Compre...w::Zlib(3perl) Perl Programmers Reference GuideCompre...w::Zlib(3perl)
NAME
Compress::Raw::Zlib - Low-Level Interface to zlib or zlib-ng compression
library
SYNOPSIS
use Compress::Raw::Zlib ;
($d, $status) = new Compress::Raw::Zlib::Deflate( [OPT] ) ;
$status = $d->deflate($input, $output) ;
$status = $d->flush($output [, $flush_type]) ;
$d->deflateReset() ;
$d->deflateParams(OPTS) ;
$d->deflateTune(OPTS) ;
$d->dict_adler() ;
$d->crc32() ;
$d->adler32() ;
$d->total_in() ;
$d->total_out() ;
$d->msg() ;
$d->get_Strategy();
$d->get_Level();
$d->get_BufSize();
($i, $status) = new Compress::Raw::Zlib::Inflate( [OPT] ) ;
$status = $i->inflate($input, $output [, $eof]) ;
$status = $i->inflateSync($input) ;
$i->inflateReset() ;
$i->dict_adler() ;
$d->crc32() ;
$d->adler32() ;
$i->total_in() ;
$i->total_out() ;
$i->msg() ;
$d->get_BufSize();
$crc = adler32($buffer [,$crc]) ;
$crc = crc32($buffer [,$crc]) ;
$crc = crc32_combine($crc1, $crc2, $len2);
$adler = adler32_combine($adler1, $adler2, $len2);
my $version = Compress::Raw::Zlib::zlib_version();
my $flags = Compress::Raw::Zlib::zlibCompileFlags();
is_zlib_native();
is_zlibng_native();
is_zlibng_compat();
is_zlibng();
DESCRIPTION
The Compress::Raw::Zlib module provides a Perl interface to the zlib or
zlib-ng compression libraries (see "SEE ALSO" for details about where to
get zlib or zlib-ng).
In the text below all references to zlib are also applicable to zlib-ng
unless otherwise stated.
Compress::Raw::Zlib::Deflate
This section defines an interface that allows in-memory compression
using the deflate interface provided by zlib.
Here is a definition of the interface available:
($d, $status) = new Compress::Raw::Zlib::Deflate( [OPT] )
Initialises a deflation object.
If you are familiar with the zlib library, it combines the features of
the zlib functions "deflateInit", "deflateInit2" and
"deflateSetDictionary".
If successful, it will return the initialised deflation object, $d and a
$status of "Z_OK" in a list context. In scalar context it returns the
deflation object, $d, only.
If not successful, the returned deflation object, $d, will be undef and
$status will hold the a zlib error code.
The function optionally takes a number of named options specified as
"Name => value" pairs. This allows individual options to be tailored
without having to specify them all in the parameter list.
For backward compatibility, it is also possible to pass the parameters
as a reference to a hash containing the name=>value pairs.
Below is a list of the valid options:
-Level
Defines the compression level. Valid values are 0 through 9,
"Z_NO_COMPRESSION", "Z_BEST_SPEED", "Z_BEST_COMPRESSION", and
"Z_DEFAULT_COMPRESSION".
The default is "Z_DEFAULT_COMPRESSION".
-Method
Defines the compression method. The only valid value at present
(and the default) is "Z_DEFLATED".
-WindowBits
To compress an RFC 1950 data stream, set "WindowBits" to a positive
number between 8 and 15.
To compress an RFC 1951 data stream, set "WindowBits" to
"-MAX_WBITS".
To compress an RFC 1952 data stream (i.e. gzip), set "WindowBits"
to "WANT_GZIP".
For a definition of the meaning and valid values for "WindowBits"
refer to the zlib documentation for deflateInit2.
Defaults to "MAX_WBITS".
-MemLevel
For a definition of the meaning and valid values for "MemLevel"
refer to the zlib documentation for deflateInit2.
Defaults to MAX_MEM_LEVEL.
-Strategy
Defines the strategy used to tune the compression. The valid values
are "Z_DEFAULT_STRATEGY", "Z_FILTERED", "Z_RLE", "Z_FIXED" and
"Z_HUFFMAN_ONLY".
