perf target: Simplify handling of strerror_r return

Commit-ID:  17e44dc46f035ca27847bbf75ffd3072ed49f13c
Gitweb:     http://git.kernel.org/tip/17e44dc46f035ca27847bbf75ffd3072ed49f13c
Author:     Arnaldo Carvalho de Melo <[email protected]>
AuthorDate: Mon, 23 Mar 2015 18:23:02 -0300
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Tue, 24 Mar 2015 12:08:30 -0300

perf target: Simplify handling of strerror_r return

To deal with forwarding the strerror_r (GNU) return we need to check if the returned value is the buffer we passed or maybe some constant (unknown error), simplify that action by using scnprintf, that will do all the buflen size checks, trimming if needed.

---
 tools/perf/util/target.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

index e74c596..a53603b 100644
@@ -123,11 +123,8 @@ int target__strerror(struct target *target, int errnum,
 	if (errnum >= 0) {
 		const char *err = strerror_r(errnum, buf, buflen);
 
-		if (err != buf) {
-			size_t len = strlen(err);
-			memcpy(buf, err, min(buflen - 1, len));
-			*(buf + min(buflen - 1, len)) = '\0';
-		}
+		if (err != buf)
+			scnprintf(buf, buflen, "%s", err);
 
 		return 0;
 	}