_add_fd(interested_parties, fdobj);
 
-  ac = static_cast<async_connect*>(gpr_malloc(sizeof(async_connect)));
+  async_connect* ac = new async_connect();
   ac->closure = closure;
   ac->ep = ep;
   ac->fd = fdobj;
@@ -327,7 +318,7 @@ void grpc_tcp_client_create_from_prepared_fd(
 
   if (GRPC_TRACE_FLAG_ENABLED(grpc_tcp_trace)) {
     gpr_log(GPR_INFO, "CLIENT_CONNECT: %s: asynchronously connecting fd %p",
-            ac->addr_str, fdobj);
+            ac->addr_str.c_str(), fdobj);
   }
 
   gpr_mu_lock(&ac->mu);

src/core/lib/iomgr/tcp_client_windows.cc

@@ -39,6 +39,7 @@
 #include "src/core/lib/iomgr/tcp_client.h"
 #include "src/core/lib/iomgr/tcp_windows.h"
 #include "src/core/lib/iomgr/timer.h"
+#include "src/core/lib/slice/slice_internal.h"
 
 struct async_connect {
   grpc_closure* on_done;
@@ -46,12 +47,13 @@ struct async_connect {
   grpc_winsocket* socket;
   grpc_timer alarm;
   grpc_closure on_alarm;
-  char* addr_name;
+  std::string addr_name;
   int refs;
   grpc_closure on_connect;
   grpc_endpoint** endpoint;
   grpc_channel_args* channel_args;
 };
+
 static void async_connect_unlock_and_cleanup(async_connect* ac,
                                              grpc_winsocket* socket) {
   int done = (--ac->refs == 0);
@@ -59,8 +61,7 @@ static void async_connect_unlock_and_cleanup(async_connect* ac,
   if (done) {
     grpc_channel_args_destroy(ac->channel_args);
     gpr_mu_destroy(&ac->mu);
-    gpr_free(ac->addr_name);
-    gpr_free(ac);
+    delete ac;
   }
   if (socket != NULL) grpc_winsocket_destroy(socket);
 }
@@ -105,7 +106,7 @@ static void on_connect(void* acp, grpc_error* error) {
         error = GRPC_WSA_ERROR(WSAGetLastError(), "ConnectEx");
         closesocket(socket->socket);
       } else {
-        *ep = grpc_tcp_create(socket, ac->channel_args, ac->addr_name);
+        *ep = grpc_tcp_create(socket, ac->channel_args, ac->addr_name.c_str());
         socket = NULL;
       }
     } else {
@@ -131,13 +132,13 @@ static void tcp_connect(grpc_closure* on_done, grpc_endpoint** endpoint,
   int status;
   grpc_resolved_address addr6_v4mapped;
   grpc_resolved_address local_address;
-  async_connect* ac;
   grpc_winsocket* socket = NULL;
   LPFN_CONNECTEX ConnectEx;
   GUID guid = WSAID_CONNECTEX;
   DWORD ioctl_num_bytes;
   grpc_winsocket_callback_info* info;
   grpc_error* error = GRPC_ERROR_NONE;
+  async_connect* ac = NULL;
 
   *endpoint = NULL;
 
@@ -194,7 +195,7 @@ static void tcp_connect(grpc_closure* on_done, grpc_endpoint** endpoint,
     }
   }
 
-  ac = (async_connect*)gpr_malloc(sizeof(async_connect));
+  ac = new async_connect();
   ac->on_done = on_done;
   ac->socket = socket;
   gpr_mu_init(&ac->mu);
@@ -211,13 +212,12 @@ static void tcp_connect(grpc_closure* on_done, grpc_endpoint** endpoint,
 
 failure:
   GPR_ASSERT(error != GRPC_ERROR_NONE);
-  char* target_uri = grpc_sockaddr_to_uri(addr);
+  std::string target_uri = grpc_sockaddr_to_uri(addr);
   grpc_error* final_error =
       grpc_error_set_str(GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
                              "Failed to connect", &error, 1),
                          GRPC_ERROR_STR_TARGET_ADDRESS,
-                         grpc_slice_from_copied_string(
-                             target_uri == nullptr ? "NULL" : target_uri));
+                         grpc_slice_from_cpp_string(std::move(target_uri)));
   GRPC_ERROR_UNREF(error);
   if (socket != NULL) {
     grpc_winsocket_destroy(socket);

src/core/lib/iomgr/tcp_custom.cc

@@ -345,7 +345,7 @@ static grpc_endpoint_vtable vtable = {endpoint_read,
 
 grpc_endpoint* custom_tcp_endpoint_create(grpc_custom_socket* socket,
                                           grpc_resource_quota* resource_quota,
-                                          char* peer_string) {
+                                          const char* peer_string) {
   custom_tcp_endpoint* tcp =
       (custom_tcp_endpoint*)gpr_malloc(sizeof(custom_tcp_endpoint));
   grpc_core::ApplicationCallbackExecCtx callback_exec_ctx;

src/core/lib/iomgr/tcp_custom.h

@@ -79,6 +79,6 @@ void grpc_custom_close_server_callback(grpc_tcp_listener* listener);
 
 grpc_endpoint* custom_tcp_endpoint_create(grpc_custom_socket* socket,
                                           grpc_resource_quota* resource_quota,
-                                          char* peer_string);
+                                          const char* peer_string);
 
 #endif /* GRPC_CORE_LIB_IOMGR_TCP_CUSTOM_H */

src/core/lib/iomgr/tcp_server_custom.cc

@@ -216,10 +216,9 @@ static void finish_accept(grpc_tcp_listener* sp, grpc_custom_socket* socket) {
       (grpc_tcp_server_acceptor*)gpr_malloc(sizeof(*acceptor));
   grpc_endpoint* ep = nullptr;
   grpc_resolved_address peer_name;
-  char* peer_name_string;
+  std::string peer_name_string;
   grpc_error* err;
 
-  peer_name_string = nullptr;
   memset(&peer_name, 0, sizeof(grpc_resolved_address));
   peer_name.len = GRPC_MAX_SOCKADDR_SIZE;
   err = grpc_custom_socket_vtable->getpeername(
@@ -231,21 +230,16 @@ static void finish_accept(grpc_tcp_listener* sp, grpc_custom_socket* socket) {
     GRPC_ERROR_UNREF(err);
   }
   if (GRPC_TRACE_FLAG_ENABLED(grpc_tcp_trace)) {
-    if (peer_name_string) {
-      gpr_log(GPR_INFO, "SERVER_CONNECT: %p accepted connection: %s",
-              sp->server, peer_name_string);
-    } else {
-      gpr_log(GPR_INFO, "SERVER_CONNECT: %p accepted connection", sp->server);
-    }
+    gpr_log(GPR_INFO, "SERVER_CONNECT: %p accepted connection: %s", sp->server,
+            peer_name_string.c_str());
   }
   ep = custom_tcp_endpoint_create(socket, sp->server->resource_quota,
-                                  peer_name_string);
+                                  peer_name_string.c_str());
   acceptor->from_server = sp->server;
   acceptor->port_index = sp->port_index;
   acceptor->fd_index = 0;
   acceptor->external_connection = false;
   sp->server->on_accept_cb(sp->server->on_accept_cb_arg, ep, nullptr, acceptor);
-  gpr_free(peer_name_string);
 }
 
 static void custom_accept_callback(grpc_custom_socket* socket,

src/core/lib/iomgr/tcp_server_posix.cc

@@ -39,9 +39,11 @@
 
 #include <string>
 
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 #include <grpc/support/time.h>
 
@@ -196,8 +198,6 @@ static void on_read(void* arg, grpc_error* err) {
   /* loop until accept4 returns EAGAIN, and then re-arm notification */
   for (;;) {
     grpc_resolved_address addr;
-    char* addr_str;
-    char* name;
     memset(&addr, 0, sizeof(addr));
     addr.len = static_cast<socklen_t>(sizeof(struct sockaddr_storage));
     /* Note: If we ever decide to return this address to the user, remember to
@@ -238,14 +238,14 @@ static void on_read(void* arg, grpc_error* err) {
 
     grpc_set_socket_no_sigpipe_if_possible(fd);
 
-    addr_str = grpc_sockaddr_to_uri(&addr);
-    gpr_asprintf(&name, "tcp-server-connection:%s", addr_str);
-
+    std::string addr_str = grpc_sockaddr_to_uri(&addr);
     if (GRPC_TRACE_FLAG_ENABLED(grpc_tcp_trace)) {
-      gpr_log(GPR_INFO, "SERVER_CONNECT: incoming connection: %s", addr_str);
+      gpr_log(GPR_INFO, "SERVER_CONNECT: incoming connection: %s",
+              addr_str.c_str());
     }
 
-    grpc_fd* fdobj = grpc_fd_create(fd, name, true);
+    std::string name = absl::StrCat("tcp-server-connection:", addr_str);
+    grpc_fd* fdobj = grpc_fd_create(fd, name.c_str(), true);
 
     read_notifier_pollset =
         sp->server->pollsets[static_cast<size_t>(gpr_atm_no_barrier_fetch_add(
@@ -264,11 +264,8 @@ static void on_read(void* arg, grpc_error* err) {
 
     sp->server->on_accept_cb(
         sp->server->on_accept_cb_arg,
-        grpc_tcp_create(fdobj, sp->server->channel_args, addr_str),
+        grpc_tcp_create(fdobj, sp->server->channel_args, addr_str.c_str()),
         read_notifier_pollset, acceptor);
-
-    gpr_free(name);
-    gpr_free(addr_str);
   }
 
