Archive::Tar
Archive::Tar(3) User Contributed Perl Documentation Archive::Tar(3)
NAME
Archive::Tar - module for manipulations of tar archives
SYNOPSIS
use Archive::Tar;
my $tar = Archive::Tar->new;
$tar->read(’origin.tgz’);
$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’); # plain tar
$tar->write(’files.tgz’, COMPRESS_GZIP); # gzip compressed
$tar->write(’files.tbz’, COMPRESS_BZIP); # bzip2 compressed
DESCRIPTION
Archive::Tar provides an object oriented mechanism for handling tar
files. It provides class methods for quick and easy files handling
while also allowing for the creation of tar file objects for custom
manipulation. If you have the IO::Zlib module installed, Archive::Tar
will also support compressed or gzipped tar files.
An object of class Archive::Tar represents a .tar(.gz) archive full of
files and things.
Object Methods
Archive::Tar->new( [$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 "read" will replace any previous content in $tar!
The second argument may be considered optional, but remains for back-
wards compatibility. Archive::Tar now looks at the file magic to
determine what class should be used to open the file and will trans-
parently Do The Right Thing.
Archive::Tar will warn if you try to pass a bzip2 compressed file and
the IO::Zlib / IO::Uncompress::Bunzip2 modules are not available and
simply return.
Note that you can currently not pass a "gzip" compressed filehandle,
which is not opened with "IO::Zlib", a "bzip2" compressed filehandle,
which is not opened with "IO::Uncompress::Bunzip2", nor a string con-
taining the full archive information (either compressed or uncom-
pressed). These are worth while features, but not currently imple-
mented. See the "TODO" section.
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 useful if you have
very big archives, and are only interested in the first few files.
filter
Can be set to a regular expression. Only files with names that
match the expression will be read.
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. This means no "Archive::Tar::File"
objects are created for you to inspect.
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 cannot 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 @file-
names 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 conver-
sions 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 con-
tents 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 native
path (including filename) the entry will be written to.
For example:
$tar->extract_file( ’name/in/archive’, ’name/i/want/to/give/it’ );
$tar->extract_file( $at_file_object, ’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 proper-
ties 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 argu-
ments.
$tar->get_files( [@filenames] )
Returns the "Archive::Tar::File" objects matching the filenames pro-
vided. 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 han-
dle 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).
The second argument is used to indicate compression. You can either
compress using "gzip" or "bzip2". If you pass a digit, it’s assumed to
be the "gzip" compression level (between 1 and 9), but the use of con-
stants is prefered:
# write a gzip compressed file
$tar->write( ’out.tgz’, COMPRESS_GZIP );
# write a bzip compressed file
$tar->write( ’out.tbz’, COMPRESS_BZIP );
Note that when you pass in a filehandle, the compression argument is
ignored, as all files are printed verbatim to your filehandle. If you
wish to enable compression with filehandles, use an "IO::Zlib" or
"IO::Compress::Bzip2" filehandle instead.
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 equiva-
lent 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.
Instead of a filename, you can also pass it an existing
"Archive::Tar::File" object from, for example, another archive. The
object will be clone, and effectively be a copy of the original, not
an alias.
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 con-
tent $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, type. (On MacOS, the file’s path and modification
times are converted to Unix equivalents.)
Valid values for the file type are the following constants defined in
Archive::Tar::Constants:
FILE
Regular file.
HARDLINK
SYMLINK
Hard and symbolic ("soft") links; linkname should specify target.
CHARDEV
BLOCKDEV
Character and block devices. devmajor and devminor should specify
the major and minor device numbers.
DIR Directory.
FIFO
FIFO (named pipe).
SOCKET
Socket.
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 although it is much recommended you use the
method call instead.
$tar->setcwd( $cwd );
"Archive::Tar" needs to know the current directory, and it will run
"Cwd::cwd()" every time it extracts a relative entry from the tarfile
and saves it in the file system. (As of version 1.30, however,
"Archive::Tar" will use the speed optimization described below auto-
matically, so it’s only relevant if you’re using "extract_file()").
