[PATCH 22/28] perf pmu: Suppress potential format-truncation warning

Arnaldo Carvalho de Melo
2018-11-22T03:37:31Z

From: Ben Hutchings <ben@decadent.org.uk>

Depending on which functions are inlined in util/pmu.c, the snprintf()
calls in perf_pmu__parse_{scale,unit,per_pkg,snapshot}() might trigger a
warning:

util/pmu.c: In function 'pmu_aliases':
util/pmu.c:178:31: error: '%s' directive output may be truncated writing up to 255 bytes into a region of size between 0 and 4095 [-Werror=format-truncation=]
snprintf(path, PATH_MAX, "%s/%s.unit", dir, name);
^~

I found this when trying to build perf from Linux 3.16 with gcc 8.
However I can reproduce the problem in mainline if I force
__perf_pmu__new_alias() to be inlined.

Suppress this by using scnprintf() as has been done elsewhere in perf.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20181111184524.fux4taownc6ndbx6@decadent.org.uk
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/pmu.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 7e49baad304d..7348eea0248f 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -145,7 +145,7 @@ static int perf_pmu__parse_scale(struct perf_pmu_alias *alias, char *dir, char *
int fd, ret = -1;
char path[PATH_MAX];

- snprintf(path, PATH_MAX, "%s/%s.scale", dir, name);
+ scnprintf(path, PATH_MAX, "%s/%s.scale", dir, name);

fd = open(path, O_RDONLY);
if (fd == -1)
@@ -175,7 +175,7 @@ static int perf_pmu__parse_unit(struct perf_pmu_alias *alias, char *dir, char *n
ssize_t sret;
int fd;

- snprintf(path, PATH_MAX, "%s/%s.unit", dir, name);
+ scnprintf(path, PATH_MAX, "%s/%s.unit", dir, name);

fd = open(path, O_RDONLY);
if (fd == -1)
@@ -205,7 +205,7 @@ perf_pmu__parse_per_pkg(struct perf_pmu_alias *alias, char *dir, char *name)
char path[PATH_MAX];
int fd;

- snprintf(path, PATH_MAX, "%s/%s.per-pkg", dir, name);
+ scnprintf(path, PATH_MAX, "%s/%s.per-pkg", dir, name);

fd = open(path, O_RDONLY);
if (fd == -1)
@@ -223,7 +223,7 @@ static int perf_pmu__parse_snapshot(struct perf_pmu_alias *alias,
char path[PATH_MAX];
int fd;

- snprintf(path, PATH_MAX, "%s/%s.snapshot", dir, name);
+ scnprintf(path, PATH_MAX, "%s/%s.snapshot", dir, name);

fd = open(path, O_RDONLY);
if (fd == -1)
--
2.14.5