use Compress::Bzip2 qw(:all :constant :utilities :gzip); ($bz, $status) = bzdeflateInit( [PARAMS] ); ($out, $status) = $bz->bzdeflate($buffer) ; # compress ($bz, $status) = bzinflateInit( [PARAMS] ); ($out, $status) = $bz->bzinflate($buffer); # uncompress ($out, $status) = $bz->bzflush() ; ($out, $status) = $bz->bzclose() ; $dest = memBzip($source); alias compress $dest = memBunzip($source); alias decompress $bz = Compress::Bzip2->new( [PARAMS] ); $bz = bzopen($filename or filehandle, $mode); alternate, with $bz created by new(): $bz->bzopen($filename or filehandle, $mode); $bytesread = $bz->bzread($buffer [,$size]) ; $bytesread = $bz->bzreadline($line); $byteswritten = $bz->bzwrite($buffer [,$limit]); $errstring = $bz->bzerror(); $status = $bz->bzeof(); $status = $bz->bzflush(); $status = $bz->bzclose() ; $status = $bz->bzsetparams( $param => $setting ); $bz->total_in() ; $bz->total_out() ; $verstring = $bz->bzversion(); $Compress::Bzip2::bzerrno
All string parameters can either be a scalar or a scalar reference.
The module can be split into two general areas of functionality, namely in-memory compression/decompression and read/write access to bzip2 files. Each of these areas will be discussed separately below.
NOTE
Compress::Bzip2 is just a simple bzip2 binding, comparable to the old Compress::Zlib library. It is not well integrated into PerlIO, use the preferred IO::Compress::Bzip2 instead.
The mode parameter is used to specify both whether the file is opened for reading or writing, with ``r'' or ``w'' respectively.
If a reference to an open filehandle is passed in place of the filename, it better be positioned to the start of a compression/decompression sequence.
WARNING: With Perl 5.6 you cannot use a filehandle because of SEGV in destruction with bzclose or an implicit close.
Returns the number of bytes actually read. On EOF it returns 0 and in the case of an error, -1.
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 bzread and bzreadline.
At this time bzreadline ignores the variable $/ ($INPUT_RECORD_SEPARATOR or $RS when "English" is in use). The end of a line is denoted by the C character '\n'.
If $limit is given and non-zero, then only that many bytes from $buffer will be written.
Returns "BZ_OK" if $flush is "BZ_FINISH" and all output could be flushed. Otherwise the bzlib error code is returned.
Refer to the bzlib documentation for the valid values of $flush.
The list of the valid options is shown below. Options not specified will remain unchanged.
The default is "-verbosity => 0".
Defines the buffering factor of compression method. The algorithm buffers all data until the buffer is full, then it flushes all the data out. Use -blockSize100k to specify the size of the buffer.
Valid settings are 1 through 9, representing a blocking in multiples of 100k.
Note that each such block has an overhead of leading and trailing synchronization bytes. bzip2 recovery uses this information to pull useable data out of a corrupted file.
A streaming application would probably want to set the blocking low.
The workFactor setting tells the deflation algorithm how much work to invest to compensate for repetitive data.
workFactor may be a number from 0 to 250 inclusive. The default setting is 30.
See the bzip documentation for more information.
small may be 0 or 1. Set "small" to one to use a slower, less memory intensive algorithm.
BZ_CONFIG_ERROR BZ_DATA_ERROR BZ_DATA_ERROR_MAGIC BZ_FINISH BZ_FINISH_OK BZ_FLUSH BZ_FLUSH_OK BZ_IO_ERROR BZ_MAX_UNUSED BZ_MEM_ERROR BZ_OK BZ_OUTBUFF_FULL BZ_PARAM_ERROR BZ_RUN BZ_RUN_OK BZ_SEQUENCE_ERROR BZ_STREAM_END BZ_UNEXPECTED_EOF
As with bzerror() it returns an error number in numeric context and an error message in string context. Unlike bzerror() though, the error message will correspond to the bzlib message when the error is associated with bzlib itself, or the UNIX error message when it is not (i.e. bzlib returned "Z_ERRORNO").
As there is an overlap between the error numbers used by bzlib and UNIX, $bzerrno should only be used to check for the presence of an error in numeric context. Use bzerror() to check for specific bzlib errors. The bzcat example below shows how the variable can be used safely.
-level, alias to -blockSize100k -buffer, to set the buffer size.
The -buffer option is ignored. The intermediate buffer size is not changeable.
To make the interoperability even easier, all the Compress::Zlib method names have been used as aliases or cover functions for the bzip2 methods.
Therefore, most code that uses Compress::Zlib should be able to use this package, with a one line change.
Simply change
$gz = Compress::Zlib::gzopen( "filename", "w" );
to
$gz = Compress::Bzip2::gzopen( "filename", "w" );
Some of the Compress::Zlib aliases don't return anything useful, like crc32 or adler32, cause bzip2 doesn't do that sort of thing.
See the Compress::Zlib documentation for more information.
The buffer parameter can either be a scalar or a scalar reference.
Essentially, an in-memory bzip file is created. It creates a minimal bzip header, which adds 5 bytes before the bzip2 specific BZh header.
The source buffer can either be a scalar or a scalar reference.
The buffer parameter can either be a scalar or a scalar reference. The contents of the buffer parameter are destroyed after calling this function.
Here is a definition of the interface available:
If successful, it will return the initialised deflation stream, $d and $status of "BZ_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 bzip2 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.
Here is a list of the valid options:
The default is "-verbosity => 0".
Valid settings are 1 through 9, representing a blocking in multiples of 100k.
Note that each such block has an overhead of leading and trailing synchronization bytes. bzip2 recovery uses this information to pull useable data out of a corrupted file.