Since "Archive::Tar" doesn’t change the current directory internally
while it is extracting the items in a tarball, all calls to
"Cwd::cwd()" can be avoided if we can guarantee that the current
directory doesn’t get changed externally.
To use this performance boost, set the current directory via
use Cwd;
$tar->setcwd( cwd() );
once before calling a function like "extract_file" and "Archive::Tar"
will use the current directory setting from then on and won’t call
"Cwd::cwd()" internally.
To switch back to the default behaviour, use
$tar->setcwd( undef );
and "Archive::Tar" will call "Cwd::cwd()" internally again.
If you’re using "Archive::Tar"’s "exract()" method, "setcwd()" will be
called for you.
Class Methods
Archive::Tar->create_archive($file, $compressed, @filelist)
Creates a tar file from the list of files provided. The first argu-
ment 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 is used to indicate compression. You can either
compress using "gzip" or "bzip2". If you pass a digit, it’s assumed to
be the "gzip" compression level (between 1 and 9), but the use of con-
stants is prefered:
# write a gzip compressed file
Archive::Tar->create_archive( ’out.tgz’, COMPRESS_GZIP, @filelist );
# write a bzip compressed file
Archive::Tar->create_archive( ’out.tbz’, COMPRESS_BZIP, @filelist );
Note that when you pass in a filehandle, the compression argument is
ignored, as all files are printed verbatim to your filehandle. If you
wish to enable compression with filehandles, use an "IO::Zlib" or
"IO::Compress::Bzip2" filehandle instead.
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 false. Please use the "error" method to find the cause of the
failure.
Note that this method does not write "on the fly" as it were; it still
reads all the files into memory before writing out the archive. Con-
sult the FAQ below if this is a problem.
Archive::Tar->iter( $filename, [ $compressed, {opt => $val} ] )
Returns an iterator function that reads the tar file without loading
it all in memory. Each time the function is called it will return the
next file in the tarball. The files are returned as
"Archive::Tar::File" objects. The iterator function returns the empty
list once it has exhausted the the files contained.
The second argument can be a hash reference with options, which are
identical to the arguments passed to "read()".
Example usage:
my $next = Archive::Tar->iter( "example.tar.gz", 1, {filter => qr/\.pm$/} );
while( my $f = $next->() ) {
print $f->name, "\n";
$f->extract or warn "Extraction failed";
# ....
}
Archive::Tar->list_archive($file, $compressed, [\@properties])
Returns a list of the names of all the files in the archive. The
first argument can either be the name of the tar file to list or a
reference to an open file handle (e.g. a GLOB reference).
If "list_archive()" is passed an array reference as its third argument
it returns a list of hash references containing the requested proper-
ties of each file. The following list of properties is supported:
full_path, name, size, mtime (last modified date), mode, uid, gid,
linkname, uname, gname, devmajor, devminor, prefix.
See "Archive::Tar::File" for details about supported properties.
Passing an array reference containing only one element, ’name’, is
special cased to return a list of names rather than a list of hash
references.
Archive::Tar->extract_archive($file, $compressed)
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 fail-
ure.
$bool = Archive::Tar->has_io_string
Returns true if we currently have "IO::String" support loaded.
Either "IO::String" or "perlio" support is needed to support writing
stringified archives. Currently, "perlio" is the preferred method, if
available.
See the "GLOBAL VARIABLES" section to see how to change this prefer-
ence.
$bool = Archive::Tar->has_perlio
Returns true if we currently have "perlio" support loaded.
This requires "perl-5.8" or higher, compiled with "perlio"
Either "IO::String" or "perlio" support is needed to support writing
stringified archives. Currently, "perlio" is the preferred method, if
available.
See the "GLOBAL VARIABLES" section to see how to change this prefer-
ence.
