phpMan > perldoc > Compress::Zlib

NAME
    Compress::Zlib - Interface to zlib compression library

SYNOPSIS
        use Compress::Zlib ;

        ($d, $status) = deflateInit( [OPT] ) ;
        $status = $d->deflate($input, $output) ;
        $status = $d->flush([$flush_type]) ;
        $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) = inflateInit( [OPT] ) ;
        $status = $i->inflate($input, $output [, $eof]) ;
        $status = $i->inflateSync($input) ;
        $i->dict_adler() ;
        $d->crc32() ;
        $d->adler32() ;
        $i->total_in() ;
        $i->total_out() ;
        $i->msg() ;
        $d->get_BufSize();

        $dest = compress($source) ;
        $dest = uncompress($source) ;

        $gz = gzopen($filename or filehandle, $mode) ;
        $bytesread = $gz->gzread($buffer [,$size]) ;
        $bytesread = $gz->gzreadline($line) ;
        $byteswritten = $gz->gzwrite($buffer) ;
        $status = $gz->gzflush($flush) ;
        $offset = $gz->gztell() ;
        $status = $gz->gzseek($offset, $whence) ;
        $status = $gz->gzclose() ;
        $status = $gz->gzeof() ;
        $status = $gz->gzsetparams($level, $strategy) ;
        $errstring = $gz->gzerror() ;
        $gzerrno

        $dest = Compress::Zlib::memGzip($buffer) ;
        $dest = Compress::Zlib::memGunzip($buffer) ;

        $crc = adler32($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();

DESCRIPTION
    The *Compress::Zlib* module provides a Perl interface to the *zlib* compression library (see
    "AUTHOR" for details about where to get *zlib*).

    The "Compress::Zlib" module can be split into two general areas of functionality, namely a
    simple read/write interface to *gzip* files and a low-level in-memory compression/decompression
    interface.

    Each of these areas will be discussed in the following sections.

  Notes for users of Compress::Zlib version 1
    The main change in "Compress::Zlib" version 2.x is that it does not now interface directly to
    the zlib library. Instead it uses the "IO::Compress::Gzip" and "IO::Uncompress::Gunzip" modules
    for reading/writing gzip files, and the "Compress::Raw::Zlib" module for some low-level zlib
    access.

    The interface provided by version 2 of this module should be 100% backward compatible with
    version 1. If you find a difference in the expected behaviour please contact the author (See
    "AUTHOR"). See "GZIP INTERFACE"

    With the creation of the "IO::Compress" and "IO::Uncompress" modules no new features are planned
    for "Compress::Zlib" - the new modules do everything that "Compress::Zlib" does and then some.
    Development on "Compress::Zlib" will be limited to bug fixes only.

    If you are writing new code, your first port of call should be one of the new "IO::Compress" or
    "IO::Uncompress" modules.

GZIP INTERFACE
    A number of functions are supplied in *zlib* for reading and writing *gzip* files that conform
    to RFC 1952. This module provides an interface to most of them.

    If you have previously used "Compress::Zlib" 1.x, the following enhancements/changes have been
    made to the "gzopen" interface:

    1    If you want to open either STDIN or STDOUT with "gzopen", you can now optionally use the
         special filename ""-"" as a synonym for "\*STDIN" and "\*STDOUT".

    2    In "Compress::Zlib" version 1.x, "gzopen" used the zlib library to open the underlying
         file. This made things especially tricky when a Perl filehandle was passed to "gzopen".
         Behind the scenes the numeric C file descriptor had to be extracted from the Perl
         filehandle and this passed to the zlib library.

         Apart from being non-portable to some operating systems, this made it difficult to use
         "gzopen" in situations where you wanted to extract/create a gzip data stream that is
         embedded in a larger file, without having to resort to opening and closing the file
         multiple times.

         It also made it impossible to pass a perl filehandle that wasn't associated with a real
         filesystem file, like, say, an "IO::String".

         In "Compress::Zlib" version 2.x, the "gzopen" interface has been completely rewritten to
         use the IO::Compress::Gzip for writing gzip files and IO::Uncompress::Gunzip for reading
         gzip files. None of the limitations mentioned above apply.

