[PATCH 4/7] perf list: fix a bug of segmentation fault

From: Yunlong Song <yunlong.song@huawei.com>
To: <a.p.zijlstra@chello.nl>, <paulus@samba.org>, <mingo@redhat.com>,
	<acme@kernel.org>
Cc: <linux-kernel@vger.kernel.org>, <wangnan0@huawei.com>
Subject: [PATCH 4/7] perf list: fix a bug of segmentation fault
Date: Fri, 13 Feb 2015 21:11:52 +0800	[thread overview]
Message-ID: <1423833115-11199-5-git-send-email-yunlong.song@huawei.com> (raw)
In-Reply-To: <1423833115-11199-1-git-send-email-yunlong.song@huawei.com>

Fix the 'segmentation fault' bug of 'perf list --list-cmds', which
also happens in other cases (e.g. record, report ...). This bug happens
when there are no cmds to list at all.

Example
Before this patch:
$perf list --list-cmds
Segmentation fault
$

After this patch:
$perf list --list-cmds
$

As shown above, the result prints nothing rather than a segmentation
fault. The null result means 'perf list' has no cmds to display at this
time.

Signed-off-by: Yunlong Song <yunlong.song@huawei.com>
---
 tools/perf/util/parse-options.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/parse-options.c b/tools/perf/util/parse-options.c
index 4a015f7..4ee9a86 100644
--- a/tools/perf/util/parse-options.c
+++ b/tools/perf/util/parse-options.c
@@ -510,8 +510,10 @@ int parse_options_subcommand(int argc, const char **argv, const struct option *o
 		}
 		exit(130);
 	case PARSE_OPT_LIST_SUBCMDS:
-		for (int i = 0; subcommands[i]; i++)
-			printf("%s ", subcommands[i]);
+		if (subcommands) {
+			for (int i = 0; subcommands[i]; i++)
+				printf("%s ", subcommands[i]);
+		}
 		exit(130);
 	default: /* PARSE_OPT_UNKNOWN */
 		if (ctx.argv[0][1] == '-') {
-- 
1.8.5.5

