Compress::Zlib(3p) Perl Programmers Reference Guide Compress::Zlib(3p) #
Compress::Zlib(3p) Perl Programmers Reference Guide Compress::Zlib(3p)
NNAAMMEE #
Compress::Zlib - Interface to zlib compression library
SSYYNNOOPPSSIISS #
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();
DDEESSCCRRIIPPTTIIOONN #
The _C_o_m_p_r_e_s_s_:_:_Z_l_i_b module provides a Perl interface to the _z_l_i_b
compression library (see "AUTHOR" for details about where to get _z_l_i_b).
The "Compress::Zlib" module can be split into two general areas of
functionality, namely a simple read/write interface to _g_z_i_p files and a
low-level in-memory compression/decompression interface.
Each of these areas will be discussed in the following sections.
NNootteess ffoorr uusseerrss ooff CCoommpprreessss::::ZZlliibb vveerrssiioonn 11 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.
GGZZIIPP IINNTTEERRFFAACCEE #
A number of functions are supplied in _z_l_i_b for reading and writing _g_z_i_p
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.
$$ggzz == ggzzooppeenn(($$ffiilleennaammee,, $$mmooddee))
$$ggzz == ggzzooppeenn(($$ffiilleehhaannddllee,, $$mmooddee))
This function opens either the _g_z_i_p 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 _a_l_w_a_y_s 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 _z_l_i_b documentation for the exact format of the $mode
parameter.
$$bbyytteessrreeaadd == $$ggzz-->>ggzzrreeaadd(($$bbuuffffeerr [[,, $$ssiizzee]])) ;;
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.
$$bbyytteessrreeaadd == $$ggzz-->>ggzzrreeaaddlliinnee(($$lliinnee)) ;;
Reads the next line from the compressed file into $line.
Returns the number of bytes actually read. On EOF it returns 0 and
in the case of an error, -1.
It is legal to intermix calls to "gzread" and "gzreadline".
To maintain backward compatibility with version 1.x of this module
"gzreadline" ignores the $/ variable - it _a_l_w_a_y_s uses the string
"\n" as the line delimiter.
If you want to read a gzip file a line at a time and have it respect
the $/ variable (or $INPUT_RECORD_SEPARATOR, or $RS when "English"
is in use) see IO::Uncompress::Gunzip.
$$bbyytteesswwrriitttteenn == $$ggzz-->>ggzzwwrriittee(($$bbuuffffeerr)) ;;
Writes the contents of $buffer to the compressed file. Returns the
number of bytes actually written, or 0 on error.
$$ssttaattuuss == $$ggzz-->>ggzzfflluusshh(($$fflluusshh__ttyyppee)) ;;
Flushes all pending output into the compressed file.
This method takes an optional parameter, $flush_type, that controls
how the flushing will be carried out. By default the $flush_type
used is "Z_FINISH". Other valid values for $flush_type are
"Z_NO_FLUSH", "Z_SYNC_FLUSH", "Z_FULL_FLUSH" and "Z_BLOCK". It is
strongly recommended that you only set the "flush_type" parameter if
you fully understand the implications of what it does - overuse of
"flush" can seriously degrade the level of compression achieved. See
the "zlib" documentation for details.
Returns 0 on success.
$$ooffffsseett == $$ggzz-->>ggzztteellll(()) ;;
Returns the uncompressed file offset.
$$ssttaattuuss == $$ggzz-->>ggzzsseeeekk(($$ooffffsseett,, $$wwhheennccee)) ;;
Provides a sub-set of the "seek" functionality, with the restriction
that it is only legal to seek forward in the compressed file. It is
a fatal error to attempt to seek backward.
When opened for writing, empty parts of the file will have NULL
(0x00) bytes written to them.
The $whence parameter should be one of SEEK_SET, SEEK_CUR or
SEEK_END. #
Returns 1 on success, 0 on failure.
$$ggzz-->>ggzzcclloossee
Closes the compressed file. Any pending data is flushed to the file
before it is closed.
Returns 0 on success.
$$ggzz-->>ggzzsseettppaarraammss(($$lleevveell,, $$ssttrraatteeggyy
Change settings for the deflate stream $gz.
The list of the valid options is shown below. Options not specified
will remain unchanged.
