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IO::Uncompress::UnLzopUser Contributed Perl DocumentaIO::Uncompress::UnLzop(3)

NAME
       IO::Uncompress::UnLzop -	Read lzop files/buffers

SYNOPSIS
	   use IO::Uncompress::UnLzop qw(unlzop	$UnLzopError) ;

	   my $status =	unlzop $input => $output [,OPTS]
	       or die "unlzop failed: $UnLzopError\n";

	   my $z = new IO::Uncompress::UnLzop $input [OPTS]
	       or die "unlzop failed: $UnLzopError\n";

	   $status = $z->read($buffer)
	   $status = $z->read($buffer, $length)
	   $status = $z->read($buffer, $length,	$offset)
	   $line = $z->getline()
	   $char = $z->getc()
	   $char = $z->ungetc()
	   $char = $z->opened()

	   $data = $z->trailingData()
	   $status = $z->nextStream()
	   $data = $z->getHeaderInfo()
	   $z->tell()
	   $z->seek($position, $whence)
	   $z->binmode()
	   $z->fileno()
	   $z->eof()
	   $z->close()

	   $UnLzopError	;

	   # IO::File mode

	   <$z>
	   read($z, $buffer);
	   read($z, $buffer, $length);
	   read($z, $buffer, $length, $offset);
	   tell($z)
	   seek($z, $position, $whence)
	   binmode($z)
	   fileno($z)
	   eof($z)
	   close($z)

DESCRIPTION
       This module provides a Perl interface that allows the reading of	lzo
       files/buffers.

       For writing lzop	files/buffers, see the companion module
       IO::Compress::Lzop.

Functional Interface
       A top-level function, "unlzop", is provided to carry out	"one-shot"
       uncompression between buffers and/or files. For finer control over the
       uncompression process, see the "OO Interface" section.

	   use IO::Uncompress::UnLzop qw(unlzop	$UnLzopError) ;

	   unlzop $input_filename_or_reference => $output_filename_or_reference	[,OPTS]
	       or die "unlzop failed: $UnLzopError\n";

       The functional interface	needs Perl5.005	or better.

   unlzop $input_filename_or_reference => $output_filename_or_reference	[,
       OPTS]
       "unlzop"	expects	at least two parameters, $input_filename_or_reference
       and $output_filename_or_reference and zero or more optional parameters
       (see "Optional Parameters")

       The $input_filename_or_reference	parameter

       The parameter, $input_filename_or_reference, is used to define the
       source of the compressed	data.

       It can take one of the following	forms:

       A filename
	    If the $input_filename_or_reference	parameter is a simple scalar,
	    it is assumed to be	a filename. This file will be opened for
	    reading and	the input data will be read from it.

       A filehandle
	    If the $input_filename_or_reference	parameter is a filehandle, the
	    input data will be read from it.  The string '-' can be used as an
	    alias for standard input.

       A scalar	reference
	    If $input_filename_or_reference is a scalar	reference, the input
	    data will be read from $$input_filename_or_reference.

       An array	reference
	    If $input_filename_or_reference is an array	reference, each
	    element in the array must be a filename.

	    The	input data will	be read	from each file in turn.

	    The	complete array will be walked to ensure	that it	only contains
	    valid filenames before any data is uncompressed.

       An Input	FileGlob string
	    If $input_filename_or_reference is a string	that is	delimited by
	    the	characters "<" and ">" "unlzop"	will assume that it is an
	    input fileglob string. The input is	the list of files that match
	    the	fileglob.

	    See	File::GlobMapper for more details.

       If the $input_filename_or_reference parameter is	any other type,
       "undef" will be returned.

       The $output_filename_or_reference parameter

       The parameter $output_filename_or_reference is used to control the
       destination of the uncompressed data. This parameter can	take one of
       these forms.

       A filename
	    If the $output_filename_or_reference parameter is a	simple scalar,
	    it is assumed to be	a filename.  This file will be opened for
	    writing and	the uncompressed data will be written to it.

       A filehandle
	    If the $output_filename_or_reference parameter is a	filehandle,
	    the	uncompressed data will be written to it.  The string '-' can
	    be used as an alias	for standard output.

