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.\" ========================================================================
.\"
.IX Title "Compress::Raw::Bzip2 3pm"
.TH Compress::Raw::Bzip2 3pm 2023-11-28 "perl v5.38.2" "Perl Programmers Reference Guide"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
Compress::Raw::Bzip2 \- Low\-Level Interface to bzip2 compression library
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&    use Compress::Raw::Bzip2 ;
\&
\&    my ($bz, $status) = new Compress::Raw::Bzip2 [OPTS]
\&        or die "Cannot create bzip2 object: $bzerno\en";
\&
\&    $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\en";
\&
\&    $status = $bz\->bzinflate($input, $output);
\&
\&    my $version = Compress::Raw::Bzip2::bzlibversion();
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
\&\f(CW\*(C`Compress::Raw::Bzip2\*(C'\fR provides an interface to the in-memory
compression/uncompression functions from the bzip2 compression library.
.PP
Although the primary purpose for the existence of \f(CW\*(C`Compress::Raw::Bzip2\*(C'\fR
is for use by the  \f(CW\*(C`IO::Compress::Bzip2\*(C'\fR and \f(CW\*(C`IO::Compress::Bunzip2\*(C'\fR
modules, it can be used on its own for simple compression/uncompression
tasks.
.SH Compression
.IX Header "Compression"
.ie n .SS "($z, $status) = new Compress::Raw::Bzip2 $appendOutput, $blockSize100k, $workfactor;"
.el .SS "($z, \f(CW$status\fP) = new Compress::Raw::Bzip2 \f(CW$appendOutput\fP, \f(CW$blockSize100k\fP, \f(CW$workfactor\fP;"
.IX Subsection "($z, $status) = new Compress::Raw::Bzip2 $appendOutput, $blockSize100k, $workfactor;"
Creates a new compression object.
.PP
If successful, it will return the initialised compression object, \f(CW$z\fR
and a \f(CW$status\fR of \f(CW\*(C`BZ_OK\*(C'\fR in a list context. In scalar context it
returns the deflation object, \f(CW$z\fR, only.
.PP
If not successful, the returned compression object, \f(CW$z\fR, will be
\&\fIundef\fR and \f(CW$status\fR will hold the a \fIbzip2\fR error code.
.PP
Below is a list of the valid options:
.ie n .IP \fR\fB$appendOutput\fR\fB\fR 5
.el .IP \fR\f(CB$appendOutput\fR\fB\fR 5
.IX Item "$appendOutput"
Controls whether the compressed data is appended to the output buffer in
the \f(CW\*(C`bzdeflate\*(C'\fR, \f(CW\*(C`bzflush\*(C'\fR and \f(CW\*(C`bzclose\*(C'\fR methods.
.Sp
Defaults to 1.
.ie n .IP \fR\fB$blockSize100k\fR\fB\fR 5
.el .IP \fR\f(CB$blockSize100k\fR\fB\fR 5
.IX Item "$blockSize100k"
To quote the bzip2 documentation
.Sp
.Vb 4
\&    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.
.Ve
.Sp
Defaults to 1.
.ie n .IP \fR\fB$workfactor\fR\fB\fR 5
.el .IP \fR\f(CB$workfactor\fR\fB\fR 5
.IX Item "$workfactor"
To quote the bzip2 documentation
.Sp
.Vb 7
\&    This parameter controls how the compression phase behaves when
\&    presented with worst case, highly repetitive, input data. If
\&    compression runs into difficulties caused by repetitive data, the
\&    library switches from the standard sorting algorithm to a fallback
\&    algorithm. The fallback is slower than the standard algorithm by
\&    perhaps a factor of three, but always behaves reasonably, no matter how
\&    bad the input.
\&
\&    Lower values of workFactor reduce the amount of effort the standard
\&    algorithm will expend before resorting to the fallback. You should set
\&    this parameter carefully; too low, and many inputs will be handled by
\&    the fallback algorithm and so compress rather slowly, too high, and
\&    your average\-to\-worst case compression times can become very large. The
\&    default value of 30 gives reasonable behaviour over a wide range of
\&    circumstances.
\&
\&    Allowable values range from 0 to 250 inclusive. 0 is a special case,
\&    equivalent to using the default value of 30.
.Ve
.Sp
Defaults to 0.