The default is "Z_DEFAULT_STRATEGY".
-Dictionary
When a dictionary is specified Compress::Raw::Zlib will
automatically call "deflateSetDictionary" directly after calling
"deflateInit". The Adler32 value for the dictionary can be obtained
by calling the method "$d->dict_adler()".
The default is no dictionary.
-Bufsize
Sets the initial size for the output buffer used by the
"$d->deflate" and "$d->flush" methods. If the buffer has to be
reallocated to increase the size, it will grow in increments of
"Bufsize".
The default buffer size is 4096.
-AppendOutput
This option controls how data is written to the output buffer by
the "$d->deflate" and "$d->flush" methods.
If the "AppendOutput" option is set to false, the output buffers in
the "$d->deflate" and "$d->flush" methods will be truncated before
uncompressed data is written to them.
If the option is set to true, uncompressed data will be appended to
the output buffer in the "$d->deflate" and "$d->flush" methods.
This option defaults to false.
-CRC32
If set to true, a crc32 checksum of the uncompressed data will be
calculated. Use the "$d->crc32" method to retrieve this value.
This option defaults to false.
-ADLER32
If set to true, an adler32 checksum of the uncompressed data will
be calculated. Use the "$d->adler32" method to retrieve this value.
This option defaults to false.
Here is an example of using the "Compress::Raw::Zlib::Deflate" optional
parameter list to override the default buffer size and compression
level. All other options will take their default values.
my $d = new Compress::Raw::Zlib::Deflate ( -Bufsize => 300,
-Level => Z_BEST_SPEED ) ;
$status = $d->deflate($input, $output)
Deflates the contents of $input and writes the compressed data to
$output.
The $input and $output parameters can be either scalars or scalar
references.
When finished, $input will be completely processed (assuming there were
no errors). If the deflation was successful it writes the deflated data
to $output and returns a status value of "Z_OK".
On error, it returns a zlib error code.
If the "AppendOutput" option is set to true in the constructor for the
$d object, the compressed data will be appended to $output. If it is
false, $output will be truncated before any compressed data is written
to it.
Note: This method will not necessarily write compressed data to $output
every time it is called. So do not assume that there has been an error
if the contents of $output is empty on returning from this method. As
long as the return code from the method is "Z_OK", the deflate has
succeeded.
$status = $d->flush($output [, $flush_type])
Typically used to finish the deflation. Any pending output will be
written to $output.
Returns "Z_OK" if successful.
Note that flushing can seriously degrade the compression ratio, so it
should only be used to terminate a decompression (using "Z_FINISH") or
when you want to create a full flush point (using "Z_FULL_FLUSH").
By default the "flush_type" used is "Z_FINISH". Other valid values for
"flush_type" are "Z_NO_FLUSH", "Z_PARTIAL_FLUSH", "Z_SYNC_FLUSH" and
"Z_FULL_FLUSH". It is strongly recommended that you only set the
"flush_type" parameter if you fully understand the implications of what
it does. See the "zlib" documentation for details.
If the "AppendOutput" option is set to true in the constructor for the
$d object, the compressed data will be appended to $output. If it is
false, $output will be truncated before any compressed data is written
to it.
$status = $d->deflateReset()
This method will reset the deflation object $d. It can be used when you
are compressing multiple data streams and want to use the same object to
compress each of them. It should only be used once the previous data
stream has been flushed successfully, i.e. a call to
"$d->flush(Z_FINISH)" has returned "Z_OK".
Returns "Z_OK" if successful.
$status = $d->deflateParams([OPT])
Change settings for the deflate object $d.
The list of the valid options is shown below. Options not specified will
remain unchanged.
-Level
Defines the compression level. Valid values are 0 through 9,
"Z_NO_COMPRESSION", "Z_BEST_SPEED", "Z_BEST_COMPRESSION", and
"Z_DEFAULT_COMPRESSION".
-Strategy
Defines the strategy used to tune the compression. The valid values
are "Z_DEFAULT_STRATEGY", "Z_FILTERED" and "Z_HUFFMAN_ONLY".
