Archive::Tar::Wrapper(3pm)				User Contributed Perl Documentation				Archive::Tar::Wrapper(3pm)

NAME

       Archive::Tar::Wrapper - API wrapper around the 'tar' utility

SYNOPSIS

	   use Archive::Tar::Wrapper;

	   my $arch = Archive::Tar::Wrapper->new();

	       # Open a tarball, expand it into a temporary directory
	   $arch->read("archive.tgz");

	       # Iterate over all entries in the archive
	   $arch->list_reset(); # Reset Iterator
				# Iterate through archive
	   while(my $entry = $arch->list_next()) {
	       my($tar_path, $phys_path) = @$entry;
	       print "$tar_path
";
	   }

	       # Get a huge list with all entries
	   for my $entry (@{$arch->list_all()}) {
	       my($tar_path, $real_path) = @$entry;
	       print "Tarpath: $tar_path Tempfile: $real_path
";
	   }

	       # Add a new entry
	   $arch->add($logic_path, $file_or_stringref);

	       # Remove an entry
	   $arch->remove($logic_path);

	       # Find the physical location of a temporary file
	   my($tmp_path) = $arch->locate($tar_path);

	       # Create a tarball
	   $arch->write($tarfile, $compress);

DESCRIPTION

       Archive::Tar::Wrapper is an API wrapper around the 'tar' command line utility. It never stores anything in memory, but works on temporary
       directory structures on disk instead. It provides a mapping between the logical paths in the tarball and the 'real' files in the temporary
       directory on disk.

       It differs from Archive::Tar in two ways:

       o   Archive::Tar::Wrapper doesn't hold anything in memory. Everything is stored on disk.

       o   Archive::Tar::Wrapper is 100% compliant with the platform's "tar" utility, because it uses it internally.

METHODS

       my $arch = Archive::Tar::Wrapper->new()
	   Constructor for the tar wrapper class. Finds the "tar" executable by searching "PATH" and returning the first hit. In case you want to
	   use a different tar executable, you can specify it as a parameter:

	       my $arch = Archive::Tar::Wrapper->new(tar => '/path/to/tar');

	   Since "Archive::Tar::Wrapper" creates temporary directories to store tar data, the location of the temporary directory can be
	   specified:

	       my $arch = Archive::Tar::Wrapper->new(tmpdir => '/path/to/tmpdir');

	   Tremendous performance increases can be achieved if the temporary directory is located on a ram disk. Check the "Using RAM Disks"
	   section below for details.

	   Additional options can be passed to the "tar" command by using the "tar_read_options" and "tar_write_options" parameters. Example:

		my $arch = Archive::Tar::Wrapper->new(
			      tar_read_options => "p"
			   );

	   will use "tar xfp archive.tgz" to extract the tarball instead of just "tar xf archive.tgz". Gnu tar supports even more options, these
	   can be passed in via

		my $arch = Archive::Tar::Wrapper->new(
			       tar_gnu_read_options => ["--numeric-owner"],
			   );

	   By default, the "list_*()" functions will return only file entries.	Directories will be suppressed. To have "list_*()" return
	   directories as well, use

		my $arch = Archive::Tar::Wrapper->new(
			      dirs  => 1
			   );

	   If more files are added to a tarball than the command line can handle, "Archive::Tar::Wrapper" will switch from using the command

	       tar cfv tarfile file1 file2 file3 ...

	   to

	       tar cfv tarfile -T filelist

	   where "filelist" is a file containing all file to be added. The default for this switch is 512, but it can be changed by setting the
	   parameter "max_cmd_line_args":

		my $arch = Archive::Tar::Wrapper->new(
		    max_cmd_line_args  => 1024
		);

       $arch->read("archive.tgz")
	   "read()" opens the given tarball, expands it into a temporary directory and returns 1 on success und "undef" on failure.  The temporary
	   directory holding the tar data gets cleaned up when $arch goes out of scope.

	   "read" handles both compressed and uncompressed files. To find out if a file is compressed or uncompressed, it tries to guess by
	   extension, then by checking the first couple of bytes in the tarfile.

	   If only a limited number of files is needed from a tarball, they can be specified after the tarball name:

	       $arch->read("archive.tgz", "path/file.dat", "path/sub/another.txt");

	   The file names are passed unmodified to the "tar" command, make sure that the file paths match exactly what's in the tarball, otherwise
	   "read()" will fail.

       $arch->list_reset()
	   Resets the list iterator. To be used before the first call to $arch-list_next()>.

       my($tar_path, $phys_path, $type) = $arch->list_next()
	   Returns the next item in the tarfile. It returns a list of three scalars: the relative path of the item in the tarfile, the physical
	   path to the unpacked file or directory on disk, and the type of the entry (f=file, d=directory, l=symlink). Note that by default,
	   Archive::Tar::Wrapper won't display directories, unless the "dirs" parameter is set when running the constructor.

       my $items = $arch->list_all()
	   Returns a reference to a (possibly huge) array of items in the tarfile. Each item is a reference to an array, containing two elements:
	   the relative path of the item in the tarfile and the physical path to the unpacked file or directory on disk.