A streaming application would probably want to set the blocking low.
workFactor may be a number from 0 to 250 inclusive. The default setting is 30.
See the bzip documentation for more information.
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.
bzdeflateInit( -blockSize100k => 1, -verbosity => 1 );
On error, $out will be undef and $status will contain the zlib error code.
In a scalar context bzdeflate will return $out only.
As with the internal buffering of the deflate function in bzip2, 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. In fact, given the size of bzdeflates internal buffer, with most files it's likely you won't see any output at all until flush or close.
In a scalar context bzflush will return $out only.
Note that flushing can seriously degrade the compression ratio, so it should only be used to terminate a decompression (using "BZ_FLUSH") or when you want to create a full flush point (using "BZ_FINISH").
The allowable values for "flush_type" are "BZ_FLUSH" and "BZ_FINISH".
For a handle opened for ``w'' (bzwrite), the default is "BZ_FLUSH". For a stream, the default for "flush_type" is "BZ_FINISH" (which is essentially a close and reopen).
It is strongly recommended that you only set the "flush_type" parameter if you fully understand the implications of what it does. See the "bzip2" documentation for details.
use strict ; use warnings ; use Compress::Bzip2 ; binmode STDIN; binmode STDOUT; my $x = bzdeflateInit() or die "Cannot create a deflation stream\n" ; my ($output, $status) ; while (<>) { ($output, $status) = $x->bzdeflate($_) ; $status == BZ_OK or die "deflation failed\n" ; print $output ; } ($output, $status) = $x->bzclose() ; $status == BZ_OK or die "deflation failed\n" ; print $output ;
In a list context it returns the inflation stream, $i, and the zlib status code ($status). In a scalar context it returns the inflation stream only.
If successful, $i will hold the inflation stream and $status will be "BZ_OK".
If not successful, $i will be undef and $status will hold the bzlib.h 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:
The default is "-verbosity => 0".
Here is an example of using the bzinflateInit optional parameter.
bzinflateInit( -small => 1, -verbosity => 1 );
Returns "BZ_OK" if successful and "BZ_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 bzlib error code.
The $buffer parameter is modified by "bzinflate". 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 "BZ_OK". When the return status is "BZ_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.
use strict ; use warnings ; use Compress::Bzip2; my $x = bzinflateInit() 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->bzinflate(\$input) ; print $output if $status == BZ_OK or $status == BZ_STREAM_END ; last if $status != BZ_OK ; } die "inflation failed\n" unless $status == BZ_STREAM_END ;
use strict ; use warnings ; use Compress::Bzip2 ; die "Usage: bzcat file...\n" unless @ARGV ; my $file ; foreach $file (@ARGV) { my $buffer ; my $bz = bzopen($file, "rb") or die "Cannot open $file: $bzerrno\n" ; print $buffer while $bz->bzread($buffer) > 0 ; die "Error reading from $file: $bzerrno" . ($bzerrno+0) . "\n" if $bzerrno != BZ_STREAM_END ; $bz->bzclose() ; }
use strict ; use warnings ; use Compress::Bzip2 ; die "Usage: bzgrep pattern file...\n" unless @ARGV >= 2; my $pattern = shift ; my $file ; foreach $file (@ARGV) { my $bz = bzopen($file, "rb") or die "Cannot open $file: $bzerrno\n" ; while ($bz->bzreadline($_) > 0) { print if /$pattern/ ; } die "Error reading from $file: $bzerrno\n" if $bzerrno != Z_STREAM_END ; $bz->bzclose() ; }
use strict ; use warnings ; use Compress::Bzip2 ; binmode STDOUT; # bzopen only sets it on the fd my $bz = bzopen(\*STDOUT, "wb") or die "Cannot open stdout: $bzerrno\n" ; while (<>) { $bz->bzwrite($_) or die "error writing: $bzerrno\n" ; } $bz->bzclose ;
compress decompress compress_init decompress_init version
These are actually aliases to memBzip and memBunzip.
bzopen bzinflateInit bzdeflateInit memBzip memBunzip bzip2 bunzip2 bzcat bzlibversion $bzerrno
gzopen gzinflateInit gzdeflateInit memGzip memGunzip $gzerrno
BZ_CONFIG_ERROR BZ_DATA_ERROR BZ_DATA_ERROR_MAGIC BZ_FINISH BZ_FINISH_OK BZ_FLUSH BZ_FLUSH_OK BZ_IO_ERROR BZ_MAX_UNUSED BZ_MEM_ERROR BZ_OK BZ_OUTBUFF_FULL BZ_PARAM_ERROR BZ_RUN BZ_RUN_OK BZ_SEQUENCE_ERROR BZ_STREAM_END BZ_UNEXPECTED_EOF
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.3 or, at your option, any later version of Perl 5 you may have available.
The first Compress::Bzip2 module was written by Gawdi Azem azemgi@rupert.informatik.uni-stuttgart.de. It provided an interface to the in memory inflate and deflate routines.
Compress::Bzip2 was subsequently passed on to Marco Carnut kiko@tempest.com.br who shepherded it through to version 1.03, a set of changes which included upgrades to handle bzlib 1.0.2, and improvements to the in memory inflate and deflate routines. The streaming interface and error information were added by David Robins dbrobins@davidrobins.net.
Version 2 of Compress::Bzip2 is due to Rob Janes, of arjay@cpan.org. This release is intended to give an interface close to that of Compress::Zlib. It's development forks from 1.00, not 1.03, so the streaming interface is not the same as that in 1.03, although apparently compatible as it passes the 1.03 test suite.
Minor subsequent fixes and releases were done by Reini Urban, rurban@cpan.org.
2.00 Second public release of Compress::Bzip2.