   GPR_UNREACHABLE_CODE(return );
@@ -352,7 +349,6 @@ static grpc_error* add_wildcard_addrs_to_server(grpc_tcp_server* s,
 static grpc_error* clone_port(grpc_tcp_listener* listener, unsigned count) {
   grpc_tcp_listener* sp = nullptr;
   std::string addr_str;
-  char* name;
   grpc_error* err;
 
   for (grpc_tcp_listener* l = listener->next; l && l->is_sibling; l = l->next) {
@@ -371,7 +367,6 @@ static grpc_error* clone_port(grpc_tcp_listener* listener, unsigned count) {
     if (err != GRPC_ERROR_NONE) return err;
     listener->server->nports++;
     addr_str = grpc_sockaddr_to_string(&listener->addr, true);
-    gpr_asprintf(&name, "tcp-server-listener:%s/clone-%d", addr_str.c_str(), i);
     sp = static_cast<grpc_tcp_listener*>(gpr_malloc(sizeof(grpc_tcp_listener)));
     sp->next = listener->next;
     listener->next = sp;
@@ -382,7 +377,11 @@ static grpc_error* clone_port(grpc_tcp_listener* listener, unsigned count) {
     listener->sibling = sp;
     sp->server = listener->server;
     sp->fd = fd;
-    sp->emfd = grpc_fd_create(fd, name, true);
+    sp->emfd = grpc_fd_create(
+        fd,
+        absl::StrFormat("tcp-server-listener:%s/clone-%d", addr_str.c_str(), i)
+            .c_str(),
+        true);
     memcpy(&sp->addr, &listener->addr, sizeof(grpc_resolved_address));
     sp->port = port;
     sp->port_index = listener->port_index;
@@ -391,7 +390,6 @@ static grpc_error* clone_port(grpc_tcp_listener* listener, unsigned count) {
     while (listener->server->tail->next != nullptr) {
       listener->server->tail = listener->server->tail->next;
     }
-    gpr_free(name);
   }
 
   return GRPC_ERROR_NONE;
@@ -577,8 +575,6 @@ class ExternalConnectionHandler : public grpc_core::TcpServerFdHandler {
   void Handle(int listener_fd, int fd, grpc_byte_buffer* buf) override {
     grpc_pollset* read_notifier_pollset;
     grpc_resolved_address addr;
-    char* addr_str;
-    char* name;
     memset(&addr, 0, sizeof(addr));
     addr.len = static_cast<socklen_t>(sizeof(struct sockaddr_storage));
     grpc_core::ExecCtx exec_ctx;
@@ -590,13 +586,13 @@ class ExternalConnectionHandler : public grpc_core::TcpServerFdHandler {
       return;
     }
     grpc_set_socket_no_sigpipe_if_possible(fd);
-    addr_str = grpc_sockaddr_to_uri(&addr);
-    gpr_asprintf(&name, "tcp-server-connection:%s", addr_str);
+    std::string addr_str = grpc_sockaddr_to_uri(&addr);
     if (grpc_tcp_trace.enabled()) {
       gpr_log(GPR_INFO, "SERVER_CONNECT: incoming external connection: %s",
-              addr_str);
+              addr_str.c_str());
     }
-    grpc_fd* fdobj = grpc_fd_create(fd, name, true);
+    std::string name = absl::StrCat("tcp-server-connection:", addr_str);
+    grpc_fd* fdobj = grpc_fd_create(fd, name.c_str(), true);
     read_notifier_pollset =
         s_->pollsets[static_cast<size_t>(gpr_atm_no_barrier_fetch_add(
                          &s_->next_pollset_to_assign, 1)) %
@@ -611,10 +607,8 @@ class ExternalConnectionHandler : public grpc_core::TcpServerFdHandler {
     acceptor->listener_fd = listener_fd;
     acceptor->pending_data = buf;
     s_->on_accept_cb(s_->on_accept_cb_arg,
-                     grpc_tcp_create(fdobj, s_->channel_args, addr_str),
+                     grpc_tcp_create(fdobj, s_->channel_args, addr_str.c_str()),
                      read_notifier_pollset, acceptor);
-    gpr_free(name);
-    gpr_free(addr_str);
   }
 
  private:

src/core/lib/iomgr/tcp_server_utils_posix_common.cc

@@ -31,9 +31,10 @@
 
 #include <string>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 
 #include "src/core/lib/iomgr/error.h"
@@ -85,15 +86,13 @@ static grpc_error* add_socket_to_server(grpc_tcp_server* s, int fd,
                                         grpc_tcp_listener** listener) {
   grpc_tcp_listener* sp = nullptr;
   int port = -1;
-  std::string addr_str;
-  char* name;
 
   grpc_error* err =
       grpc_tcp_server_prepare_socket(s, fd, addr, s->so_reuseport, &port);
   if (err == GRPC_ERROR_NONE) {
     GPR_ASSERT(port > 0);
-    addr_str = grpc_sockaddr_to_string(addr, true);
-    gpr_asprintf(&name, "tcp-server-listener:%s", addr_str.c_str());
+    std::string addr_str = grpc_sockaddr_to_string(addr, true);
+    std::string name = absl::StrCat("tcp-server-listener:", addr_str);
     gpr_mu_lock(&s->mu);
     s->nports++;
     GPR_ASSERT(!s->on_accept_cb && "must add ports before starting server");
@@ -107,7 +106,7 @@ static grpc_error* add_socket_to_server(grpc_tcp_server* s, int fd,
     s->tail = sp;
     sp->server = s;
     sp->fd = fd;
-    sp->emfd = grpc_fd_create(fd, name, true);
+    sp->emfd = grpc_fd_create(fd, name.c_str(), true);
     memcpy(&sp->addr, addr, sizeof(grpc_resolved_address));
     sp->port = port;
     sp->port_index = port_index;
@@ -116,7 +115,6 @@ static grpc_error* add_socket_to_server(grpc_tcp_server* s, int fd,
     sp->sibling = nullptr;
     GPR_ASSERT(sp->emfd);
     gpr_mu_unlock(&s->mu);
-    gpr_free(name);
   }
 
   *listener = sp;

src/core/lib/iomgr/tcp_server_utils_posix_ifaddrs.cc

@@ -31,9 +31,10 @@
 
 #include <string>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/iomgr/error.h"
 #include "src/core/lib/iomgr/sockaddr.h"
@@ -145,14 +146,8 @@ grpc_error* grpc_tcp_server_add_all_local_addrs(grpc_tcp_server* s,
     }
     if ((err = grpc_tcp_server_add_addr(s, &addr, port_index, fd_index, &dsmode,
                                         &new_sp)) != GRPC_ERROR_NONE) {
-      char* err_str = nullptr;
-      grpc_error* root_err;
-      if (gpr_asprintf(&err_str, "Failed to add listener: %s",
-                       addr_str.c_str()) < 0) {
-        err_str = gpr_strdup("Failed to add listener");
-      }
-      root_err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(err_str);
-      gpr_free(err_str);
+      grpc_error* root_err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrCat("Failed to add listener: ", addr_str).c_str());
       err = grpc_error_add_child(root_err, err);
       break;
     } else {

src/core/lib/iomgr/tcp_server_windows.cc

@@ -27,6 +27,8 @@
 #include <inttypes.h>
 #include <io.h>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/log_windows.h>
@@ -42,6 +44,7 @@
 #include "src/core/lib/iomgr/socket_windows.h"
 #include "src/core/lib/iomgr/tcp_server.h"
 #include "src/core/lib/iomgr/tcp_windows.h"
+#include "src/core/lib/slice/slice_internal.h"
 
 #define MIN_SAFE_ACCEPT_QUEUE_SIZE 100
 
@@ -222,14 +225,13 @@ static grpc_error* prepare_socket(SOCKET sock,
 
 failure:
   GPR_ASSERT(error != GRPC_ERROR_NONE);
-  char* tgtaddr = grpc_sockaddr_to_uri(addr);
   grpc_error_set_int(
-      grpc_error_set_str(GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
-                             "Failed to prepare server socket", &error, 1),
-                         GRPC_ERROR_STR_TARGET_ADDRESS,
-                         grpc_slice_from_copied_string(tgtaddr)),
+      grpc_error_set_str(
+          GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
+              "Failed to prepare server socket", &error, 1),
+          GRPC_ERROR_STR_TARGET_ADDRESS,
+          grpc_slice_from_cpp_string(grpc_sockaddr_to_uri(addr))),
       GRPC_ERROR_INT_FD, (intptr_t)sock);
-  gpr_free(tgtaddr);
   GRPC_ERROR_UNREF(error);
   if (sock != INVALID_SOCKET) closesocket(sock);
   return error;
@@ -301,8 +303,6 @@ static void on_accept(void* arg, grpc_error* error) {
   grpc_winsocket_callback_info* info = &sp->socket->read_info;
   grpc_endpoint* ep = NULL;
   grpc_resolved_address peer_name;
-  char* peer_name_string;
-  char* fd_name;
   DWORD transfered_bytes;
   DWORD flags;
   BOOL wsa_success;
@@ -337,7 +337,6 @@ static void on_accept(void* arg, grpc_error* error) {
     closesocket(sock);
   } else {
     if (!sp->shutting_down) {
-      peer_name_string = NULL;
       err = setsockopt(sock, SOL_SOCKET, SO_UPDATE_ACCEPT_CONTEXT,
                        (char*)&sp->socket->socket, sizeof(sp->socket->socket));
       if (err) {
@@ -348,6 +347,7 @@ static void on_accept(void* arg, grpc_error* error) {
       int peer_name_len = (int)peer_name.len;
       err = getpeername(sock, (grpc_sockaddr*)peer_name.addr, &peer_name_len);
       peer_name.len = (size_t)peer_name_len;
+      std::string peer_name_string;
       if (!err) {
         peer_name_string = grpc_sockaddr_to_uri(&peer_name);
       } else {
@@ -355,11 +355,9 @@ static void on_accept(void* arg, grpc_error* error) {
         gpr_log(GPR_ERROR, "getpeername error: %s", utf8_message);
         gpr_free(utf8_message);
       }
-      gpr_asprintf(&fd_name, "tcp_server:%s", peer_name_string);
-      ep = grpc_tcp_create(grpc_winsocket_create(sock, fd_name),
-                           sp->server->channel_args, peer_name_string);
-      gpr_free(fd_name);
-      gpr_free(peer_name_string);
+      std::string fd_name = absl::StrCat("tcp_server:", peer_name_string);
+      ep = grpc_tcp_create(grpc_winsocket_create(sock, fd_name.c_str()),
+                           sp->server->channel_args, peer_name_string.c_str());
     } else {
       closesocket(sock);
     }

src/core/lib/iomgr/timer_generic.cc

@@ -22,12 +22,15 @@
 
 #include <inttypes.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+
 #include "src/core/lib/iomgr/timer.h"
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/cpu.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 
 #include "src/core/lib/debug/trace.h"
@@ -706,38 +709,36 @@ static grpc_timer_check_result timer_check(grpc_millis* next) {
 
