cognusion / Fuse Copyfs

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                A copy-on-write, versionned filesystem
                            Version 1.3.1M

                                By
                           Nicolas Vigier
                      ([email protected])
                               and
                           Thomas Joubert
                       ([email protected])

                       http://n0x.org/copyfs/

                         Contributions From:
                           Matthew Keller
                 https://github.com/cognusion/copyfs

CopyFS aims to solve a common problem : given a directory, especially one full of configuration files, or other files that one can modify, and which can affect the functionning of a system, or of programs, that may be important to other users (or to the user himself), how to be sure that a person modifying the files will do a backup of the working version first ?

This filesystem solves the problem by making the whole process transparent, automatically keeping versionned copies of all the changes done to file under its control.

It also allows a user to select an old version of the files, for example to repair a mistake, and allows him/her to continue edition from this point.

CopyFS is distributed under the terms of the GNU GPL.

System requirements

Filesystem in Userspace (FUSE) is required to use this filesystem. FUSE was merged into the mainstream Linux kernel tree in kernel version 2.6.14, so any version >= 2.6.14 should be fine, if the option was selected when the kernel was compiled.

More informations about FUSE is available on http://fuse.sourceforge.net/

It might work on FreeBSD and OpenSolaris too, but we never tried yet.

How to install

Simply do :

copyfs-1.0 % ./configure
copyfs-1.0 % make all
copyfs-1.0 % su
Password:
copyfs-1.0 # make install

How to use

To mount a CopyFS, you need to use the command 'copyfs-mount' : if you want to mount a CopyFS at '/mnt/fs', whose version directory is at /var/versions, you would use :

root # copyfs-mount /var/versions /mnt/fs

To unmount it, simply do :

root # umount /mnt/fs

As you would do for any filesystem.

Accessing old versions

To know which versions are available, you can use the copyfs-fversion tool :

cpy-fs $ copyfs-fversion test
File test ('*' is active) :
  v1.0  : -rw-r--r--  widan    users             0 Fri Dec 10 14:17:47 2004
  v2.0  : -rw-r--r--  widan    users            21 Fri Dec 10 14:17:55 2004
  v2.1  : -rwx------  widan    users            21 Fri Dec 10 14:17:55 2004
  v3.0  : -rwx------  widan    users            29 Fri Dec 10 14:19:35 2004 [*]

You know there are 4 versions, with their associated information. In that state you are viewing version 3.0 (ie the last one). If you want to see another one, you can 'lock' it :

cpy-fs $ cat test
version 3.0
cpy-fs $ copyfs-fversion -l 2.0 test
cpy-fs $ cat test
version 2.0

If you want to remove the version lock, and return to the latest version available, use :

cpy-fs $ copyfs-fversion -r test

Tagging files

Let's say you have the following file tree :

cpy-fs $ copyfs-fversion somedir/file-1
File file-1 ('*' is active) :
  v1.0  : -rw-r--r--  widan    users             3 Fri Dec 10 14:21:41 2004
  v2.0  : -rw-r--r--  widan    users             3 Fri Dec 10 14:21:43 2004 [*]
  v3.0  : -rw-r--r--  widan    users             3 Fri Dec 10 14:21:45 2004
cpy-fs $ copyfs-fversion somedir/file-2
File file-2 ('*' is active) :
  v1.0  : -rw-r--r--  widan    users             5 Fri Dec 10 14:21:51 2004 [*]
  v2.0  : -rw-r--r--  widan    users             5 Fri Dec 10 14:21:53 2004
cpy-fs $ copyfs-fversion somedir/file-3
File file-3 ('*' is active) :
  v1.0  : -rw-r--r--  widan    users             5 Fri Dec 10 14:21:58 2004
  v2.0  : -rw-r--r--  widan    users             5 Fri Dec 10 14:22:03 2004 [*]

You have :

cpy-fs $ cat somedir/file-1
v2
cpy-fs $ cat somedir/file-2
2 v1
cpy-fs $ cat somedir/file-3
3 v2

