Jos Boumans > Archive-Tar-1.09 > Archive::Tar

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Module Version: 1.09   Source   Latest Release: Archive-Tar-2.04

NAME ^

Archive::Tar - module for manipulations of tar archives

SYNOPSIS ^

    use Archive::Tar;
    my $tar = Archive::Tar->new;
    
    $tar->read('origin.tgz',1); 
    $tar->extract();
    
    $tar->add_files('file/foo.pl', 'docs/README');
    $tar->add_data('file/baz.txt', 'This is the contents now');
    
    $tar->rename('oldname', 'new/file/name');
    
    $tar->write('files.tar');

DESCRIPTION ^

Archive::Tar provides an object oriented mechanism for handling tar files. It provides class methods for quick and easy files handling while also allowing for the creation of tar file objects for custom manipulation. If you have the IO::Zlib module installed, Archive::Tar will also support compressed or gzipped tar files.

An object of class Archive::Tar represents a .tar(.gz) archive full of files and things.

Object Methods ^

Archive::Tar->new( [$file, $compressed] )

Returns a new Tar object. If given any arguments, new() calls the read() method automatically, passing on the arguments provided to the read() method.

If new() is invoked with arguments and the read() method fails for any reason, new() returns undef.

$tar->read ( $filename|$handle, $compressed, {opt => 'val'} )

Read the given tar file into memory. The first argument can either be the name of a file or a reference to an already open filehandle (or an IO::Zlib object if it's compressed) The second argument indicates whether the file referenced by the first argument is compressed.

The read will replace any previous content in $tar!

The second argument may be considered optional if IO::Zlib is installed, since it will transparently Do The Right Thing. Archive::Tar will warn if you try to pass a compressed file if IO::Zlib is not available and simply return.

The third argument can be a hash reference with options. Note that all options are case-sensitive.

limit

Do not read more than limit files. This is usefull if you have very big archives, and are only interested in the first few files.

extract

If set to true, immediately extract entries when reading them. This gives you the same memory break as the extract_archive function. Note however that entries will not be read into memory, but written straight to disk.

All files are stored internally as Archive::Tar::File objects. Please consult the Archive::Tar::File documentation for details.

Returns the number of files read in scalar context, and a list of Archive::Tar::File objects in list context.

$tar->contains_file( $filename )

Check if the archive contains a certain file. It will return true if the file is in the archive, false otherwise.

Note however, that this function does an exact match using eq on the full path. So it can not compensate for case-insensitive file- systems or compare 2 paths to see if they would point to the same underlying file.

$tar->extract( [@filenames] )

Write files whose names are equivalent to any of the names in @filenames to disk, creating subdirectories as necessary. This might not work too well under VMS. Under MacPerl, the file's modification time will be converted to the MacOS zero of time, and appropriate conversions will be done to the path. However, the length of each element of the path is not inspected to see whether it's longer than MacOS currently allows (32 characters).

If extract is called without a list of file names, the entire contents of the archive are extracted.

Returns a list of filenames extracted.

$tar->extract_file( $file, [$extract_path )

Write an entry, whose name is equivalent to the file name provided to disk. Optionally takes a second parameter, which is the full path (including filename) the entry will be written to.

For example:

    $tar->extract_file( 'name/in/archive', 'name/i/want/to/give/it' );

Returns true on success, false on failure.

$tar->list_files( [\@properties] )

Returns a list of the names of all the files in the archive.

If list_files() is passed an array reference as its first argument it returns a list of hash references containing the requested properties of each file. The following list of properties is supported: name, size, mtime (last modified date), mode, uid, gid, linkname, uname, gname, devmajor, devminor, prefix.

Passing an array reference containing only one element, 'name', is special cased to return a list of names rather than a list of hash references, making it equivalent to calling list_files without arguments.

$tar->get_files( [@filenames] )

Returns the Archive::Tar::File objects matching the filenames provided. If no filename list was passed, all Archive::Tar::File objects in the current Tar object are returned.

Please refer to the Archive::Tar::File documentation on how to handle these objects.

$tar->get_content( $file )

Return the content of the named file.

$tar->replace_content( $file, $content )

Make the string $content be the content for the file named $file.

