Graham Ollis

NAME

Archive::Ar::Libarchive - Interface for manipulating ar archives with libarchive

VERSION

version 2.05

SYNOPSIS

 use Archive::Ar::Libarchive;
 
 my $ar = Archive::Ar->new('libfoo.a');
 
 $ar->add_data('newfile.txt', 'some contents', { uid => 101, gid => 102 });
 
 $ar->add_files('./bar.tar.gz', 'bat.pl');
  
 $ar->remove('file1', 'file2');
 
 my $content = $ar->get_content('file3')->{data};
 
 my @files = $ar->list_files;
 
 $ar->write('libbar.a');
 
 my @file_list = $ar->list_files;

DESCRIPTION

This module is a XS alternative to Archive::Ar that uses libarchive to read and write ar BSD, GNU and common ar archives.

There is no standard for the ar format. Most modern archives are based on a common format with two extension variants, BSD and GNU. Other esoteric variants (such as AIX (small), AIX (big) and Coherent) vary significantly from the common format and are not supported. Debian's package format (.deb files) use the common format.

The interface attempts to be identical (with a couple of minor extensions) to Archive::Ar and the documentation presented here is based on that module. The diagnostic messages issued on error mostly come directly from libarchive, so they will likely not match exactly what Archive::Ar would produce, but it should issue a warning under similar circumstances.

The main advantage of Archive::Ar over this module is that it is written in pure perl, and thus does not require a compiler or libarchive. As an XS module using libarchive it may be faster.

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

METHODS

new

 my $ar = Archive::Ar::Libarchive->new;
 my $ar = Archive::Ar::Libarchive->new($filename);
 my $ar = Archive::Ar::Libarchive->new($fh);

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

set_opt

 $ar->set_opt($name, $value);

Assign option $name value $value. Supported options include:

warn

Warning level. Levels are zero for no warnings, 1 for brief warnings, and 2 for warnings with a stack trace. Default is zero.

Warnings that originate with libarchive itself will not include a stacktrace, even with a warn level set to 2.

chmod

Change the file permissions of files created when extracting. Default is true (non-zero).

This option is provided only for compatibility with Archive::Ar. Libarchive does not provide an equivalent to this option, so setting it to false will has no effect.

same_perms

When setting file permissions, use the values in the archive unchanged. If false, removes setuid bits and applies the user's umask. Default is true.

In Archive::Ar this option is true for root only.

chown

Change the owners of extracted files, if possible. Default is true.

type

Archive type. May be GNU, BSD or COMMON, or undef if no archive has been read. Defaults to the type of the archive read or undef.

symbols

Provide a filename for the symbol table, if present. If set, the symbol table is treated as a file that can be read from or written to an archive. It is an error if the filename provided matches the name of a file in the archive. If undef, the symbol table is ignored. Defaults to undef.

get_opt

 my $value = $ar->get_opt($name);

Returns the value of the option $name.

type

 my $type = $ar->type;

Returns the type of the ar archive. The type is undefined until an archive is loaded. If the archive displays characteristics of a GNU-style archive, GNU is returned. If it looks like a bsd-style archive, BSD is returned. Otherwise, COMMON is returned. Note that unless filenames exceed 16 characters in length, bsd archives look like the common format.

clear

 $ar->clear;

Clears the current in-memory archive.

read

 my $br = $ar->read($filename);
 my $br = $ar->read($fh);

This reads a new file into the object, removing any ar archive already represented in the object. The argument may be either a filename, filehandle or IO::Handle object. Returns the number of bytes read, undef on failure.

read_memory

 my $br = $ar->read_memory($data);

This reads information from the first parameter, and attempts to parse and treat it like an ar archive. Like Archive::Ar::Libarchive#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.

contains_file

 my $bool = $ar->contains_file($filename)

Returns true if the archive contains a file with the name $filename. Returns undef otherwise.

extract

 $ar->extract;

Extract all files from the archive. Extracted files are assigned the permissions and modification time stored in the archive, and, if possible, the user and group ownership. Returns true on success, undef for failure.

extract_file

 $ar->extract_file($filename);

Extracts a single file from the archive. The extracted file is assigned the permissions and modification time stored in the archive, and, if possible, the user and group ownership. Returns true on success, undef for failure.

rename

 $ar->rename($filename, $newname);

Changes the name of a file in the in-memory archive.

chmod

 $ar->chmod($filename, $mode);

Change the permission mode of the member to $mode.

chown

 $ar->chown($filename, $uid, $gid);
 $ar->chown($filename, $uid);

Change the ownership of the member to user id $udi and (optionally) group id $gid. Negative id values are ignored.

remove

 my $count = $ar->remove(@pathnames);
 my $count = $ar->remove(\@pathnames);

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.

list_files

 my @list = $ar->list_files;
 my $list = $ar->list_files;

This lists the files contained inside of the archive by filename, as an array. If called in a scalar context, returns a reference to an array.

add_files

 $ar->add_files(@filenames);
 $ar->add_files(\@filenames);

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, Archive::Ar::Libarchive#add_files will store the uid, gid, mode, size, and creation date of the file as returned by stat.

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

add_data

 my $size = $ar->add_data($filename, $data, $filedata);

Takes an filename and a set of data to represent it. Unlike Archive::Ar::Libarchive#add_files, Archive::Ar::Libarchive#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 = {
   uid  => $uid,   #defaults to zero
   gid  => $gid,   #defaults to zero
   date => $date,  #date in epoch seconds. Defaults to now.
   mode => $mode,  #defaults to 0100644;
 };

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

write

 my $content = $ar->write;
 my $size = $ar->write($filename);

This method will return the data as an .ar archive, or will write to the filename present if specified. If given a filename, Archive::Ar::Libarchive#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

 my $hash = get_content($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

get_data

 my $data = $ar->get_data($filename);

Returns a scalar containing the file data of the given archive member. On error returns undef.

get_handle

 my $handle = $ar->get_handle($filename);

Returns a file handle to the in-memory file data of the given archive member. On error returns undef. This can be useful for unpacking nested archives.

error

 my $error_string = $ar->error($trace);

Returns the current error string, which is usually the last error reported. If a true value is provided, returns the error message and stack trace.

SEE ALSO

Alien::Libarchive
Archive::Ar

AUTHOR

Graham Ollis <plicease@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2013 by Graham Ollis.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.