Avoid infinite loops; from NetBSD PR 3285

diff --git a/sbin/dmesg/dmesg.c b/sbin/dmesg/dmesg.c
index 9e63bd7..e047523 100644 (file)
--- a/sbin/dmesg/dmesg.c
+++ b/sbin/dmesg/dmesg.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: dmesg.c,v 1.4 1997/01/15 23:41:10 millert Exp $       */
+/*     $OpenBSD: dmesg.c,v 1.5 1997/03/29 20:28:20 tholo Exp $ */
 /*     $NetBSD: dmesg.c,v 1.8 1995/03/18 14:54:49 cgd Exp $    */
 
 /*-
@@ -44,7 +44,7 @@ static char copyright[] =
 #if 0
 static char sccsid[] = "@(#)dmesg.c    8.1 (Berkeley) 6/5/93";
 #else
-static char rcsid[] = "$OpenBSD: dmesg.c,v 1.4 1997/01/15 23:41:10 millert Exp $";
+static char rcsid[] = "$OpenBSD: dmesg.c,v 1.5 1997/03/29 20:28:20 tholo Exp $";
 #endif
 #endif /* not lint */
 
@@ -129,10 +129,10 @@ main(argc, argv)
         * The message buffer is circular; start at the read pointer, and
         * go to the write pointer - 1.
         */
-       p = cur.msg_bufc + cur.msg_bufx;
-       ep = cur.msg_bufc + cur.msg_bufx - 1;
-       for (newl = skip = 0; p != ep; ++p) {
-               if (p == cur.msg_bufc + MSG_BSIZE)
+       p = ep = cur.msg_bufc + (cur.msg_bufx - 1 + MSG_BSIZE) % MSG_BSIZE;
+       newl = skip = 0;
+       do {
+               if (++p == cur.msg_bufc + MSG_BSIZE)
                        p = cur.msg_bufc;
                ch = *p;
                /* Skip "\n<.*>" syslog sequences. */
@@ -153,7 +153,7 @@ main(argc, argv)
                        (void)putchar(buf[0]);
                else
                        (void)printf("%s", buf);
-       }
+       } while (p != ep);
        if (!newl)
                (void)putchar('\n');
        exit(0);