-BufSize
Sets the initial size for the output buffer used by the
"$d->deflate" and "$d->flush" methods. If the buffer has to be
reallocated to increase the size, it will grow in increments of
"Bufsize".
$status = $d->deflateTune($good_length, $max_lazy, $nice_length, $max_chain)
Tune the internal settings for the deflate object $d. This option is
only available if you are running zlib 1.2.2.3 or better.
Refer to the documentation in zlib.h for instructions on how to fly
"deflateTune".
$d->dict_adler()
Returns the adler32 value for the dictionary.
$d->crc32()
Returns the crc32 value for the uncompressed data to date.
If the "CRC32" option is not enabled in the constructor for this object,
this method will always return 0;
$d->adler32()
Returns the adler32 value for the uncompressed data to date.
$d->msg()
Returns the last error message generated by zlib.
$d->total_in()
Returns the total number of bytes uncompressed bytes input to deflate.
$d->total_out()
Returns the total number of compressed bytes output from deflate.
$d->get_Strategy()
Returns the deflation strategy currently used. Valid values are
"Z_DEFAULT_STRATEGY", "Z_FILTERED" and "Z_HUFFMAN_ONLY".
$d->get_Level()
Returns the compression level being used.
$d->get_BufSize()
Returns the buffer size used to carry out the compression.
Example
Here is a trivial example of using "deflate". It simply reads standard
input, deflates it and writes it to standard output.
use strict ;
use warnings ;
use Compress::Raw::Zlib ;
binmode STDIN;
binmode STDOUT;
my $x = new Compress::Raw::Zlib::Deflate
or die "Cannot create a deflation stream\n" ;
my ($output, $status) ;
while (<>)
{
$status = $x->deflate($_, $output) ;
$status == Z_OK
or die "deflation failed\n" ;
print $output ;
}
$status = $x->flush($output) ;
$status == Z_OK
or die "deflation failed\n" ;
print $output ;
Compress::Raw::Zlib::Inflate
This section defines an interface that allows in-memory uncompression
using the inflate interface provided by zlib.
Here is a definition of the interface:
($i, $status) = new Compress::Raw::Zlib::Inflate( [OPT] )
Initialises an inflation object.
In a list context it returns the inflation object, $i, and the zlib
status code ($status). In a scalar context it returns the inflation
object only.
If successful, $i will hold the inflation object and $status will be
"Z_OK".
If not successful, $i will be undef and $status will hold the zlib error
code.
The function optionally takes a number of named options specified as
"-Name => value" pairs. This allows individual options to be tailored
without having to specify them all in the parameter list.
For backward compatibility, it is also possible to pass the parameters
as a reference to a hash containing the "name=>value" pairs.
Here is a list of the valid options:
-WindowBits
To uncompress an RFC 1950 data stream, set "WindowBits" to a
positive number between 8 and 15.
To uncompress an RFC 1951 data stream, set "WindowBits" to
"-MAX_WBITS".
To uncompress an RFC 1952 data stream (i.e. gzip), set "WindowBits"
to "WANT_GZIP".
To auto-detect and uncompress an RFC 1950 or RFC 1952 data stream
(i.e. gzip), set "WindowBits" to "WANT_GZIP_OR_ZLIB".
For a full definition of the meaning and valid values for
"WindowBits" refer to the zlib documentation for inflateInit2.
Defaults to "MAX_WBITS".
-Bufsize
Sets the initial size for the output buffer used by the
"$i->inflate" method. If the output buffer in this method has to be
reallocated to increase the size, it will grow in increments of
"Bufsize".
Default is 4096.
-Dictionary
The default is no dictionary.
-AppendOutput
This option controls how data is written to the output buffer by
the "$i->inflate" method.
If the option is set to false, the output buffer in the
"$i->inflate" method will be truncated before uncompressed data is
written to it.
If the option is set to true, uncompressed data will be appended to
the output buffer by the "$i->inflate" method.
This option defaults to false.
-CRC32
If set to true, a crc32 checksum of the uncompressed data will be
calculated. Use the "$i->crc32" method to retrieve this value.
This option defaults to false.