    3    Addition of "gzseek" to provide a restricted "seek" interface.

    4.   Added "gztell".

    A more complete and flexible interface for reading/writing gzip files/buffers is included with
    the module "IO-Compress-Zlib". See IO::Compress::Gzip and IO::Uncompress::Gunzip for more
    details.

    $gz = gzopen($filename, $mode)
    $gz = gzopen($filehandle, $mode)
         This function opens either the *gzip* file $filename for reading or writing or attaches to
         the opened filehandle, $filehandle. It returns an object on success and "undef" on failure.

         When writing a gzip file this interface will *always* create the smallest possible gzip
         header (exactly 10 bytes). If you want greater control over what gets stored in the gzip
         header (like the original filename or a comment) use IO::Compress::Gzip instead. Similarly
         if you want to read the contents of the gzip header use IO::Uncompress::Gunzip.

         The second parameter, $mode, is used to specify whether the file is opened for reading or
         writing and to optionally specify a compression level and compression strategy when
         writing. The format of the $mode parameter is similar to the mode parameter to the 'C'
         function "fopen", so "rb" is used to open for reading, "wb" for writing and "ab" for
         appending (writing at the end of the file).

         To specify a compression level when writing, append a digit between 0 and 9 to the mode
         string -- 0 means no compression and 9 means maximum compression. If no compression level
         is specified Z_DEFAULT_COMPRESSION is used.

         To specify the compression strategy when writing, append 'f' for filtered data, 'h' for
         Huffman only compression, or 'R' for run-length encoding. If no strategy is specified
         Z_DEFAULT_STRATEGY is used.

         So, for example, "wb9" means open for writing with the maximum compression using the
         default strategy and "wb4R" means open for writing with compression level 4 and run-length
         encoding.

         Refer to the *zlib* documentation for the exact format of the $mode parameter.

    $bytesread = $gz->gzread($buffer [, $size]) ;
         Reads $size bytes from the compressed file into $buffer. If $size is not specified, it will
         default to 4096. If the scalar $buffer is not large enough, it will be extended
         automatically.

         Returns the number of bytes actually read. On EOF it returns 0 and in the case of an error,
         -1.

    $bytesread = $gz->gzreadline($line) ;
         Reads the next line from the compressed file into $line.

         Returns the number of bytes actually read. On EOF it returns 0 and in the case of an error,
         -1.

         It is legal to intermix calls to "gzread" and "gzreadline".

         To maintain backward compatibility with version 1.x of this module "gzreadline" ignores the
         $/ variable - it *always* uses the string "\n" as the line delimiter.

         If you want to read a gzip file a line at a time and have it respect the $/ variable (or
         $INPUT_RECORD_SEPARATOR, or $RS when "English" is in use) see IO::Uncompress::Gunzip.

    $byteswritten = $gz->gzwrite($buffer) ;
         Writes the contents of $buffer to the compressed file. Returns the number of bytes actually
         written, or 0 on error.

    $status = $gz->gzflush($flush_type) ;
         Flushes all pending output into the compressed file.

         This method takes an optional parameter, $flush_type, that controls how the flushing will
         be carried out. By default the $flush_type used is "Z_FINISH". Other valid values for
         $flush_type are "Z_NO_FLUSH", "Z_SYNC_FLUSH", "Z_FULL_FLUSH" and "Z_BLOCK". It is strongly
         recommended that you only set the "flush_type" parameter if you fully understand the
         implications of what it does - overuse of "flush" can seriously degrade the level of
         compression achieved. See the "zlib" documentation for details.

         Returns 0 on success.

    $offset = $gz->gztell() ;
         Returns the uncompressed file offset.

    $status = $gz->gzseek($offset, $whence) ;
         Provides a sub-set of the "seek" functionality, with the restriction that it is only legal
         to seek forward in the compressed file. It is a fatal error to attempt to seek backward.

         When opened for writing, empty parts of the file will have NULL (0x00) bytes written to
         them.

         The $whence parameter should be one of SEEK_SET, SEEK_CUR or SEEK_END.

