Provided by: libarchive-tar-wrapper-perl_0.18-1_all 
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\n";
}
# 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\n";
}
# 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:
• Archive::Tar::Wrapper doesn't hold anything in memory. Everything is stored on disk.
• 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\n";
}
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
• Currently, only "tar" programs supporting the "z" option (for
compressing/decompressing) are supported. Future version will use "gzip"
alternatively.
• 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.
• 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.
• 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>