       A scalar	reference
	    If $output_filename_or_reference is	a scalar reference, the
	    uncompressed data will be stored in
	    $$output_filename_or_reference.

       An Array	Reference
	    If $output_filename_or_reference is	an array reference, the
	    uncompressed data will be pushed onto the array.

       An Output FileGlob
	    If $output_filename_or_reference is	a string that is delimited by
	    the	characters "<" and ">" "unlzop"	will assume that it is an
	    output fileglob string. The	output is the list of files that match
	    the	fileglob.

	    When $output_filename_or_reference is an fileglob string,
	    $input_filename_or_reference must also be a	fileglob string.
	    Anything else is an	error.

	    See	File::GlobMapper for more details.

       If the $output_filename_or_reference parameter is any other type,
       "undef" will be returned.

   Notes
       When $input_filename_or_reference maps to multiple compressed
       files/buffers and $output_filename_or_reference is a single
       file/buffer, after uncompression	$output_filename_or_reference will
       contain a concatenation of all the uncompressed data from each of the
       input files/buffers.

   Optional Parameters
       The optional parameters for the one-shot	function "unlzop" are (for the
       most part) identical to those used with the OO interface	defined	in the
       "Constructor Options" section. The exceptions are listed	below

       "AutoClose => 0|1"
	    This option	applies	to any input or	output data streams to
	    "unlzop" that are filehandles.

	    If "AutoClose" is specified, and the value is true,	it will	result
	    in all input and/or	output filehandles being closed	once "unlzop"
	    has	completed.

	    This parameter defaults to 0.

       "BinModeOut => 0|1"
	    This option	is now a no-op.	All files will be written  in binmode.

       "Append => 0|1"
	    The	behaviour of this option is dependent on the type of output
	    data stream.

	    o	 A Buffer

		 If "Append" is	enabled, all uncompressed data will be append
		 to the	end of the output buffer. Otherwise the	output buffer
		 will be cleared before	any uncompressed data is written to
		 it.

	    o	 A Filename

		 If "Append" is	enabled, the file will be opened in append
		 mode. Otherwise the contents of the file, if any, will	be
		 truncated before any uncompressed data	is written to it.

	    o	 A Filehandle

		 If "Append" is	enabled, the filehandle	will be	positioned to
		 the end of the	file via a call	to "seek" before any
		 uncompressed data is written to it.  Otherwise	the file
		 pointer will not be moved.

	    When "Append" is specified,	and set	to true, it will append	all
	    uncompressed data to the output data stream.

	    So when the	output is a filehandle it will carry out a seek	to the
	    eof	before writing any uncompressed	data. If the output is a
	    filename, it will be opened	for appending. If the output is	a
	    buffer, all	uncompressed data will be appended to the existing
	    buffer.

	    Conversely when "Append" is	not specified, or it is	present	and is
	    set	to false, it will operate as follows.

	    When the output is a filename, it will truncate the	contents of
	    the	file before writing any	uncompressed data. If the output is a
	    filehandle its position will not be	changed. If the	output is a
	    buffer, it will be wiped before any	uncompressed data is output.

	    Defaults to	0.

       "MultiStream => 0|1"
	    If the input file/buffer contains multiple compressed data
	    streams, this option will uncompress the whole lot as a single
	    data stream.

	    Defaults to	0.

       "TrailingData =>	$scalar"
	    Returns the	data, if any, that is present immediately after	the
	    compressed data stream once	uncompression is complete.

	    This option	can be used when there is useful information
	    immediately	following the compressed data stream, and you don't
	    know the length of the compressed data stream.

	    If the input is a buffer, "trailingData" will return everything
	    from the end of the	compressed data	stream to the end of the
	    buffer.

	    If the input is a filehandle, "trailingData" will return the data
	    that is left in the	filehandle input buffer	once the end of	the
	    compressed data stream has been reached. You can then use the
	    filehandle to read the rest	of the input file.

	    Don't bother using "trailingData" if the input is a	filename.

	    If you know	the length of the compressed data stream before	you
	    start uncompressing, you can avoid having to use "trailingData" by
	    setting the	"InputLength" option.

