Backport the grpc_channel_arg_get_integer function

src/core/ext/client_config/subchannel.c

@@ -33,6 +33,7 @@
 
 #include "src/core/ext/client_config/subchannel.h"
 
+#include <limits.h>
 #include <string.h>
 
 #include <grpc/support/alloc.h>

src/core/lib/channel/channel_args.c

@@ -271,3 +271,21 @@ int grpc_channel_args_compare(const grpc_channel_args *a,
   }
   return 0;
 }
+
+int grpc_channel_arg_get_integer(grpc_arg *arg, grpc_integer_options options) {
+  if (arg->type != GRPC_ARG_INTEGER) {
+    gpr_log(GPR_ERROR, "%s ignored: it must be an integer", arg->key);
+    return options.default_value;
+  }
+  if (arg->value.integer < options.min_value) {
+    gpr_log(GPR_ERROR, "%s ignored: it must be >= %d", arg->key,
+            options.min_value);
+    return options.default_value;
+  }
+  if (arg->value.integer > options.max_value) {
+    gpr_log(GPR_ERROR, "%s ignored: it must be <= %d", arg->key,
+            options.max_value);
+    return options.default_value;
+  }
+  return arg->value.integer;
+}

src/core/lib/channel/channel_args.h

@@ -87,4 +87,12 @@ uint32_t grpc_channel_args_compression_algorithm_get_states(
 int grpc_channel_args_compare(const grpc_channel_args *a,
                               const grpc_channel_args *b);
 
+typedef struct grpc_integer_options {
+  int default_value;  // Return this if value is outside of expected bounds.
+  int min_value;
+  int max_value;
+} grpc_integer_options;
+/** Returns the value of \a arg, subject to the contraints in \a options. */
+int grpc_channel_arg_get_integer(grpc_arg *arg, grpc_integer_options options);
+
 #endif /* GRPC_CORE_LIB_CHANNEL_CHANNEL_ARGS_H */