$bool = Archive::Tar->has_zlib_support
Returns true if "Archive::Tar" can extract "zlib" compressed archives
$bool = Archive::Tar->has_bzip2_support
Returns true if "Archive::Tar" can extract "bzip2" compressed archives
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" and
"IO::Compress::Bzip2" or false if not both are 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, as defined per
POSIX-standard. However, some (older) tar programs do not implement
this spec. To retain compatibility with these older or non-POSIX com-
pliant 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.
Note that clients who do not support the "GNU Extended Header" feature
will not be able to read these archives. Such clients include tars on
"Solaris", "Irix" and "AIX".
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. Per-
sonally 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;
$Archive::Tar::INSECURE_EXTRACT_MODE
This variable indicates whether "Archive::Tar" should allow files to
be extracted outside their current working directory.
Allowing this could have security implications, as a malicious tar
archive could alter or replace any file the extracting user has per-
missions to. Therefor, the default is to not allow insecure extrac-
tions.
If you trust the archive, or have other reasons to allow the archive
to write files outside your current working directory, set this vari-
able to "true".
Note that this is a backwards incompatible change from version 1.36
and before.
$Archive::Tar::HAS_PERLIO
This variable holds a boolean indicating if we currently have "perlio"
support loaded. This will be enabled for any perl greater than 5.8
compiled with "perlio".
If you feel strongly about disabling it, set this variable to "false".
Note that you will then need "IO::String" installed to support writing
stringified archives.
Don’t change this variable unless you really know what you’re doing.
$Archive::Tar::HAS_IO_STRING
This variable holds a boolean indicating if we currently have
"IO::String" support loaded. This will be enabled for any perl that
has a loadable "IO::String" module.
If you feel strongly about disabling it, set this variable to "false".
Note that you will then need "perlio" support from your perl to be
able to write stringified archives.
Don’t change this variable unless you really know what you’re doing.
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, con-
sider using "/bin/tar" instead.
Isn’t Archive::Tar heavier on memory than /bin/tar?
Yes it is, see previous answer. Since "Compress::Zlib" and there-
fore "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.
Another option is to use the "iter" class method to iterate over
the files in the tarball without reading them all in memory at
once.
Can you lazy-load data instead?
In some cases, yes. You can use the "iter" class method to iterate
over the files in the tarball without reading them all in memory
at once.
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 the "iter" class method, or
"/bin/tar" instead.
What do you do with unsupported filetypes in an archive?
"Unix" has a few filetypes that aren’t supported on other plat-
forms, 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 cannot use the class methods, includ-
ing "iter" 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.
I’m using WinZip, or some other non-POSIX client, and files are not
being extracted properly!
By default, "Archive::Tar" is in a completely POSIX-compatible
mode, which uses the POSIX-specification of "tar" to store files.
For paths greather than 100 characters, this is done using the
"POSIX header prefix". Non-POSIX-compatible clients may not sup-
port this part of the specification, and may only support the "GNU
Extended Header" functionality. To facilitate those clients, you
can set the $Archive::Tar::DO_NOT_USE_PREFIX variable to "true".
See the "GLOBAL VARIABLES" section for details on this variable.
Note that GNU tar earlier than version 1.14 does not cope well
with the "POSIX header prefix". If you use such a version, con-
sider setting the $Archive::Tar::DO_NOT_USE_PREFIX variable to
"true".
How do I extract only files that have property X from an archive?
Sometimes, you might not wish to extract a complete archive, just
the files that are relevant to you, based on some criteria.
You can do this by filtering a list of "Archive::Tar::File"
objects based on your criteria. For example, to extract only files
that have the string "foo" in their title, you would use:
$tar->extract(
grep { $_->full_path =~ /foo/ } $tar->get_files
);
This way, you can filter on any attribute of the files in the
archive. Consult the "Archive::Tar::File" documentation on how to
use these objects.
How do I access .tar.Z files?
The "Archive::Tar" module can optionally use "Compress::Zlib" (via
the "IO::Zlib" module) to access tar files that have been com-
pressed with "gzip". Unfortunately tar files compressed with the
Unix "compress" utility cannot be read by "Compress::Zlib" and so
cannot be directly accesses by "Archive::Tar".
