Expose a disk block device as a regular file (FUSE)

Many utilities, such as mksquashfs, rsync and tar, will treat a disk device as a small block-special file, but sometimes you want them to see the actual contents of the disk.

Example: diskfile /dev/sdb1 /dev/sdb4 /dev/sdb6 /path/to/mountpount

Now files mountpoint/sdb1 and friends exist as regular files with the size and content of the actual disk. You can run mksquashfs mountpoint/sdb1 disk.squashfs to create a Fedora-style nested squashfs filesystem. Or tar czf backup.tgz mountpoint is a convenient, if inefficient, way to backup several partitions.

• Code is not well tested, with little error-checking
• Only disk block-devices are tested, I've no idea what will happen with other such devices
• Only Mac OS X, FreeBSD and Linux supported
• Only read access is allowed
• There's no support for fancy parameters like offset and file mode. For those, check out fusefile.

All the above should be fixable, patches welcome!