-ADLER32
If set to true, an adler32 checksum of the uncompressed data will
be calculated. Use the "$i->adler32" method to retrieve this value.
This option defaults to false.
-ConsumeInput
If set to true, this option will remove compressed data from the
input buffer of the "$i->inflate" method as the inflate progresses.
This option can be useful when you are processing compressed data
that is embedded in another file/buffer. In this case the data that
immediately follows the compressed stream will be left in the input
buffer.
This option defaults to true.
-LimitOutput
The "LimitOutput" option changes the behavior of the "$i->inflate"
method so that the amount of memory used by the output buffer can
be limited.
When "LimitOutput" is used the size of the output buffer used will
either be the value of the "Bufsize" option or the amount of memory
already allocated to $output, whichever is larger. Predicting the
output size available is tricky, so don't rely on getting an exact
output buffer size.
When "LimitOutout" is not specified "$i->inflate" will use as much
memory as it takes to write all the uncompressed data it creates by
uncompressing the input buffer.
If "LimitOutput" is enabled, the "ConsumeInput" option will also be
enabled.
This option defaults to false.
See "The LimitOutput option" for a discussion on why "LimitOutput"
is needed and how to use it.
Here is an example of using an optional parameter to override the
default buffer size.
my ($i, $status) = new Compress::Raw::Zlib::Inflate( -Bufsize => 300 ) ;
$status = $i->inflate($input, $output [,$eof])
Inflates the complete contents of $input and writes the uncompressed
data to $output. The $input and $output parameters can either be scalars
or scalar references.
Returns "Z_OK" if successful and "Z_STREAM_END" if the end of the
compressed data has been successfully reached.
If not successful $status will hold the zlib error code.
If the "ConsumeInput" option has been set to true when the
"Compress::Raw::Zlib::Inflate" object is created, the $input parameter
is modified by "inflate". On completion it will contain what remains of
the input buffer after inflation. In practice, this means that when the
return status is "Z_OK" the $input parameter will contain an empty
string, and when the return status is "Z_STREAM_END" the $input
parameter will contains what (if anything) was stored in the input
buffer after the deflated data stream.
This feature is useful when processing a file format that encapsulates a
compressed data stream (e.g. gzip, zip) and there is useful data
immediately after the deflation stream.
If the "AppendOutput" option is set to true in the constructor for this
object, the uncompressed data will be appended to $output. If it is
false, $output will be truncated before any uncompressed data is written
to it.
The $eof parameter needs a bit of explanation.
Prior to version 1.2.0, zlib assumed that there was at least one
trailing byte immediately after the compressed data stream when it was
carrying out decompression. This normally isn't a problem because the
majority of zlib applications guarantee that there will be data directly
after the compressed data stream. For example, both gzip (RFC 1950) and
zip both define trailing data that follows the compressed data stream.
The $eof parameter only needs to be used if all of the following
conditions apply
1. You are either using a copy of zlib that is older than version
1.2.0 or you want your application code to be able to run with as
many different versions of zlib as possible.
2. You have set the "WindowBits" parameter to "-MAX_WBITS" in the
constructor for this object, i.e. you are uncompressing a raw
deflated data stream (RFC 1951).
3. There is no data immediately after the compressed data stream.
If all of these are the case, then you need to set the $eof parameter to
true on the final call (and only the final call) to "$i->inflate".
If you have built this module with zlib >= 1.2.0, the $eof parameter is
ignored. You can still set it if you want, but it won't be used behind
the scenes.
$status = $i->inflateSync($input)
This method can be used to attempt to recover good data from a
compressed data stream that is partially corrupt. It scans $input until
it reaches either a full flush point or the end of the buffer.
If a full flush point is found, "Z_OK" is returned and $input will be
have all data up to the flush point removed. This data can then be
passed to the "$i->inflate" method to be uncompressed.
Any other return code means that a flush point was not found. If more
data is available, "inflateSync" can be called repeatedly with more
compressed data until the flush point is found.
Note full flush points are not present by default in compressed data
streams. They must have been added explicitly when the data stream was
created by calling "Compress::Deflate::flush" with "Z_FULL_FLUSH".
