Ubuntu Manpage: Compress::Raw::Lzma - Low-Level Interface to lzma compression library

Provided by: libcompress-raw-lzma-perl_2.204-1_amd64

NAME

       Compress::Raw::Lzma - Low-Level Interface to lzma compression library

SYNOPSIS

           use Compress::Raw::Lzma ;

           # Encoders
           my ($lz, $status) = new Compress::Raw::Lzma::EasyEncoder [OPTS]
               or die "Cannot create lzma object: $status\n";

           my ($lz, $status) = new Compress::Raw::Lzma::AloneEncoder [OPTS]
               or die "Cannot create lzma object: $status\n";

           my ($lz, $status) = new Compress::Raw::Lzma::StreamEncoder [OPTS]
               or die "Cannot create lzma object: $status\n";

           my ($lz, $status) = new Compress::Raw::Lzma::RawEncoder [OPTS]
               or die "Cannot create lzma object: $status\n";

           $status = $lz->code($input, $output);
           $status = $lz->flush($output);

           # Decoders
           my ($lz, $status) = new Compress::Raw::Lzma::AloneDecoder [OPTS]
               or die "Cannot create bunzip2 object: $status\n";

           my ($lz, $status) = new Compress::Raw::Lzma::AutoDecoder [OPTS]
               or die "Cannot create bunzip2 object: $status\n";

           my ($lz, $status) = new Compress::Raw::Lzma::StreamDecoder [OPTS]
               or die "Cannot create bunzip2 object: $status\n";

           my ($lz, $status) = new Compress::Raw::Lzma::RawDecoder [OPTS]
               or die "Cannot create bunzip2 object: $status\n";

           $status = $lz->code($input, $output);

           my $version = Compress::Raw::Lzma::lzma_version_number();
           my $version = Compress::Raw::Lzma::lzma_version_string();

DESCRIPTION

       "Compress::Raw::Lzma" provides an interface to the in-memory compression/uncompression
       functions from the lzma compression library.

       Although the primary purpose for the existence of "Compress::Raw::Lzma" is for use by the
       "IO::Compress::Lzma", "IO::Uncompress::UnLzma", "IO::Compress::Xz" and
       "IO::Uncompress::UnXz" modules, it can be used on its own for simple
       compression/uncompression tasks.

       There are two functions, called "code" and "flush", used in all the compression and
       uncompression interfaces defined in this module. By default both of these functions
       overwrites any data stored in its output buffer parameter. If you want to
       compress/uncompress to a single buffer, and have "code" and "flush" append to that buffer,
       enable the "AppendOutput" option when you create the compression/decompression object.

Compression

There are four compression interfaces available in this module.

Compress::Raw::Lzma::EasyEncoder =item Compress::Raw::Lzma::AloneEncoder =item
Compress::Raw::Lzma::StreamEncoder =item Compress::Raw::Lzma::RawEncoder

($z, $status) = new Compress::Raw::Lzma::EasyEncoder [OPTS];
Creates a new xz compression object.

If successful, it will return the initialised compression object, $z and a $status of
"LZMA_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 an lzma error code.

Below is a list of the valid options:

Preset => $preset
Used to choose the compression preset.

Valid values are 0-9 and "LZMA_PRESET_DEFAULT".

0 is the fastest compression with the lowest memory usage and the lowest compression.

9 is the slowest compression with the highest memory usage but with the best
compression.

Defaults to "LZMA_PRESET_DEFAULT".

Extreme => 0|1
Makes the compression a lot slower, but a small compression gain.

Defaults to 0.

Check => $check
Used to specify the integrity check used in the xz data stream. Valid values are
"LZMA_CHECK_NONE", "LZMA_CHECK_CRC32", "LZMA_CHECK_CRC64", "LZMA_CHECK_SHA256".

Defaults to "LZMA_CHECK_CRC32".

AppendOutput => 0|1
Controls whether the compressed data is appended to the output buffer in the "code"
and "flush" methods.

Defaults to 0. (Note in versions of this module prior to 2.072 the default value was
incorrectly documented as 1).

BufSize => $number
Sets the initial size for the output buffer used by the "$d->code" method. If the
buffer has to be reallocated to increase the size, it will grow in increments of
"Bufsize".

Defaults to 16k.

($z, $status) = new Compress::Raw::Lzma::AloneEncoder [OPTS];
Creates a legacy lzma compression object. This format is also know as lzma_alone.

