Provided by: libarchive-tar-wrapper-perl_0.38-3_all bug

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 expectable 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 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.

   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 tarfile:

           $arch->add($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 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".

   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.

   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 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 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.

LEGALESE

       This software is copyright (c) 2005 of Mike Schilli.

       This program is free software: you can redistribute it and/or modify it under the terms of
       the GNU General Public License as published by the Free Software Foundation, either
       version 3 of the License, or (at your option) any later version.

       This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
       without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
       See the GNU General Public License for more details.

       You should have received a copy of the GNU General Public License along with Archive-Tar-
       Wrapper. If not, see <http://www.gnu.org/licenses/>.

SEE ALSO

       •   Linux Gazette article from Ben Okopnik, issue 87
           <https://linuxgazette.net/87/okopnik.html>.

AUTHOR

       2005, Mike Schilli <cpan@perlmeister.com>

MAINTAINER

       2018, Alceu Rodrigues de Freitas Junior <arfreitas@cpan.org>