$status = $i->inflateReset()
This method will reset the inflation object $i. It can be used when you
are uncompressing multiple data streams and want to use the same object
to uncompress each of them.
Returns "Z_OK" if successful.
$i->dict_adler()
Returns the adler32 value for the dictionary.
$i->crc32()
Returns the crc32 value for the uncompressed data to date.
If the "CRC32" option is not enabled in the constructor for this object,
this method will always return 0;
$i->adler32()
Returns the adler32 value for the uncompressed data to date.
If the "ADLER32" option is not enabled in the constructor for this
object, this method will always return 0;
$i->msg()
Returns the last error message generated by zlib.
$i->total_in()
Returns the total number of bytes compressed bytes input to inflate.
$i->total_out()
Returns the total number of uncompressed bytes output from inflate.
$d->get_BufSize()
Returns the buffer size used to carry out the decompression.
Examples
Here is an example of using "inflate".
use strict ;
use warnings ;
use Compress::Raw::Zlib;
my $x = new Compress::Raw::Zlib::Inflate()
or die "Cannot create a inflation stream\n" ;
my $input = '' ;
binmode STDIN;
binmode STDOUT;
my ($output, $status) ;
while (read(STDIN, $input, 4096))
{
$status = $x->inflate($input, $output) ;
print $output ;
last if $status != Z_OK ;
}
die "inflation failed\n"
unless $status == Z_STREAM_END ;
The next example show how to use the "LimitOutput" option. Notice the
use of two nested loops in this case. The outer loop reads the data from
the input source - STDIN and the inner loop repeatedly calls "inflate"
until $input is exhausted, we get an error, or the end of the stream is
reached. One point worth remembering is by using the "LimitOutput"
option you also get "ConsumeInput" set as well - this makes the code
below much simpler.
use strict ;
use warnings ;
use Compress::Raw::Zlib;
my $x = new Compress::Raw::Zlib::Inflate(LimitOutput => 1)
or die "Cannot create a inflation stream\n" ;
my $input = '' ;
binmode STDIN;
binmode STDOUT;
my ($output, $status) ;
OUTER:
while (read(STDIN, $input, 4096))
{
do
{
$status = $x->inflate($input, $output) ;
print $output ;
last OUTER
unless $status == Z_OK || $status == Z_BUF_ERROR ;
}
while length $input;
}
die "inflation failed\n"
unless $status == Z_STREAM_END ;
CHECKSUM FUNCTIONS
Two functions are provided by zlib to calculate checksums. For the Perl
interface, the order of the two parameters in both functions has been
reversed. This allows both running checksums and one off calculations to
be done.
$crc = adler32($buffer [,$crc]) ;
$crc = crc32($buffer [,$crc]) ;
The buffer parameters can either be a scalar or a scalar reference.
If the $crc parameters is "undef", the crc value will be reset.
If you have built this module with zlib 1.2.3 or better, two more CRC-
related functions are available.
$crc = crc32_combine($crc1, $crc2, $len2);
$adler = adler32_combine($adler1, $adler2, $len2);
These functions allow checksums to be merged. Refer to the zlib
documentation for more details.
Misc
my $version = Compress::Raw::Zlib::zlib_version();
Returns the version of the zlib library if this module has been built
with the zlib library. If this module has been built with zlib-ng in
native mode, this function will return a empty string. If this module
has been built with zlib-ng in compat mode, this function will return
the Izlib> API verion that zlib-ng is supporting.
my $version = Compress::Raw::Zlib::zlibng_version();
Returns the version of the zlib-ng library if this module has been built
with the zlib-ng library. If this module has been built with zlib, this
function will return a empty string.
my $flags = Compress::Raw::Zlib::zlibCompileFlags();
Returns the flags indicating compile-time options that were used to
build the zlib or zlib-ng library. See the zlib documentation for a
description of the flags returned by "zlibCompileFlags".
Note that when the zlib sources are built along with this module the
"sprintf" flags (bits 24, 25 and 26) should be ignored.
