Compress::Raw::Bzip2 - Low-Level Interface to bzip2 compression library
- use Compress::Raw::Bzip2 ;
- my ($bz, $status) = new Compress::Raw::Bzip2 [OPTS]
- or die "Cannot create bzip2 object: $bzerno\n";
- $status = $bz->bzdeflate($input, $output);
- $status = $bz->bzflush($output);
- $status = $bz->bzclose($output);
- my ($bz, $status) = new Compress::Raw::Bunzip2 [OPTS]
- or die "Cannot create bunzip2 object: $bzerno\n";
- $status = $bz->bzinflate($input, $output);
- my $version = Compress::Raw::Bzip2::bzlibversion();
Compress::Raw::Bzip2
provides an interface to the in-memory
compression/uncompression functions from the bzip2 compression library.
Although the primary purpose for the existence of Compress::Raw::Bzip2
is for use by the IO::Compress::Bzip2
and IO::Compress::Bunzip2
modules, it can be used on its own for simple compression/uncompression
tasks.
Creates a new compression object.
If successful, it will return the initialised compression object, $z
and a $status
of BZ_OK
in a list context. In scalar context it
returns the deflation object, $z
, only.
If not successful, the returned compression object, $z
, will be
undef and $status
will hold the a bzip2 error code.
Below is a list of the valid options:
Controls whether the compressed data is appended to the output buffer in
the bzdeflate
, bzflush
and bzclose
methods.
Defaults to 1.
To quote the bzip2 documentation
- blockSize100k specifies the block size to be used for compression. It
- should be a value between 1 and 9 inclusive, and the actual block size
- used is 100000 x this figure. 9 gives the best compression but takes
- most memory.
Defaults to 1.
To quote the bzip2 documentation
- This parameter controls how the compression phase behaves when
- presented with worst case, highly repetitive, input data. If
- compression runs into difficulties caused by repetitive data, the
- library switches from the standard sorting algorithm to a fallback
- algorithm. The fallback is slower than the standard algorithm by
- perhaps a factor of three, but always behaves reasonably, no matter how
- bad the input.
- Lower values of workFactor reduce the amount of effort the standard
- algorithm will expend before resorting to the fallback. You should set
- this parameter carefully; too low, and many inputs will be handled by
- the fallback algorithm and so compress rather slowly, too high, and
- your average-to-worst case compression times can become very large. The
- default value of 30 gives reasonable behaviour over a wide range of
- circumstances.
- Allowable values range from 0 to 250 inclusive. 0 is a special case,
- equivalent to using the default value of 30.
Defaults to 0.
Reads the contents of $input
, compresses it and writes the compressed
data to $output
.
Returns BZ_RUN_OK
on success and a bzip2
error code on failure.
If appendOutput
is enabled in the constructor for the bzip2 object, the
compressed data will be appended to $output
. If not enabled, $output
will be truncated before the compressed data is written to it.
Flushes any pending compressed data to $output
.
Returns BZ_RUN_OK
on success and a bzip2
error code on failure.
Terminates the compressed data stream and flushes any pending compressed
data to $output
.
Returns BZ_STREAM_END
on success and a bzip2
error code on failure.
If successful, it will return the initialised uncompression object, $z
and a $status
of BZ_OK
in a list context. In scalar context it
returns the deflation object, $z
, only.
If not successful, the returned uncompression object, $z
, will be
undef and $status
will hold the a bzip2 error code.
Below is a list of the valid options:
Controls whether the compressed data is appended to the output buffer in the
bzinflate
, bzflush
and bzclose
methods.
Defaults to 1.
To quote the bzip2 documentation
- If small is nonzero, the library will use an alternative decompression
- algorithm which uses less memory but at the cost of decompressing more
- slowly (roughly speaking, half the speed, but the maximum memory
- requirement drops to around 2300k).
Defaults to 0.
The LimitOutput
option changes the behavior of the $i->bzinflate
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 16k 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->bzinflate
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.
This parameter is ignored.
Defaults to 0.
Uncompresses $input
and writes the uncompressed data to $output
.
Returns BZ_OK
if the uncompression was successful, but the end of the
compressed data stream has not been reached. Returns BZ_STREAM_END
on
successful uncompression and the end of the compression stream has been
reached.
If consumeInput
is enabled in the constructor for the bunzip2 object,
$input
will have all compressed data removed from it after
uncompression. On BZ_OK
return this will mean that $input
will be an
empty string; when BZ_STREAM_END
$input
will either be an empty
string or will contain whatever data immediately followed the compressed
data stream.
If appendOutput
is enabled in the constructor for the bunzip2 object,
the uncompressed data will be appended to $output
. If not enabled,
$output
will be truncated before the uncompressed data is written to it.
Returns the version of the underlying bzip2 library.
The following bzip2 constants are exported by this module
- BZ_RUN
- BZ_FLUSH
- BZ_FINISH
- BZ_OK
- BZ_RUN_OK
- BZ_FLUSH_OK
- BZ_FINISH_OK
- BZ_STREAM_END
- BZ_SEQUENCE_ERROR
- BZ_PARAM_ERROR
- BZ_MEM_ERROR
- BZ_DATA_ERROR
- BZ_DATA_ERROR_MAGIC
- BZ_IO_ERROR
- BZ_UNEXPECTED_EOF
- BZ_OUTBUFF_FULL
- BZ_CONFIG_ERROR
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::Lzop, IO::Uncompress::UnLzop, IO::Compress::Lzf, IO::Uncompress::UnLzf, IO::Uncompress::AnyInflate, IO::Uncompress::AnyUncompress
File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib
The primary site for the bzip2 program is http://www.bzip.org.
See the module Compress::Bzip2
This module was written by Paul Marquess, pmqs@cpan.org.
See the Changes file.
Copyright (c) 2005-2014 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.