   Examples
       To read the contents of the file	"file1.txt.lzo"	and write the
       uncompressed data to the	file "file1.txt".

	   use strict ;
	   use warnings	;
	   use IO::Uncompress::UnLzop qw(unlzop	$UnLzopError) ;

	   my $input = "file1.txt.lzo";
	   my $output =	"file1.txt";
	   unlzop $input => $output
	       or die "unlzop failed: $UnLzopError\n";

       To read from an existing	Perl filehandle, $input, and write the
       uncompressed data to a buffer, $buffer.

	   use strict ;
	   use warnings	;
	   use IO::Uncompress::UnLzop qw(unlzop	$UnLzopError) ;
	   use IO::File	;

	   my $input = new IO::File "<file1.txt.lzo"
	       or die "Cannot open 'file1.txt.lzo': $!\n" ;
	   my $buffer ;
	   unlzop $input => \$buffer
	       or die "unlzop failed: $UnLzopError\n";

       To uncompress all files in the directory	"/my/home" that	match
       "*.txt.lzo" and store the compressed data in the	same directory

	   use strict ;
	   use warnings	;
	   use IO::Uncompress::UnLzop qw(unlzop	$UnLzopError) ;

	   unlzop '</my/home/*.txt.lzo>' => '</my/home/#1.txt>'
	       or die "unlzop failed: $UnLzopError\n";

       and if you want to compress each	file one at a time, this will do the
       trick

	   use strict ;
	   use warnings	;
	   use IO::Uncompress::UnLzop qw(unlzop	$UnLzopError) ;

	   for my $input ( glob	"/my/home/*.txt.lzo" )
	   {
	       my $output = $input;
	       $output =~ s/.lzo// ;
	       unlzop $input =>	$output
		   or die "Error compressing '$input': $UnLzopError\n";
	   }

OO Interface
   Constructor
       The format of the constructor for IO::Uncompress::UnLzop	is shown below

	   my $z = new IO::Uncompress::UnLzop $input [OPTS]
	       or die "IO::Uncompress::UnLzop failed: $UnLzopError\n";

       Returns an "IO::Uncompress::UnLzop" object on success and undef on
       failure.	 The variable $UnLzopError will	contain	an error message on
       failure.

       If you are running Perl 5.005 or	better the object, $z, returned	from
       IO::Uncompress::UnLzop can be used exactly like an IO::File filehandle.
       This means that all normal input	file operations	can be carried out
       with $z.	 For example, to read a	line from a compressed file/buffer you
       can use either of these forms

	   $line = $z->getline();
	   $line = <$z>;

       The mandatory parameter $input is used to determine the source of the
       compressed data.	This parameter can take	one of three forms.

       A filename
	    If the $input parameter is a scalar, it is assumed to be a
	    filename. This file	will be	opened for reading and the compressed
	    data will be read from it.

       A filehandle
	    If the $input parameter is a filehandle, the compressed data will
	    be read from it.  The string '-' can be used as an alias for
	    standard input.

       A scalar	reference
	    If $input is a scalar reference, the compressed data will be read
	    from $$input.

   Constructor Options
       The option names	defined	below are case insensitive and can be
       optionally prefixed by a	'-'.  So all of	the following are valid

	   -AutoClose
	   -autoclose
	   AUTOCLOSE
	   autoclose

       OPTS is a combination of	the following options:

       "AutoClose => 0|1"
	    This option	is only	valid when the $input parameter	is a
	    filehandle.	If specified, and the value is true, it	will result in
	    the	file being closed once either the "close" method is called or
	    the	IO::Uncompress::UnLzop object is destroyed.

	    This parameter defaults to 0.

       "MultiStream => 0|1"
	    Treats the complete	lzop file/buffer as a single compressed	data
	    stream. When reading in multi-stream mode each member of the lzop
	    file/buffer	will be	uncompressed in	turn until the end of the
	    file/buffer	is encountered.

	    This parameter defaults to 0.

       "Prime => $string"
	    This option	will uncompress	the contents of	$string	before
	    processing the input file/buffer.

	    This option	can be useful when the compressed data is embedded in
	    another file/data structure	and it is not possible to work out
	    where the compressed data begins without having to read the	first
	    few	bytes. If this is the case, the	uncompression can be primed
	    with these bytes using this	option.

       "Transparent => 0|1"
	    If this option is set and the input	file/buffer is not compressed
	    data, the module will allow	reading	of it anyway.

