php: fix channel get_target leak

src/php/ext/grpc/channel.c

@@ -41,6 +41,7 @@
 
 #include <grpc/grpc.h>
 #include <grpc/grpc_security.h>
+#include <grpc/support/alloc.h>
 
 #include "completion_queue.h"
 #include "channel_credentials.h"
@@ -323,7 +324,8 @@ PHP_METHOD(Channel, getTarget) {
   }
   char *target = grpc_channel_get_target(channel->wrapper->wrapped);
   gpr_mu_unlock(&channel->wrapper->mu);
-  PHP_GRPC_RETURN_STRING(target, 1);
+  PHP_GRPC_RETVAL_STRING(target, 1);
+  gpr_free(target);
 }
 
 /**

src/php/ext/grpc/php7_wrapper.h

@@ -33,6 +33,7 @@
 #define php_grpc_add_next_index_stringl(data, str, len, b) \
   add_next_index_stringl(data, str, len, b)
 
+#define PHP_GRPC_RETVAL_STRING(val, dup) RETVAL_STRING(val, dup)
 #define PHP_GRPC_RETURN_STRING(val, dup) RETURN_STRING(val, dup)
 #define PHP_GRPC_MAKE_STD_ZVAL(pzv) MAKE_STD_ZVAL(pzv)
 #define PHP_GRPC_FREE_STD_ZVAL(pzv)
@@ -145,6 +146,7 @@ static inline int php_grpc_zend_hash_find(HashTable *ht, char *key, int len,
 #define php_grpc_add_next_index_stringl(data, str, len, b) \
   add_next_index_stringl(data, str, len)
 
+#define PHP_GRPC_RETVAL_STRING(val, dup) RETVAL_STRING(val)
 #define PHP_GRPC_RETURN_STRING(val, dup) RETURN_STRING(val)
 #define PHP_GRPC_MAKE_STD_ZVAL(pzv) \
   pzv = (zval *)emalloc(sizeof(zval));