   // tracing
   if (GRPC_TRACE_FLAG_ENABLED(grpc_timer_check_trace)) {
-    char* next_str;
+    std::string next_str;
     if (next == nullptr) {
-      next_str = gpr_strdup("NULL");
+      next_str = "NULL";
     } else {
-      gpr_asprintf(&next_str, "%" PRId64, *next);
+      next_str = absl::StrCat(*next);
     }
 #if GPR_ARCH_64
     gpr_log(GPR_INFO,
             "TIMER CHECK BEGIN: now=%" PRId64 " next=%s tls_min=%" PRId64
             " glob_min=%" PRId64,
-            now, next_str, min_timer,
+            now, next_str.c_str(), min_timer,
             static_cast<grpc_millis>(gpr_atm_no_barrier_load(
                 (gpr_atm*)(&g_shared_mutables.min_timer))));
 #else
     gpr_log(GPR_INFO, "TIMER CHECK BEGIN: now=%" PRId64 " next=%s min=%" PRId64,
-            now, next_str, min_timer);
+            now, next_str.c_str(), min_timer);
 #endif
-    gpr_free(next_str);
   }
   // actual code
   grpc_timer_check_result r =
       run_some_expired_timers(now, next, shutdown_error);
   // tracing
   if (GRPC_TRACE_FLAG_ENABLED(grpc_timer_check_trace)) {
-    char* next_str;
+    std::string next_str;
     if (next == nullptr) {
-      next_str = gpr_strdup("NULL");
+      next_str = "NULL";
     } else {
-      gpr_asprintf(&next_str, "%" PRId64, *next);
+      next_str = absl::StrCat(*next);
     }
-    gpr_log(GPR_INFO, "TIMER CHECK END: r=%d; next=%s", r, next_str);
-    gpr_free(next_str);
+    gpr_log(GPR_INFO, "TIMER CHECK END: r=%d; next=%s", r, next_str.c_str());
   }
   return r;
 }

src/core/lib/iomgr/udp_server.cc

@@ -44,7 +44,10 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+#include <string>
+
 #include "absl/container/inlined_vector.h"
+#include "absl/strings/str_cat.h"
 
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
@@ -148,13 +151,11 @@ GrpcUdpListener::GrpcUdpListener(grpc_udp_server* server, int fd,
       server_(server),
       orphan_notified_(false),
       already_shutdown_(false) {
-  char* name;
   std::string addr_str = grpc_sockaddr_to_string(addr, true);
-  gpr_asprintf(&name, "udp-server-listener:%s", addr_str.c_str());
-  emfd_ = grpc_fd_create(fd, name, true);
+  std::string name = absl::StrCat("udp-server-listener:", addr_str);
+  emfd_ = grpc_fd_create(fd, name.c_str(), true);
   memcpy(&addr_, addr, sizeof(grpc_resolved_address));
   GPR_ASSERT(emfd_);
-  gpr_free(name);
   gpr_mu_init(&mutex_);
 }
 

src/core/lib/iomgr/unix_sockets_posix.cc

@@ -28,6 +28,8 @@
 #include <sys/types.h>
 #include <sys/un.h>
 
+#include "absl/strings/str_cat.h"
+
 #include "src/core/lib/iomgr/unix_sockets_posix.h"
 
 #include <grpc/support/alloc.h>
@@ -44,14 +46,10 @@ grpc_error* grpc_resolve_unix_domain_address(const char* name,
   struct sockaddr_un* un;
   if (strlen(name) >
       GPR_ARRAY_SIZE(((struct sockaddr_un*)nullptr)->sun_path) - 1) {
-    char* err_msg;
-    grpc_error* err;
-    gpr_asprintf(&err_msg,
-                 "Path name should not have more than %" PRIuPTR " characters.",
-                 GPR_ARRAY_SIZE(un->sun_path) - 1);
-    err = GRPC_ERROR_CREATE_FROM_COPIED_STRING(err_msg);
-    gpr_free(err_msg);
-    return err;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Path name should not have more than ",
+                     GPR_ARRAY_SIZE(un->sun_path) - 1, " characters")
+            .c_str());
   }
   *addrs = static_cast<grpc_resolved_addresses*>(
       gpr_malloc(sizeof(grpc_resolved_addresses)));
@@ -88,17 +86,14 @@ void grpc_unlink_if_unix_domain_socket(
   }
 }
 
-char* grpc_sockaddr_to_uri_unix_if_possible(
+std::string grpc_sockaddr_to_uri_unix_if_possible(
     const grpc_resolved_address* resolved_addr) {
   const grpc_sockaddr* addr =
       reinterpret_cast<const grpc_sockaddr*>(resolved_addr->addr);
   if (addr->sa_family != AF_UNIX) {
-    return nullptr;
+    return "";
   }
-
-  char* result;
-  gpr_asprintf(&result, "unix:%s", ((struct sockaddr_un*)addr)->sun_path);
-  return result;
+  return absl::StrCat("unix:", ((struct sockaddr_un*)addr)->sun_path);
 }
 
 #endif

src/core/lib/iomgr/unix_sockets_posix.h

@@ -21,6 +21,8 @@
 
 #include <grpc/support/port_platform.h>
 
+#include <string>
+
 #include "src/core/lib/iomgr/port.h"
 
 #include <grpc/support/string_util.h>
@@ -37,7 +39,7 @@ int grpc_is_unix_socket(const grpc_resolved_address* resolved_addr);
 void grpc_unlink_if_unix_domain_socket(
     const grpc_resolved_address* resolved_addr);
 
-char* grpc_sockaddr_to_uri_unix_if_possible(
+std::string grpc_sockaddr_to_uri_unix_if_possible(
     const grpc_resolved_address* resolved_addr);
 
 #endif /* GRPC_CORE_LIB_IOMGR_UNIX_SOCKETS_POSIX_H */

src/core/lib/iomgr/unix_sockets_posix_noop.cc

@@ -22,6 +22,8 @@
 
 #ifndef GRPC_HAVE_UNIX_SOCKET
 
+#include <string>
+
 #include <grpc/support/log.h>
 
 void grpc_create_socketpair_if_unix(int sv[2]) {
@@ -42,8 +44,9 @@ int grpc_is_unix_socket(const grpc_resolved_address* addr) { return false; }
 
 void grpc_unlink_if_unix_domain_socket(const grpc_resolved_address* addr) {}
 
-char* grpc_sockaddr_to_uri_unix_if_possible(const grpc_resolved_address* addr) {
-  return NULL;
+std::string grpc_sockaddr_to_uri_unix_if_possible(
+    const grpc_resolved_address* addr) {
+  return "";
 }
 
 #endif

src/core/lib/json/json_reader.cc

@@ -20,8 +20,12 @@
 
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/json/json.h"
 
@@ -176,11 +180,10 @@ Json* JsonReader::CreateAndLinkValue() {
         if (errors_.size() == GRPC_JSON_MAX_ERRORS) {
           truncated_errors_ = true;
         } else {
-          char* msg;
-          gpr_asprintf(&msg, "duplicate key \"%s\" at index %" PRIuPTR,
-                       key_.c_str(), CurrentIndex());
-          errors_.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg));
-          gpr_free(msg);
+          errors_.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+              absl::StrFormat("duplicate key \"%s\" at index %" PRIuPTR, key_,
+                              CurrentIndex())
+                  .c_str()));
         }
       }
       value = &(*parent->mutable_object())[std::move(key_)];
@@ -198,11 +201,10 @@ bool JsonReader::StartContainer(Json::Type type) {
     if (errors_.size() == GRPC_JSON_MAX_ERRORS) {
       truncated_errors_ = true;
     } else {
-      char* msg;
-      gpr_asprintf(&msg, "exceeded max stack depth (%d) at index %" PRIuPTR,
-                   GRPC_JSON_MAX_DEPTH, CurrentIndex());
-      errors_.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg));
-      gpr_free(msg);
+      errors_.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrFormat("exceeded max stack depth (%d) at index %" PRIuPTR,
+                          GRPC_JSON_MAX_DEPTH, CurrentIndex())
+              .c_str()));
     }
     return false;
   }
@@ -824,17 +826,14 @@ grpc_error* JsonReader::Parse(absl::string_view input, Json* output) {
         "errors and try again to see additional errors"));
   }
   if (status == Status::GRPC_JSON_INTERNAL_ERROR) {
-    char* msg;
-    gpr_asprintf(&msg, "internal error in JSON parser at index %" PRIuPTR,
-                 reader.CurrentIndex());
-    reader.errors_.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg));
-    gpr_free(msg);
+    reader.errors_.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("internal error in JSON parser at index ",
+                     reader.CurrentIndex())
+            .c_str()));
   } else if (status == Status::GRPC_JSON_PARSE_ERROR) {
-    char* msg;
-    gpr_asprintf(&msg, "JSON parse error at index %" PRIuPTR,
-                 reader.CurrentIndex());
-    reader.errors_.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg));
-    gpr_free(msg);
+    reader.errors_.push_back(GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("JSON parse error at index ", reader.CurrentIndex())
+            .c_str()));
   }
   if (!reader.errors_.empty()) {
     return GRPC_ERROR_CREATE_FROM_VECTOR("JSON parsing failed",

src/core/lib/security/credentials/credentials.h

@@ -23,6 +23,8 @@
 
 #include <string.h>
 
+#include <string>
+
 #include <grpc/grpc.h>
 #include <grpc/grpc_security.h>
 #include <grpc/support/sync.h>
@@ -79,13 +81,13 @@ typedef enum {
 /* --- Google utils --- */
 
 /* It is the caller's responsibility to gpr_free the result if not NULL. */
-char* grpc_get_well_known_google_credentials_file_path(void);
+std::string grpc_get_well_known_google_credentials_file_path(void);
 
