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IO::Uncompress::BunzipUser Contributed Perl DocumentIO::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_filename_or_reference => $output_filename_or_reference [,OPTS]
               or die "bunzip2 failed: $Bunzip2Error\n";

       The functional interface needs Perl5.005 or better.

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

       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 ">" "bunzip2" 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 ">" "bunzip2"
            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
       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"
            The behaviour of this option is dependent on the type of output data stream.

            ?    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.

            ?    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.

            ?    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.bz2" and write the uncompressed 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 $$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::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/buffer 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 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::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::Compress::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::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

       IO::Compress::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, pmqsATcpan.org.

MODIFICATION HISTORY
       See the Changes file.

COPYRIGHT AND LICENSE
       Copyright (c) 2005-2015 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 v5.10.1                      2015-09-26        IO::Uncompress::Bunzip2(3)