This tool is designed to manipulate FAT filesystems, in order to explore, extract, repair, recover and forensic them. It currently supports FAT12, FAT16 and FAT32.
Tutorials & examplesYou can build
fatcat this way:mkdir build
cd build
cmake ..
makemake installExploring
Using fatcat
Fatcat takes an image as argument:
fatcat disk.img [options]-O, this could be useful if there is multiple partitions on a block devices, for instance:fatcat disk.img -O 1048576 [options]Listing
You can explore the FAT partition using
-l option like this:$ fatcat disk.img -l /
Listing path /
Cluster: 2
d 24/10/2013 12:06:00 some_directory/ c=4661
d 24/10/2013 12:06:02 other_directory/ c=4662
f 24/10/2013 12:06:40 picture.jpg c=4672 s=532480 (520K)
f 24/10/2013 12:06:06 hello.txt c=4671 s=13 (13B)-l /some/directory.Using
-L, you can provide a cluster number instead of a path, this may be useful sometime.If you add
-d, you will also see deleted files.In the listing, the prefix is
f or d to tell if the line concerns a file or a directory.The
c= indicates the cluster number, s= indicates the site in bytes (which should be the same as the pretty size just after).The
h letter at the end indicates that the file is supposed to be hidden.The
d letter at the end indicates that the file was deleted.Reading a file
You can read a file using
-r, the file will be wrote on the standard output:$ fatcat disk.img -r /hello.txt
Hello world!
$ fatcat disk.img -r /picture.jpg > save.jpg-R, you can provide a cluster number instead of a path, but the file size information will be lost and the file will be rounded to the number of clusters it fits, unless you provide the -s option to specify the file size to read.You can use
-x to extract the FAT filesystem directories to a directory:fatcat disk.img -x output/-c.If you provide
-d to extract, deleted files will be extracted too.Undelete
Browsing deleted files & directories
As explaines above, deleted files can be found in listing by providing
-d:$ fatcat disk.img -l / -d
f 24/10/2013 12:13:24 delete_me.txt c=5764 s=16 (16B) dRetrieving deleted file
To retrieve a deleted file, simply use
-r to read it. Note that the produced file will be read contiguously from the original FAT system and may be broken.Retreiving deleted directory
To retrieve a deleted directory, note its cluster number and extract it like above:
# If your deleted directory cluster is 71829
fatcat disk.img -x output/ -c 71829Recover
Damaged file system
Assuming your disk has broken sectors, you may want to do recovering on it.
The first advice is to make a copy of your data using
ddrescue, and save your disk to another one or into a sane file.When sectors are broken, their bytes will be replaced with
0s in the ddrescue image.A first way to go is trying to explore your image using
-l as above and check -i to find out if fatcat recognizes the disk as a FAT system.Then, you can try to have a look at
-2, to check if the file allocation tables differs, and if it looks mergeable. It is very likely that is will be mergeable, in this case, you can try -m to merge the FAT tables, don't forget to backup it before (see below).Orphan files
When your filesystem is broken, there are files and lost files and lost directories that we call "orphaned", because you can't reach them from the normal system.
fatcat provides you an option to find those nodes, it will do an automated analysis of your system and explore allocated sectors of your filesystem, this is done with -o.You will get a list of directories and files, like this:
There is 2 orphaned elements:
Directory clusters 4592 to 4592: 2 elements, 49B
File clusters 4611 to 4611: ~512B-L and -R to have a look into those files and directories:$ fatcat disk.img -L 4592
Listing cluster 4592
Cluster: 4592
d 23/10/2013 17:45:06 ./ c=4592
d 23/10/2013 17:45:06 ../ c=0
f 23/10/2013 17:45:22 poor_orphan.txt c=4601 s=49 (49B)See also: orphaned files tutorial
Hacking
You can use
fatcat to hack your FAT filesystemInformations
The
-i flag will provide you a lot of information about the filesystem:fatcat disk.img -iYou can also get information about a specific cluster by using
-@:fatcat disk.img -@ 1384Backuping & restoring FAT
You can use
-b to backup your FAT tables:fatcat disk.img -b backup.fats-p to write it back:fatcat disk.img -p backup.fatsWriting to the FATs
You can write to the FAT tables with
-w and -v:fatcat disk.img -w 123 -v 124124 as value of the next cluster of 123.You can also choose the table with
-t, 0 is both tables, 1 is the first and 2 the second.Diff & merge the FATs
You can have a look at the diff of the two FATs by using
-2:# Watching the diff
$ fatcat disk.img -2
Comparing the FATs
FATs are exactly equals
# Writing 123 in the 500th cluster only in FAT1
$ fatcat disk.img -w 500 -v 123 -t 1
Writing next cluster of 500 from 0 to 123
Writing on FAT1
# Watching the diff
$ fatcat disk.img -2
Comparing the FATs
[000001f4] 1:0000007b 2:00000000
FATs differs
It seems mergeable-m. For each different entries in the table, if one is zero and not the other, the non-zero file will be choosen:$ fatcat disk.img -m
Begining the merge...
Merging cluster 500
Merge complete, 1 clusters mergedDirectories fixing
Fatcat can fix directories having broken FAT chaining.
To do this, use
-f. All the filesystem tree will be walked and the directories that are unallocated in the FAT but that fatcat can read will be fixed in the FAT.Entries hacking
You can have information about an entry with
-e:fatcat disk.img -e /hello.txtYou can add the flag
-c [cluster] to change the cluster of the entry and the flag -s [size] to change the entry size.See also: fun with fat tutorial
You can use
-k to search for a cluster reference.Erasing unallocated files
You can erase unallocated sectors data, with zeroes using
-z, or using random data using -S.For instance, deleted files will then become unreadables.
