handle null arguments to legacy bsd err.h functions

diff --git a/src/linux/err.c b/src/linux/err.c
index abc2680..c291136 100644 (file)
--- a/src/linux/err.c
+++ b/src/linux/err.c
@@ -5,13 +5,13 @@
 
 void vwarn(const char *fmt, va_list ap)
 {
-       vfprintf(stderr, fmt, ap);
+       if (fmt) vfprintf(stderr, fmt, ap);
        perror("");
 }
 
 void vwarnx(const char *fmt, va_list ap)
 {
-       vfprintf(stderr, fmt, ap);
+       if (fmt) vfprintf(stderr, fmt, ap);
        putc('\n', stderr);
 }