 /* Implementation function for the different platforms. */
-char* grpc_get_well_known_google_credentials_file_path_impl(void);
+std::string grpc_get_well_known_google_credentials_file_path_impl(void);
 
 /* Override for testing only. Not thread-safe */
-typedef char* (*grpc_well_known_credentials_path_getter)(void);
+typedef std::string (*grpc_well_known_credentials_path_getter)(void);
 void grpc_override_well_known_credentials_path_getter(
     grpc_well_known_credentials_path_getter getter);
 

src/core/lib/security/credentials/google_default/credentials_generic.cc

@@ -20,22 +20,24 @@
 
 #include "src/core/lib/security/credentials/google_default/google_default_credentials.h"
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/gpr/env.h"
-#include "src/core/lib/gpr/string.h"
 
-char* grpc_get_well_known_google_credentials_file_path_impl(void) {
-  char* result = nullptr;
+std::string grpc_get_well_known_google_credentials_file_path_impl(void) {
   char* base = gpr_getenv(GRPC_GOOGLE_CREDENTIALS_PATH_ENV_VAR);
   if (base == nullptr) {
     gpr_log(GPR_ERROR, "Could not get " GRPC_GOOGLE_CREDENTIALS_PATH_ENV_VAR
                        " environment variable.");
-    return nullptr;
+    return "";
   }
-  gpr_asprintf(&result, "%s/%s", base, GRPC_GOOGLE_CREDENTIALS_PATH_SUFFIX);
+  std::string result =
+      absl::StrCat(base, "/", GRPC_GOOGLE_CREDENTIALS_PATH_SUFFIX);
   gpr_free(base);
   return result;
 }

src/core/lib/security/credentials/google_default/google_default_credentials.cc

@@ -216,18 +216,19 @@ static int is_metadata_server_reachable() {
 
 /* Takes ownership of creds_path if not NULL. */
 static grpc_error* create_default_creds_from_path(
-    char* creds_path, grpc_core::RefCountedPtr<grpc_call_credentials>* creds) {
+    const std::string& creds_path,
+    grpc_core::RefCountedPtr<grpc_call_credentials>* creds) {
   grpc_auth_json_key key;
   grpc_auth_refresh_token token;
   grpc_core::RefCountedPtr<grpc_call_credentials> result;
   grpc_slice creds_data = grpc_empty_slice();
   grpc_error* error = GRPC_ERROR_NONE;
   Json json;
-  if (creds_path == nullptr) {
+  if (creds_path.empty()) {
     error = GRPC_ERROR_CREATE_FROM_STATIC_STRING("creds_path unset");
     goto end;
   }
-  error = grpc_load_file(creds_path, 0, &creds_data);
+  error = grpc_load_file(creds_path.c_str(), 0, &creds_data);
   if (error != GRPC_ERROR_NONE) goto end;
   json = Json::Parse(grpc_core::StringViewFromSlice(creds_data), &error);
   if (error != GRPC_ERROR_NONE) goto end;
@@ -267,7 +268,6 @@ static grpc_error* create_default_creds_from_path(
 
 end:
   GPR_ASSERT((result == nullptr) + (error == GRPC_ERROR_NONE) == 1);
-  if (creds_path != nullptr) gpr_free(creds_path);
   grpc_slice_unref_internal(creds_data);
   *creds = result;
   return error;
@@ -286,10 +286,13 @@ grpc_channel_credentials* grpc_google_default_credentials_create() {
   gpr_once_init(&g_once, init_default_credentials);
 
   /* First, try the environment variable. */
-  err = create_default_creds_from_path(
-      gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR), &call_creds);
-  if (err == GRPC_ERROR_NONE) goto end;
-  error = grpc_error_add_child(error, err);
+  char* path_from_env = gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR);
+  if (path_from_env != nullptr) {
+    err = create_default_creds_from_path(path_from_env, &call_creds);
+    gpr_free(path_from_env);
+    if (err == GRPC_ERROR_NONE) goto end;
+    error = grpc_error_add_child(error, err);
+  }
 
   /* Then the well-known file. */
   err = create_default_creds_from_path(
@@ -372,7 +375,7 @@ void grpc_flush_cached_google_default_credentials(void) {
 
 static grpc_well_known_credentials_path_getter creds_path_getter = nullptr;
 
-char* grpc_get_well_known_google_credentials_file_path(void) {
+std::string grpc_get_well_known_google_credentials_file_path(void) {
   if (creds_path_getter != nullptr) return creds_path_getter();
   return grpc_get_well_known_google_credentials_file_path_impl();
 }

src/core/lib/security/credentials/jwt/jwt_credentials.cc

@@ -23,8 +23,13 @@
 #include <inttypes.h>
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+
 #include "src/core/lib/gprpp/ref_counted.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/api_trace.h"
 
 #include <grpc/support/alloc.h>
@@ -81,16 +86,14 @@ bool grpc_service_account_jwt_access_credentials::get_request_metadata(
     jwt = grpc_jwt_encode_and_sign(&key_, context.service_url, jwt_lifetime_,
                                    nullptr);
     if (jwt != nullptr) {
-      char* md_value;
-      gpr_asprintf(&md_value, "Bearer %s", jwt);
+      std::string md_value = absl::StrCat("Bearer ", jwt);
       gpr_free(jwt);
       cached_.jwt_expiration =
           gpr_time_add(gpr_now(GPR_CLOCK_REALTIME), jwt_lifetime_);
       cached_.service_url = gpr_strdup(context.service_url);
       cached_.jwt_md = grpc_mdelem_from_slices(
           grpc_slice_from_static_string(GRPC_AUTHORIZATION_METADATA_KEY),
-          grpc_slice_from_copied_string(md_value));
-      gpr_free(md_value);
+          grpc_slice_from_cpp_string(std::move(md_value)));
       jwt_md = GRPC_MDELEM_REF(cached_.jwt_md);
     }
     gpr_mu_unlock(&cache_mu_);

src/core/lib/security/credentials/oauth2/oauth2_credentials.cc

@@ -24,6 +24,8 @@
 #include <string.h>
 
 #include "absl/container/inlined_vector.h"
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
 #include "absl/strings/str_join.h"
 
 #include <grpc/grpc_security.h>
@@ -33,7 +35,6 @@
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
 
-#include "absl/strings/str_format.h"
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
 #include "src/core/lib/iomgr/error.h"
@@ -136,7 +137,6 @@ grpc_oauth2_token_fetcher_credentials_parse_server_response(
     const grpc_http_response* response, grpc_mdelem* token_md,
     grpc_millis* token_lifetime) {
   char* null_terminated_body = nullptr;
-  char* new_access_token = nullptr;
   grpc_credentials_status status = GRPC_CREDENTIALS_OK;
   Json json;
 
@@ -202,12 +202,12 @@ grpc_oauth2_token_fetcher_credentials_parse_server_response(
       goto end;
     }
     expires_in = it->second.string_value().c_str();
-    gpr_asprintf(&new_access_token, "%s %s", token_type, access_token);
     *token_lifetime = strtol(expires_in, nullptr, 10) * GPR_MS_PER_SEC;
     if (!GRPC_MDISNULL(*token_md)) GRPC_MDELEM_UNREF(*token_md);
     *token_md = grpc_mdelem_from_slices(
         grpc_core::ExternallyManagedSlice(GRPC_AUTHORIZATION_METADATA_KEY),
-        grpc_core::UnmanagedMemorySlice(new_access_token));
+        grpc_slice_from_cpp_string(
+            absl::StrCat(token_type, " ", access_token)));
     status = GRPC_CREDENTIALS_OK;
   }
 
@@ -216,8 +216,7 @@ end:
     GRPC_MDELEM_UNREF(*token_md);
     *token_md = GRPC_MDNULL;
   }
-  if (null_terminated_body != nullptr) gpr_free(null_terminated_body);
-  if (new_access_token != nullptr) gpr_free(new_access_token);
+  gpr_free(null_terminated_body);
   return status;
 }
 
@@ -442,10 +441,9 @@ void grpc_google_refresh_token_credentials::fetch_oauth2(
       const_cast<char*>("Content-Type"),
       const_cast<char*>("application/x-www-form-urlencoded")};
   grpc_httpcli_request request;
-  char* body = nullptr;
-  gpr_asprintf(&body, GRPC_REFRESH_TOKEN_POST_BODY_FORMAT_STRING,
-               refresh_token_.client_id, refresh_token_.client_secret,
-               refresh_token_.refresh_token);
+  std::string body = absl::StrFormat(
+      GRPC_REFRESH_TOKEN_POST_BODY_FORMAT_STRING, refresh_token_.client_id,
+      refresh_token_.client_secret, refresh_token_.refresh_token);
   memset(&request, 0, sizeof(grpc_httpcli_request));
   request.host = (char*)GRPC_GOOGLE_OAUTH2_SERVICE_HOST;
   request.http.path = (char*)GRPC_GOOGLE_OAUTH2_SERVICE_TOKEN_PATH;
@@ -457,13 +455,12 @@ void grpc_google_refresh_token_credentials::fetch_oauth2(
      extreme memory pressure. */
   grpc_resource_quota* resource_quota =
       grpc_resource_quota_create("oauth2_credentials_refresh");
-  grpc_httpcli_post(httpcli_context, pollent, resource_quota, &request, body,
-                    strlen(body), deadline,
+  grpc_httpcli_post(httpcli_context, pollent, resource_quota, &request,
+                    body.c_str(), body.size(), deadline,
                     GRPC_CLOSURE_INIT(&http_post_cb_closure_, response_cb,
                                       metadata_req, grpc_schedule_on_exec_ctx),
                     &metadata_req->response);
   grpc_resource_quota_unref_internal(resource_quota);
-  gpr_free(body);
 }
 
 grpc_google_refresh_token_credentials::grpc_google_refresh_token_credentials(
@@ -487,16 +484,15 @@ std::string grpc_google_refresh_token_credentials::debug_string() {
                          grpc_oauth2_token_fetcher_credentials::debug_string());
 }
 
