strncmp is a more reasonable way to check the beginning of a string.

diff --git a/usr.bin/mg/fileio.c b/usr.bin/mg/fileio.c
index 667ad69..1888fd0 100644 (file)
--- a/usr.bin/mg/fileio.c
+++ b/usr.bin/mg/fileio.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: fileio.c,v 1.102 2016/07/28 21:37:45 tedu Exp $       */
+/*     $OpenBSD: fileio.c,v 1.103 2016/07/28 21:40:25 tedu Exp $       */
 
 /* This file is in the public domain. */
 
@@ -681,13 +681,10 @@ toggleleavetmp(int f, int n)
 int
 bkupleavetmp(const char *fn)
 {
-       char    *tmp = NULL;
-
        if (!leavetmp)
                return(FALSE);
 
-       tmp = strstr(fn, "/tmp");
-       if (tmp == fn)
+       if (strncmp(fn, "/tmp", 4) == 0)
                return (TRUE);
 
        return (FALSE);