If successful, it will return the initialised compression object, $z and a $status of
"LZMA_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 an lzma error code.

Below is a list of the valid options:

Filter => $filter
The $filter option must be an object of type "Lzma::Filter::Lzma1". See
"Lzma::Filter::Lzma" in Compress::Raw::Lzma for a definition of
"Lzma::Filter::Lzma1".

If this option is not present an "Lzma::Filter::Lzma1" object with default values
will be used.

AppendOutput => 0|1
Controls whether the compressed data is appended to the output buffer in the "code"
and "flush" methods.

Defaults to 0. (Note in versions of this module prior to 2.072 the default value was
incorrectly documented as 1).

BufSize => $number
Sets the initial size for the output buffer used by the "$d->code" method. If the
buffer has to be reallocated to increase the size, it will grow in increments of
"Bufsize".

Defaults to 16k.

($z, $status) = new Compress::Raw::Lzma::StreamEncoder [OPTS];
Creates a xz compression object.

If successful, it will return the initialised compression object, $z and a $status of
"LZMA_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 an lzma error code.

Below is a list of the valid options:

Filter => $filter =item Filter => [$filter1, $filter2,...]
This option is used to change the bahaviour of the StreamEncoder by applying between
one and "LZMA_FILTERS_MAX" filters to the data stream during compression. See
"Filters" for more details on the available filters.

If this option is present it must either contain a single "Lzma::Filter::Lzma" filter
object or an array reference containing between one and "LZMA_FILTERS_MAX" filter
objects.

If this option is not present an "Lzma::Filter::Lzma2" object with default values
will be used.

Check => $check
Used to specify the integrity check used in the xz data stream. Valid values are
"LZMA_CHECK_NONE", "LZMA_CHECK_CRC32", "LZMA_CHECK_CRC64", "LZMA_CHECK_SHA256".

Defaults to "LZMA_CHECK_CRC32".

AppendOutput => 0|1
Controls whether the compressed data is appended to the output buffer in the "code"
and "flush" methods.

Defaults to 0. (Note in versions of this module prior to 2.072 the default value was
incorrectly documented as 1).

BufSize => $number
Sets the initial size for the output buffer used by the "$d->code" method. If the
buffer has to be reallocated to increase the size, it will grow in increments of
"Bufsize".

Defaults to 16k.

($z, $status) = new Compress::Raw::Lzma::RawEncoder [OPTS];
Low level access to lzma.

If successful, it will return the initialised compression object, $z and a $status of
"LZMA_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 an lzma error code.

Below is a list of the valid options:

Filter => $filter =item Filter => [$filter1, $filter2,...]
This option is used to change the bahaviour of the RawEncoder by applying between one
and "LZMA_FILTERS_MAX" filters to the data stream during compression. See "Filters"
for more details on the available filters.

If this option is present it must either contain a single "Lzma::Filter::Lzma" filter
object or an array reference containing between one and "LZMA_FILTERS_MAX" filter
objects.

If this option is not present an "Lzma::Filter::Lzma2" object with default values
will be used.

AppendOutput => 0|1
Controls whether the compressed data is appended to the output buffer in the "code"
and "flush" methods.

Defaults to 0. (Note in versions of this module prior to 2.072 the default value was
incorrectly documented as 1).

BufSize => $number
Sets the initial size for the output buffer used by the "$d->code" method. If the
buffer has to be reallocated to increase the size, it will grow in increments of
"Bufsize".

Defaults to 16k.

ForZip => 1/0
This boolean option is used to enable prefixing the compressed data stream with an
encoded copy of the filter properties.

Defaults to 0.

$status = $lz->code($input, $output);
Reads the contents of $input, compresses it and writes the compressed data to $output.

Returns "LZMA_OK" on success and an "lzma" error code on failure.

If "appendOutput" is enabled in the constructor for the lzma object, the compressed data
will be appended to $output. If not enabled, $output will be truncated before the
compressed data is written to it.

$status = $lz->flush($output, LZMA_FINISH);
Flushes any pending compressed data to $output. By default it terminates the compressed
data stream.

Returns "LZMA_OK" on success and an "lzma" error code on failure.

Example
TODO

Uncompression

There are four uncompression interfaces available in this module.

