perf env: Do not return pointers to local variables

It is possible to return a pointer to a local variable when looking up the architecture name for the running system and no normalization is done on that value, i.e. we may end up returning the uts.machine local variable. While this doesn't happen on most arches, as normalization takes place, lets fix this by making that a static variable and optimize it a bit by not always running uname(), only the first time. Noticed in fedora rawhide running with: [perfbuilder@a5ff49d6e6e4 ~]$ gcc --version gcc (GCC) 10.0.1 20200216 (Red Hat 10.0.1-0.8) Reported-by: Jiri Olsa <[email protected]> Cc: Adrian Hunter <[email protected]> Cc: Namhyung Kim <[email protected]> Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>
zandrey · Mar 2, 2020 · ebcb946 · ebcb946
1 parent cff20b3
commit ebcb946
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/tools/perf/util/env.c b/tools/perf/util/env.c
@@ -343,11 +343,11 @@ static const char *normalize_arch(char *arch)
 
 const char *perf_env__arch(struct perf_env *env)
 {
-	struct utsname uts;
 	char *arch_name;
 
 	if (!env || !env->arch) { /* Assume local operation */
-		if (uname(&uts) < 0)
+		static struct utsname uts = { .machine[0] = '\0', };
+		if (uts.machine[0] == '\0' && uname(&uts) < 0)
 			return NULL;
 		arch_name = uts.machine;
 	} else