$tar->rename( $file, $new_name )

Rename the file of the in-memory archive to $new_name.

Note that you must specify a Unix path for $new_name, since per tar standard, all files in the archive must be Unix paths.

Returns true on success and false on failure.

$tar->remove (@filenamelist)

Removes any entries with names matching any of the given filenames from the in-memory archive. Returns a list of Archive::Tar::File objects that remain.

$tar->clear

clear clears the current in-memory archive. This effectively gives you a 'blank' object, ready to be filled again. Note that clear only has effect on the object, not the underlying tarfile.

$tar->write ( [$file, $compressed, $prefix] )

Write the in-memory archive to disk. The first argument can either be the name of a file or a reference to an already open filehandle (a GLOB reference). If the second argument is true, the module will use IO::Zlib to write the file in a compressed format. If IO::Zlib is not available, the write method will fail and return.

Specific levels of compression can be chosen by passing the values 2 through 9 as the second parameter.

The third argument is an optional prefix. All files will be tucked away in the directory you specify as prefix. So if you have files 'a' and 'b' in your archive, and you specify 'foo' as prefix, they will be written to the archive as 'foo/a' and 'foo/b'.

If no arguments are given, write returns the entire formatted archive as a string, which could be useful if you'd like to stuff the archive into a socket or a pipe to gzip or something.

$tar->add_files( @filenamelist )

Takes a list of filenames and adds them to the in-memory archive.

The path to the file is automatically converted to a Unix like equivalent for use in the archive, and, if on MacOS, the file's modification time is converted from the MacOS epoch to the Unix epoch. So tar archives created on MacOS with Archive::Tar can be read both with tar on Unix and applications like suntar or Stuffit Expander on MacOS.

Be aware that the file's type/creator and resource fork will be lost, which is usually what you want in cross-platform archives.

Returns a list of Archive::Tar::File objects that were just added.

$tar->add_data ( $filename, $data, [$opthashref] )

Takes a filename, a scalar full of data and optionally a reference to a hash with specific options.

Will add a file to the in-memory archive, with name $filename and content $data. Specific properties can be set using $opthashref. The following list of properties is supported: name, size, mtime (last modified date), mode, uid, gid, linkname, uname, gname, devmajor, devminor, prefix. (On MacOS, the file's path and modification times are converted to Unix equivalents.)

Returns the Archive::Tar::File object that was just added, or undef on failure.

$tar->error( [$BOOL] )

Returns the current errorstring (usually, the last error reported). If a true value was specified, it will give the Carp::longmess equivalent of the error, in effect giving you a stacktrace.

For backwards compatibility, this error is also available as $Archive::Tar::error allthough it is much recommended you use the method call instead.

Class Methods ^

Archive::Tar->create_archive($file, $compression, @filelist)

Creates a tar file from the list of files provided. The first argument can either be the name of the tar file to create or a reference to an open file handle (e.g. a GLOB reference).

The second argument specifies the level of compression to be used, if any. Compression of tar files requires the installation of the IO::Zlib module. Specific levels of compression may be requested by passing a value between 2 and 9 as the second argument. Any other value evaluating as true will result in the default compression level being used.

The remaining arguments list the files to be included in the tar file. These files must all exist. Any files which don\'t exist or can\'t be read are silently ignored.

If the archive creation fails for any reason, create_archive will return. Please use the error method to find the cause of the failure.

Archive::Tar->list_archive ($file, $compressed, [\@properties])

Returns a list of the names of all the files in the archive. The first argument can either be the name of the tar file to list or a reference to an open file handle (e.g. a GLOB reference).

If list_archive() is passed an array reference as its third argument it returns a list of hash references containing the requested properties of each file. The following list of properties is supported: name, size, mtime (last modified date), mode, uid, gid, linkname, uname, gname, devmajor, devminor, prefix.

Passing an array reference containing only one element, 'name', is special cased to return a list of names rather than a list of hash references.

Archive::Tar->extract_archive ($file, $gzip)

Extracts the contents of the tar file. The first argument can either be the name of the tar file to create or a reference to an open file handle (e.g. a GLOB reference). All relative paths in the tar file will be created underneath the current working directory.

extract_archive will return a list of files it extracted. If the archive extraction fails for any reason, extract_archive will return false. Please use the error method to find the cause of the failure.