Note: This method is only available if you are running zlib 1.0.6 or
better.
$$lleevveell
Defines the compression level. Valid values are 0 through 9,
"Z_NO_COMPRESSION", "Z_BEST_SPEED", "Z_BEST_COMPRESSION", and
“Z_DEFAULT_COMPRESSION”. #
$$ssttrraatteeggyy
Defines the strategy used to tune the compression. The valid
values are "Z_DEFAULT_STRATEGY", "Z_FILTERED" and
“Z_HUFFMAN_ONLY”. #
$$ggzz-->>ggzzeerrrroorr
Returns the _z_l_i_b error message or number for the last operation
associated with $gz. The return value will be the _z_l_i_b error number
when used in a numeric context and the _z_l_i_b error message when used
in a string context. The _z_l_i_b 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 #
$$ggzzeerrrrnnoo
The $gzerrno scalar holds the error code associated with the most
recent _g_z_i_p routine. Note that unlike "gzerror()", the error is _n_o_t
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 _z_l_i_b message when the error
is associated with _z_l_i_b itself, or the UNIX error message when it is
not (i.e. _z_l_i_b returned "Z_ERRORNO").
As there is an overlap between the error numbers used by _z_l_i_b and
UNIX, $gzerrno should only be used to check for the presence of _a_n
error in numeric context. Use "gzerror()" to check for specific _z_l_i_b
errors. The _g_z_c_a_t example below shows how the variable can be used
safely.
EExxaammpplleess Here is an example script which uses the interface. It implements a _g_z_c_a_t 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 _g_r_e_p 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, _g_z_s_t_r_e_a_m, does the opposite of the _g_z_c_a_t 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 ;
CCoommpprreessss::::ZZlliibb::::mmeemmGGzziipp 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.
CCoommpprreessss::::ZZlliibb::::mmeemmGGuunnzziipp 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.
CCOOMMPPRREESSSS//UUNNCCOOMMPPRREESSSS #
Two functions are provided to perform in-memory compression/uncompression
of RFC 1950 data streams. They are called "compress" and "uncompress".
$$ddeesstt == ccoommpprreessss(($$ssoouurrccee [[,, $$lleevveell]] )) ;;
Compresses $source. If successful it returns the compressed data.
Otherwise it returns _u_n_d_e_f.
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.
$$ddeesstt == uunnccoommpprreessss(($$ssoouurrccee)) ;;
Uncompresses $source. If successful it returns the uncompressed
data. Otherwise it returns _u_n_d_e_f.
The source buffer can either be a scalar or a scalar reference.
Please note: the two functions defined above are _n_o_t 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.
DDeeffllaattee IInntteerrffaaccee This section defines an interface that allows in-memory compression using the _d_e_f_l_a_t_e interface provided by zlib.
Here is a definition of the interface available:
(($$dd,, $$ssttaattuuss)) == ddeeffllaatteeIInniitt(( [[OOPPTT]] )) Initialises a deflation stream.
It combines the features of the _z_l_i_b 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 _u_n_d_e_f and
$status will hold the exact _z_l_i_b error code.
The function optionally takes a number of named options specified as
"-Name=>value" pairs. This allows individual options to be tailored
without having to specify them all in the parameter list.
For backward compatibility, it is also possible to pass the parameters as
a reference to a hash containing the name=>value pairs.
The function takes one optional parameter, a reference to a hash. The
contents of the hash allow the deflation interface to be tailored.
Here is a list of the valid options:
--LLeevveell
Defines the compression level. Valid values are 0 through 9,
"Z_NO_COMPRESSION", "Z_BEST_SPEED", "Z_BEST_COMPRESSION", and
“Z_DEFAULT_COMPRESSION”. #
The default is Z_DEFAULT_COMPRESSION.
--MMeetthhoodd
Defines the compression method. The only valid value at present (and
the default) is Z_DEFLATED.
--WWiinnddoowwBBiittss
To create an RFC 1950 data stream, set "WindowBits" to a positive
number.
To create an RFC 1951 data stream, set "WindowBits" to "-MAX_WBITS".
For a full definition of the meaning and valid values for
"WindowBits" refer to the _z_l_i_b documentation for _d_e_f_l_a_t_e_I_n_i_t_2.
Defaults to MAX_WBITS.
