$bz = bzopen(filename or filehandle, mode)

The mode parameter is used to specify both whether the file is opened for reading or writing, with "r" or "w" respectively.

If a reference to an open filehandle is passed in place of the filename, it better be positioned to the start of a compression/decompression sequence.

WARNING: With Perl 5.6 you cannot use a filehandle because of SEGV in destruction with bzclose or an implicit close.

$bz = Compress::Bzip2->new( [PARAMS] )

$bz->bzopen(filename or filehandle, mode)

$bytesread = $bz->bzread($buffer [, $size]) ;

Returns the number of bytes actually read. On EOF it returns 0 and in the case of an error, -1.

$bytesread = $bz->bzreadline($line) ;

Returns the number of bytes actually read. On EOF it returns 0 and in the case of an error, -1.

It IS legal to intermix calls to bzread and bzreadline.

At this time bzreadline ignores the variable $/ ($INPUT_RECORD_SEPARATOR or $RS when "English" is in use). The end of a line is denoted by the C character '\n'.

$byteswritten = $bz->bzwrite($buffer [, $limit]) ;

If $limit is given and non-zero, then only that many bytes from $buffer will be written.

$status = $bz->bzflush($flush) ;

Returns "BZ_OK" if $flush is "BZ_FINISH" and all output could be flushed. Otherwise the bzlib error code is returned.

Refer to the bzlib documentation for the valid values of $flush.

$status = $bz->bzeof() ;

$bz->bzclose

$bz->bzsetparams( [PARAMS] );

The list of the valid options is shown below. Options not specified will remain unchanged.

-verbosity

Defines the verbosity level. Valid values are 0 through 4,

The default is "-verbosity => 0".

-blockSize100k

For bzip object opened for stream deflation or write.

Defines the buffering factor of compression method. The algorithm buffers all data until the buffer is full, then it flushes all the data out. Use -blockSize100k to specify the size of the buffer.

Valid settings are 1 through 9, representing a blocking in multiples of 100k.

Note that each such block has an overhead of leading and trailing synchronization bytes. bzip2 recovery uses this information to pull useable data out of a corrupted file.

A streaming application would probably want to set the blocking low.

-workFactor

For bzip object opened for stream deflation or write.

The workFactor setting tells the deflation algorithm how much work to invest to compensate for repetitive data.

workFactor may be a number from 0 to 250 inclusive. The default setting is 30.

See the bzip documentation for more information.

-small

For bzip object opened for stream inflation or read.

small may be 0 or 1. Set "small" to one to use a slower, less memory intensive algorithm.

$bz->bzerror

  BZ_CONFIG_ERROR
  BZ_DATA_ERROR
  BZ_DATA_ERROR_MAGIC
  BZ_FINISH
  BZ_FINISH_OK
  BZ_FLUSH
  BZ_FLUSH_OK
  BZ_IO_ERROR
  BZ_MAX_UNUSED
  BZ_MEM_ERROR
  BZ_OK
  BZ_OUTBUFF_FULL
  BZ_PARAM_ERROR
  BZ_RUN
  BZ_RUN_OK
  BZ_SEQUENCE_ERROR
  BZ_STREAM_END
  BZ_UNEXPECTED_EOF

$bz->bzclearerr

$bzerrno

As with bzerror() it returns an error number in numeric context and an error message in string context. Unlike bzerror() though, the error message will correspond to the bzlib message when the error is associated with bzlib itself, or the UNIX error message when it is not (i.e. bzlib returned "Z_ERRORNO").

As there is an overlap between the error numbers used by bzlib and UNIX, $bzerrno should only be used to check for the presence of an error in numeric context. Use bzerror() to check for specific bzlib errors. The bzcat example below shows how the variable can be used safely.

$bz->prefix

bzip2( [OPTS], filename)

bunzip2(filename)

bzcat(filenames...)

bzlibversion()

bzinflateInit( opts... )

bz_seterror(errno, msg) =head2 $bz->is_read() =head2 $bz->is_stream() =head2 $bz->is_write() =head2 $bz->total_in() =head2 $bz->total_out() =head2 version()

$dest = compress( $string, [$level] )

On error undef is returned.

$dest = decompress($string, [$level])

On error undef is returned.

uncompress($string, [$level])

$stream = compress_init( [PARAMS] )

   -level, alias to -blockSize100k
   -buffer, to set the buffer size.

The -buffer option is ignored. The intermediate buffer size is not changeable.