         Returns 1 on success, 0 on failure.

    $gz->gzclose
         Closes the compressed file. Any pending data is flushed to the file before it is closed.

         Returns 0 on success.

    $gz->gzsetparams($level, $strategy
         Change settings for the deflate stream $gz.

         The list of the valid options is shown below. Options not specified will remain unchanged.

         Note: This method is only available if you are running zlib 1.0.6 or better.

         $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".

    $gz->gzerror
         Returns the *zlib* error message or number for the last operation associated with $gz. The
         return value will be the *zlib* error number when used in a numeric context and the *zlib*
         error message when used in a string context. The *zlib* error number constants, shown
         below, are available for use.

             Z_OK
             Z_STREAM_END
             Z_ERRNO
             Z_STREAM_ERROR
             Z_DATA_ERROR
             Z_MEM_ERROR
             Z_BUF_ERROR

    $gzerrno
         The $gzerrno scalar holds the error code associated with the most recent *gzip* routine.
         Note that unlike "gzerror()", the error is *not* associated with a particular file.

         As with "gzerror()" it returns an error number in numeric context and an error message in
         string context. Unlike "gzerror()" though, the error message will correspond to the *zlib*
         message when the error is associated with *zlib* itself, or the UNIX error message when it
         is not (i.e. *zlib* returned "Z_ERRORNO").

         As there is an overlap between the error numbers used by *zlib* and UNIX, $gzerrno should
         only be used to check for the presence of *an* error in numeric context. Use "gzerror()" to
         check for specific *zlib* errors. The *gzcat* example below shows how the variable can be
         used safely.

  Examples
    Here is an example script which uses the interface. It implements a *gzcat* function.

        use strict ;
        use warnings ;

        use Compress::Zlib ;

        # use stdin if no files supplied
        @ARGV = '-' unless @ARGV ;

        foreach my $file (@ARGV) {
            my $buffer ;

            my $gz = gzopen($file, "rb")
                 or die "Cannot open $file: $gzerrno\n" ;

            print $buffer while $gz->gzread($buffer) > 0 ;

            die "Error reading from $file: $gzerrno" . ($gzerrno+0) . "\n"
                if $gzerrno != Z_STREAM_END ;

            $gz->gzclose() ;
        }

    Below is a script which makes use of "gzreadline". It implements a very simple *grep* like
    script.

        use strict ;
        use warnings ;

        use Compress::Zlib ;

        die "Usage: gzgrep pattern [file...]\n"
            unless @ARGV >= 1;

        my $pattern = shift ;

        # use stdin if no files supplied
        @ARGV = '-' unless @ARGV ;

        foreach my $file (@ARGV) {
            my $gz = gzopen($file, "rb")
                 or die "Cannot open $file: $gzerrno\n" ;

            while ($gz->gzreadline($_) > 0) {
                print if /$pattern/ ;
            }

            die "Error reading from $file: $gzerrno\n"
                if $gzerrno != Z_STREAM_END ;

            $gz->gzclose() ;
        }

    This script, *gzstream*, does the opposite of the *gzcat* script above. It reads from standard
    input and writes a gzip data stream to standard output.

        use strict ;
        use warnings ;

        use Compress::Zlib ;

        binmode STDOUT;  # gzopen only sets it on the fd

        my $gz = gzopen(\*STDOUT, "wb")
              or die "Cannot open stdout: $gzerrno\n" ;

        while (<>) {
            $gz->gzwrite($_)
              or die "error writing: $gzerrno\n" ;
        }

        $gz->gzclose ;

  Compress::Zlib::memGzip
    This function is used to create an in-memory gzip file with the minimum possible gzip header
    (exactly 10 bytes).

        $dest = Compress::Zlib::memGzip($buffer)
            or die "Cannot compress: $gzerrno\n";

    If successful, it returns the in-memory gzip file. Otherwise it returns "undef" and the $gzerrno
    variable will store the zlib error code.

    The $buffer parameter can either be a scalar or a scalar reference.

    See IO::Compress::Gzip for an alternative way to carry out in-memory gzip compression.

  Compress::Zlib::memGunzip
    This function is used to uncompress an in-memory gzip file.