-static char* create_loggable_refresh_token(grpc_auth_refresh_token* token) {
+static std::string create_loggable_refresh_token(
+    grpc_auth_refresh_token* token) {
   if (strcmp(token->type, GRPC_AUTH_JSON_TYPE_INVALID) == 0) {
-    return gpr_strdup("<Invalid json token>");
+    return "<Invalid json token>";
   }
-  char* loggable_token = nullptr;
-  gpr_asprintf(&loggable_token,
-               "{\n type: %s\n client_id: %s\n client_secret: "
-               "<redacted>\n refresh_token: <redacted>\n}",
-               token->type, token->client_id);
-  return loggable_token;
+  return absl::StrFormat(
+      "{\n type: %s\n client_id: %s\n client_secret: "
+      "<redacted>\n refresh_token: <redacted>\n}",
+      token->type, token->client_id);
 }
 
 grpc_call_credentials* grpc_google_refresh_token_credentials_create(
@@ -504,12 +500,10 @@ grpc_call_credentials* grpc_google_refresh_token_credentials_create(
   grpc_auth_refresh_token token =
       grpc_auth_refresh_token_create_from_string(json_refresh_token);
   if (GRPC_TRACE_FLAG_ENABLED(grpc_api_trace)) {
-    char* loggable_token = create_loggable_refresh_token(&token);
     gpr_log(GPR_INFO,
             "grpc_refresh_token_credentials_create(json_refresh_token=%s, "
             "reserved=%p)",
-            loggable_token, reserved);
-    gpr_free(loggable_token);
+            create_loggable_refresh_token(&token).c_str(), reserved);
   }
   GPR_ASSERT(reserved == nullptr);
   return grpc_refresh_token_credentials_create_from_auth_refresh_token(token)
@@ -744,13 +738,10 @@ void grpc_access_token_credentials::cancel_get_request_metadata(
 grpc_access_token_credentials::grpc_access_token_credentials(
     const char* access_token)
     : grpc_call_credentials(GRPC_CALL_CREDENTIALS_TYPE_OAUTH2) {
-  char* token_md_value;
-  gpr_asprintf(&token_md_value, "Bearer %s", access_token);
   grpc_core::ExecCtx exec_ctx;
   access_token_md_ = grpc_mdelem_from_slices(
       grpc_core::ExternallyManagedSlice(GRPC_AUTHORIZATION_METADATA_KEY),
-      grpc_core::UnmanagedMemorySlice(token_md_value));
-  gpr_free(token_md_value);
+      grpc_slice_from_cpp_string(absl::StrCat("Bearer ", access_token)));
 }
 
 std::string grpc_access_token_credentials::debug_string() {

src/core/lib/security/credentials/plugin/plugin_credentials.cc

@@ -22,10 +22,11 @@
 
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 
 #include "src/core/lib/slice/slice_internal.h"
@@ -86,11 +87,10 @@ static grpc_error* process_plugin_result(
     size_t num_md, grpc_status_code status, const char* error_details) {
   grpc_error* error = GRPC_ERROR_NONE;
   if (status != GRPC_STATUS_OK) {
-    char* msg;
-    gpr_asprintf(&msg, "Getting metadata from plugin failed with error: %s",
-                 error_details);
-    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
+    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Getting metadata from plugin failed with error: ",
+                     error_details)
+            .c_str());
   } else {
     bool seen_illegal_header = false;
     for (size_t i = 0; i < num_md; ++i) {

src/core/lib/security/security_connector/fake/fake_security_connector.cc

@@ -22,6 +22,8 @@
 
 #include <stdbool.h>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
@@ -227,11 +229,10 @@ static void fake_check_peer(
   prop_name = peer.properties[0].name;
   if (prop_name == nullptr ||
       strcmp(prop_name, TSI_CERTIFICATE_TYPE_PEER_PROPERTY)) {
-    char* msg;
-    gpr_asprintf(&msg, "Unexpected property in fake peer: %s.",
-                 prop_name == nullptr ? "<EMPTY>" : prop_name);
-    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
+    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Unexpected property in fake peer: ",
+                     prop_name == nullptr ? "<EMPTY>" : prop_name)
+            .c_str());
     goto end;
   }
   if (strncmp(peer.properties[0].value.data, TSI_FAKE_CERTIFICATE_TYPE,
@@ -243,11 +244,10 @@ static void fake_check_peer(
   prop_name = peer.properties[1].name;
   if (prop_name == nullptr ||
       strcmp(prop_name, TSI_SECURITY_LEVEL_PEER_PROPERTY) != 0) {
-    char* msg;
-    gpr_asprintf(&msg, "Unexpected property in fake peer: %s.",
-                 prop_name == nullptr ? "<EMPTY>" : prop_name);
-    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
+    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Unexpected property in fake peer: ",
+                     prop_name == nullptr ? "<EMPTY>" : prop_name)
+            .c_str());
     goto end;
   }
   if (strncmp(peer.properties[1].value.data, TSI_FAKE_SECURITY_LEVEL,

src/core/lib/security/security_connector/ssl/ssl_security_connector.cc

@@ -22,11 +22,12 @@
 
 #include <stdbool.h>
 
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
 #include "absl/strings/string_view.h"
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/transport/chttp2/alpn/alpn.h"
 #include "src/core/lib/channel/handshaker.h"
@@ -53,11 +54,9 @@ grpc_error* ssl_check_peer(
   }
   /* Check the peer name if specified. */
   if (peer_name != nullptr && !grpc_ssl_host_matches_name(peer, peer_name)) {
-    char* msg;
-    gpr_asprintf(&msg, "Peer name %s is not in peer certificate", peer_name);
-    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return error;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Peer name ", peer_name, " is not in peer certificate")
+            .c_str());
   }
   *auth_context =
       grpc_ssl_peer_to_auth_context(peer, GRPC_SSL_TRANSPORT_SECURITY_TYPE);
@@ -163,11 +162,10 @@ class grpc_ssl_channel_security_connector final
             verify_options_->verify_peer_callback_userdata);
         gpr_free(peer_pem);
         if (callback_status) {
-          char* msg;
-          gpr_asprintf(&msg, "Verify peer callback returned a failure (%d)",
-                       callback_status);
-          error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-          gpr_free(msg);
+          error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+              absl::StrFormat("Verify peer callback returned a failure (%d)",
+                              callback_status)
+                  .c_str());
         }
       }
     }

src/core/lib/security/security_connector/ssl_utils.cc

@@ -20,12 +20,13 @@
 
 #include "src/core/lib/security/security_connector/ssl_utils.h"
 
+#include <vector>
+
+#include "absl/strings/str_cat.h"
+
 #include <grpc/slice_buffer.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-
-#include <vector>
 
 #include "src/core/ext/transport/chttp2/alpn/alpn.h"
 #include "src/core/lib/channel/channel_args.h"
@@ -170,12 +171,9 @@ grpc_error* grpc_ssl_check_peer_name(absl::string_view peer_name,
                                      const tsi_peer* peer) {
   /* Check the peer name if specified. */
   if (!peer_name.empty() && !grpc_ssl_host_matches_name(peer, peer_name)) {
-    char* msg;
-    gpr_asprintf(&msg, "Peer name %s is not in peer certificate",
-                 peer_name.data());
-    grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return error;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Peer name ", peer_name, " is not in peer certificate")
+            .c_str());
   }
   return GRPC_ERROR_NONE;
 }

src/core/lib/security/security_connector/tls/tls_security_connector.cc

@@ -23,6 +23,7 @@
 #include <stdbool.h>
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 
 #include <grpc/grpc.h>
@@ -130,11 +131,9 @@ grpc_status_code TlsFetchKeyMaterials(
 grpc_error* TlsCheckHostName(const char* peer_name, const tsi_peer* peer) {
   /* Check the peer name if specified. */
   if (peer_name != nullptr && !grpc_ssl_host_matches_name(peer, peer_name)) {
-    char* msg;
-    gpr_asprintf(&msg, "Peer name %s is not in peer certificate", peer_name);
-    grpc_error* error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
-    return error;
+    return GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Peer name ", peer_name, " is not in peer certificate")
+            .c_str());
   }
   return GRPC_ERROR_NONE;
 }
@@ -402,31 +401,30 @@ void TlsChannelSecurityConnector::ServerAuthorizationCheckDone(
 grpc_error* TlsChannelSecurityConnector::ProcessServerAuthorizationCheckResult(
     grpc_tls_server_authorization_check_arg* arg) {
   grpc_error* error = GRPC_ERROR_NONE;
-  char* msg = nullptr;
   /* Server authorization check is cancelled by caller. */
   if (arg->status == GRPC_STATUS_CANCELLED) {
-    gpr_asprintf(&msg,
-                 "Server authorization check is cancelled by the caller with "
-                 "error: %s",
-                 arg->error_details->error_details().c_str());
-    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
+    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("Server authorization check is cancelled by the caller "
+                     "with error: ",
+                     arg->error_details->error_details())
+            .c_str());
   } else if (arg->status == GRPC_STATUS_OK) {
     /* Server authorization check completed successfully but returned check
      * failure. */
     if (!arg->success) {
-      gpr_asprintf(&msg, "Server authorization check failed with error: %s",
-                   arg->error_details->error_details().c_str());
-      error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
+      error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrCat("Server authorization check failed with error: ",
+                       arg->error_details->error_details())
+              .c_str());
     }
     /* Server authorization check did not complete correctly. */
   } else {
-    gpr_asprintf(
-        &msg,
-        "Server authorization check did not finish correctly with error: %s",
-        arg->error_details->error_details().c_str());
-    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
+    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat(
+            "Server authorization check did not finish correctly with error: ",
+            arg->error_details->error_details())
+            .c_str());
   }
-  gpr_free(msg);
   return error;
 }
 

src/core/lib/security/transport/client_auth_filter.cc

@@ -22,6 +22,10 @@
 
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
@@ -331,18 +335,15 @@ static void on_host_checked(void* arg, grpc_error* error) {
   if (error == GRPC_ERROR_NONE) {
     send_security_metadata(elem, batch);
   } else {
-    char* error_msg;
-    char* host = grpc_slice_to_c_string(calld->host);
-    gpr_asprintf(&error_msg, "Invalid host %s set in :authority metadata.",
-                 host);
-    gpr_free(host);
+    std::string error_msg = absl::StrCat(
+        "Invalid host ", grpc_core::StringViewFromSlice(calld->host),
+        " set in :authority metadata.");
     grpc_transport_stream_op_batch_finish_with_failure(
         batch,
-        grpc_error_set_int(GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg),
-                           GRPC_ERROR_INT_GRPC_STATUS,
-                           GRPC_STATUS_UNAUTHENTICATED),
+        grpc_error_set_int(
+            GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg.c_str()),
+            GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAUTHENTICATED),
         calld->call_combiner);
-    gpr_free(error_msg);
   }
   GRPC_CALL_STACK_UNREF(calld->owning_call, "check_call_host");
 }

src/core/lib/security/util/json_util.cc

@@ -18,14 +18,16 @@
 
 #include <grpc/support/port_platform.h>
 
-#include "src/core/lib/iomgr/error.h"
-#include "src/core/lib/security/util/json_util.h"
-
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/support/log.h>
 #include <grpc/support/string_util.h>
 