Compress::Raw::Lzma::AutoDecoder =item Compress::Raw::Lzma::AloneDecoder =item
Compress::Raw::Lzma::StreamDecoder =item Compress::Raw::Lzma::RawDecoder

($z, $status) = new Compress::Raw::Lzma::AutoDecoder [OPTS] ;
Create an object that can uncompress any of the compressed data streams that can be
created by this module.

If successful, it will return the initialised uncompression object, $z and a $status of
"LZMA_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 an lzma error code.

Below is a list of the valid options:

-MemLimit
The number of bytes to use when uncompressing.

Default is unlimited.

-Bufsize
Sets the initial size for the output buffer used by the "$i->code" method. If the
output buffer in this method has to be reallocated to increase the size, it will grow
in increments of "Bufsize".

Default is 16k.

-AppendOutput
This option controls how data is written to the output buffer by the "$i->code"
method.

If the option is set to false, the output buffer in the "$i->code" method will be
truncated before uncompressed data is written to it.

If the option is set to true, uncompressed data will be appended to the output buffer
by the "$i->code" method.

This option defaults to false.

-ConsumeInput
If set to true, this option will remove compressed data from the input buffer of the
"$i->code" method as the uncompression progresses.

This option can be useful when you are processing compressed data that is embedded in
another file/buffer. In this case the data that immediately follows the compressed
stream will be left in the input buffer.

This option defaults to true.

-LimitOutput
The "LimitOutput" option changes the behavior of the "$i->code" 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
value of the "Bufsize" option 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->code" 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.

See "The LimitOutput option" for a discussion on why "LimitOutput" is needed and how
to use it.

($z, $status) = new Compress::Raw::Lzma::AloneDecoder [OPTS] ;
Create an object that can uncompress an lzma_alone data stream.

If successful, it will return the initialised uncompression object, $z and a $status of
"LZMA_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 an lzma error code.

Below is a list of the valid options:

-MemLimit
The number of bytes to use when uncompressing.

Default is unlimited.

Default is 16k.

-AppendOutput
This option controls how data is written to the output buffer by the "$i->code"
method.

If the option is set to false, the output buffer in the "$i->code" method will be
truncated before uncompressed data is written to it.

If the option is set to true, uncompressed data will be appended to the output buffer
by the "$i->code" method.

This option defaults to false.

-ConsumeInput
If set to true, this option will remove compressed data from the input buffer of the
"$i->code" method as the uncompression progresses.

This option defaults to true.

-LimitOutput
The "LimitOutput" option changes the behavior of the "$i->code" method so that the
amount of memory used by the output buffer can be limited.

When "LimitOutout" is not specified "$i->code" 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.

See "The LimitOutput option" for a discussion on why "LimitOutput" is needed and how
to use it.

$status = $z->code($input, $output);
Uncompresses $input and writes the uncompressed data to $output.

Returns "LZMA_OK" if the uncompression was successful, but the end of the compressed data
stream has not been reached. Returns "LZMA_STREAM_END" on successful uncompression and the
end of the compression stream has been reached.

If "consumeInput" is enabled in the constructor for the lzma object, $input will have all
compressed data removed from it after uncompression. On "LZMA_OK" return this will mean
that $input will be an empty string; when "LZMA_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 lzma object, the uncompressed data
will be appended to $output. If not enabled, $output will be truncated before the
uncompressed data is written to it.

Filters

TODO - more here

A number of the Lzma compression interfaces (namely "Compress::Raw::Lzma::StreamEncoder" &
"Compress::Raw::Lzma::AloneEncoder") and the raw lzma uncompression interface make use of
filters. These filters are used to change the behaviour of compression (and raw
uncompression).

All Lzma Filters are sub-classed from the "Lzma::Filter" base-class.

Lzma::Filter::Lzma
The "Lzma::Filter::Lzma" class is used to... TODO - more here

There are two subclasses of "Lzma::Filter::Lzma", namely "Lzma::Filter::Lzma1" and
"Lzma::Filter::Lzma2".

The former is typically used with "Compress::Raw::Lzma::AloneEncoder". The latter with
"Compress::Raw::Lzma::StreamEncoder".

When using Lzma filters an "Lzma::Filter::Lzma" must be included and it must be the last
filter in the chain. There can only be one "Lzma::Filter::Lzma" filter in any filter
chain.

The "Lzma::Filter::Lzma" construction takes the following options.

DictSize => $value
Dictionary size in bytes. This controls how many bytes of the recently processed
uncompressed data is kept in memory. The size of the dictionary must be at least
"LZMA_DICT_SIZE_MIN".

