linux-kernel - [tip:perf/core] perf pmu: Suppress potential format-truncation warning

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Message-ID: <tip-11a64a05dc649815670b1be9fe63d205cb076401@git.kernel.org>
Date:   Wed, 21 Nov 2018 23:13:02 -0800
From:   tip-bot for Ben Hutchings <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     ben@...adent.org.uk, acme@...hat.com, namhyung@...nel.org,
        linux-kernel@...r.kernel.org, peterz@...radead.org,
        jolsa@...hat.com, mingo@...nel.org, tglx@...utronix.de,
        alexander.shishkin@...ux.intel.com, hpa@...or.com
Subject: [tip:perf/core] perf pmu: Suppress potential format-truncation
 warning

Commit-ID:  11a64a05dc649815670b1be9fe63d205cb076401
Gitweb:     https://git.kernel.org/tip/11a64a05dc649815670b1be9fe63d205cb076401
Author:     Ben Hutchings <ben@...adent.org.uk>
AuthorDate: Sun, 11 Nov 2018 18:45:24 +0000
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Wed, 21 Nov 2018 22:39:56 -0300

perf pmu: Suppress potential format-truncation warning

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@...adent.org.uk>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: stable@...r.kernel.org
Link: http://lkml.kernel.org/r/20181111184524.fux4taownc6ndbx6@decadent.org.uk
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.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)