dumpfs(8) diff: retry with raw device on failure

[Lawrence Teo <lteo.openbsd1@xxxxxxxxxxxx>]

This diff lets dumpfs(8) retry with raw device on failure.

For example, if you run "dumpfs /dev/wd0a" it will automatically
fallback to /dev/rwd0a if /dev/wd0a cannot be opened (busy, etc.).

Please let me know what you think.

Thanks,
Lawrence



Index: dumpfs.c
===================================================================
RCS file: /cvs/src/sbin/dumpfs/dumpfs.c,v
retrieving revision 1.25
diff -u -p -r1.25 dumpfs.c
--- dumpfs.c    8 Jun 2008 03:00:20 -0000       1.25
+++ dumpfs.c    13 Jul 2008 21:08:23 -0000
@@ -65,6 +65,7 @@ static const char rcsid[] = "$OpenBSD: d
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <unistd.h>
 
 union {
@@ -136,11 +137,19 @@ open_disk(const char *name)
 {
        int fd, i, sbtry[] = SBLOCKSEARCH;
        ssize_t n;
+       char rawspec[MAXPATHLEN], *p;
 
-       /* XXX - should retry w/raw device on failure */
+       /* Retry with raw device on failure. */
        if ((fd = open(name, O_RDONLY, 0)) < 0) {
-               warn("%s", name);
-               return(-1);
+               if ((p = strrchr(name, '/')) != NULL)
+                       snprintf(rawspec, sizeof(rawspec), "%.*s/r%s",
+                               (int)(p - name), name, p + 1);
+               else
+                       snprintf(rawspec, sizeof(rawspec), "r%s", name);
+               if ((fd = open(rawspec, O_RDONLY, 0)) < 0) {
+                       warn("%s", rawspec);
+                       return(-1);
+               }
        }
 
        /* Read superblock, could be UFS1 or UFS2. */