Archive::Tar->can_handle_compressed_files

A simple checking routine, which will return true if Archive::Tar is able to uncompress compressed archives on the fly with IO::Zlib, or false if IO::Zlib is not installed.

You can use this as a shortcut to determine whether Archive::Tar will do what you think before passing compressed archives to its read method.

GLOBAL VARIABLES ^

$Archive::Tar::FOLLOW_SYMLINK

Set this variable to 1 to make Archive::Tar effectively make a copy of the file when extracting. Default is 0, which means the symlink stays intact. Of course, you will have to pack the file linked to as well.

This option is checked when you write out the tarfile using write or create_archive.

This works just like /bin/tar's -h option.

$Archive::Tar::CHOWN

By default, Archive::Tar will try to chown your files if it is able to. In some cases, this may not be desired. In that case, set this variable to 0 to disable chown-ing, even if it were possible.

The default is 1.

$Archive::Tar::CHMOD

By default, Archive::Tar will try to chmod your files to whatever mode was specified for the particular file in the archive. In some cases, this may not be desired. In that case, set this variable to 0 to disable chmod-ing.

The default is 1.

$Archive::Tar::DO_NOT_USE_PREFIX

By default, Archive::Tar will try to put paths that are over 100 characters in the prefix field of your tar header. However, some older tar programs do not implement this spec. To retain compatibillity with these older versions, you can set the $DO_NOT_USE_PREFIX variable to a true value, and Archive>Tar> will use an alternate way of dealing with paths over 100 characters by using the GNU Extended Header feature.

The default is 0.

$Archive::Tar::DEBUG

Set this variable to 1 to always get the Carp::longmess output of the warnings, instead of the regular carp. This is the same message you would get by doing:

    $tar->error(1);

Defaults to 0.

$Archive::Tar::WARN

Set this variable to 0 if you do not want any warnings printed. Personally I recommend against doing this, but people asked for the option. Also, be advised that this is of course not threadsafe.

Defaults to 1.

$Archive::Tar::error

Holds the last reported error. Kept for historical reasons, but its use is very much discouraged. Use the error() method instead:

    warn $tar->error unless $tar->extract;

FAQ ^

What's the minimum perl version required to run Archive::Tar?

You will need perl version 5.005_03 or newer.

Isn't Archive::Tar slow?

Yes it is. It's pure perl, so it's a lot slower then your /bin/tar However, it's very portable. If speed is an issue, consider using /bin/tar instead.

Isn't Archive::Tar heavier on memory than /bin/tar?

Yes it is, see previous answer. Since Compress::Zlib and therefore IO::Zlib doesn't support seek on their filehandles, there is little choice but to read the archive into memory. This is ok if you want to do in-memory manipulation of the archive. If you just want to extract, use the extract_archive class method instead. It will optimize and write to disk immediately.

Can't you lazy-load data instead?

No, not easily. See previous question.

How much memory will an X kb tar file need?

Probably more than X kb, since it will all be read into memory. If this is a problem, and you don't need to do in memory manipulation of the archive, consider using /bin/tar instead.

What do you do with unsupported filetypes in an archive?

Unix has a few filetypes that aren't supported on other platforms, like Win32. If we encounter a hardlink or symlink we'll just try to make a copy of the original file, rather than throwing an error.

This does require you to read the entire archive in to memory first, since otherwise we wouldn't know what data to fill the copy with. (This means that you can not use the class methods on archives that have incompatible filetypes and still expect things to work).

For other filetypes, like chardevs and blockdevs we'll warn that the extraction of this particular item didn't work.

TODO ^

Check if passed in handles are open for read/write

Currently I don't know of any portable pure perl way to do this. Suggestions welcome.

AUTHOR ^

This module by Jos Boumans <kane@cpan.org>.

ACKNOWLEDGEMENTS ^

Thanks to Sean Burke, Chris Nandor, Chip Salzenberg, Tim Heaney and Andrew Savige for their help and suggestions.

COPYRIGHT ^

This module is copyright (c) 2002 Jos Boumans <kane@cpan.org>. All rights reserved.

This library is free software; you may redistribute and/or modify it under the same terms as Perl itself.

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