--MMeemmLLeevveell
For a definition of the meaning and valid values for "MemLevel"
refer to the _z_l_i_b documentation for _d_e_f_l_a_t_e_I_n_i_t_2.
Defaults to MAX_MEM_LEVEL.
--SSttrraatteeggyy
Defines the strategy used to tune the compression. The valid values
are "Z_DEFAULT_STRATEGY", "Z_FILTERED" and "Z_HUFFMAN_ONLY".
The default is Z_DEFAULT_STRATEGY.
--DDiiccttiioonnaarryy
When a dictionary is specified _C_o_m_p_r_e_s_s_:_:_Z_l_i_b will automatically
call "deflateSetDictionary" directly after calling "deflateInit".
The Adler32 value for the dictionary can be obtained by calling the
method "$d->dict_adler()".
The default is no dictionary.
--BBuuffssiizzee
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 ) ;
(($$oouutt,, $$ssttaattuuss)) == $$dd-->>ddeeffllaattee(($$bbuuffffeerr)) 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 _u_n_d_e_f and $status will contain the _z_l_i_b error
code.
In a scalar context "deflate" will return $out only.
As with the _d_e_f_l_a_t_e function in _z_l_i_b, 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.
(($$oouutt,, $$ssttaattuuss)) == $$dd-->>fflluusshh(()) ==hheeaadd22 (($$oouutt,, $$ssttaattuuss)) == $$dd-->>fflluusshh(($$fflluusshh__ttyyppee)) Typically used to finish the deflation. Any pending output will be returned via $out. $status will have a value “Z_OK” if successful.
In a scalar context "flush" will return $out only.
Note that flushing can seriously degrade the compression ratio, so it
should only be used to terminate a decompression (using "Z_FINISH") or
when you want to create a _f_u_l_l _f_l_u_s_h _p_o_i_n_t (using "Z_FULL_FLUSH").
By default the "flush_type" used is "Z_FINISH". Other valid values for
"flush_type" are "Z_NO_FLUSH", "Z_PARTIAL_FLUSH", "Z_SYNC_FLUSH" and
"Z_FULL_FLUSH". It is strongly recommended that you only set the
"flush_type" parameter if you fully understand the implications of what
it does. See the "zlib" documentation for details.
$$ssttaattuuss == $$dd-->>ddeeffllaatteePPaarraammss(([[OOPPTT]])) Change settings for the deflate stream $d.
The list of the valid options is shown below. Options not specified will
remain unchanged.
--LLeevveell
Defines the compression level. Valid values are 0 through 9,
"Z_NO_COMPRESSION", "Z_BEST_SPEED", "Z_BEST_COMPRESSION", and
“Z_DEFAULT_COMPRESSION”. #
--SSttrraatteeggyy
Defines the strategy used to tune the compression. The valid values
are "Z_DEFAULT_STRATEGY", "Z_FILTERED" and "Z_HUFFMAN_ONLY".
$$dd-->>ddiicctt__aaddlleerr(()) Returns the adler32 value for the dictionary.
$$dd-->>mmssgg(()) Returns the last error message generated by zlib.
$$dd-->>ttoottaall__iinn(()) Returns the total number of bytes uncompressed bytes input to deflate.
$$dd-->>ttoottaall__oouutt(()) Returns the total number of compressed bytes output from deflate.
EExxaammppllee Here is a trivial example of using “deflate”. It simply reads standard input, deflates it and writes it to standard output.
use strict ;
use warnings ;
use Compress::Zlib ;
binmode STDIN;
binmode STDOUT;
my $x = deflateInit()
or die "Cannot create a deflation stream\n" ;
my ($output, $status) ;
while (<>)
{
($output, $status) = $x->deflate($_) ;
$status == Z_OK
or die "deflation failed\n" ;
print $output ;
}
($output, $status) = $x->flush() ;
$status == Z_OK
or die "deflation failed\n" ;
print $output ;
IInnffllaattee IInntteerrffaaccee This section defines the interface available that allows in-memory uncompression using the _d_e_f_l_a_t_e interface provided by zlib.
Here is a definition of the interface:
(($$ii,, $$ssttaattuuss)) == iinnffllaatteeIInniitt(()) Initialises an inflation stream.