+#include "src/core/lib/iomgr/error.h"
+#include "src/core/lib/security/util/json_util.h"
+
 const char* grpc_json_get_string_property(const grpc_core::Json& json,
                                           const char* prop_name,
                                           grpc_error** error) {
@@ -39,21 +41,18 @@ const char* grpc_json_get_string_property(const grpc_core::Json& json,
   auto it = json.object_value().find(prop_name);
   if (it == json.object_value().end()) {
     if (error != nullptr) {
-      char* error_msg;
-      gpr_asprintf(&error_msg, "Property %s not found in JSON object.",
-                   prop_name);
-      *error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg);
-      gpr_free(error_msg);
+      *error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrCat("Property ", prop_name, " not found in JSON object.")
+              .c_str());
     }
     return nullptr;
   }
   if (it->second.type() != grpc_core::Json::Type::STRING) {
     if (error != nullptr) {
-      char* error_msg;
-      gpr_asprintf(&error_msg, "Property %s in JSON object is not a string.",
-                   prop_name);
-      *error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(error_msg);
-      gpr_free(error_msg);
+      *error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+          absl::StrCat("Property ", prop_name,
+                       " n JSON object is not a string.")
+              .c_str());
     }
     return nullptr;
   }

src/core/lib/slice/slice.cc

@@ -156,7 +156,7 @@ class NewWithLenSliceRefcount {
 /** grpc_slice_from_moved_(string|buffer) ref count .*/
 class MovedStringSliceRefCount {
  public:
-  MovedStringSliceRefCount(grpc_core::UniquePtr<char>&& str)
+  explicit MovedStringSliceRefCount(grpc_core::UniquePtr<char>&& str)
       : base_(grpc_slice_refcount::Type::REGULAR, &refs_, Destroy, this,
               &base_),
         str_(std::move(str)) {}
@@ -173,6 +173,26 @@ class MovedStringSliceRefCount {
   grpc_core::UniquePtr<char> str_;
 };
 
+// grpc_slice_from_cpp_string() ref count.
+class MovedCppStringSliceRefCount {
+ public:
+  explicit MovedCppStringSliceRefCount(std::string&& str)
+      : base_(grpc_slice_refcount::Type::REGULAR, &refs_, Destroy, this,
+              &base_),
+        str_(std::move(str)) {}
+
+  grpc_slice_refcount* base_refcount() { return &base_; }
+
+ private:
+  static void Destroy(void* arg) {
+    delete static_cast<MovedCppStringSliceRefCount*>(arg);
+  }
+
+  grpc_slice_refcount base_;
+  grpc_core::RefCount refs_;
+  std::string str_;
+};
+
 }  // namespace grpc_core
 
 grpc_slice grpc_slice_new_with_len(void* p, size_t len,
@@ -232,6 +252,23 @@ grpc_slice grpc_slice_from_moved_string(grpc_core::UniquePtr<char> p) {
   return grpc_slice_from_moved_buffer(std::move(p), len);
 }
 
+grpc_slice grpc_slice_from_cpp_string(std::string str) {
+  grpc_slice slice;
+  if (str.size() <= sizeof(slice.data.inlined.bytes)) {
+    slice.refcount = nullptr;
+    slice.data.inlined.length = str.size();
+    memcpy(GRPC_SLICE_START_PTR(slice), str.data(), str.size());
+  } else {
+    slice.data.refcounted.bytes =
+        reinterpret_cast<uint8_t*>(const_cast<char*>(str.data()));
+    slice.data.refcounted.length = str.size();
+    slice.refcount =
+        (new grpc_core::MovedCppStringSliceRefCount(std::move(str)))
+            ->base_refcount();
+  }
+  return slice;
+}
+
 namespace {
 
 class MallocRefCount {

src/core/lib/slice/slice_internal.h

@@ -338,6 +338,7 @@ inline uint32_t grpc_slice_hash_internal(const grpc_slice& s) {
 grpc_slice grpc_slice_from_moved_buffer(grpc_core::UniquePtr<char> p,
                                         size_t len);
 grpc_slice grpc_slice_from_moved_string(grpc_core::UniquePtr<char> p);
+grpc_slice grpc_slice_from_cpp_string(std::string str);
 
 // Returns the memory used by this slice, not counting the slice structure
 // itself. This means that inlined and slices from static strings will return

src/core/lib/surface/call.cc

@@ -24,6 +24,11 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+
 #include <grpc/compression.h>
 #include <grpc/grpc.h>
 #include <grpc/slice.h>
@@ -1051,14 +1056,12 @@ static void recv_trailing_filter(void* args, grpc_metadata_batch* b,
         grpc_get_status_code_from_metadata(b->idx.named.grpc_status->md);
     grpc_error* error = GRPC_ERROR_NONE;
     if (status_code != GRPC_STATUS_OK) {
-      char* peer_msg = nullptr;
       char* peer = grpc_call_get_peer(call);
-      gpr_asprintf(&peer_msg, "Error received from peer %s", peer);
-      error = grpc_error_set_int(GRPC_ERROR_CREATE_FROM_COPIED_STRING(peer_msg),
-                                 GRPC_ERROR_INT_GRPC_STATUS,
-                                 static_cast<intptr_t>(status_code));
+      error = grpc_error_set_int(
+          GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+              absl::StrCat("Error received from peer ", peer).c_str()),
+          GRPC_ERROR_INT_GRPC_STATUS, static_cast<intptr_t>(status_code));
       gpr_free(peer);
-      gpr_free(peer_msg);
     }
     if (b->idx.named.grpc_message != nullptr) {
       error = grpc_error_set_str(
@@ -1369,49 +1372,41 @@ static void receiving_stream_ready_in_call_combiner(void* bctlp,
 
 static void GPR_ATTRIBUTE_NOINLINE
 handle_both_stream_and_msg_compression_set(grpc_call* call) {
-  char* error_msg = nullptr;
-  gpr_asprintf(&error_msg,
-               "Incoming stream has both stream compression (%d) and message "
-               "compression (%d).",
-               call->incoming_stream_compression_algorithm,
-               call->incoming_message_compression_algorithm);
-  gpr_log(GPR_ERROR, "%s", error_msg);
-  cancel_with_status(call, GRPC_STATUS_INTERNAL, error_msg);
-  gpr_free(error_msg);
+  std::string error_msg = absl::StrFormat(
+      "Incoming stream has both stream compression (%d) and message "
+      "compression (%d).",
+      call->incoming_stream_compression_algorithm,
+      call->incoming_message_compression_algorithm);
+  gpr_log(GPR_ERROR, "%s", error_msg.c_str());
+  cancel_with_status(call, GRPC_STATUS_INTERNAL, error_msg.c_str());
 }
 
 static void GPR_ATTRIBUTE_NOINLINE
 handle_error_parsing_compression_algorithm(grpc_call* call) {
-  char* error_msg = nullptr;
-  gpr_asprintf(&error_msg,
-               "Error in incoming message compression (%d) or stream "
-               "compression (%d).",
-               call->incoming_stream_compression_algorithm,
-               call->incoming_message_compression_algorithm);
-  cancel_with_status(call, GRPC_STATUS_INTERNAL, error_msg);
-  gpr_free(error_msg);
+  std::string error_msg = absl::StrFormat(
+      "Error in incoming message compression (%d) or stream "
+      "compression (%d).",
+      call->incoming_stream_compression_algorithm,
+      call->incoming_message_compression_algorithm);
+  cancel_with_status(call, GRPC_STATUS_INTERNAL, error_msg.c_str());
 }
 
 static void GPR_ATTRIBUTE_NOINLINE handle_invalid_compression(
     grpc_call* call, grpc_compression_algorithm compression_algorithm) {
-  char* error_msg = nullptr;
-  gpr_asprintf(&error_msg, "Invalid compression algorithm value '%d'.",
-               compression_algorithm);
-  gpr_log(GPR_ERROR, "%s", error_msg);
-  cancel_with_status(call, GRPC_STATUS_UNIMPLEMENTED, error_msg);
-  gpr_free(error_msg);
+  std::string error_msg = absl::StrFormat(
+      "Invalid compression algorithm value '%d'.", compression_algorithm);
+  gpr_log(GPR_ERROR, "%s", error_msg.c_str());
+  cancel_with_status(call, GRPC_STATUS_UNIMPLEMENTED, error_msg.c_str());
 }
 
 static void GPR_ATTRIBUTE_NOINLINE handle_compression_algorithm_disabled(
     grpc_call* call, grpc_compression_algorithm compression_algorithm) {
-  char* error_msg = nullptr;
   const char* algo_name = nullptr;
   grpc_compression_algorithm_name(compression_algorithm, &algo_name);
-  gpr_asprintf(&error_msg, "Compression algorithm '%s' is disabled.",
-               algo_name);
-  gpr_log(GPR_ERROR, "%s", error_msg);
-  cancel_with_status(call, GRPC_STATUS_UNIMPLEMENTED, error_msg);
-  gpr_free(error_msg);
+  std::string error_msg =
+      absl::StrFormat("Compression algorithm '%s' is disabled.", algo_name);
+  gpr_log(GPR_ERROR, "%s", error_msg.c_str());
+  cancel_with_status(call, GRPC_STATUS_UNIMPLEMENTED, error_msg.c_str());
 }
 
