perf header: Use argv style storage for cmdline feature data

We will reuse argv style data in following change to display counters
header showing monitored command line.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1437481927-29538-12-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/header.c

@@ -923,17 +923,13 @@ static void print_cmdline(struct perf_header *ph, int fd __maybe_unused,
 			  FILE *fp)
 {
 	int nr, i;
-	char *str;
 
 	nr = ph->env.nr_cmdline;
-	str = ph->env.cmdline;
 
 	fprintf(fp, "# cmdline : ");
 
-	for (i = 0; i < nr; i++) {
-		fprintf(fp, "%s ", str);
-		str += strlen(str) + 1;
-	}
+	for (i = 0; i < nr; i++)
+		fprintf(fp, "%s ", ph->env.cmdline_argv[i]);
 	fputc('\n', fp);
 }
 
@@ -1541,14 +1537,13 @@ process_event_desc(struct perf_file_section *section __maybe_unused,
 	return 0;
 }
 
-static int process_cmdline(struct perf_file_section *section __maybe_unused,
+static int process_cmdline(struct perf_file_section *section,
 			   struct perf_header *ph, int fd,
 			   void *data __maybe_unused)
 {
 	ssize_t ret;
-	char *str;
-	u32 nr, i;
-	struct strbuf sb;
+	char *str, *cmdline = NULL, **argv = NULL;
+	u32 nr, i, len = 0;
 
 	ret = readn(fd, &nr, sizeof(nr));
 	if (ret != sizeof(nr))
@@ -1558,22 +1553,32 @@ static int process_cmdline(struct perf_file_section *section __maybe_unused,
 		nr = bswap_32(nr);
 
 	ph->env.nr_cmdline = nr;
-	strbuf_init(&sb, 128);
+
+	cmdline = zalloc(section->size + nr + 1);
+	if (!cmdline)
+		return -1;
+
+	argv = zalloc(sizeof(char *) * (nr + 1));
+	if (!argv)
+		goto error;
 
 	for (i = 0; i < nr; i++) {
 		str = do_read_string(fd, ph);
 		if (!str)
 			goto error;
 
-		/* include a NULL character at the end */
-		strbuf_add(&sb, str, strlen(str) + 1);
+		argv[i] = cmdline + len;
+		memcpy(argv[i], str, strlen(str) + 1);
+		len += strlen(str) + 1;
 		free(str);
 	}
-	ph->env.cmdline = strbuf_detach(&sb, NULL);
+	ph->env.cmdline = cmdline;
+	ph->env.cmdline_argv = (const char **) argv;
 	return 0;
 
 error:
-	strbuf_release(&sb);
+	free(argv);
+	free(cmdline);
 	return -1;
 }
 

tools/perf/util/header.h

@@ -84,6 +84,7 @@ struct perf_session_env {
 	int			nr_pmu_mappings;
 	int			nr_groups;
 	char			*cmdline;
+	const char		**cmdline_argv;
 	char			*sibling_cores;
 	char			*sibling_threads;
 	char			*numa_nodes;

tools/perf/util/session.c

@@ -180,6 +180,7 @@ static void perf_session_env__delete(struct perf_session_env *env)
 	zfree(&env->cpuid);
 
 	zfree(&env->cmdline);
+	zfree(&env->cmdline_argv);
 	zfree(&env->sibling_cores);
 	zfree(&env->sibling_threads);
 	zfree(&env->numa_nodes);