Suppose you want to save all the "current" versions for the directory 'somedir', you can create a tag file with :

cpy-fs $ copyfs-fversion -t tag-file somedir

Then you can edit the files as you want, and if you want to put all the files back to the version they were at when you tagged them, simply do :

cpy-fs $ copyfs-fversion -u tag-file somedir

Example :

cpy-fs $ echo "new 1" > somedir/file-1
cpy-fs $ echo "new 2" > somedir/file-2
cpy-fs $ cat somedir/file-{1,2,3}
new 1
new 2
3 v2
cpy-fs $ copyfs-fversion -t tag-file-new somedir
cpy-fs $ copyfs-fversion -u tag-file somedir
Restored somedir/file-1 to version 2.0
Restored somedir/file-2 to version 1.0
Restored somedir/file-3 to version 2.0
cpy-fs $ cat somedir/file-{1,2,3}
v2
2 v1
3 v2
cpy-fs $ copyfs-fversion -u tag-file-new somedir
Restored somedir/file-1 to version 6.0
Restored somedir/file-2 to version 3.0
Restored somedir/file-3 to version 2.0
cpy-fs $ cat somedir/file-{1,2,3}
new 1
new 2
3 v2

Viewing the changes between version of text files

Example:

[workspace]$ echo "Hello world" > testfile
[workspace]$ echo "There's always room for JELLO" >> testfile
[workspace]$ copyfs-fversion testfile
File testfile ('*' is active) :
  v1.0  : -rw-rw-r--  kellermg kellermg         12 Mon 13 Feb 2006 12:59:28 PM EST
  v2.0  : -rw-rw-r--  kellermg kellermg         42 Mon 13 Feb 2006 12:59:55 PM EST [*]
[workspace]$ copyfs-fversion -d 1.0,2.0 testfile
2 -
2 + There's always room for JELLO
--------
[workspace]$ cat testfile
Hello world
There's always room for JELLO

We will balk if you try to diff a binary file:

[copyfs]$ copyfs-fversion -d 41.0,53.0 copyfs-daemon
I will not diff binary files

Searching (ala grep) for a pattern in all version of a text file

Example:

[workspace]$ echo "Hello world" > testfile
[workspace]$ echo "There's always room for JELLO" >> testfile
[workspace]$ echo "Thanks for all the fish" >> testfile
[workspace]$ echo "So long" >> testfile
[workspace]$ echo "Blah Blah Blah" >> testfile
[workspace]$ echo "Another fish" >> testfile
[workspace]$ copyfs-fversion -G fish testfile
Do not mess with this file... search in progress...
v3.0: Thanks for all the fish
v4.0: Thanks for all the fish
v5.0: Thanks for all the fish
v6.0: Thanks for all the fish
v6.0: Another fish
5 results.

You can also search for a regexp!:

[workspace]$ copyfs-fversion -G ^Blah testfile
Do not mess with this file... search in progress...
v5.0: Blah Blah Blah
v6.0: Blah Blah Blah
2 results.

Purging (Culling) old versions of files

Purging of folders not yet supported... maybe someday. The recursions necessary scares me.

Example:

[workspace]$ copyfs-fversion testfile
File testfile ('*' is active) :
  v1.0  : -rw-rw-r--  kellermg kellermg         12 Mon 13 Feb 2006 12:59:28 PM EST
  v2.0  : -rw-rw-r--  kellermg kellermg         42 Mon 13 Feb 2006 12:59:55 PM EST
  v3.0  : -rw-rw-r--  kellermg kellermg         66 Mon 13 Feb 2006 01:03:24 PM EST
  v4.0  : -rw-rw-r--  kellermg kellermg         74 Mon 13 Feb 2006 01:04:44 PM EST
  v5.0  : -rw-rw-r--  kellermg kellermg         89 Mon 13 Feb 2006 01:04:56 PM EST
  v6.0  : -rw-rw-r--  kellermg kellermg        102 Mon 13 Feb 2006 01:05:02 PM EST [*]
[workspace]$ copyfs-fversion -p 3 testfile
[workspace]$ copyfs-fversion testfile
File testfile ('*' is active) :
  v4.0  : -rw-rw-r--  kellermg kellermg         74 Mon 13 Feb 2006 01:04:44 PM EST
  v5.0  : -rw-rw-r--  kellermg kellermg         89 Mon 13 Feb 2006 01:04:56 PM EST
  v6.0  : -rw-rw-r--  kellermg kellermg        102 Mon 13 Feb 2006 01:05:02 PM EST [*]

Or you can just kill the very existance of the file:

[workspace]$ copyfs-fversion -p A testfile
[workspace]$ copyfs-fversion testfile
fversion: testfile: No such file or directory