From: Ben Hutchings <b...@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 <b...@decadent.org.uk>
Cc: Alexander Shishkin <alexander.shish...@linux.intel.com>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: sta...@vger.kernel.org
Link: http://lkml.kernel.org/r/20181111184524.fux4taownc6nd...@decadent.org.uk
Signed-off-by: Arnaldo Carvalho de Melo <a...@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

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