Hi Folks,
This is a module that I wrote for in-house use as I am somewhat apprehensive
about the reliability of low-end SATA raid controllers. Admittedly, this
module scratches a rather niche itch. My two questions are a) is this
functionality general enough to warrant placing it on CPAN and b) is the
namespace appropriate?
Cheers,
-J
--
NAME
File::Corruption - Detect file corruption
SYNOPSIS
use File::Corruption;
use File::Find::Rule;
my $checker= File::Corruption->new(
db => './test.yml',
verbose => 1,
autoflush => 1,
);
my $checker2 = $checker->clone;
my @files = File::Find::Rule->file->name( '*' )->in( "." );
my $added = $checker->add( [EMAIL PROTECTED] );
my $bad = $checker->check( [EMAIL PROTECTED] );
my $deleted = $checker->delete( [EMAIL PROTECTED] );
print "has file\n" if $checker->has( qw( foo ) );
$checker->save;
DESCRIPTION
This module attempts to detect file corruption caused by errors in the
storage medium. The design philosophy is very different from intrusion
detection systems like Tripwire and AIDE. While both of those well known
systems will detect and report file corruption, they will also detect
(and report) almost *any* file modification. In contrast this module
attempts to *stay out of your face* by ignoring intentional file
modification and only reporting files that have had bit values
*silently* changed.
File corruption is detected by recording a file's "mtime" and it's SHA1
checksum into a persistent database. The next time a file is inspected
by "check" the file's current "mtime" is compared to the value stored in
the database. If the "mtime"s are the same but the checksum has changed
then the file is said to be corrupted. If the "mtime"s are different
then the new "mtime" and checksum are recorded to the database.
Obvously, this technique is NOT suitable for intrusion detection.
USAGE
Import Parameters
This module accepts no arguments to it's "import" method and exports no
*symbols*.
Methods
Constructors
* new(...)
Accepts a mandatory hash and returns a File::Corruption object.
my $checker = File::Corruption->new(
db => './foo.yml',
verbose => 1,
autoflush => 1
);
* db
A file path to either a pre-existing File::Corruption YAML
database or a location where a new database can be created. A
pre-existing database must be writable. If a path to a new
database is specified the directory must already exist (new
directories will not be automatically created) and have
permissions that allow file creation.
* verbose
A boolean value (0, 1, undef). Causes corrupt, non-existent, and
non-plain files to be reported to the STDERR.
This key is optional.
* autoflush
A boolean value (0, 1, undef). When set to true, check will
flush any files from the database that were not passed in to be
tested. This behavior is on a per invocation basis.
This key is optional.
* clone
This object method returns a replica of the given object.
Object Methods
* add
Accepts either a filename or an arrayref to filenames that will be
added to the File::Corruption database.
Returns a list of File::Corruption::Stat objects representing files
actually added to the database. In scalar context returns either an
arrayref to File::Corruption::Stat objects or undef if no files were
added.
* check
Accepts either a filename or an arrayref to filenames that will be
checked against the File::Corruption database. Filenames that don't
already exist in the database will be automatically added.
Returns a list of File::Corruption::Detected objects representing
files that are suspected to have been corrupted. In scalar context
returns either an arrayref to File::Corruption::Detected objects or
undef if no corrupt files were detected.
* delete
Accepts either a filename or an arrayref to filenames that will be
deleted from the File::Corruption database.
Returns a list of File::Corruption::Stat objects representing the
files actually deleted from the database. In scalar context returns
either an arrayref to File::Corruption::Stat objects or undef if no
files were deleted.
* has
Accepts a filename.
Returns a File::Corruption::Stat object if the filename has an entry
in the database or undef if it doesn't.
* save
Accepts no arguments. Writes the in memory database to disk.
Destructors
* DESTROY
Calls save.
DEVELOPER NOTES
In the environment this module was development in the file processing is
completely I/O bound. If this was not the case, performance could be
enhanced on SMP systems by placing the files to be "check"ed into a work
queue and having them processed by a pool of worker threads.
If you believe that your environment is CPU bound and would scale with
multi-threading please e-mail the author.
REFERENCES
* Tripwire
<http://www.tripwire.com/>
<http://www.tripwire.org/>
* AIDE
<http://www.cs.tut.fi/~rammer/aide.html>
<http://sourceforge.net/projects/aide>
CREDITS
Just me, myself, and I.
SUPPORT
Please contact the author directly via e-mail.
AUTHOR
Joshua Hoblitt <[EMAIL PROTECTED]>
COPYRIGHT
Copyright (C) 2004 Joshua Hoblitt. All rights reserved.
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2 of the License, or (at your
option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
The full text of the license can be found in the LICENSE file included
with this module, or in the perlgpl Pod as supplied with Perl 5.8.1 and
later.
SEE ALSO
File::Corruption::Stat, File::Corruption::Detected, stat(2),
Digest::SHA1