If you are using zlib 1.2.0 or older, "zlibCompileFlags" will return 0.
is_zlib_native(); =head2 is_zlibng_native(); =head2 is_zlibng_compat();
=head2 is_zlibng();
These function can use used to check if "Compress::Raw::Zlib" was been
built with zlib or zlib-ng.
The function "is_zlib_native" returns true if "Compress::Raw::Zlib" was
built with zlib. The function "is_zlibng" returns true if
"Compress::Raw::Zlib" was built with zlib-ng.
The zlib-ng library has an option to build with a zlib-compataible API.
The c<is_zlibng_compat> function retuens true if zlib-ng has ben built
with this API.
Finally, "is_zlibng_native" returns true if zlib-ng was built with its
native API.
The LimitOutput option.
By default "$i->inflate($input, $output)" will uncompress all data in
$input and write all of the uncompressed data it has generated to
$output. This makes the interface to "inflate" much simpler - if the
method has uncompressed $input successfully all compressed data in
$input will have been dealt with. So if you are reading from an input
source and uncompressing as you go the code will look something like
this
use strict ;
use warnings ;
use Compress::Raw::Zlib;
my $x = new Compress::Raw::Zlib::Inflate()
or die "Cannot create a inflation stream\n" ;
my $input = '' ;
my ($output, $status) ;
while (read(STDIN, $input, 4096))
{
$status = $x->inflate($input, $output) ;
print $output ;
last if $status != Z_OK ;
}
die "inflation failed\n"
unless $status == Z_STREAM_END ;
The points to note are
• The main processing loop in the code handles reading of compressed
data from STDIN.
• The status code returned from "inflate" will only trigger
termination of the main processing loop if it isn't "Z_OK". When
"LimitOutput" has not been used the "Z_OK" status means that the
end of the compressed data stream has been reached or there has
been an error in uncompression.
• After the call to "inflate" all of the uncompressed data in $input
will have been processed. This means the subsequent call to "read"
can overwrite it's contents without any problem.
For most use-cases the behavior described above is acceptable (this
module and it's predecessor, "Compress::Zlib", have used it for over 10
years without an issue), but in a few very specific use-cases the amount
of memory required for $output can prohibitively large. For example, if
the compressed data stream contains the same pattern repeated thousands
of times, a relatively small compressed data stream can uncompress into
hundreds of megabytes. Remember "inflate" will keep allocating memory
until all the uncompressed data has been written to the output buffer -
the size of $output is unbounded.
The "LimitOutput" option is designed to help with this use-case.
The main difference in your code when using "LimitOutput" is having to
deal with cases where the $input parameter still contains some
uncompressed data that "inflate" hasn't processed yet. The status code
returned from "inflate" will be "Z_OK" if uncompression took place and
"Z_BUF_ERROR" if the output buffer is full.
Below is typical code that shows how to use "LimitOutput".
use strict ;
use warnings ;
use Compress::Raw::Zlib;
my $x = new Compress::Raw::Zlib::Inflate(LimitOutput => 1)
or die "Cannot create a inflation stream\n" ;
my $input = '' ;
binmode STDIN;
binmode STDOUT;
my ($output, $status) ;
OUTER:
while (read(STDIN, $input, 4096))
{
do
{
$status = $x->inflate($input, $output) ;
print $output ;
last OUTER
unless $status == Z_OK || $status == Z_BUF_ERROR ;
}
while length $input;
}
die "inflation failed\n"
unless $status == Z_STREAM_END ;
Points to note this time:
• There are now two nested loops in the code: the outer loop for
reading the compressed data from STDIN, as before; and the inner
loop to carry out the uncompression.
• There are two exit points from the inner uncompression loop.
Firstly when "inflate" has returned a status other than "Z_OK" or
"Z_BUF_ERROR". This means that either the end of the compressed
data stream has been reached ("Z_STREAM_END") or there is an error
in the compressed data. In either of these cases there is no point
in continuing with reading the compressed data, so both loops are
terminated.
The second exit point tests if there is any data left in the input
buffer, $input - remember that the "ConsumeInput" option is
automatically enabled when "LimitOutput" is used. When the input
buffer has been exhausted, the outer loop can run again and
overwrite a now empty $input.