        $dest = Compress::Zlib::memGunzip($buffer)
            or die "Cannot uncompress: $gzerrno\n";

    If successful, it returns the uncompressed gzip file. Otherwise it returns "undef" and the
    $gzerrno variable will store the zlib error code.

    The $buffer parameter can either be a scalar or a scalar reference. The contents of the $buffer
    parameter are destroyed after calling this function.

    If $buffer consists of multiple concatenated gzip data streams only the first will be
    uncompressed. Use "gunzip" with the "MultiStream" option in the "IO::Uncompress::Gunzip" module
    if you need to deal with concatenated data streams.

    See IO::Uncompress::Gunzip for an alternative way to carry out in-memory gzip uncompression.

COMPRESS/UNCOMPRESS
    Two functions are provided to perform in-memory compression/uncompression of RFC 1950 data
    streams. They are called "compress" and "uncompress".

    $dest = compress($source [, $level] ) ;
         Compresses $source. If successful it returns the compressed data. Otherwise it returns
         *undef*.

         The source buffer, $source, can either be a scalar or a scalar reference.

         The $level parameter defines the compression level. Valid values are 0 through 9,
         "Z_NO_COMPRESSION", "Z_BEST_SPEED", "Z_BEST_COMPRESSION", and "Z_DEFAULT_COMPRESSION". If
         $level is not specified "Z_DEFAULT_COMPRESSION" will be used.

    $dest = uncompress($source) ;
         Uncompresses $source. If successful it returns the uncompressed data. Otherwise it returns
         *undef*.

         The source buffer can either be a scalar or a scalar reference.

    Please note: the two functions defined above are *not* compatible with the Unix commands of the
    same name.

    See IO::Deflate and IO::Inflate included with this distribution for an alternative interface for
    reading/writing RFC 1950 files/buffers.

Deflate Interface
    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) = deflateInit( [OPT] )
    Initialises a deflation stream.

    It combines the features of the *zlib* functions "deflateInit", "deflateInit2" and
    "deflateSetDictionary".

    If successful, it will return the initialised deflation stream, $d and $status of "Z_OK" in a
    list context. In scalar context it returns the deflation stream, $d, only.

    If not successful, the returned deflation stream ($d) will be *undef* and $status will hold the
    exact *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.

    The function takes one optional parameter, a reference to a hash. The contents of the hash allow
    the deflation interface to be tailored.

    Here 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 create an RFC 1950 data stream, set "WindowBits" to a positive number.

         To create an RFC 1951 data stream, set "WindowBits" to "-MAX_WBITS".

         For a full 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" and "Z_HUFFMAN_ONLY".

         The default is Z_DEFAULT_STRATEGY.

    -Dictionary
         When a dictionary is specified *Compress::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 deflation buffer. If the buffer has to be reallocated to
         increase the size, it will grow in increments of "Bufsize".

         The default is 4096.

    Here is an example of using the "deflateInit" optional parameter list to override the default
    buffer size and compression level. All other options will take their default values.

        deflateInit( -Bufsize => 300,
                     -Level => Z_BEST_SPEED  ) ;

  ($out, $status) = $d->deflate($buffer)
    Deflates the contents of $buffer. The buffer can either be a scalar or a scalar reference. When
    finished, $buffer will be completely processed (assuming there were no errors). If the deflation
    was successful it returns the deflated output, $out, and a status value, $status, of "Z_OK".

    On error, $out will be *undef* and $status will contain the *zlib* error code.

    In a scalar context "deflate" will return $out only.

    As with the *deflate* function in *zlib*, it is not necessarily the case that any output will be
    produced by this method. So don't rely on the fact that $out is empty for an error test.

  ($out, $status) = $d->flush()
=head2 ($out, $status) = $d->flush($flush_type)
    Typically used to finish the deflation. Any pending output will be returned via $out. $status
    will have a value "Z_OK" if successful.

    In a scalar context "flush" will return $out only.

    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.

  $status = $d->deflateParams([OPT])
    Change settings for the deflate stream $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".

  $d->dict_adler()
    Returns the adler32 value for the dictionary.

