[tip:perf/core] perf utils: use sizeof(buf) - 1 in readlink() call

[tip-bot for Tommi Rantala <tipbot@zytor.com>]

Commit-ID:  b7126ef78612a3d4a37aadf39125cff048cebb9b
Gitweb:     http://git.kernel.org/tip/b7126ef78612a3d4a37aadf39125cff048cebb9b
Author:     Tommi Rantala <tommi.t.rantala@nokia.com>
AuthorDate: Wed, 22 Mar 2017 15:06:22 +0200
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 27 Mar 2017 15:36:27 -0300

perf utils: use sizeof(buf) - 1 in readlink() call

Ensure that we have space for the null byte in buf.

Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170322130624.21881-5-tommi.t.rantala@nokia.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/header.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 05714d5..cf22962 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -378,7 +378,7 @@ static int write_cmdline(int fd, struct perf_header *h __maybe_unused,
 	 * actual atual path to perf binary
 	 */
 	sprintf(proc, "/proc/%d/exe", getpid());
-	ret = readlink(proc, buf, sizeof(buf));
+	ret = readlink(proc, buf, sizeof(buf) - 1);
 	if (ret <= 0)
 		return -1;