Device::Blkid::E2fsprogs version 0.40 ===================================== NOTE: This extension only supports the older e2fsprogs versions of libblkid (numbered 1.xx.x) and not the newer versions now bundled as a part of util-linux-ng (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 interface is reportedly 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 libblkid version which is a part of the e2fsprogs package. With respect to version numbers, it is the convention that libblkid adopts a version number which matches the package of which it is a part, so when the library was migrated to the util-linux-ng package it jumped in version number from 1.41.4 to 2.15. As such, the rule of thumb here is that if the version of libblkid on your system begins with a '1', it is an e2fsprogs-based version of the library, whereas those which begin with a '2' are the newer util-linux-ng based builds. Another key difference is the default location of the cache file between the two packages; the e2fsprogs-based versions use a default cache file at /etc/blkid/blkid.tab whereas the util-linux-ng versions of libblkid maintain their default cache file at /etc/blkid.tab. 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 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 has become common in modern linux distributions and can be seen in use in places such as configuration files where device paths had been formerly used, such as fstab. The library provides a means of probing block devices for this various meta information as well as accessing the blkid cache file which stores this data on a local disk. Use of the cache file can allow an unpriviledged user access to this information even though they might not have read access to the block device. I have endeavored to provide a more Perlish interface to the library where possible rather than simply map the C calls to Perl ones. Most calls return an undef on failure and those which deal with object allocations will throw a catchable exception when something goes wrong. Perl hash types are returned as well in a number of cases. Please read the README file in the package archive for instructions should you encounter any problems while using this software package. E2FSPROGS-LIBBLKID VERSION HISTORY Libblkid first appeared in version 1.33 of the e2fsprogs package back in 2003. The initial release of the library exposed 17 function calls as part of its API. When libblkid stopped shipping with the e2fsprogs package, the function count numbered at 25 calls which had been the case since version 1.40 of the interface. A brief outline of the API history is as follows: v1.33 - 17 calls v1.34 - 18 calls v1.36 - 21 calls v1.38 - 24 calls v1.40 - 25 calls In version 1.36 of libblkid two functions appeared which returned version information about the library, those were: int blkid_parse_version_string(const char *ver_string); int blkid_get_library_version(const char **ver_string, const char **date_string); These calls have been used to provide for dynamic library version detection during the initial configuration in the package Makefile.PL script. As these calls were not available prior to version 1.36, dynamic configuration is not yet possible for the two earlier versions and a default baseline target of v1.33 will be generated. INSTALLATION This module uses an optional dynamic libblkid version detection mechanism to try and ascertain which version of libblkid is installed on the target system. It will attempt to detect the version of the libblkid library installed on your target system and should this fail, it assumes a pre-1.36 version and builds a default v1.33 baseline which is compatible with all versions of the library. To install and begin dynamic version detection: perl Makefile.PL make make test make install ===== libblkid version detection ===== I have made use of a customized Devel::CheckLib module and Makefile.PL in an attempt to detect the version of libblkid currently installed on the target system and to then generate a Perl XS interface which directly targets and matches the API interface of that libblkid version. This process is expected to work on all versions of libblkid later than v1.35. In the event that the target system has a pre-1.36 version of the library, a default baseline target of v1.33 is configured for build. Should you have any problems with this process, evident either in running the Makefile.PL or in running make on its resulting Makefile, please see the Makefile.PL as well as the E2fsprogs.xs file to troubleshoot. If you wish to report any problems with this version detection, please include any output from the installation process as well as a copy of your /usr/include/blkid/blkid.h file. DEPENDENCIES Perl 5.8.0 This module also requires these other modules and libraries: E2fsprogs v1.33-v1.41 * Note: This package supports both dynamic version detection during the configuration phase of running Makefile.PL, as well as manual selection of a build target by version. If neither of these are suitable to your needs or there is some sort of problem with this on your target system, please refer to the Makefile.PL as well as Devel::CheckLib files; both are well documented and relatively easy to modify. 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 relevant packages installed on your system or at least the exact version of e2fsprogs which you have installed, perhaps by providing the blkid.h file. Should 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, 2011 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. Thanks! Thanks to David Cantrell, David Golden and Yasuhiro Matsumoto for Devel::CheckLib. I hacked it up a little bit to manage my dynamic version checks and build, hope you don't mind. Thanks to Tom Erskine for your insight and experience in all things Perl. I would also like to thank Larry McInnis for the loan of some hardware on which to develop this module. Most everything I have had been tied up and developing on the latest and greatest version of Debian didn't make much sense. 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. FUTURE Please note that this module should be considered early release. As such, this information or its API may change at any time. Please check CPAN for the latest version of this software.