gdb_server: do not copy feature names for tdesc generation

We always have feature names defined by string literals and the
standard guarantees static storage duration for them. Hence, there's
no need duplicating and then freeing them.

Valgrind-tested.

Change-Id: I1b77f966c548e3694141c63bd8680735f0f47505
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Reviewed-on: http://openocd.zylin.com/2028
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

src/server/gdb_server.c

@@ -1998,7 +1998,7 @@ static int gdb_generate_reg_type_description(struct target *target,
 /* Get a list of available target registers features. feature_list must
  * be freed by caller.
  */
-static int get_reg_features_list(struct target *target, char **feature_list[], int *feature_list_size,
+static int get_reg_features_list(struct target *target, char const **feature_list[], int *feature_list_size,
 		struct reg **reg_list, int reg_list_size)
 {
 	int tbl_sz = 0;
@@ -2019,7 +2019,7 @@ static int get_reg_features_list(struct target *target, char **feature_list[], i
 			 */
 			for (int j = 0; j < (tbl_sz + 1); j++) {
 				if (!((*feature_list)[j])) {
-					(*feature_list)[tbl_sz++] = strdup(reg_list[i]->feature->name);
+					(*feature_list)[tbl_sz++] = reg_list[i]->feature->name;
 					*feature_list = realloc(*feature_list, sizeof(char *) * (tbl_sz + 1));
 					(*feature_list)[tbl_sz] = NULL;
 					break;
@@ -2042,7 +2042,7 @@ static int gdb_generate_target_description(struct target *target, char **tdesc_o
 	int retval = ERROR_OK;
 	struct reg **reg_list = NULL;
 	int reg_list_size;
-	char **features = NULL;
+	char const **features = NULL;
 	int feature_list_size = 0;
 	char *tdesc = NULL;
 	int pos = 0;
@@ -2149,10 +2149,6 @@ static int gdb_generate_target_description(struct target *target, char **tdesc_o
 			"</target>\n");
 
 error:
-
-	/* note: features[] contains (feature_list_size + 1) elements */
-	for (int j = feature_list_size; j >= 0; j--)
-		free(features[j]);
 	free(features);
 	free(reg_list);
 
@@ -2223,7 +2219,7 @@ static int gdb_target_description_supported(struct target *target, int *supporte
 	int retval = ERROR_OK;
 	struct reg **reg_list = NULL;
 	int reg_list_size = 0;
-	char **features = NULL;
+	char const **features = NULL;
 	int feature_list_size = 0;
 
 	retval = target_get_gdb_reg_list(target, &reg_list,
@@ -2254,10 +2250,6 @@ static int gdb_target_description_supported(struct target *target, int *supporte
 	}
 
 error:
-
-	/* note: features[] contains (feature_list_size + 1) elements */
-	for (int j = feature_list_size; j >= 0; j--)
-		free(features[j]);
 	free(features);
 
 	free(reg_list);