commit baf6b6bdebd6e91c401f64e8013fed49697ed2cc
author Jeff Brown <jeffbrown@google.com> Wed Jul 13 22:12:18 2011 -0700
committer Jeff Brown <jeffbrown@google.com> Thu Jul 14 13:43:57 2011 -0700
tree d55867253951a285af3221ba0e0557890af323be
parent e877ad7ae3ea3c1a631652c86887a627ef9feb3f

Show why umount failed.

Change-Id: Id2b3fbc46b8dfbe2f05637fb35c298915cd5f524

toolbox/umount.c

diff --git a/toolbox/umount.c b/toolbox/umount.c
index 6eb8b92..890e870 100644
--- a/toolbox/umount.c
+++ b/toolbox/umount.c
@@ -6,6 +6,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <linux/loop.h>
+#include <errno.h>
 
 #define LOOPDEV_MAXLEN 64
 #define LOOP_MAJOR 7
@@ -36,7 +37,7 @@
     
     f = fopen("/proc/mounts", "r");
     if (!f) {
-        fprintf(stdout, "could not open /proc/mounts\n");
+        fprintf(stdout, "could not open /proc/mounts: %s\n", strerror(errno));
         return -1;
     }
 
@@ -66,8 +67,8 @@
     }
 
     loop = is_loop_mount(argv[1], loopdev);
-    if(umount(argv[1])){
-        fprintf(stderr,"failed.\n");
+    if (umount(argv[1])) {
+        fprintf(stderr, "failed: %s\n", strerror(errno));
         return 1;
     }
 
@@ -75,11 +76,11 @@
         // free the loop device
         loop_fd = open(loopdev, O_RDONLY);
         if (loop_fd < 0) {
-            perror("open loop device failed");
+            fprintf(stderr, "open loop device failed: %s\n", strerror(errno));
             return 1;
         }
         if (ioctl(loop_fd, LOOP_CLR_FD, 0) < 0) {
-            perror("ioctl LOOP_CLR_FD failed");
+            fprintf(stderr, "ioctl LOOP_CLR_FD failed: %s\n", strerror(errno));
             return 1;
         }