	   To iterate over the list, the following construct can be used:

		   # Get a huge list with all entries
	       for my $entry (@{$arch->list_all()}) {
		   my($tar_path, $real_path) = @$entry;
		   print "Tarpath: $tar_path Tempfile: $real_path
";
	       }

	   If the list of items in the tarfile is big, use "list_reset()" and "list_next()" instead of "list_all".

       $arch->add($logic_path, $file_or_stringref, [$options])
	   Add a new file to the tarball. $logic_path is the virtual path of the file within the tarball. $file_or_stringref is either a scalar,
	   in which case it holds the physical path of a file on disk to be transferred (i.e. copied) to the tarball. Or it is a reference to a
	   scalar, in which case its content is interpreted to be the data of the file.

	   If no additional parameters are given, permissions and user/group id settings of a file to be added are copied. If you want different
	   settings, specify them in the options hash:

	       $arch->add($logic_path, $stringref,
			  { perm => 0755, uid => 123, gid => 10 });

	   If $file_or_stringref is a reference to a Unicode string, the "binmode" option has to be set to make sure the string gets written as
	   proper UTF-8 into the tarfile:

	       $arch->add($logic_path, $stringref, { binmode => ":utf8" });

       $arch->remove($logic_path)
	   Removes a file from the tarball. $logic_path is the virtual path of the file within the tarball.

       $arch->locate($logic_path)
	   Finds the physical location of a file, specified by $logic_path, which is the virtual path of the file within the tarball. Returns a
	   path to the temporary file "Archive::Tar::Wrapper" created to manipulate the tarball on disk.

       $arch->write($tarfile, $compress)
	   Write out the tarball by tarring up all temporary files and directories and store it in $tarfile on disk. If $compress holds a true
	   value, compression is used.

       $arch->tardir()
	   Return the directory the tarball was unpacked in. This is sometimes useful to play dirty tricks on "Archive::Tar::Wrapper" by mass-
	   manipulating unpacked files before wrapping them back up into the tarball.

       $arch->is_gnu()
	   Checks if the tar executable is a GNU tar by running 'tar --version' and parsing the output for "GNU".

Using RAM Disks
       On Linux, it's quite easy to create a RAM disk and achieve tremendous speedups while untarring or modifying a tarball. You can either
       create the RAM disk by hand by running

	  # mkdir -p /mnt/myramdisk
	  # mount -t tmpfs -o size=20m tmpfs /mnt/myramdisk

       and then feeding the ramdisk as a temporary directory to Archive::Tar::Wrapper, like

	  my $tar = Archive::Tar::Wrapper->new( tmpdir => '/mnt/myramdisk' );

       or using Archive::Tar::Wrapper's built-in option 'ramdisk':

	  my $tar = Archive::Tar::Wrapper->new(
	      ramdisk => {
		  type => 'tmpfs',
		  size => '20m',   # 20 MB
	      },
	  );

       Only drawback with the latter option is that creating the RAM disk needs to be performed as root, which often isn't desirable for security
       reasons.  For this reason, Archive::Tar::Wrapper offers a utility functions that mounts the ramdisk and returns the temporary directory
       it's located in:

	     # Create new ramdisk (as root):
	   my $tmpdir = Archive::Tar::Wrapper->ramdisk_mount(
	       type => 'tmpfs',
	       size => '20m',	# 20 MB
	   );

	     # Delete a ramdisk (as root):
	   Archive::Tar::Wrapper->ramdisk_unmount();

       Optionally, the "ramdisk_mount()" command accepts a "tmpdir" parameter pointing to a temporary directory for the ramdisk if you wish to set
       it yourself instead of letting Archive::Tar::Wrapper create it automatically.

KNOWN LIMITATIONS

       o   Currently, only "tar" programs supporting the "z" option (for compressing/decompressing) are supported. Future version will use "gzip"
	   alternatively.

       o   Currently, you can't add empty directories to a tarball directly.  You could add a temporary file within a directory, and then
	   "remove()" the file.

       o   If you delete a file, the empty directories it was located in stay in the tarball. You could try to "locate()" them and delete them.
	   This will be fixed, though.

       o   Filenames containing newlines are causing problems with the list iterators. To be fixed.

BUGS

       Archive::Tar::Wrapper doesn't currently handle filenames with embedded newlines.

LEGALESE

       Copyright 2005 by Mike Schilli, all rights reserved.  This program is free software, you can redistribute it and/or modify it under the
       same terms as Perl itself.

AUTHOR

       2005, Mike Schilli <cpan@perlmeister.com>

perl v5.14.2							    2012-03-21						Archive::Tar::Wrapper(3pm)