	    In addition, if the	input file/buffer does contain compressed data
	    and	there is non-compressed	data immediately following it, setting
	    this option	will make this module treat the	whole file/buffer as a
	    single data	stream.

	    This option	defaults to 1.

       "BlockSize => $num"
	    When reading the compressed	input data, IO::Uncompress::UnLzop
	    will read it in blocks of $num bytes.

	    This option	defaults to 4096.

       "InputLength => $size"
	    When present this option will limit	the number of compressed bytes
	    read from the input	file/buffer to $size. This option can be used
	    in the situation where there is useful data	directly after the
	    compressed data stream and you know	beforehand the exact length of
	    the	compressed data	stream.

	    This option	is mostly used when reading from a filehandle, in
	    which case the file	pointer	will be	left pointing to the first
	    byte directly after	the compressed data stream.

	    This option	defaults to off.

       "Append => 0|1"
	    This option	controls what the "read" method	does with uncompressed
	    data.

	    If set to 1, all uncompressed data will be appended	to the output
	    parameter of the "read" method.

	    If set to 0, the contents of the output parameter of the "read"
	    method will	be overwritten by the uncompressed data.

	    Defaults to	0.

       "Strict => 0|1"
	    This option	controls whether the extra checks defined below	are
	    used when carrying out the decompression. When Strict is on, the
	    extra tests	are carried out, when Strict is	off they are not.

	    The	default	for this option	is off.

   Examples
       TODO

Methods
   read
       Usage is

	   $status = $z->read($buffer)

       Reads a block of	compressed data	(the size of the compressed block is
       determined by the "Buffer" option in the	constructor), uncompresses it
       and writes any uncompressed data	into $buffer. If the "Append"
       parameter is set	in the constructor, the	uncompressed data will be
       appended	to the $buffer parameter. Otherwise $buffer will be
       overwritten.

       Returns the number of uncompressed bytes	written	to $buffer, zero if
       eof or a	negative number	on error.

   read
       Usage is

	   $status = $z->read($buffer, $length)
	   $status = $z->read($buffer, $length,	$offset)

	   $status = read($z, $buffer, $length)
	   $status = read($z, $buffer, $length,	$offset)

       Attempt to read $length bytes of	uncompressed data into $buffer.

       The main	difference between this	form of	the "read" method and the
       previous	one, is	that this one will attempt to return exactly $length
       bytes. The only circumstances that this function	will not is if end-of-
       file or an IO error is encountered.

       Returns the number of uncompressed bytes	written	to $buffer, zero if
       eof or a	negative number	on error.

   getline
       Usage is

	   $line = $z->getline()
	   $line = <$z>

       Reads a single line.

       This method fully supports the use of the variable $/ (or
       $INPUT_RECORD_SEPARATOR or $RS when "English" is	in use)	to determine
       what constitutes	an end of line.	Paragraph mode,	record mode and	file
       slurp mode are all supported.

   getc
       Usage is

	   $char = $z->getc()

       Read a single character.

   ungetc
       Usage is

	   $char = $z->ungetc($string)

   getHeaderInfo
       Usage is

	   $hdr	 = $z->getHeaderInfo();
	   @hdrs = $z->getHeaderInfo();

       This method returns either a hash reference (in scalar context) or a
       list or hash references (in array context) that contains	information
       about each of the header	fields in the compressed data stream(s).

   tell
       Usage is

	   $z->tell()
	   tell	$z

       Returns the uncompressed	file offset.

   eof
       Usage is

	   $z->eof();
	   eof($z);

       Returns true if the end of the compressed input stream has been
       reached.

   seek
	   $z->seek($position, $whence);
	   seek($z, $position, $whence);

       Provides	a sub-set of the "seek"	functionality, with the	restriction
       that it is only legal to	seek forward in	the input file/buffer.	It is
       a fatal error to	attempt	to seek	backward.

       Note that the implementation of "seek" in this module does not provide
       true random access to a compressed file/buffer. It  works by
       uncompressing data from the current offset in the file/buffer until it
       reaches the uncompressed	offset specified in the	parameters to "seek".
       For very	small files this may be	acceptable behaviour. For large	files
       it may cause an unacceptable delay.