ACCESSING ZIP FILES
Although it is possible (with some effort on your part) to use this
module to access .zip files, there are other perl modules available that
will do all the hard work for you. Check out "Archive::Zip",
"Archive::Zip::SimpleZip", "IO::Compress::Zip" and
"IO::Uncompress::Unzip".
FAQ
Compatibility with Unix compress/uncompress.
This module is not compatible with Unix "compress".
If you have the "uncompress" program available, you can use this to read
compressed files
open F, "uncompress -c $filename |";
while (<F>)
{
...
Alternatively, if you have the "gunzip" program available, you can use
this to read compressed files
open F, "gunzip -c $filename |";
while (<F>)
{
...
and this to write compress files, if you have the "compress" program
available
open F, "| compress -c $filename ";
print F "data";
...
close F ;
Accessing .tar.Z files
See previous FAQ item.
If the "Archive::Tar" module is installed and either the "uncompress" or
"gunzip" programs are available, you can use one of these workarounds to
read ".tar.Z" files.
Firstly with "uncompress"
use strict;
use warnings;
use Archive::Tar;
open F, "uncompress -c $filename |";
my $tar = Archive::Tar->new(*F);
...
and this with "gunzip"
use strict;
use warnings;
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 strict;
use warnings;
use Archive::Tar;
use IO::File;
my $fh = new IO::File "| compress -c >$filename";
my $tar = Archive::Tar->new();
...
$tar->write($fh);
$fh->close ;
Zlib Library Version Support
By default "Compress::Raw::Zlib" will build with a private copy of
version 1.2.5 of the zlib library. (See the README file for details of
how to override this behaviour)
If you decide to use a different version of the zlib library, you need
to be aware of the following issues
• First off, you must have zlib 1.0.5 or better.
• You need to have zlib 1.2.1 or better if you want to use the
"-Merge" option with "IO::Compress::Gzip", "IO::Compress::Deflate"
and "IO::Compress::RawDeflate".
CONSTANTS
All the zlib constants are automatically imported when you make use of
Compress::Raw::Zlib.
SUPPORT
General feedback/questions/bug reports should be sent to
<https://github.com/pmqs/Compress-Raw-Zlib/issues> (preferred) or
<https://rt.cpan.org/Public/Dist/Display.html?Name=Compress-Raw-Zlib>.
SEE ALSO
Compress::Zlib, IO::Compress::Gzip, IO::Uncompress::Gunzip,
IO::Compress::Deflate, IO::Uncompress::Inflate,
IO::Compress::RawDeflate, IO::Uncompress::RawInflate,
IO::Compress::Bzip2, IO::Uncompress::Bunzip2, IO::Compress::Lzma,
IO::Uncompress::UnLzma, IO::Compress::Xz, IO::Uncompress::UnXz,
IO::Compress::Lzip, IO::Uncompress::UnLzip, IO::Compress::Lzop,
IO::Uncompress::UnLzop, IO::Compress::Lzf, IO::Uncompress::UnLzf,
IO::Compress::Zstd, IO::Uncompress::UnZstd, IO::Uncompress::AnyInflate,
IO::Uncompress::AnyUncompress
IO::Compress::FAQ
File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib
For RFC 1950, 1951 and 1952 see
<https://datatracker.ietf.org/doc/html/rfc1950>,
<https://datatracker.ietf.org/doc/html/rfc1951> and
<https://datatracker.ietf.org/doc/html/rfc1952>
The zlib compression library was written by Jean-loup Gailly
"gzip@prep.ai.mit.edu" and Mark Adler "madler@alumni.caltech.edu".
The primary site for the zlib compression library is
<http://www.zlib.org>.
The primary site for the zlib-ng compression library is
<https://github.com/zlib-ng/zlib-ng>.
The primary site for gzip is <http://www.gzip.org>.
AUTHOR
This module was written by Paul Marquess, "pmqs@cpan.org".
MODIFICATION HISTORY
See the Changes file.
COPYRIGHT AND LICENSE
Copyright (c) 2005-2024 Paul Marquess. All rights reserved.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perl v5.40.1 2026-08-30 Compre...w::Zlib(3perl)
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