If the "uncompress" or "gunzip" programs are available, you can
use one of these workarounds to read ".tar.Z" files from
"Archive::Tar"
Firstly with "uncompress"
use Archive::Tar;
open F, "uncompress -c $filename │";
my $tar = Archive::Tar->new(*F);
...
and this with "gunzip"
use Archive::Tar;
open F, "gunzip -c $filename │";
my $tar = Archive::Tar->new(*F);
...
Similarly, if the "compress" program is available, you can use
this to write a ".tar.Z" file
use Archive::Tar;
use IO::File;
my $fh = new IO::File "│ compress -c >$filename";
my $tar = Archive::Tar->new();
...
$tar->write($fh);
$fh->close ;
How do I handle Unicode strings?
"Archive::Tar" uses byte semantics for any files it reads from or
writes to disk. This is not a problem if you only deal with files
and never look at their content or work solely with byte strings.
But if you use Unicode strings with character semantics, some
additional steps need to be taken.
For example, if you add a Unicode string like
# Problem
$tar->add_data(’file.txt’, "Euro: \x{20AC}");
then there will be a problem later when the tarfile gets written
out to disk via "$tar-"write()>:
Wide character in print at .../Archive/Tar.pm line 1014.
The data was added as a Unicode string and when writing it out to
disk, the ":utf8" line discipline wasn’t set by "Archive::Tar", so
Perl tried to convert the string to ISO-8859 and failed. The writ-
ten file now contains garbage.
For this reason, Unicode strings need to be converted to
UTF-8-encoded bytestrings before they are handed off to
"add_data()":
use Encode;
my $data = "Accented character: \x{20AC}";
$data = encode(’utf8’, $data);
$tar->add_data(’file.txt’, $data);
A opposite problem occurs if you extract a UTF8-encoded file from
a tarball. Using "get_content()" on the "Archive::Tar::File"
object will return its content as a bytestring, not as a Unicode
string.
If you want it to be a Unicode string (because you want character
semantics with operations like regular expression matching), you
need to decode the UTF8-encoded content and have Perl convert it
into a Unicode string:
use Encode;
my $data = $tar->get_content();
# Make it a Unicode string
$data = decode(’utf8’, $data);
There is no easy way to provide this functionality in
"Archive::Tar", because a tarball can contain many files, and each
of which could be encoded in a different way.
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.
Allow archives to be passed in as string
Currently, we only allow opened filehandles or filenames, but not
strings. The internals would need some reworking to facilitate
stringified archives.
Facilitate processing an opened filehandle of a compressed archive
Currently, we only support this if the filehandle is an IO::Zlib
object. Environments, like apache, will present you with an
opened filehandle to an uploaded file, which might be a compressed
archive.
SEE ALSO
The GNU tar specification
"http://www.gnu.org/software/tar/manual/tar.html"
The PAX format specication
The specifcation which tar derives from; " http://www.open-
group.org/onlinepubs/007904975/utilities/pax.html"
A comparison of GNU and POSIX tar standards; "http://www.delo-
rie.com/gnu/docs/tar/tar_114.html"
GNU tar intends to switch to POSIX compatibility
GNU Tar authors have expressed their intention to become com-
pletely POSIX-compatible; "http://www.gnu.org/software/tar/man-
ual/html_node/Formats.html"
A Comparison between various tar implementations
Lists known issues and incompatibilities;
"http://gd.tuwien.ac.at/utils/archivers/star/README.otherbugs"
AUTHOR
This module by Jos Boumans <kane@cpan.org>.
Please reports bugs to <bug-archive-tar@rt.cpan.org>.
ACKNOWLEDGEMENTS
Thanks to Sean Burke, Chris Nandor, Chip Salzenberg, Tim Heaney, Gisle
Aas and especially Andrew Savige for their help and suggestions.
COPYRIGHT
This module is copyright (c) 2002 - 2008 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.
perl v5.8.8 2009-04-20 Archive::Tar(3)
