These images contain various forms of corrupted filesystem which e2fsck will correct. They are used as a regression test for e2fsck.
The test_script program will automatically run e2fsck against the filesystem images. It will run them two times, and display the exit status for each run. The meaning of the exit status codes are as follows:
0 No filesystem errors were detected
1 Filesystem errors detected, but corrected
2 System should be rebooted
4 Filesystem errors left uncorrected
8 Operational error (generally means internal error,
or filesystem error that the e2fsck was not
prepared to deal with)
16 Usage or syntax error
During the regression test, the first exit code should be 1, and the second exit code should be 0. In other words, all (with one exception) of the test filesystems in this directory have some sort of filesystem corruption, which e2fsck should fix on the first pass. After the first pass, e2fsck should leave a fully consistent filesystem with no detectable errors found in the second pass. The exception is the okgroup.img filesystem, which contains no errors, and so both exit codes should be 0.
NOTE: It appears that at least some versions of the original e2fsck do not exit with an exit status code of 1 after correcting filesystem errors. So if you modify the test_script to try running these filesystems against the original e2fsck, you will have to inspect the test_script.log file manually.
Here's a one-line descriptons of the various test images in this directory:
baddir.img Filesystem with a corrupted directory
badbblocks.img Filesystem with illegal blocks in the bad block inode.
badinode.img Filesystem with various different corrupted inode
entries.
badlkcnt.img Filesystem with deleted files with non-zero link count
badroot.img Filesystem with a file for a root directory
badtable.img Filesystem with blocks shared between the bitmaps and
inode table blocks and the bad block inode
bbfile.img Filesystem with files containing bad blocks
bitmaps.img Filesystem with corrupted inode and block bitmaps
dirlink.img Filesystem with a hard link to a directory
dup.img Filesystem with blocks claimed by two different files
dup2.img Filesystem with blocks claimed by three different files
dupfsblks.img Filesystem with blocks claimed by a file and
inode/block bitmaps and inode tables
dupsuper.img Filesystem with blocks claimed by a file and
the superblock / group descriptors
end-bitmap.img Filesystem with corruption at the end of the block
bitmap
expand.img Tests e2fsck's ability to expand lost+found if
necessary
lpf.img Filesystem with disconnected files and no /lost+found
directory
mke2fs2b.img Filesystem with corruption similar to that
created by mke2fs version 0.2b
noroot.img Filesystem with a deleted root directory
okgroup.img Filesystem that's exactly 8193 blocks long
(otherwise OK)
overfsblks.img Filesystem with overlapping inode and block bitmaps
symlinks.img Filesystem with bad symlink sizes