$stream = decompress_init( [PARAMS] )

$output = $stream->add( $string )

$output = $stream->finish( [$string] )

$stream->error

$stream->input_size

$stream->output_size

$gz = gzopen( $filename, $mode )

$gz->gzread( $buffer, [ $length ] )

$gz->gzreadline( $buffer )

$gz->gzwrite( $buffer )

$gz->gzflush( [$flushtype] )

$gz->gzclose( )

$gz->gzeof( )

$gz->gzerror( )

$gz->gzsetparams( $level, $strategy )

$d = deflateInit( [OPTS] )

All OPTS are ignored.

$d->deflate( $buffer )

$d->deflateParams( [OPTS] )

$d->flush( [$flushtype] )

See the Compress::Zlib documentation for more information.

$d->dict_adler( )

$d->msg( )

$d = inflateInit( [OPTS] )

All OPTS are ignored.

$d->inflate( )

$d->inflateSync( )

$d->adler32( $crc )

$d->crc32( $crc )

$buffer = memGzip( $buffer )

$buffer = memGunzip( $buffer )

$compressed = memBzip($buffer);

The buffer parameter can either be a scalar or a scalar reference.

Essentially, an in-memory bzip file is created. It creates a minimal bzip header, which adds 5 bytes before the bzip2 specific BZh header.

$uncompressed = memBunzip($buffer);

The source buffer can either be a scalar or a scalar reference.

The buffer parameter can either be a scalar or a scalar reference. The contents of the buffer parameter are destroyed after calling this function.

($d, $status) = bzdeflateInit( [PARAMS] )

If successful, it will return the initialised deflation stream, $d and $status of "BZ_OK" in a list context. In scalar context it returns the deflation stream, $d, only.

If not successful, the returned deflation stream ($d) will be undef and $status will hold the exact bzip2 error code.

The function optionally takes a number of named options specified as "-Name=>value" pairs. This allows individual options to be tailored without having to specify them all in the parameter list.

Here is a list of the valid options:

-verbosity

Defines the verbosity level. Valid values are 0 through 4,

The default is "-verbosity => 0".

-blockSize100k

Defines the buffering factor of compression method. The algorithm buffers all data until the buffer is full, then it flushes all the data out. Use -blockSize100k to specify the size of the buffer.

Valid settings are 1 through 9, representing a blocking in multiples of 100k.

Note that each such block has an overhead of leading and trailing synchronization bytes. bzip2 recovery uses this information to pull useable data out of a corrupted file.

A streaming application would probably want to set the blocking low.

-workFactor

The workFactor setting tells the deflation algorithm how much work to invest to compensate for repetitive data.

workFactor may be a number from 0 to 250 inclusive. The default setting is 30.

See the bzip documentation for more information.

Here is an example of using the deflateInit optional parameter list to override the default buffer size and compression level. All other options will take their default values.

    bzdeflateInit( -blockSize100k => 1, -verbosity => 1 );

($out, $status) = $d->bzdeflate($buffer)

On error, $out will be undef and $status will contain the zlib error code.

In a scalar context bzdeflate will return $out only.

As with the internal buffering of the deflate function in bzip2, it is not necessarily the case that any output will be produced by this method. So don't rely on the fact that $out is empty for an error test. In fact, given the size of bzdeflates internal buffer, with most files it's likely you won't see any output at all until flush or close.

($out, $status) = $d->bzflush([flush_type])

In a scalar context bzflush will return $out only.

Note that flushing can seriously degrade the compression ratio, so it should only be used to terminate a decompression (using "BZ_FLUSH") or when you want to create a full flush point (using "BZ_FINISH").

The allowable values for "flush_type" are "BZ_FLUSH" and "BZ_FINISH".

For a handle opened for "w" (bzwrite), the default is "BZ_FLUSH". For a stream, the default for "flush_type" is "BZ_FINISH" (which is essentially a close and reopen).

It is strongly recommended that you only set the "flush_type" parameter if you fully understand the implications of what it does. See the "bzip2" documentation for details.

Example

    use strict ;
    use warnings ;

    use Compress::Bzip2 ;

    binmode STDIN;
    binmode STDOUT;
    my $x = bzdeflateInit()
       or die "Cannot create a deflation stream\n" ;

    my ($output, $status) ;
    while (<>)
    {
        ($output, $status) = $x->bzdeflate($_) ;

        $status == BZ_OK
            or die "deflation failed\n" ;

        print $output ;
    }

    ($output, $status) = $x->bzclose() ;

    $status == BZ_OK
        or die "deflation failed\n" ;

    print $output ;

($i, $status) = inflateInit()

In a list context it returns the inflation stream, $i , and the zlib status code ($status ). In a scalar context it returns the inflation stream only.