.ie n .SS "$status = $bz\->bzdeflate($input, $output);"
.el .SS "\f(CW$status\fP = \f(CW$bz\fP\->bzdeflate($input, \f(CW$output\fP);"
.IX Subsection "$status = $bz->bzdeflate($input, $output);"
Reads the contents of \f(CW$input\fR, compresses it and writes the compressed
data to \f(CW$output\fR.
.PP
Returns \f(CW\*(C`BZ_RUN_OK\*(C'\fR on success and a \f(CW\*(C`bzip2\*(C'\fR error code on failure.
.PP
If \f(CW\*(C`appendOutput\*(C'\fR is enabled in the constructor for the bzip2 object, the
compressed data will be appended to \f(CW$output\fR. If not enabled, \f(CW$output\fR
will be truncated before the compressed data is written to it.
.ie n .SS "$status = $bz\->bzflush($output);"
.el .SS "\f(CW$status\fP = \f(CW$bz\fP\->bzflush($output);"
.IX Subsection "$status = $bz->bzflush($output);"
Flushes any pending compressed data to \f(CW$output\fR.
.PP
Returns \f(CW\*(C`BZ_RUN_OK\*(C'\fR on success and a \f(CW\*(C`bzip2\*(C'\fR error code on failure.
.ie n .SS "$status = $bz\->bzclose($output);"
.el .SS "\f(CW$status\fP = \f(CW$bz\fP\->bzclose($output);"
.IX Subsection "$status = $bz->bzclose($output);"
Terminates the compressed data stream and flushes any pending compressed
data to \f(CW$output\fR.
.PP
Returns \f(CW\*(C`BZ_STREAM_END\*(C'\fR on success and a \f(CW\*(C`bzip2\*(C'\fR error code on failure.
.SS Example
.IX Subsection "Example"
.SH Uncompression
.IX Header "Uncompression"
.ie n .SS "($z, $status) = new Compress::Raw::Bunzip2 $appendOutput, $consumeInput, $small, $verbosity, $limitOutput;"
.el .SS "($z, \f(CW$status\fP) = new Compress::Raw::Bunzip2 \f(CW$appendOutput\fP, \f(CW$consumeInput\fP, \f(CW$small\fP, \f(CW$verbosity\fP, \f(CW$limitOutput\fP;"
.IX Subsection "($z, $status) = new Compress::Raw::Bunzip2 $appendOutput, $consumeInput, $small, $verbosity, $limitOutput;"
If successful, it will return the initialised uncompression object, \f(CW$z\fR
and a \f(CW$status\fR of \f(CW\*(C`BZ_OK\*(C'\fR in a list context. In scalar context it
returns the deflation object, \f(CW$z\fR, only.
.PP
If not successful, the returned uncompression object, \f(CW$z\fR, will be
\&\fIundef\fR and \f(CW$status\fR will hold the a \fIbzip2\fR error code.
.PP
Below is a list of the valid options:
.ie n .IP \fR\fB$appendOutput\fR\fB\fR 5
.el .IP \fR\f(CB$appendOutput\fR\fB\fR 5
.IX Item "$appendOutput"
Controls whether the compressed data is appended to the output buffer in the
\&\f(CW\*(C`bzinflate\*(C'\fR, \f(CW\*(C`bzflush\*(C'\fR and \f(CW\*(C`bzclose\*(C'\fR methods.
.Sp
Defaults to 1.
.ie n .IP \fR\fB$consumeInput\fR\fB\fR 5
.el .IP \fR\f(CB$consumeInput\fR\fB\fR 5
.IX Item "$consumeInput"
.PD 0
.ie n .IP \fR\fB$small\fR\fB\fR 5
.el .IP \fR\f(CB$small\fR\fB\fR 5
.IX Item "$small"
.PD
To quote the bzip2 documentation
.Sp
.Vb 4
\&    If small is nonzero, the library will use an alternative decompression
\&    algorithm which uses less memory but at the cost of decompressing more
\&    slowly (roughly speaking, half the speed, but the maximum memory
\&    requirement drops to around 2300k).
.Ve
.Sp
Defaults to 0.