 static void GPR_ATTRIBUTE_NOINLINE handle_compression_algorithm_not_accepted(

src/core/lib/uri/uri_parser.cc

@@ -22,10 +22,13 @@
 
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <grpc/slice_buffer.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/slice/percent_encoding.h"
@@ -37,22 +40,12 @@
 
 static grpc_uri* bad_uri(const char* uri_text, size_t pos, const char* section,
                          bool suppress_errors) {
-  char* line_prefix;
-  size_t pfx_len;
-
   if (!suppress_errors) {
-    gpr_asprintf(&line_prefix, "bad uri.%s: '", section);
-    pfx_len = strlen(line_prefix) + pos;
-    gpr_log(GPR_ERROR, "%s%s'", line_prefix, uri_text);
-    gpr_free(line_prefix);
-
-    line_prefix = static_cast<char*>(gpr_malloc(pfx_len + 1));
-    memset(line_prefix, ' ', pfx_len);
-    line_prefix[pfx_len] = 0;
-    gpr_log(GPR_ERROR, "%s^ here", line_prefix);
-    gpr_free(line_prefix);
+    std::string line_prefix = absl::StrFormat("bad uri.%s: '", section);
+    gpr_log(GPR_ERROR, "%s%s'", line_prefix.c_str(), uri_text);
+    size_t pfx_len = line_prefix.size() + pos;
+    gpr_log(GPR_ERROR, "%s^ here", std::string(pfx_len, ' ').c_str());
   }
-
   return nullptr;
 }
 

test/core/client_channel/parse_address_with_named_scope_id_test.cc

@@ -26,9 +26,10 @@
 #include <sys/un.h>
 #endif
 
+#include "absl/strings/str_format.h"
+
 #include <grpc/grpc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/lib/gprpp/host_port.h"
 #include "src/core/lib/gprpp/memory.h"
@@ -108,18 +109,17 @@ int main(int argc, char** argv) {
     }
   }
   GPR_ASSERT(strlen(arbitrary_interface_name) > 0);
-  char* target = nullptr;
-  gpr_asprintf(&target, "ipv6:[fe80::1234%%%s]:12345",
-               arbitrary_interface_name);
+  std::string target =
+      absl::StrFormat("ipv6:[fe80::1234%%%s]:12345", arbitrary_interface_name);
   struct sockaddr_in6 result_from_getaddrinfo =
-      resolve_with_gettaddrinfo(target);
+      resolve_with_gettaddrinfo(target.c_str());
   // Run the test
   gpr_log(GPR_DEBUG,
           "Run test_grpc_parse_ipv6_parity_with_getaddrinfo with target: %s",
-          target);
-  test_grpc_parse_ipv6_parity_with_getaddrinfo(target, result_from_getaddrinfo);
+          target.c_str());
+  test_grpc_parse_ipv6_parity_with_getaddrinfo(target.c_str(),
+                                               result_from_getaddrinfo);
   // Cleanup
-  gpr_free(target);
   gpr_free(arbitrary_interface_name);
   grpc_shutdown();
 }

test/core/client_channel/resolvers/fake_resolver_test.cc

@@ -18,9 +18,12 @@
 
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 
 #include "src/core/ext/filters/client_channel/parse_address.h"
 #include "src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h"
@@ -85,13 +88,12 @@ static grpc_core::OrphanablePtr<grpc_core::Resolver> build_fake_resolver(
 static grpc_core::Resolver::Result create_new_resolver_result() {
   static size_t test_counter = 0;
   const size_t num_addresses = 2;
-  char* uri_string;
   // Create address list.
   grpc_core::Resolver::Result result;
   for (size_t i = 0; i < num_addresses; ++i) {
-    gpr_asprintf(&uri_string, "ipv4:127.0.0.1:100%" PRIuPTR,
-                 test_counter * num_addresses + i);
-    grpc_uri* uri = grpc_uri_parse(uri_string, true);
+    std::string uri_string = absl::StrFormat("ipv4:127.0.0.1:100%" PRIuPTR,
+                                             test_counter * num_addresses + i);
+    grpc_uri* uri = grpc_uri_parse(uri_string.c_str(), true);
     grpc_resolved_address address;
     GPR_ASSERT(grpc_parse_uri(uri, &address));
     absl::InlinedVector<grpc_arg, 2> args_to_add;
@@ -99,7 +101,6 @@ static grpc_core::Resolver::Result create_new_resolver_result() {
         address.addr, address.len,
         grpc_channel_args_copy_and_add(nullptr, nullptr, 0));
     grpc_uri_destroy(uri);
-    gpr_free(uri_string);
   }
   ++test_counter;
   return result;

test/core/end2end/dualstack_socket_test.cc

@@ -66,9 +66,8 @@ static void log_resolved_addrs(const char* label, const char* hostname) {
     return;
   }
   for (size_t i = 0; i < res->naddrs; ++i) {
-    char* addr_str = grpc_sockaddr_to_uri(&res->addrs[i]);
-    gpr_log(GPR_INFO, "%s: %s", label, addr_str);
-    gpr_free(addr_str);
+    gpr_log(GPR_INFO, "%s: %s", label,
+            grpc_sockaddr_to_uri(&res->addrs[i]).c_str());
   }
   grpc_resolved_addresses_destroy(res);
 }

test/core/end2end/fixtures/h2_http_proxy.cc

@@ -20,9 +20,12 @@
 
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 
 #include "src/core/ext/filters/client_channel/client_channel.h"
@@ -66,21 +69,19 @@ void chttp2_init_client_fullstack(grpc_end2end_test_fixture* f,
                                   grpc_channel_args* client_args) {
   fullstack_fixture_data* ffd =
       static_cast<fullstack_fixture_data*>(f->fixture_data);
-  char* proxy_uri;
-
   /* If testing for proxy auth, add credentials to proxy uri */
-  const grpc_arg* proxy_auth_arg =
-      grpc_channel_args_find(client_args, GRPC_ARG_HTTP_PROXY_AUTH_CREDS);
-  const char* proxy_auth_str = grpc_channel_arg_get_string(proxy_auth_arg);
+  const char* proxy_auth_str = grpc_channel_args_find_string(
+      client_args, GRPC_ARG_HTTP_PROXY_AUTH_CREDS);
+  std::string proxy_uri;
   if (proxy_auth_str == nullptr) {
-    gpr_asprintf(&proxy_uri, "http://%s",
-                 grpc_end2end_http_proxy_get_proxy_name(ffd->proxy));
+    proxy_uri = absl::StrFormat(
+        "http://%s", grpc_end2end_http_proxy_get_proxy_name(ffd->proxy));
   } else {
-    gpr_asprintf(&proxy_uri, "http://%s@%s", proxy_auth_str,
-                 grpc_end2end_http_proxy_get_proxy_name(ffd->proxy));
+    proxy_uri =
+        absl::StrFormat("http://%s@%s", proxy_auth_str,
+                        grpc_end2end_http_proxy_get_proxy_name(ffd->proxy));
   }
-  gpr_setenv("http_proxy", proxy_uri);
-  gpr_free(proxy_uri);
+  gpr_setenv("http_proxy", proxy_uri.c_str());
   f->client = grpc_insecure_channel_create(ffd->server_addr.c_str(),
                                            client_args, nullptr);
   GPR_ASSERT(f->client);

test/core/end2end/fixtures/h2_uds.cc

@@ -22,9 +22,12 @@
 #include <string.h>
 #include <unistd.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 
 #include "src/core/ext/filters/client_channel/client_channel.h"
@@ -37,22 +40,20 @@
 #include "test/core/util/port.h"
 #include "test/core/util/test_config.h"
 
-typedef struct fullstack_fixture_data {
-  char* localaddr;
-} fullstack_fixture_data;
+struct fullstack_fixture_data {
+  std::string localaddr;
+};
 
 static int unique = 1;
 
 static grpc_end2end_test_fixture chttp2_create_fixture_fullstack(
     grpc_channel_args* /*client_args*/, grpc_channel_args* /*server_args*/) {
+  fullstack_fixture_data* ffd = new fullstack_fixture_data;
+  ffd->localaddr = absl::StrFormat("unix:/tmp/grpc_fullstack_test.%d.%d",
+                                   getpid(), unique++);
+
   grpc_end2end_test_fixture f;
-  fullstack_fixture_data* ffd = static_cast<fullstack_fixture_data*>(
-      gpr_malloc(sizeof(fullstack_fixture_data)));
   memset(&f, 0, sizeof(f));
-
-  gpr_asprintf(&ffd->localaddr, "unix:/tmp/grpc_fullstack_test.%d.%d", getpid(),
-               unique++);
-
   f.fixture_data = ffd;
   f.cq = grpc_completion_queue_create_for_next(nullptr);
   f.shutdown_cq = grpc_completion_queue_create_for_pluck(nullptr);
@@ -64,8 +65,8 @@ void chttp2_init_client_fullstack(grpc_end2end_test_fixture* f,
                                   grpc_channel_args* client_args) {
   fullstack_fixture_data* ffd =
       static_cast<fullstack_fixture_data*>(f->fixture_data);
-  f->client =
-      grpc_insecure_channel_create(ffd->localaddr, client_args, nullptr);
+  f->client = grpc_insecure_channel_create(ffd->localaddr.c_str(), client_args,
+                                           nullptr);
 }
 
 void chttp2_init_server_fullstack(grpc_end2end_test_fixture* f,
@@ -77,15 +78,15 @@ void chttp2_init_server_fullstack(grpc_end2end_test_fixture* f,
   }
   f->server = grpc_server_create(server_args, nullptr);
   grpc_server_register_completion_queue(f->server, f->cq, nullptr);
-  GPR_ASSERT(grpc_server_add_insecure_http2_port(f->server, ffd->localaddr));
+  GPR_ASSERT(
+      grpc_server_add_insecure_http2_port(f->server, ffd->localaddr.c_str()));
   grpc_server_start(f->server);
 }
 
 void chttp2_tear_down_fullstack(grpc_end2end_test_fixture* f) {
   fullstack_fixture_data* ffd =
       static_cast<fullstack_fixture_data*>(f->fixture_data);
-  gpr_free(ffd->localaddr);
-  gpr_free(ffd);
+  delete ffd;
 }
 
