Provided by: libarchive-tar-wrapper-perl_0.42-1_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 program. 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 almost doesn't hold anything in memory (see "write" method), instead using disk
as storage.
• Archive::Tar::Wrapper is 100% compliant with the platform's "tar" utility because it uses it
internally.
METHODS
new
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" in Archive::Tar::Wrapper section 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"],
);
Similarly, "tar_gnu_write_options" can be used to provide additional options for GNU tar implementations.
For example, the tar object
my $tar = Archive::Tar::Wrapper->new(
tar_gnu_write_options => ["--exclude=foo"],
);
will call the "tar" utility internally like
tar cf tarfile --exclude=foo ...
when the "write" method gets called.
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
);
The allowable parameters are:
• "tar"
• "tmpdir"
• "tar_read_options"
• "tar_write_options"
• "tar_gnu_read_options"
• "tar_gnu_write_options"
• "max_cmd_line_args": defaults to 512
• "ramdisk"
Returns a new instance of the class.
read
$arch->read("archive.tgz");
read() opens the given tarball, expands it into a temporary directory and returns 1 on success or "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 tar file.
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.
list_reset
$arch->list_reset()
Resets the list iterator. To be used before the first call to list_next().
tardir
$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.
is_compressed
Returns a string to identify if the tarball is compressed or not.
Expect as parameter a string with the path to the tarball.
Returns:
• a "z" character if the file is compressed with "gzip".
• a "j" character if the file is compressed with "bzip2".
• a "" character if the file is not compressed at all.
locate
$arch->locate($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.
add
$arch->add($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 tar file:
$arch->add($logic_path, $stringref, { binmode => ":utf8" });
perm_cp
Copies the permissions from a file to another.
Expects as parameters:
1. string of the path to the file which permissions will be copied from.
2. string of the path to the file which permissions will be copied to.
Returns 1 if everything works as expected.
perm_get
Gets the permissions from a file.
Expects as parameter the path to the source file.
Returns an array reference with only the permissions values, as returned by "stat".
perm_set
Sets the permission on a file.
Expects as parameters:
1. The path to the file where the permissions should be applied to.
2. An array reference with the permissions (see "perm_set")
Returns 1 if everything goes fine.
Ignore errors here, as we can't change uid/gid unless we're the superuser (see LIMITATIONS section).
remove
$arch->remove($logic_path);
Removes a file from the tarball. $logic_path is the virtual path of the file within the tarball.
list_all
my $items = $arch->list_all();
Returns a reference to a (possibly huge) array of items in the tar file. Each item is a reference to an
array, containing two elements: the relative path of the item in the tar file 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: $real_path\n";
}
If the list of items in the tar file is big, use list_reset() and list_next() instead of "list_all".
list_next
my ($tar_path, $phys_path, $type) = $arch->list_next();
Returns the next item in the tar file. It returns a list of three scalars: the relative path of the item
in the tar file, 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.
write
$arch->write($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.
is_gnu
$arch->is_gnu();
Checks if the tar executable is a GNU tar by running 'tar --version' and parsing the output for "GNU".
Returns true or false (in Perl terms).
is_bsd
$arch->is_bsd();
Same as is_gnu(), but for BSD.
ramdisk_mount
Mounts a RAM disk.
It executes the "mount" program under the hood to mount a RAM disk.
Expects as parameter a hash with options to mount the RAM disk, like:
• "size"
• "type" (most probably "tmpfs")
• "tmpdir"
Returns 1 if everything goes fine.
Be sure to check the "Using RAM Disks" in Archive::Tar::Wrapper for full details on using RAM disks.
ramdisk_unmount
Unmounts the RAM disk already mounted with "ramdisk_mount".
Don't expect parameters and returns 1 if everything goes fine.
Be sure to check the "Using RAM Disks" in Archive::Tar::Wrapper for full details on using RAM disks.
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 RAM disk 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 RAM disk 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 RAM disk 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.
• If you ask Archive::Tar::Wrapper to add a file to a tarball, it copies it into a temporary directory
and then calls the system tar to wrap up that directory into a tarball.
This approach has limitations when it comes to file permissions: If the file to be added belongs to a
different user/group, Archive::Tar::Wrapper will adjust the uid/gid/permissions of the target file in
the temporary directory to reflect the original file's settings, to make sure the system tar will add
it like that to the tarball, just like a regular tar run on the original file would. But this will
fail of course if the original file's uid is different from the current user's, unless the script is
running with superuser rights. The tar program by itself (without Archive::Tar::Wrapper) works
differently: It'll just make a note of a file's uid/gid/permissions in the tarball (which it can do
without superuser rights) and upon extraction, it'll adjust the permissions of newly generated files
if the -p option is given (default for superuser).
BUGS
Archive::Tar::Wrapper doesn't currently handle filenames with embedded newlines.
Microsoft Windows support
Support on Microsoft Windows is limited.
Versions below Windows 10 will not be supported for desktops, and for servers only Windows 2012 and
above.
The GNU "tar.exe" program doesn't work properly with the current interface of Archive::Tar::Wrapper.
You must use the "bsdtar.exe" and make sure it appears first in the "PATH" environment variable than the
GNU tar (if it is installed). See <http://libarchive.org/> for details about how to download and install
"bsdtar.exe", or go to <http://gnuwin32.sourceforge.net/packages.html> for a direct download. Be sure to
look for the "bzip2" program package to install it as well.
Windows 10 might come already with "bsdtar" program already installed. Please search for that on the
appropriate page (Microsoft keeps changing the link to keep track of it here).
Having spaces in the path string to the tar program might be an issue too. Although there is some effort
in terms of workaround it, you best might avoid it completely by installing in a different path than
"C:\Program Files". Installing both "bsdtar" and "bzip2" in "C:\GnuWin32" will probably be enough when
running the installers.
SEE ALSO
• Linux Gazette article from Ben Okopnik, issue 87 <https://linuxgazette.net/87/okopnik.html>.
BUGS
Please report any bugs or feature requests on the bugtracker website
<https://github.com/haarg/Archive-Tar-Wrapper/issues>
When submitting a bug or request, please include a test-file or a patch to an existing test-file that
illustrates the bug or desired feature.
AUTHORS
• Mike Schilli <cpan@perlmeister.com>
• Alceu Rodrigues de Freitas Junior <glasswalk3r@yahoo.com.br>
CONTRIBUTORS
• Chris Weyl <cweyl@alumni.drew.edu>
• David Cantrell <david@cantrell.org.uk>
• David Precious <davidp@preshweb.co.uk>
• Graham Knop <haarg@haarg.org>
• intrigeri <intrigeri@boum.org>
• Kent Fredric <kentfredric@gmail.com>
• Mark Gardner <mjg+github@phoenixtrap.com>
• Mike Schilli <github@perlmeister.com>
• Mohammad S Anwar <mohammad.anwar@yahoo.com>
• Paulo Custodio <pauloscustodio@gmail.com>
• Randy Stauner <randy@magnificent-tears.com>
• Sanko Robinson <sanko@cpan.org>
• Shoichi Kaji <skaji@cpan.org>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2024 by Mike Schilli.
This is free software, licensed under:
The GNU General Public License, Version 3, June 2007
perl v5.40.0 2024-09-01 Archive::Tar::Wrapper(3pm)