.ie n .IP \fR\fB$limitOutput\fR\fB\fR 5
.el .IP \fR\f(CB$limitOutput\fR\fB\fR 5
.IX Item "$limitOutput"
The \f(CW\*(C`LimitOutput\*(C'\fR option changes the behavior of the \f(CW\*(C`$i\->bzinflate\*(C'\fR
method so that the amount of memory used by the output buffer can be
limited.
.Sp
When \f(CW\*(C`LimitOutput\*(C'\fR is used the size of the output buffer used will either
be the 16k or the amount of memory already allocated to \f(CW$output\fR,
whichever is larger. Predicting the output size available is tricky, so
don't rely on getting an exact output buffer size.
.Sp
When \f(CW\*(C`LimitOutout\*(C'\fR is not specified \f(CW\*(C`$i\->bzinflate\*(C'\fR will use as much
memory as it takes to write all the uncompressed data it creates by
uncompressing the input buffer.
.Sp
If \f(CW\*(C`LimitOutput\*(C'\fR is enabled, the \f(CW\*(C`ConsumeInput\*(C'\fR option will also be
enabled.
.Sp
This option defaults to false.
.ie n .IP \fR\fB$verbosity\fR\fB\fR 5
.el .IP \fR\f(CB$verbosity\fR\fB\fR 5
.IX Item "$verbosity"
This parameter is ignored.
.Sp
Defaults to 0.
.ie n .SS "$status = $z\->bzinflate($input, $output);"
.el .SS "\f(CW$status\fP = \f(CW$z\fP\->bzinflate($input, \f(CW$output\fP);"
.IX Subsection "$status = $z->bzinflate($input, $output);"
Uncompresses \f(CW$input\fR and writes the uncompressed data to \f(CW$output\fR.
.PP
Returns \f(CW\*(C`BZ_OK\*(C'\fR if the uncompression was successful, but the end of the
compressed data stream has not been reached. Returns \f(CW\*(C`BZ_STREAM_END\*(C'\fR on
successful uncompression and the end of the compression stream has been
reached.
.PP
If \f(CW\*(C`consumeInput\*(C'\fR is enabled in the constructor for the bunzip2 object,
\&\f(CW$input\fR will have all compressed data removed from it after
uncompression. On \f(CW\*(C`BZ_OK\*(C'\fR return this will mean that \f(CW$input\fR will be an
empty string; when \f(CW\*(C`BZ_STREAM_END\*(C'\fR \f(CW$input\fR will either be an empty
string or will contain whatever data immediately followed the compressed
data stream.
.PP
If \f(CW\*(C`appendOutput\*(C'\fR is enabled in the constructor for the bunzip2 object,
the uncompressed data will be appended to \f(CW$output\fR. If not enabled,
\&\f(CW$output\fR will be truncated before the uncompressed data is written to it.
.SH Misc
.IX Header "Misc"
.ie n .SS "my $version = \fBCompress::Raw::Bzip2::bzlibversion()\fP;"
.el .SS "my \f(CW$version\fP = \fBCompress::Raw::Bzip2::bzlibversion()\fP;"
.IX Subsection "my $version = Compress::Raw::Bzip2::bzlibversion();"
Returns the version of the underlying bzip2 library.
.SH Constants
.IX Header "Constants"
The following bzip2 constants are exported by this module
.PP
.Vb 3
\&                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
.Ve
.SH SUPPORT
.IX Header "SUPPORT"
General feedback/questions/bug reports should be sent to
<https://github.com/pmqs/Compress\-Raw\-Bzip2/issues> (preferred) or
<https://rt.cpan.org/Public/Dist/Display.html?Name=Compress\-Raw\-Bzip2>.
.SH "SEE ALSO"
.IX Header "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
.PP
IO::Compress::FAQ
.PP
File::GlobMapper, Archive::Zip,
Archive::Tar,
IO::Zlib
.PP
The primary site for the bzip2 program is <https://sourceware.org/bzip2/>.
.PP
See the module Compress::Bzip2
.SH AUTHOR
.IX Header "AUTHOR"
This module was written by Paul Marquess, \f(CW\*(C`pmqs@cpan.org\*(C'\fR.
.SH "MODIFICATION HISTORY"
.IX Header "MODIFICATION HISTORY"
See the Changes file.
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
Copyright (c) 2005\-2023 Paul Marquess. All rights reserved.
.PP
This program is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.