perf tools: Make perf_exec_path() always return malloc'd string

Since system_path() returns malloc'd string if given path is not an
absolute path, perf_exec_path() sometimes returns a static string and
sometimes returns a malloc'd string depending on the environment
variables or command options.

This may cause a memory leak because the caller can not unconditionally
free the returned string.

This fixes perf_exec_path() and system_path() to always return a
malloc'd string, so the caller can always free it.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20151119060453.14210.65666.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/exec_cmd.c

@@ -9,17 +9,17 @@
 static const char *argv_exec_path;
 static const char *argv0_path;
 
-const char *system_path(const char *path)
+char *system_path(const char *path)
 {
 	static const char *prefix = PREFIX;
 	struct strbuf d = STRBUF_INIT;
 
 	if (is_absolute_path(path))
-		return path;
+		return strdup(path);
 
 	strbuf_addf(&d, "%s/%s", prefix, path);
 	path = strbuf_detach(&d, NULL);
-	return path;
+	return (char *)path;
 }
 
 const char *perf_extract_argv0_path(const char *argv0)
@@ -52,17 +52,16 @@ void perf_set_argv_exec_path(const char *exec_path)
 
 
 /* Returns the highest-priority, location to look for perf programs. */
-const char *perf_exec_path(void)
+char *perf_exec_path(void)
 {
-	const char *env;
+	char *env;
 
 	if (argv_exec_path)
-		return argv_exec_path;
+		return strdup(argv_exec_path);
 
 	env = getenv(EXEC_PATH_ENVIRONMENT);
-	if (env && *env) {
-		return env;
-	}
+	if (env && *env)
+		return strdup(env);
 
 	return system_path(PERF_EXEC_PATH);
 }
@@ -83,9 +82,11 @@ void setup_path(void)
 {
 	const char *old_path = getenv("PATH");
 	struct strbuf new_path = STRBUF_INIT;
+	char *tmp = perf_exec_path();
 
-	add_path(&new_path, perf_exec_path());
+	add_path(&new_path, tmp);
 	add_path(&new_path, argv0_path);
+	free(tmp);
 
 	if (old_path)
 		strbuf_addstr(&new_path, old_path);

tools/perf/util/exec_cmd.h

@@ -3,10 +3,11 @@
 
 extern void perf_set_argv_exec_path(const char *exec_path);
 extern const char *perf_extract_argv0_path(const char *path);
-extern const char *perf_exec_path(void);
 extern void setup_path(void);
 extern int execv_perf_cmd(const char **argv); /* NULL terminated */
 extern int execl_perf_cmd(const char *cmd, ...);
-extern const char *system_path(const char *path);
+/* perf_exec_path and system_path return malloc'd string, caller must free it */
+extern char *perf_exec_path(void);
+extern char *system_path(const char *path);
 
 #endif /* __PERF_EXEC_CMD_H */

tools/perf/util/help.c

@@ -159,7 +159,7 @@ void load_command_list(const char *prefix,
 		struct cmdnames *other_cmds)
 {
 	const char *env_path = getenv("PATH");
-	const char *exec_path = perf_exec_path();
+	char *exec_path = perf_exec_path();
 
 	if (exec_path) {
 		list_commands_in_dir(main_cmds, exec_path, prefix);
@@ -187,6 +187,7 @@ void load_command_list(const char *prefix,
 		      sizeof(*other_cmds->names), cmdname_compare);
 		uniq(other_cmds);
 	}
+	free(exec_path);
 	exclude_cmds(other_cmds, main_cmds);
 }
 
@@ -203,13 +204,14 @@ void list_commands(const char *title, struct cmdnames *main_cmds,
 			longest = other_cmds->names[i]->len;
 
 	if (main_cmds->cnt) {
-		const char *exec_path = perf_exec_path();
+		char *exec_path = perf_exec_path();
 		printf("available %s in '%s'\n", title, exec_path);
 		printf("----------------");
 		mput_char('-', strlen(title) + strlen(exec_path));
 		putchar('\n');
 		pretty_print_string_list(main_cmds, longest);
 		putchar('\n');
+		free(exec_path);
 	}
 
 	if (other_cmds->cnt) {