signals: Make signal_name() thread-safe.

Signed-off-by: Ben Pfaff <blp@nicira.com>

1 files changed, 14 insertions, 13 deletions

diff --git a/lib/signals.c b/lib/signals.c
index c47fefa4a..99a36a427 100644
--- a/lib/signals.c
+++ b/lib/signals.c
@@ -137,37 +137,38 @@ signal_handler(int signr)
     }
 }
 
-/* Returns the name of signal 'signum' as a string.  The string may be in a
- * static buffer that is reused from one call to the next.
+/* Returns the name of signal 'signum' as a string.  The return value is either
+ * a statically allocated constant string or the 'bufsize'-byte buffer
+ * 'namebuf'.  'bufsize' should be at least SIGNAL_NAME_BUFSIZE.
  *
  * The string is probably a (possibly multi-word) description of the signal
  * (e.g. "Hangup") instead of just the stringified version of the macro
  * (e.g. "SIGHUP"). */
 const char *
-signal_name(int signum)
+signal_name(int signum, char *namebuf, size_t bufsize)
 {
-    const char *name = NULL;
-
 #if HAVE_DECL_SYS_SIGLIST
     if (signum >= 0 && signum < ARRAY_SIZE(sys_siglist)) {
-        name = sys_siglist[signum];
+        const char *name = sys_siglist[signum];
+        if (name) {
+            return name;
+        }
     }
 #endif
 
-    if (!name) {
-        static char buffer[7 + INT_STRLEN(int) + 1];
-        sprintf(buffer, "signal %d", signum);
-        name = buffer;
-    }
-    return name;
+    snprintf(namebuf, bufsize, "signal %d", signum);
+    return namebuf;
 }
 
 void
 xsigaction(int signum, const struct sigaction *new, struct sigaction *old)
 {
     if (sigaction(signum, new, old)) {
+        char namebuf[SIGNAL_NAME_BUFSIZE];
+
         VLOG_FATAL("sigaction(%s) failed (%s)",
-                   signal_name(signum), strerror(errno));
+                   signal_name(signum, namebuf, sizeof namebuf),
+                   strerror(errno));
     }
 }