mount: add an optional capability to create new /dev/loopN as needed

Signed-off-by: Lauri Kasanen <curaga@operamail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 12 insertions, 2 deletions

diff --git a/libbb/loop.c b/libbb/loop.c
index abf05dc4f..204fcc982 100644
--- a/libbb/loop.c
+++ b/libbb/loop.c
@@ -104,14 +104,24 @@ int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offse
 
         /* Find a loop device.  */
         try = *device ? *device : dev;
-        for (i = 0; rc; i++) {
+        for (i = 0; rc && i < 256; i++) {
                 sprintf(dev, LOOP_FORMAT, i);
 
-                /* Ran out of block devices, return failure.  */
+                IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
                 if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
+                        if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
+                         && errno == ENOENT
+                         && try == dev
+                        ) {
+                                /* Node doesn't exist, try to create it.  */
+                                if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
+                                        goto try_to_open;
+                        }
+                        /* Ran out of block devices, return failure.  */
                         rc = -ENOENT;
                         break;
                 }
+ try_to_open:
                 /* Open the sucker and check its loopiness.  */
                 dfd = open(try, mode);
                 if (dfd < 0 && errno == EROFS) {