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Archive::Ar
Interface for manipulating ar archives

Archive::Ar - Interface for manipulating ar archives


NAME

Archive::Ar - Interface for manipulating ar archives


SYNOPSIS


        use Archive::Ar;

        my $ar = new Archive::Ar("./foo.ar");

        $ar->add_data("newfile.txt","Some contents", $properties);

        $ar->add_files("./bar.tar.gz", "bat.pl")

        $ar->add_files(["./again.gz"]);

        $ar->remove("file1", "file2");

        $ar->remove(["file1", "file2");

        my $filedata = $ar->get_content("bar.tar.gz");

        my @files = $ar->list_files();

        $ar->read("foo.deb");

        $ar->write("outbound.ar");

        $ar->DEBUG();


DESCRIPTION

Archive::Ar is a pure-perl way to handle standard ar archives.

This is useful if you have those types of old archives on the system, but it is also useful because .deb packages for the Debian GNU/Linux distribution are ar archives. This is one building block in a future chain of modules to build, manipulate, extract, and test debian modules with no platform or architecture dependence.

You may notice that the API to Archive::Ar is similar to Archive::Tar, and this was done intentionally to keep similarity between the Archive::* modules

Class Methods

  • new()
  • new($filename)
  • new(*GLOB,$debug)
  • Returns a new Archive::Ar object. Without a filename or glob, it returns an empty object. If passed a filename as a scalar or in a GLOB, it will attempt to populate from either of those sources. If it fails, you will receive undef, instead of an object reference.

    This also can take a second optional debugging parameter. This acts exactly as if DEBUG() is called on the object before it is returned. If you have a new() that keeps failing, this should help.

  • read($filename)
  • read(*GLOB);
  • This reads a new file into the object, removing any ar archive already represented in the object. Any calls to DEBUG() are not lost by reading in a new file. Returns the number of bytes read, undef on failure.

  • read_memory($data)
  • This read information from the first parameter, and attempts to parse and treat it like an ar archive. Like read(), it will wipe out whatever you have in the object and replace it with the contents of the new archive, even if it fails. Returns the number of bytes read (processed) if successful, undef otherwise.

  • list_files()
  • This lists the files contained inside of the archive by filename, as an array.

  • add_files("filename1", "filename2")
  • add_files(["filename1", "filename2"])
  • Takes an array or an arrayref of filenames to add to the ar archive, in order. The filenames can be paths to files, in which case the path information is stripped off. Filenames longer than 16 characters are truncated when written to disk in the format, so keep that in mind when adding files.

    Due to the nature of the ar archive format, add_files() will store the uid, gid, mode, size, and creation date of the file as returned by stat();

    add_files() returns the number of files successfully added, or undef on failure.

  • add_data("filename", $filedata)
  • Takes an filename and a set of data to represent it. Unlike add_files, add_data is a virtual add, and does not require data on disk to be present. The data is a hash that looks like:
    
            $filedata = {
    
            "data" => $data,
    
            "uid" => $uid, #defaults to zero
    
            "gid" => $gid, #defaults to zero
    
            "date" => $date,  #date in epoch seconds. Defaults to now.
    
            "mode" => $mode, #defaults to "100644";
    
            }

    You cannot add_data over another file however. This returns the file length in bytes if it is successful, undef otherwise.

  • write()
  • write("filename.ar")
  • This method will return the data as an .ar archive, or will write to the filename present if specified. If given a filename, write() will return the length of the file written, in bytes, or undef on failure. If the filename already exists, it will overwrite that file.

  • get_content("filename")
  • This returns a hash with the file content in it, including the data that the file would naturally contain. If the file does not exist or no filename is given, this returns undef. On success, a hash is returned with the following keys:
    
            name - The file name
    
            date - The file date (in epoch seconds)
    
            uid  - The uid of the file
    
            gid  - The gid of the file
    
            mode - The mode permissions
    
            size - The size (in bytes) of the file
    
            data - The contained data

  • remove("filename1", "filename2")
  • remove(["filename1", "filename2"])
  • The remove method takes a filenames as a list or as an arrayref, and removes them, one at a time, from the Archive::Ar object. This returns the number of files successfully removed from the archive.

  • DEBUG()
  • This method turns on debugging. Optionally this can be done by passing in a value as the second parameter to new. While verbosity is enabled, Archive::Ar will toss a warn() if there is a suspicious condition or other problem while proceeding. This should help iron out any problems you have while using the module.


CHANGES


TODO

A better unit test suite perhaps. I have a private one, but a public one would be nice if there was good file faking module.

Fix / investigate stuff in the BUGS section.


BUGS

To be honest, I'm not sure of a couple of things. The first is that I know of ar archives made on old AIX systems (pre 4.3?) that have a different header with a different magic string, etc. This module perfectly (hopefully) handles ar archives made with the modern ar command from the binutils distribution. If anyone knows of anyway to produce these old-style AIX archives, or would like to produce a few for testing, I would be much grateful.

There's no really good reason why this module shouldn't run on Win32 platforms, but admittedly, this might change when we have a file exporting function that supports owner and permission writing.

If you read in and write out a file, you get different md5sums, but it's still a valid archive. I'm still investigating this, and consider it a minor bug.


COPYRIGHT

Archive::Ar is copyright 2003 Jay Bonci <jaybonci@cpan.org>. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

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