If successful, $i will hold the inflation stream and $status will be "BZ_OK".

If not successful, $i will be undef and $status will hold the bzlib.h error code.

The function optionally takes a number of named options specified as "-Name=>value" pairs. This allows individual options to be tailored without having to specify them all in the parameter list.

For backward compatibility, it is also possible to pass the parameters as a reference to a hash containing the name=>value pairs.

The function takes one optional parameter, a reference to a hash. The contents of the hash allow the deflation interface to be tailored.

Here is a list of the valid options:

-small

small may be 0 or 1. Set "small" to one to use a slower, less memory intensive algorithm.

-verbosity

Defines the verbosity level. Valid values are 0 through 4,

The default is "-verbosity => 0".

Here is an example of using the bzinflateInit optional parameter.

    bzinflateInit( -small => 1, -verbosity => 1 );

($out, $status) = $i->bzinflate($buffer)

Returns "BZ_OK" if successful and "BZ_STREAM_END" if the end of the compressed data has been successfully reached. If not successful, $out will be undef and $status will hold the bzlib error code.

The $buffer parameter is modified by "bzinflate". On completion it will contain what remains of the input buffer after inflation. This means that $buffer will be an empty string when the return status is "BZ_OK". When the return status is "BZ_STREAM_END" the $buffer parameter will contains what (if anything) was stored in the input buffer after the deflated data stream.

This feature is useful when processing a file format that encapsulates a compressed data stream.

Example

    use strict ;
    use warnings ;

    use Compress::Bzip2;

    my $x = bzinflateInit()
       or die "Cannot create a inflation stream\n" ;

    my $input = '' ;
    binmode STDIN;
    binmode STDOUT;

    my ($output, $status) ;
    while (read(STDIN, $input, 4096))
    {
        ($output, $status) = $x->bzinflate(\$input) ;

        print $output
            if $status == BZ_OK or $status == BZ_STREAM_END ;

        last if $status != BZ_OK ;
    }

    die "inflation failed\n"
        unless $status == BZ_STREAM_END ;

A bzcat function

  use strict ;
  use warnings ;

  use Compress::Bzip2 ;

  die "Usage: bzcat file...\n" unless @ARGV ;

  my $file ;

  foreach $file (@ARGV) {
    my $buffer ;

    my $bz = bzopen($file, "rb")
       or die "Cannot open $file: $bzerrno\n" ;

    print $buffer while $bz->bzread($buffer) > 0 ;

    die "Error reading from $file: $bzerrno" . ($bzerrno+0) . "\n"
       if $bzerrno != BZ_STREAM_END ;

    $bz->bzclose() ;
  }

A grep using bzreadline

  use strict ;
  use warnings ;

  use Compress::Bzip2 ;

  die "Usage: bzgrep pattern file...\n" unless @ARGV >= 2;

  my $pattern = shift ;

  my $file ;

  foreach $file (@ARGV) {
    my $bz = bzopen($file, "rb")
       or die "Cannot open $file: $bzerrno\n" ;

    while ($bz->bzreadline($_) > 0) {
      print if /$pattern/ ;
    }

    die "Error reading from $file: $bzerrno\n"
      if $bzerrno != Z_STREAM_END ;

    $bz->bzclose() ;
  }

Streaming Compression

  use strict ;
  use warnings ;

  use Compress::Bzip2 ;

  binmode STDOUT;       # bzopen only sets it on the fd

  my $bz = bzopen(\*STDOUT, "wb")
     or die "Cannot open stdout: $bzerrno\n" ;

  while (<>) {
    $bz->bzwrite($_) or die "error writing: $bzerrno\n" ;
  }

  $bz->bzclose ;

Export tag :all

Export tag :constants

Export tag :bzip1

   compress
   decompress
   compress_init
   decompress_init
   version

These are actually aliases to memBzip and memBunzip.

Export tag :utilities

    bzopen
    bzinflateInit
    bzdeflateInit
    memBzip
    memBunzip
    bzip2
    bunzip2
    bzcat
    bzlibversion
    $bzerrno

Export tag :gzip

    gzopen
    gzinflateInit
    gzdeflateInit
    memGzip
    memGunzip
    $gzerrno