tools lib traceevent: Fix strerror_r() use in pevent_strerror

glibc-2.16 starts to mark the function with attribute warn_unused_result
so that it can cause a build warning.

Since GNU version of strerror_r() can return a pointer to a string
without setting @buf, check the return value and copy/truncate it to our
buffer if needed.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1345618831-9148-5-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 12 insertions, 1 deletions

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 1373e4cf109e..f978c59f67bf 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -4809,7 +4809,12 @@ int pevent_strerror(struct pevent *pevent, enum pevent_errno errnum,
         const char *msg;
 
         if (errnum >= 0) {
-                strerror_r(errnum, buf, buflen);
+                msg = strerror_r(errnum, buf, buflen);
+                if (msg != buf) {
+                        size_t len = strlen(msg);
+                        char *c = mempcpy(buf, msg, min(buflen-1, len));
+                        *c = '\0';
+                }
                 return 0;
         }
 
diff --git a/tools/lib/traceevent/event-utils.h b/tools/lib/traceevent/event-utils.h
index 08296383d1e6..bc075006966e 100644
--- a/tools/lib/traceevent/event-utils.h
+++ b/tools/lib/traceevent/event-utils.h
@@ -39,6 +39,12 @@ void __vdie(const char *fmt, ...);
 void __vwarning(const char *fmt, ...);
 void __vpr_stat(const char *fmt, ...);
 
+#define min(x, y) ({                            \
+        typeof(x) _min1 = (x);                  \
+        typeof(y) _min2 = (y);                  \
+        (void) (&_min1 == &_min2);              \
+        _min1 < _min2 ? _min1 : _min2; })
+
 static inline char *strim(char *string)
 {
         char *ret;