 /* All test configurations */

test/core/end2end/fixtures/http_proxy_fixture.cc

@@ -22,12 +22,13 @@
 
 #include <string.h>
 
+#include "absl/strings/str_cat.h"
+
 #include <grpc/grpc.h>
 #include <grpc/slice_buffer.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/atm.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/sync.h>
 
 #include "src/core/lib/channel/channel_args.h"
@@ -492,11 +493,10 @@ static void on_read_request_done_locked(void* arg, grpc_error* error) {
   }
   // Make sure we got a CONNECT request.
   if (strcmp(conn->http_request.method, "CONNECT") != 0) {
-    char* msg;
-    gpr_asprintf(&msg, "HTTP proxy got request method %s",
-                 conn->http_request.method);
-    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(msg);
-    gpr_free(msg);
+    error = GRPC_ERROR_CREATE_FROM_COPIED_STRING(
+        absl::StrCat("HTTP proxy got request method ",
+                     conn->http_request.method)
+            .c_str());
     proxy_connection_failed(conn, SETUP_FAILED, "HTTP proxy read request",
                             GRPC_ERROR_REF(error));
     GRPC_ERROR_UNREF(error);

test/core/end2end/goaway_server_test.cc

@@ -23,11 +23,16 @@
 #include "src/core/lib/iomgr/sockaddr.h"
 #include "src/core/lib/iomgr/socket_utils.h"
 
+#include <string.h>
+
+#include <string>
+
+#include "absl/strings/str_cat.h"
+
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
-#include <string.h>
+
 #include "src/core/ext/filters/client_channel/resolver/dns/c_ares/grpc_ares_wrapper.h"
 #include "src/core/ext/filters/client_channel/server_address.h"
 #include "src/core/lib/iomgr/resolve_address.h"
@@ -185,7 +190,7 @@ int main(int argc, char** argv) {
   int port1 = grpc_pick_unused_port_or_die();
   int port2 = grpc_pick_unused_port_or_die();
 
-  char* addr;
+  std::string addr;
 
   grpc_channel_args client_args;
   grpc_arg arg_array[2];
@@ -242,10 +247,9 @@ int main(int argc, char** argv) {
 
   /* bring a server up on the first port */
   grpc_server* server1 = grpc_server_create(nullptr, nullptr);
-  gpr_asprintf(&addr, "127.0.0.1:%d", port1);
-  grpc_server_add_insecure_http2_port(server1, addr);
+  addr = absl::StrCat("127.0.0.1:", port1);
+  grpc_server_add_insecure_http2_port(server1, addr.c_str());
   grpc_server_register_completion_queue(server1, cq, nullptr);
-  gpr_free(addr);
   grpc_server_start(server1);
 
   /* request a call to the server */
@@ -319,10 +323,9 @@ int main(int argc, char** argv) {
   /* and bring up second server */
   set_resolve_port(port2);
   grpc_server* server2 = grpc_server_create(nullptr, nullptr);
-  gpr_asprintf(&addr, "127.0.0.1:%d", port2);
-  grpc_server_add_insecure_http2_port(server2, addr);
+  addr = absl::StrCat("127.0.0.1:", port2);
+  grpc_server_add_insecure_http2_port(server2, addr.c_str());
   grpc_server_register_completion_queue(server2, cq, nullptr);
-  gpr_free(addr);
   grpc_server_start(server2);
 
   /* request a call to the server */

test/core/end2end/tests/compressed_payload.cc

@@ -21,12 +21,15 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <grpc/byte_buffer.h>
 #include <grpc/byte_buffer_reader.h>
 #include <grpc/compression.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 
 #include "src/core/lib/channel/channel_args.h"
@@ -246,12 +249,10 @@ static void request_for_disabled_algorithm(
 
   const char* algo_name = nullptr;
   GPR_ASSERT(grpc_compression_algorithm_name(algorithm_to_disable, &algo_name));
-  char* expected_details = nullptr;
-  gpr_asprintf(&expected_details, "Compression algorithm '%s' is disabled.",
-               algo_name);
+  std::string expected_details =
+      absl::StrFormat("Compression algorithm '%s' is disabled.", algo_name);
   /* and we expect a specific reason for it */
-  GPR_ASSERT(0 == grpc_slice_str_cmp(details, expected_details));
-  gpr_free(expected_details);
+  GPR_ASSERT(0 == grpc_slice_str_cmp(details, expected_details.c_str()));
   GPR_ASSERT(0 == grpc_slice_str_cmp(call_details.method, "/foo"));
 
   grpc_slice_unref(details);

test/core/end2end/tests/high_initial_seqno.cc

@@ -21,11 +21,14 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+
 #include <grpc/byte_buffer.h>
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 
 #include "src/core/lib/gpr/string.h"
@@ -205,7 +208,6 @@ static void test_invoke_10_simple_requests(grpc_end2end_test_config config,
   grpc_end2end_test_fixture f;
   grpc_arg client_arg;
   grpc_channel_args client_args;
-  char* name;
 
   client_arg.type = GRPC_ARG_INTEGER;
   client_arg.key = const_cast<char*>(GRPC_ARG_HTTP2_INITIAL_SEQUENCE_NUMBER);
@@ -214,16 +216,15 @@ static void test_invoke_10_simple_requests(grpc_end2end_test_config config,
   client_args.num_args = 1;
   client_args.args = &client_arg;
 
-  gpr_asprintf(&name, "test_invoke_requests first_seqno=%d",
-               initial_sequence_number);
-  f = begin_test(config, name, &client_args, nullptr);
+  std::string name = absl::StrCat("test_invoke_requests first_seqno=",
+                                  initial_sequence_number);
+  f = begin_test(config, name.c_str(), &client_args, nullptr);
   for (i = 0; i < 10; i++) {
     simple_request_body(config, f);
     gpr_log(GPR_INFO, "Running test: Passed simple request %d", i);
   }
   end_test(&f);
   config.tear_down_data(&f);
-  gpr_free(name);
 }
 
 void high_initial_seqno(grpc_end2end_test_config config) {

test/core/end2end/tests/hpack_size.cc

@@ -21,11 +21,14 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <grpc/byte_buffer.h>
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 
 #include "src/core/lib/gpr/string.h"
@@ -355,7 +358,6 @@ static void test_size(grpc_end2end_test_config config, int encode_size,
   grpc_channel_args server_args;
   grpc_arg client_arg;
   grpc_channel_args client_args;
-  char* name;
 
   server_arg.type = GRPC_ARG_INTEGER;
   server_arg.key = const_cast<char*>(GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_DECODER);
@@ -369,15 +371,16 @@ static void test_size(grpc_end2end_test_config config, int encode_size,
   client_args.num_args = 1;
   client_args.args = &client_arg;
 
-  gpr_asprintf(&name, "test_size:e=%d:d=%d", encode_size, decode_size);
-  f = begin_test(config, name, encode_size != 4096 ? &client_args : nullptr,
+  std::string name =
+      absl::StrFormat("test_size:e=%d:d=%d", encode_size, decode_size);
+  f = begin_test(config, name.c_str(),
+                 encode_size != 4096 ? &client_args : nullptr,
                  decode_size != 4096 ? &server_args : nullptr);
   for (i = 0; i < 4 * GPR_ARRAY_SIZE(hobbits); i++) {
     simple_request_body(config, f, i);
   }
   end_test(&f);
   config.tear_down_data(&f);
-  gpr_free(name);
 }
 
 void hpack_size(grpc_end2end_test_config config) {

test/core/end2end/tests/invoke_large_request.cc

@@ -21,10 +21,13 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_format.h"
+
 #include <grpc/byte_buffer.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 
 #include "src/core/lib/gpr/useful.h"
@@ -90,10 +93,9 @@ static grpc_slice large_slice(void) {
 
 static void test_invoke_large_request(grpc_end2end_test_config config,
                                       int max_frame_size, int lookahead_bytes) {
-  char* name;
-  gpr_asprintf(&name,
-               "test_invoke_large_request:max_frame_size=%d:lookahead_bytes=%d",
-               max_frame_size, lookahead_bytes);
+  std::string name = absl::StrFormat(
+      "test_invoke_large_request:max_frame_size=%d:lookahead_bytes=%d",
+      max_frame_size, lookahead_bytes);
 
   grpc_arg args[2];
   args[0].type = GRPC_ARG_INTEGER;
@@ -105,8 +107,7 @@ static void test_invoke_large_request(grpc_end2end_test_config config,
   grpc_channel_args channel_args = {GPR_ARRAY_SIZE(args), args};
 
   grpc_end2end_test_fixture f =
-      begin_test(config, name, &channel_args, &channel_args);
-  gpr_free(name);
+      begin_test(config, name.c_str(), &channel_args, &channel_args);
 
   grpc_slice request_payload_slice = large_slice();
   grpc_slice response_payload_slice = large_slice();

test/core/end2end/tests/no_logging.cc

@@ -21,11 +21,14 @@
 #include <stdio.h>
 #include <string.h>
 
+#include <string>
+
+#include "absl/strings/str_cat.h"
+
 #include <grpc/byte_buffer.h>
 #include <grpc/grpc.h>
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
-#include <grpc/support/string_util.h>
 #include <grpc/support/time.h>
 #include "src/core/lib/gpr/string.h"
 #include "src/core/lib/iomgr/error.h"
@@ -38,11 +41,9 @@ static void* tag(intptr_t t) { return (void*)t; }
 void gpr_default_log(gpr_log_func_args* args);
 
 static void test_no_log(gpr_log_func_args* args) {
-  char* message = nullptr;
-  gpr_asprintf(&message, "Unwanted log: %s", args->message);
-  args->message = message;
+  std::string message = absl::StrCat("Unwanted log: ", args->message);
+  args->message = message.c_str();
   gpr_default_log(args);
-  gpr_free(message);
   abort();
 }