In a list context it returns the inflation stream, $i, and the _z_l_i_b
status code in $status. In a scalar context it returns the inflation
stream only.
If successful, $i will hold the inflation stream and $status will be
“Z_OK”. #
If not successful, $i will be _u_n_d_e_f and $status will hold the _z_l_i_b error
code.
The function optionally takes a number of named options specified as
"-Name=>value" pairs. This allows individual options to be tailored
without having to specify them all in the parameter list.
For backward compatibility, it is also possible to pass the parameters as
a reference to a hash containing the name=>value pairs.
The function takes one optional parameter, a reference to a hash. The
contents of the hash allow the deflation interface to be tailored.
Here is a list of the valid options:
--WWiinnddoowwBBiittss
To uncompress an RFC 1950 data stream, set "WindowBits" to a
positive number.
To uncompress an RFC 1951 data stream, set "WindowBits" to
“-MAX_WBITS”. #
For a full definition of the meaning and valid values for
"WindowBits" refer to the _z_l_i_b documentation for _i_n_f_l_a_t_e_I_n_i_t_2.
Defaults to MAX_WBITS.
--BBuuffssiizzee
Sets the initial size for the inflation buffer. If the buffer has to
be reallocated to increase the size, it will grow in increments of
"Bufsize".
Default is 4096.
--DDiiccttiioonnaarryy
The default is no dictionary.
Here is an example of using the "inflateInit" optional parameter to
override the default buffer size.
inflateInit( -Bufsize => 300 ) ;
(($$oouutt,, $$ssttaattuuss)) == $$ii-->>iinnffllaattee(($$bbuuffffeerr)) Inflates the complete contents of $buffer. The buffer can either be a scalar or a scalar reference.
Returns "Z_OK" if successful and "Z_STREAM_END" if the end of the
compressed data has been successfully reached. If not successful, $out
will be _u_n_d_e_f and $status will hold the _z_l_i_b error code.
The $buffer parameter is modified by "inflate". On completion it will
contain what remains of the input buffer after inflation. This means that
$buffer will be an empty string when the return status is "Z_OK". When
the return status is "Z_STREAM_END" the $buffer parameter will contains
what (if anything) was stored in the input buffer after the deflated data
stream.
This feature is useful when processing a file format that encapsulates a
compressed data stream (e.g. gzip, zip).
$$ssttaattuuss == $$ii-->>iinnffllaatteeSSyynncc(($$bbuuffffeerr)) Scans $buffer until it reaches either a _f_u_l_l _f_l_u_s_h _p_o_i_n_t or the end of the buffer.
If a _f_u_l_l _f_l_u_s_h _p_o_i_n_t 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.
$$ii-->>ddiicctt__aaddlleerr(()) Returns the adler32 value for the dictionary.
$$ii-->>mmssgg(()) Returns the last error message generated by zlib.
$$ii-->>ttoottaall__iinn(()) Returns the total number of bytes compressed bytes input to inflate.
$$ii-->>ttoottaall__oouutt(()) Returns the total number of uncompressed bytes output from inflate.
EExxaammppllee 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 ;
CCHHEECCKKSSUUMM FFUUNNCCTTIIOONNSS #
Two functions are provided by _z_l_i_b 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 _z_l_i_b
documentation for more details.
MMiisscc mmyy $$vveerrssiioonn == CCoommpprreessss::::ZZlliibb::::zzlliibb__vveerrssiioonn(());; Returns the version of the zlib library.
CCOONNSSTTAANNTTSS #
All the _z_l_i_b constants are automatically imported when you make use of
_C_o_m_p_r_e_s_s_:_:_Z_l_i_b.
SSUUPPPPOORRTT #
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>.
SSEEEE AALLSSOO #
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 _z_l_i_b 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 _z_l_i_b compression library is
<http://www.zlib.org>.
The primary site for gzip is <http://www.gzip.org>.
AAUUTTHHOORR #
This module was written by Paul Marquess, "pmqs@cpan.org".
MMOODDIIFFIICCAATTIIOONN HHIISSTTOORRYY #
See the Changes file.
CCOOPPYYRRIIGGHHTT AANNDD LLIICCEENNSSEE #
Copyright (c) 1995-2022 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 v5.36.3 2023-02-15 Compress::Zlib(3p)