perf pmu: Suppress potential format-truncation warning

commit 11a64a05dc649815670b1be9fe63d205cb076401 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 0f84371..c86c1d5 100644 (file)
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -103,7 +103,7 @@ static int perf_pmu__parse_scale(struct perf_pmu_alias *alias, char *dir, char *
        char path[PATH_MAX];
        char *lc;
 
-       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)
@@ -163,7 +163,7 @@ 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)
@@ -193,7 +193,7 @@ 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)
@@ -211,7 +211,7 @@ 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)