Defaults to "LZMA_DICT_SIZE_DEFAULT".

PresetDict => $dict
Provide an initial dictionary. This value is used to initialize the LZ77 history
window.

This feature only works correctly with raw encoding and decoding. You may not be
able to decode other formats that have been encoded with a preset dictionary.

$dict should contain typical strings that occur in the files being compressed, with
the most probably strings near the end fo the preset dictionary.

If $dict is larger than "DictSize", only the last "DictSize" bytes are processed.

Lc => $value
Number of literal context bits.

How many of the highest bits of the previous uncompressed eight-bit byte (also known
as `literal') are taken into account when predicting the bits of the next literal.

$value must be a number between "LZMA_LCLP_MIN" and "LZMA_LCLP_MAX".

Note the sum of the "Lc" and "Lp" options cannot exceed 4.

Defaults to "LZMA_LC_DEFAULT".

Lp => $value
Number of literal position bits.

How many of the lowest bits of the current position (number of bytes from the
beginning of the uncompressed data) in the uncompressed data is taken into account
when predicting the bits of the next literal (a single eight-bit byte).

Defaults to "LZMA_LP_DEFAULT".

Pb => $value
Number of position bits

How many of the lowest bits of the current position in the uncompressed data is taken
into account when estimating probabilities of matches. A match is a sequence of bytes
for which a matching sequence is found from the dictionary and thus can be stored as
distance-length pair.

$value must be a number between "LZMA_PB_MIN" and "LZMA_PB_MAX".

Defaults to "LZMA_PB_DEFAULT".

Mode => $value
The Compression Mode. Valid values are "LZMA_MODE_FAST" and "LZMA_MODE_NORMAL".

Defaults to "LZMA_MODE_NORMAL".

Nice => $value
Nice length of a match

Defaults to 64.

Mf => $value
Defines which Match Finder to use. Valid values are "LZMA_MF_HC3" "LZMA_MF_HC4",
"LZMA_MF_BT2" "LZMA_MF_BT3" and "LZMA_MF_BT4".

Defaults to "LZMA_MF_BT4".

Depth => $value
Maximum search depth in the match finder.

Defaults to 0.

Lzma::Filter::BCJ
The sub-classes of "Lzma::Filter::BCJ" are the Branch/Call/Jump conversion filters. These
filters are used to rewrite executable binary code for a number of processor
architectures. None of these classes take any options.

Lzma::Filter::X86
Filter for x86 binaries.

Lzma::Filter::PowerPC
Filter for Big endian PowerPC binaries.

Lzma::Filter::IA64
Filter for IA64 (Itanium) binaries.

Lzma::Filter::ARM
Filter for ARM binaries.

Lzma::Filter::ARMThumb
Filter for ARMThumb binaries.

Lzma::Filter::Sparc
Filter for Sparc binaries.

Lzma::Filter::Delta
Usage is

Lzma::Filter::Delta [OPTS]

Type => $type
Defines the type of Delta calculation. The only available type (and therefore the
default) is "LZMA_DELTA_TYPE_BYTE",

Distance => $value
Defines the Delta Distance. $value must be a number between "LZMA_DELTA_DIST_MIN" and
"LZMA_DELTA_DIST_MAX".

Default is "LZMA_DELTA_DIST_MIN".

Misc

   my $version = Compress::Raw::Lzma::lzma_version_number();
       Returns the version of the underlying lzma library this module is using at run-time as a
       number.

   my $version = Compress::Raw::Lzma::lzma_version_string();
       Returns the version of the underlying lzma library this module is using at run-time as a
       string.

   my $version = Compress::Raw::Lzma::LZMA_VERSION();
       Returns the version of the underlying lzma library this module was using at compile-time
       as a number.

   my $version = Compress::Raw::Lzma::LZMA_VERSION_STRING();
       Returns the version of the underlying lzma library this module was using at compile-time
       as a string.

Constants

       The following lzma constants are exported by this module

       TODO - more here

SUPPORT

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

AUTHOR

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

MODIFICATION HISTORY

       See the Changes file.

COPYRIGHT AND LICENSE

       Copyright (c) 2005-2023 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.

NAME

SYNOPSIS

DESCRIPTION

Compression

Uncompression

Filters

Misc

Constants

SUPPORT

SEE ALSO

AUTHOR

MODIFICATION HISTORY

COPYRIGHT AND LICENSE