       The $whence parameter takes one the usual values, namely	SEEK_SET,
       SEEK_CUR	or SEEK_END.

       Returns 1 on success, 0 on failure.

   binmode
       Usage is

	   $z->binmode
	   binmode $z ;

       This is a noop provided for completeness.

   opened
	   $z->opened()

       Returns true if the object currently refers to a	opened file/buffer.

   autoflush
	   my $prev = $z->autoflush()
	   my $prev = $z->autoflush(EXPR)

       If the $z object	is associated with a file or a filehandle, this	method
       returns the current autoflush setting for the underlying	filehandle. If
       "EXPR" is present, and is non-zero, it will enable flushing after every
       write/print operation.

       If $z is	associated with	a buffer, this method has no effect and	always
       returns "undef".

       Note that the special variable $| cannot	be used	to set or retrieve the
       autoflush setting.

   input_line_number
	   $z->input_line_number()
	   $z->input_line_number(EXPR)

       Returns the current uncompressed	line number. If	"EXPR" is present it
       has the effect of setting the line number. Note that setting the	line
       number does not change the current position within the file/buffer
       being read.

       The contents of $/ are used to determine	what constitutes a line
       terminator.

   fileno
	   $z->fileno()
	   fileno($z)

       If the $z object	is associated with a file or a filehandle, "fileno"
       will return the underlying file descriptor. Once	the "close" method is
       called "fileno" will return "undef".

       If the $z object	is associated with a buffer, this method will return
       "undef".

   close
	   $z->close() ;
	   close $z ;

       Closes the output file/buffer.

       For most	versions of Perl this method will be automatically invoked if
       the IO::Uncompress::UnLzop object is destroyed (either explicitly or by
       the variable with the reference to the object going out of scope). The
       exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In	these
       cases, the "close" method will be called	automatically, but not until
       global destruction of all live objects when the program is terminating.

       Therefore, if you want your scripts to be able to run on	all versions
       of Perl,	you should call	"close"	explicitly and not rely	on automatic
       closing.

       Returns true on success,	otherwise 0.

       If the "AutoClose" option has been enabled when the
       IO::Uncompress::UnLzop object was created, and the object is associated
       with a file, the	underlying file	will also be closed.

   nextStream
       Usage is

	   my $status =	$z->nextStream();

       Skips to	the next compressed data stream	in the input file/buffer. If a
       new compressed data stream is found, the	eof marker will	be cleared and
       $.  will	be reset to 0.

       Returns 1 if a new stream was found, 0 if none was found, and -1	if an
       error was encountered.

   trailingData
       Usage is

	   my $data = $z->trailingData();

       Returns the data, if any, that is present immediately after the
       compressed data stream once uncompression is complete. It only makes
       sense to	call this method once the end of the compressed	data stream
       has been	encountered.

       This option can be used when there is useful information	immediately
       following the compressed	data stream, and you don't know	the length of
       the compressed data stream.

       If the input is a buffer, "trailingData"	will return everything from
       the end of the compressed data stream to	the end	of the buffer.

       If the input is a filehandle, "trailingData" will return	the data that
       is left in the filehandle input buffer once the end of the compressed
       data stream has been reached. You can then use the filehandle to	read
       the rest	of the input file.

       Don't bother using "trailingData" if the	input is a filename.

       If you know the length of the compressed	data stream before you start
       uncompressing, you can avoid having to use "trailingData" by setting
       the "InputLength" option	in the constructor.

Importing
       No symbolic constants are required by IO::Uncompress::UnLzop at
       present.

       :all Imports "unlzop" and $UnLzopError.	Same as	doing this

		use IO::Uncompress::UnLzop qw(unlzop $UnLzopError) ;

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

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::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

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

MODIFICATION HISTORY
       See the Changes file.

COPYRIGHT AND LICENSE
       Copyright (c) 2005-2020 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 v5.32.0			  2020-07-31	     IO::Uncompress::UnLzop(3)

NAME | SYNOPSIS | DESCRIPTION | Functional Interface | OO Interface | Methods | Importing | EXAMPLES | SUPPORT | SEE ALSO | AUTHOR | MODIFICATION HISTORY | COPYRIGHT AND LICENSE

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