| |
man : Archive::Tar(3p)
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
NAME
Archive::Tar - module for manipulations of tar archives
SYNOPSIS
use Archive::Tar;
my $tar = Archive::Tar->new;
$tar->read('origin.tgz',1);
$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');
$tar->write('files.tar');
DESCRIPTION
Archive::Tar provides an object oriented mechanism for
handling tar files. It provides class methods for quick
and easy files handling while also allowing for the
creation of tar file objects for custom manipulation. If
you have the IO::Zlib module installed, Archive::Tar will
also support compressed or gzipped tar files.
An object of class Archive::Tar represents a .tar(.gz)
archive full of files and things.
Object Methods
Archive::Tar->new( [$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 second argument indicates whether the file
referenced by the first argument is compressed.
The "read" will replace any previous content in $tar!
The second argument may be considered optional if IO::Zlib
is installed, since it will transparently Do The Right
Thing. Archive::Tar will warn if you try to pass a
compressed file if IO::Zlib is not available and simply
return.
perl v5.10.0 2008-09-30 1
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
Note that you can currently not pass a "gzip" compressed
filehandle, which is not opened with "IO::Zlib", nor a
string containing the full archive information (either
compressed or uncompressed). These are worth while
features, but not currently implemented. 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.
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.
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 @filenames 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 conversions 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 contents of the archive are extracted.
perl v5.10.0 2008-09-30 2
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
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 properties 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 arguments.
$tar->get_files( [@filenames] )
Returns the "Archive::Tar::File" objects matching the
filenames provided. 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 handle 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.
perl v5.10.0 2008-09-30 3
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
$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). If the second
argument is true, the module will use IO::Zlib to write
the file in a compressed format. If IO::Zlib is not
available, the "write" method will fail and return.
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" filehandle instead.
Specific levels of compression can be chosen by passing
the values 2 through 9 as the second parameter.
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.
perl v5.10.0 2008-09-30 4
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
$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 equivalent 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.
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 content $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).
perl v5.10.0 2008-09-30 5
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
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 automatically, 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.
perl v5.10.0 2008-09-30 6
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
$bool = $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 preference.
$bool = $tar->has_perlio
Returns true if we currently have "perlio" support loaded.
This requires "perl-5.8" or higher, compiled with "perlio"
Either "IO::String" or "perlio" support is needed to
support writing stringified archives. Currently, "perlio"
is the preferred method, if available.
See the "GLOBAL VARIABLES" section to see how to change
this preference.
Class Methods
Archive::Tar->create_archive($file, $compression,
@filelist)
Creates a tar file from the list of files provided. The
first argument can either be the name of the tar file to
create or a reference to an open file handle (e.g. a GLOB
reference).
The second argument specifies the level of compression to
be used, if any. Compression of tar files requires the
installation of the IO::Zlib module. Specific levels of
compression may be requested by passing a value between 2
and 9 as the second argument. Any other value evaluating
as true will result in the default compression level being
used.
Note that when you pass in a filehandle, the compression
argument is ignored, as all files are printed verbatim to
your filehandle. If you wish to enable compression with
filehandles, use an "IO::Zlib" filehandle instead.
The remaining arguments list the files to be included in
the tar file. These files must all exist. Any files which
don't exist or can't be read are silently ignored.
If the archive creation fails for any reason,
"create_archive" will return false. Please use the "error"
method to find the cause of the failure.
perl v5.10.0 2008-09-30 7
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
Note that this method does not write "on the fly" as it
were; it still reads all the files into memory before
writing out the archive. Consult the FAQ below if this is
a problem.
Archive::Tar->list_archive ($file, $compressed,
[\@properties])
Returns a list of the names of all the files in the
archive. The first argument can either be the name of the
tar file to list or a reference to an open file handle
(e.g. a GLOB reference).
If "list_archive()" is passed an array reference as its
third argument it returns a list of hash references
containing the requested properties of each file. The
following list of properties is supported: full_path,
name, size, mtime (last modified date), mode, uid, gid,
linkname, uname, gname, devmajor, devminor, prefix.
See "Archive::Tar::File" for details about supported
properties.
Passing an array reference containing only one element,
'name', is special cased to return a list of names rather
than a list of hash references.
Archive::Tar->extract_archive ($file, $gzip)
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 failure.
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", or false if "IO::Zlib" is not
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
perl v5.10.0 2008-09-30 8
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
$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 compliant
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:
perl v5.10.0 2008-09-30 9
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
$tar->error(1);
Defaults to 0.
$Archive::Tar::WARN
Set this variable to 0 if you do not want any warnings
printed. Personally 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 permissions to. Therefor, the default
is to not allow insecure extractions.
If you trust the archive, or have other reasons to allow
the archive to write files outside your current working
directory, set this variable 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.
perl v5.10.0 2008-09-30 10
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
$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, consider using "/bin/tar" instead.
Isn't Archive::Tar heavier on memory than /bin/tar?
Yes it is, see previous answer. Since "Compress::Zlib"
and therefore "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.
Can't you lazy-load data instead?
No, not easily. See previous question.
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 "/bin/tar" instead.
What do you do with unsupported filetypes in an archive?
"Unix" has a few filetypes that aren't supported on
other platforms, 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 on archives that have
incompatible filetypes and still expect things to
work).
perl v5.10.0 2008-09-30 11
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
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 support
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, consider 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 compressed 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"
perl v5.10.0 2008-09-30 12
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
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 written file
now contains garbage.
For this reason, Unicode strings need to be converted
to UTF-8-encoded bytestrings before they are handed
perl v5.10.0 2008-09-30 13
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
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; "
perl v5.10.0 2008-09-30 14
Archive::Tar(3p) Perl Programmers Reference GuideArchive::Tar(3p)
http://www.opengroup.org/onlinepubs/007904975/utilities/pax.html"
A comparison of GNU and POSIX tar standards;
"http://www.delorie.com/gnu/docs/tar/tar_114.html"
GNU tar intends to switch to POSIX compatibility
GNU Tar authors have expressed their intention to
become completely POSIX-compatible;
"http://www.gnu.org/software/tar/manual/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 <kaneATcpan.org>.
Please reports bugs to <bug-archive-tarATrt.org>.
ACKNOWLEDGEMENTS
Thanks to Sean Burke, Chris Nandor, Chip Salzenberg, Tim
Heaney and especially Andrew Savige for their help and
suggestions.
COPYRIGHT
This module is copyright (c) 2002 - 2007 Jos Boumans
<kaneATcpan.org>. All rights reserved.
This library is free software; you may redistribute and/or
modify it under the same terms as Perl itself.
perl v5.10.0 2008-09-30 15
|
