The man page implies that the string argument to psignal() may be

NULL, in line with perror(3).  However, the code presently checks only
for a zero-length string.  Check for both.

1 files changed, 2 insertions, 4 deletions

diff --git a/lib/libc/gen/psignal.c b/lib/libc/gen/psignal.c
index b7e7ab6..96eab9d 100644
--- a/lib/libc/gen/psignal.c
+++ b/lib/libc/gen/psignal.c
@@ -49,15 +49,13 @@ psignal(sig, s)
 	const char *s;
 {
 	register const char *c;
-	register int n;
 
 	if (sig < NSIG)
 		c = sys_siglist[sig];
 	else
 		c = "Unknown signal";
-	n = strlen(s);
-	if (n) {
-		(void)write(STDERR_FILENO, s, n);
+	if (s != NULL && *s != '\0') {
+		(void)write(STDERR_FILENO, s, strlen(s));
 		(void)write(STDERR_FILENO, ": ", 2);
 	}
 	(void)write(STDERR_FILENO, c, strlen(c));