Device::Blkid::E2fsprogs version 0.16
=====================================

NOTE: This library only exposes the older e2fsprogs versions of libblkid ( numbered 1.xx.x)
and not the newer and preferred util-linux-ng versions ( v2.15 or better ). In almost
every case you would be advised to use Bastian Friedrich's util-linux-ng based Device::Blkid
module as the newer lib interface is (mostly) backward compatible with the old one. This
module would prove useful in any situation where for any reason you are limited on your
systems to a 1.xx.x libblkid version which is a part of the e2fsprogs package. Incidentally,
libblkid version numbering is based upon the version of either util-linux-ng or e2fsprogs of
which it was a part and as such, e2fsprogs based versions of the library were all numbered
v1.xx.x whereas util-linux-ng versions are numbered as v2.15 or better which was the version
of util-linux-ng in which it was added to that package. So just to be clear, when in doubt
you are advised to grab Bastian's newer util-linux-ng based libblkid interface module unless
you have some specific reason as to why you can't, perhaps something similar to what led me
to write this version.

This version has been implemented somewhat differently than Bastian's util-linux-ng build
of the library. He opted to keep much of his logic and processing in XSUB, mine is done
mostly in C; I have only used XSUB for my straight glue, everything else I kept in C. This is
not to be taken as any opinion of statement on PerlXS/XSUB, its merely a reflection of my own
background and tastes.

This package provides a Perl interface to the e2fsprogs-based versions of libblkid. It does not
support the larger and more robust API which has been added and integrated into the libblkid
library since its inclusion in the util-linux-ng package. That said, the libblkid which now
ships with util-linux-ng is reportedly backward compatible with client code dependant upon the
older, original library which would mean that this module should work with it, albeit with the
more limited selection of API calls. Please see the preceding note for additional details.

Libblkid provides a means of identifying block devices as to their content (such as filesystems)
as well as allowing for the extraction of additional information such as filesystem labels,
volume labels, serial numbers, device numbers, unique identifiers, etc. The libblkid library
maintains a mapping of all of this composite information and maintains its association with
a given block device on the system. Libblkid is becoming more commonly seen in modern linux
distributions in places such as configuration files and other such places where hard coded
device names were once used.

In addition to providing for low level probing of block devices for this information, the
library maintains an on disk cache file of this data. It is by way of the cache file that
unpriviledged users are able to access this information via a variety of library calls. Use of
the cache file as opposed to direct, low level probing of the hardware is recommended whenever
possible and feasible.

Recognizing that this is a Perl module, I have tried to provide a more 'Perlish' interface
where possible rather than merely map Perl subs to C functions. Most library functions return
an undef on failure and a number of calls return hash types.

Please read the README file in the package archive for instructions should you encounter any
problems while using this software package, as well as for instructions on building a debug
version.

It is worth noting that between versions 1.33 and 1.41.4, the entire period which libblkid
was shipping as a part of the e2fsprogs package, the number of calls present in the API
expanded from the 17 in the original release of the library back in 2003 to 24 when it was
migrated over to the util-linux-ng package in early 2009. This module supports all 24 calls
from the most recent iteration of this run. I will, in an upcoming version of this module,
provide a means for configuring this package for a target release of libblkid by way of the
in package Makefile.PL, but for now it supports the entire breadth of calls.

INSTALLATION

For a standard installation of this module type the following:

   perl Makefile.PL
   make
   make test
   make install

DEPENDENCIES

Perl 5.8.0

This module also requires these other modules and libraries:

E2fsprogs v1.33-v1.41

DEBUGGING and REPORTING A BUG

If you have any problems with the functioning of this library, please contact me at my CPAN
address at mroz@cpan.org. Please be sure and include a list of packages installed on your system
or at least the exact version of e2fsprogs which you have installed. Also, please build and
install a debug build of this library as detailed below, execute the application which is using
this package and failing, and send me the verbose debugging output from the DEBUG build of this
package.

There are two ways to produce a debug build of this module package. The first, and easiest, is
to pass a debug DEFINE to the Makefile.PL file when configuring the package for installation.
To install a DEBUG build in this way, type the following from the top level of this package:

   perl Makefile.PL DEFINE=-D__DEBUG
   make
   make test
   make install

The second method is to edit the Makefile.PL file itself and to add the '-D__DEBUG' define to
the DEFINE argument of the WriteMakefile method found in the file (see the comments inside the
file for additional details. Should you run a DEBUG build of this package you will note a much
higher level of verbosity in the output from the execution of the library. Please capture and
submit any and all of this additional verbosity to me at my CPAN address making sure to include
a complete description of the abhorrent behavior you have or are observing while using this
package.

Furthermore, If you find any problems with this package and wish to submit a patch, please
send the unified diff to my CPAN address including full patch instructions as well as a
description of what issue or bug you have found and addressed. Please patch as per recommended
best practices found in the patch(1) man page, under "NOTES FOR PATCH SENDERS".
  
COPYRIGHT AND LICENCE

Copyright (C) 2010 by Raymond Mroz

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself, either Perl version 5.10.1 or,
at your option, any later version of Perl 5 you may have available.

THANKS

Thanks to Bastian for all of is work on Device::Blkid, I was especially appreciative of your
POD as libblkid itself is not terribly well documented. While I did make a large number of my
own straight test calls in C against the library your documentation kept me in the right
direction and saved me a load of time by allowing me to concentrate my efforst in the right
place. Thanks.

BUGS

No known bugs at this time. That said, this module is largely written in C and does contain
a number of memory allocations. While these allocations are done inside of the libblkid itself,
I do make every attempt to free the memory explicitly when I am done with it. That said, leaks
are possible. Report any issues as is detailed above.
