Add -o loop= option to mount, and fix error detection in mount and umount

This fixes bug http://b.android.com/18419, which complains about a bogus
error check in the mount command (it also was wrong in the umount command)
and also asks for the mount command to support more than one loopback
device, as mentioned in the FIXME comments in mount.c.  This required some
corresponding changes to umount.c

Change-Id: Ib796c70926395e61557e487bad64984d3295d5f3

1 files changed, 19 insertions, 11 deletions

diff --git a/toolbox/mount.c b/toolbox/mount.c
index 82ecc566..27cf3c9a 100644
--- a/toolbox/mount.c
+++ b/toolbox/mount.c
@@ -15,8 +15,8 @@
 
 #define ARRAY_SIZE(x)	(sizeof(x) / sizeof(x[0]))
 
-// FIXME - only one loop mount is supported at a time
-#define LOOP_DEVICE "/dev/block/loop0"
+#define DEFAULT_LOOP_DEVICE "/dev/block/loop0"
+#define LOOPDEV_MAXLEN 64
 
 struct mount_opts {
 	const char str[8];
@@ -87,7 +87,7 @@ static void add_extra_option(struct extra_opts *extra, char *s)
 }
 
 static unsigned long
-parse_mount_options(char *arg, unsigned long rwflag, struct extra_opts *extra, int* loop)
+parse_mount_options(char *arg, unsigned long rwflag, struct extra_opts *extra, int* loop, char *loopdev)
 {
 	char *s;
     
@@ -100,8 +100,15 @@ parse_mount_options(char *arg, unsigned long rwflag, struct extra_opts *extra, i
 		if (no)
 			s += 2;
 
+        if (strncmp(s, "loop=", 5) == 0) {
+            *loop = 1;
+            strlcpy(loopdev, s + 5, LOOPDEV_MAXLEN);
+            continue;
+        }
+
         if (strcmp(s, "loop") == 0) {
             *loop = 1;
+            strlcpy(loopdev, DEFAULT_LOOP_DEVICE, LOOPDEV_MAXLEN);
             continue;
         }
 		for (i = 0, res = 1; i < ARRAY_SIZE(options); i++) {
@@ -131,7 +138,8 @@ static struct extra_opts extra;
 static unsigned long rwflag;
 
 static int
-do_mount(char *dev, char *dir, char *type, unsigned long rwflag, void *data, int loop)
+do_mount(char *dev, char *dir, char *type, unsigned long rwflag, void *data, int loop,
+         char *loopdev)
 {
 	char *s;
 	int error = 0;
@@ -142,14 +150,13 @@ do_mount(char *dev, char *dir, char *type, unsigned long rwflag, void *data, int
 
         flags = (rwflag & MS_RDONLY) ? O_RDONLY : O_RDWR;
         
-        // FIXME - only one loop mount supported at a time
         file_fd = open(dev, flags);
-        if (file_fd < -1) {
+        if (file_fd < 0) {
             perror("open backing file failed");
             return 1;
         }
-        device_fd = open(LOOP_DEVICE, flags);
-        if (device_fd < -1) {
+        device_fd = open(loopdev, flags);
+        if (device_fd < 0) {
             perror("open loop device failed");
             close(file_fd);
             return 1;
@@ -163,7 +170,7 @@ do_mount(char *dev, char *dir, char *type, unsigned long rwflag, void *data, int
 
         close(file_fd);
         close(device_fd);
-        dev = LOOP_DEVICE;
+        dev = loopdev;
     }
 
 	while ((s = strsep(&type, ",")) != NULL) {
@@ -268,6 +275,7 @@ int mount_main(int argc, char *argv[])
 	char *dir = NULL;
 	int c;
 	int loop = 0;
+	char loopdev[LOOPDEV_MAXLEN];
 
 	progname = argv[0];
 	rwflag = MS_VERBOSE;
@@ -281,7 +289,7 @@ int mount_main(int argc, char *argv[])
 			break;
 		switch (c) {
 		case 'o':
-			rwflag = parse_mount_options(optarg, rwflag, &extra, &loop);
+			rwflag = parse_mount_options(optarg, rwflag, &extra, &loop, loopdev);
 			break;
 		case 'r':
 			rwflag |= MS_RDONLY;
@@ -319,6 +327,6 @@ int mount_main(int argc, char *argv[])
 		exit(1);
 	}
 
-	return do_mount(dev, dir, type, rwflag, extra.str, loop);
+	return do_mount(dev, dir, type, rwflag, extra.str, loop, loopdev);
 	/* We leak dev and dir in some cases, but we're about to exit */
 }