  $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.

  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::Zlib ;

        binmode STDIN;
        binmode STDOUT;
        my $x = deflateInit()
           or die "Cannot create a deflation stream\n" ;

        my ($output, $status) ;
        while (<>)
        {
            ($output, $status) = $x->deflate($_) ;

            $status == Z_OK
                or die "deflation failed\n" ;

            print $output ;
        }

        ($output, $status) = $x->flush() ;

        $status == Z_OK
            or die "deflation failed\n" ;

        print $output ;

Inflate Interface
    This section defines the interface available that allows in-memory uncompression using the
    *deflate* interface provided by zlib.

    Here is a definition of the interface:

  ($i, $status) = inflateInit()
    Initialises an inflation stream.

    In a list context it returns the inflation stream, $i, and the *zlib* status code in $status. In
    a scalar context it returns the inflation stream only.

    If successful, $i will hold the inflation stream 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.

    The function takes one optional parameter, a reference to a hash. The contents of the hash allow
    the deflation interface to be tailored.

    Here is a list of the valid options:

    -WindowBits
         To uncompress an RFC 1950 data stream, set "WindowBits" to a positive number.

         To uncompress an RFC 1951 data stream, set "WindowBits" to "-MAX_WBITS".

         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 inflation buffer. If the buffer has to be reallocated to
         increase the size, it will grow in increments of "Bufsize".

         Default is 4096.

    -Dictionary
         The default is no dictionary.

    Here is an example of using the "inflateInit" optional parameter to override the default buffer
    size.

        inflateInit( -Bufsize => 300 ) ;

  ($out, $status) = $i->inflate($buffer)
    Inflates the complete contents of $buffer. The buffer can either be a scalar or a scalar
    reference.

    Returns "Z_OK" if successful and "Z_STREAM_END" if the end of the compressed data has been
    successfully reached. If not successful, $out will be *undef* and $status will hold the *zlib*
    error code.

    The $buffer parameter is modified by "inflate". On completion it will contain what remains of
    the input buffer after inflation. This means that $buffer will be an empty string when the
    return status is "Z_OK". When the return status is "Z_STREAM_END" the $buffer 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).

  $status = $i->inflateSync($buffer)
    Scans $buffer 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 $buffer will be have all data up to the
    flush point removed. This can then be passed to the "deflate" method.

    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.

  $i->dict_adler()
    Returns the adler32 value for the dictionary.

  $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.

  Example
    Here is an example of using "inflate".

        use strict ;
        use warnings ;

        use Compress::Zlib ;

        my $x = inflateInit()
           or die "Cannot create a inflation stream\n" ;

        my $input = '' ;
        binmode STDIN;
        binmode STDOUT;

        my ($output, $status) ;
        while (read(STDIN, $input, 4096))
        {
            ($output, $status) = $x->inflate(\$input) ;

            print $output
                if $status == Z_OK or $status == Z_STREAM_END ;

            last if $status != Z_OK ;
        }

        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::Zlib::zlib_version();
    Returns the version of the zlib library.

CONSTANTS
    All the *zlib* constants are automatically imported when you make use of *Compress::Zlib*.

SUPPORT
    General feedback/questions/bug reports should be sent to
    <https://github.com/pmqs/IO-Compress/issues> (preferred) or
    <https://rt.cpan.org/Public/Dist/Display.html?Name=IO-Compress>.

SEE ALSO
    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 <http://www.faqs.org/rfcs/rfc1950.html>,
    <http://www.faqs.org/rfcs/rfc1951.html> and <http://www.faqs.org/rfcs/rfc1952.html>

    The *zlib* compression library was written by Jean-loup Gailly "gzip AT prep.edu" and Mark
    Adler "madler AT alumni.edu".

    The primary site for the *zlib* compression library is <http://www.zlib.org>.

    The primary site for gzip is <http://www.gzip.org>.

AUTHOR
    This module was written by Paul Marquess, "pmqs AT cpan.org".

MODIFICATION HISTORY
    See the Changes file.

COPYRIGHT AND LICENSE
    Copyright (c) 1995-2021 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.