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IO::Uncompress::Bunzip2(3)     User Contributed Perl Documentation     IO::Uncompress::Bunzip2(3)

NAME
       IO::Uncompress::Bunzip2 - Read bzip2 files/buffers

SYNOPSIS
	   use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;

	   my $status = bunzip2 $input => $output [,OPTS]
	       or die "bunzip2 failed: $Bunzip2Error\n";

	   my $z = new IO::Uncompress::Bunzip2 $input [OPTS]
	       or die "bunzip2 failed: $Bunzip2Error\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()

	   $Bunzip2Error ;

	   # 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 bzip2 files/buffers.

       For writing bzip2 files/buffers, see the companion module IO::Compress::Bzip2.

Functional Interface
       A top-level function, "bunzip2", 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::Bunzip2 qw(bunzip2 $Bunzip2Error) ;

	   bunzip2 $input => $output [,OPTS]
	       or die "bunzip2 failed: $Bunzip2Error\n";

       The functional interface needs Perl5.005 or better.

   bunzip2 $input => $output [, OPTS]
       "bunzip2" expects at least two parameters, $input and $output.

       The $input parameter

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

       It can take one of the following forms:

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

       An array reference
	    If $input 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 is a string that is delimited by the characters "<" and ">" "bunzip2" will
	    assume that it is an input fileglob string. The input is the list of files that match
	    the fileglob.

	    If the fileglob does not match any files ...

	    See File::GlobMapper for more details.

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

       The $output parameter

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

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

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

       An Output FileGlob
	    If $output is a string that is delimited by the characters "<" and ">" "bunzip2" will
	    assume that it is an output fileglob string. The output is the list of files that
	    match the fileglob.

	    When $output is an fileglob string, $input must also be a fileglob string. Anything
	    else is an error.

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

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

   Optional Parameters
       Unless specified below, the optional parameters for "bunzip2", "OPTS", are the same as
       those used with the OO interface defined in the "Constructor Options" section below.

       "AutoClose => 0|1"
	    This option applies to any input or output data streams to "bunzip2" 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 "bunzip2" has completed.

	    This parameter defaults to 0.

       "BinModeOut => 0|1"
	    When writing to a file or filehandle, set "binmode" before writing to the file.

	    Defaults to 0.

       "Append => 0|1"
	    TODO

       "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.bz2" and write the compressed data to the file
       "file1.txt".

	   use strict ;
	   use warnings ;
	   use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;

	   my $input = "file1.txt.bz2";
	   my $output = "file1.txt";
	   bunzip2 $input => $output
	       or die "bunzip2 failed: $Bunzip2Error\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::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
	   use IO::File ;

	   my $input = new IO::File "<file1.txt.bz2"
	       or die "Cannot open 'file1.txt.bz2': $!\n" ;
	   my $buffer ;
	   bunzip2 $input => \$buffer
	       or die "bunzip2 failed: $Bunzip2Error\n";

       To uncompress all files in the directory "/my/home" that match "*.txt.bz2" and store the
       compressed data in the same directory

	   use strict ;
	   use warnings ;
	   use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;

	   bunzip2 '</my/home/*.txt.bz2>' => '</my/home/#1.txt>'
	       or die "bunzip2 failed: $Bunzip2Error\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::Bunzip2 qw(bunzip2 $Bunzip2Error) ;

	   for my $input ( glob "/my/home/*.txt.bz2" )
	   {
	       my $output = $input;
	       $output =~ s/.bz2// ;
	       bunzip2 $input => $output
		   or die "Error compressing '$input': $Bunzip2Error\n";
	   }

OO Interface
   Constructor
       The format of the constructor for IO::Uncompress::Bunzip2 is shown below

	   my $z = new IO::Uncompress::Bunzip2 $input [OPTS]
	       or die "IO::Uncompress::Bunzip2 failed: $Bunzip2Error\n";

       Returns an "IO::Uncompress::Bunzip2" object on success and undef on failure.  The variable
       $Bunzip2Error will contain an error message on failure.

       If you are running Perl 5.005 or better the object, $z, returned from
       IO::Uncompress::Bunzip2 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 $$output.

   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::Bunzip2 object is destroyed.

	    This parameter defaults to 0.

       "MultiStream => 0|1"
	    Allows multiple concatenated compressed streams to be treated as a single compressed
	    stream. Decompression will stop once either the end of the file/buffer is reached, an
	    error is encountered (premature eof, corrupt compressed data) or the end of a stream
	    is not immediately followed by the start of another stream.

	    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/bufffer as a single data stream.

	    This option defaults to 1.

       "BlockSize => $num"
	    When reading the compressed input data, IO::Uncompress::Bunzip2 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 is a no-op.

       "Small => 0|1"
	    When non-zero this options will make bzip2 use a decompression algorithm that uses
	    less memory at the expense of increasing the amount of time taken for decompression.

	    Default is 0.

   Examples
       TODO

Methods
   read
       Usage is

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

       Reads a block of compressed data (the size the 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 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.

       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 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 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::Bunzip2 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::Bunzip2 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 this IO::Uncompress::Bunzip2 at present.

       :all Imports "bunzip2" and $Bunzip2Error.  Same as doing this

		use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;

EXAMPLES
   Working with Net::FTP
       See IO::Uncompress::Bunzip2::FAQ

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::Compress::Lzop, IO::Uncompress::UnLzop, IO::Compress::Lzf,
       IO::Uncompress::UnLzf, IO::Uncompress::AnyInflate, IO::Uncompress::AnyUncompress

       Compress::Zlib::FAQ

       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

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

MODIFICATION HISTORY
       See the Changes file.

COPYRIGHT AND LICENSE
       Copyright (c) 2005-2008 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 v5.16.3				    2013-05-19		       IO::Uncompress::Bunzip2(3)
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