($z, $status) = new Compress::Raw::Bzip2 $appendOutput, $blockSize100k, $workfactor;¶

Creates a new compression object.

If successful, it will return the initialised compression object, $z and a $status of "BZ_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 a bzip2 error code.

Below is a list of the valid options:

$appendOutput

Controls whether the compressed data is appended to the output buffer in the "bzdeflate", "bzflush" and "bzclose" methods.

Defaults to 1.

$blockSize100k

To quote the bzip2 documentation

    blockSize100k specifies the block size to be used for compression. It
    should be a value between 1 and 9 inclusive, and the actual block size
    used is 100000 x this figure. 9 gives the best compression but takes
    most memory.
    

Defaults to 1.

$workfactor

To quote the bzip2 documentation

    This parameter controls how the compression phase behaves when
    presented with worst case, highly repetitive, input data. If
    compression runs into difficulties caused by repetitive data, the
    library switches from the standard sorting algorithm to a fallback
    algorithm. The fallback is slower than the standard algorithm by
    perhaps a factor of three, but always behaves reasonably, no matter how
    bad the input.
    Lower values of workFactor reduce the amount of effort the standard
    algorithm will expend before resorting to the fallback. You should set
    this parameter carefully; too low, and many inputs will be handled by
    the fallback algorithm and so compress rather slowly, too high, and
    your average-to-worst case compression times can become very large. The
    default value of 30 gives reasonable behaviour over a wide range of
    circumstances.
    Allowable values range from 0 to 250 inclusive. 0 is a special case,
    equivalent to using the default value of 30.
    

Defaults to 0.

$status = $bz->bzdeflate($input, $output);¶

Reads the contents of $input, compresses it and writes the compressed data to $output.

Returns "BZ_RUN_OK" on success and a "bzip2" error code on failure.

If "appendOutput" is enabled in the constructor for the bzip2 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 = $bz->bzflush($output);¶

Flushes any pending compressed data to $output.

Returns "BZ_RUN_OK" on success and a "bzip2" error code on failure.

$status = $bz->bzclose($output);¶

Terminates the compressed data stream and flushes any pending compressed data to $output.

Returns "BZ_STREAM_END" on success and a "bzip2" error code on failure.

Example¶

($z, $status) = new Compress::Raw::Bunzip2 $appendOutput, $consumeInput, $small, $verbosity, $limitOutput;¶

If successful, it will return the initialised uncompression object, $z and a $status of "BZ_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 a bzip2 error code.

Below is a list of the valid options:

$appendOutput

Controls whether the compressed data is appended to the output buffer in the "bzinflate", "bzflush" and "bzclose" methods.

Defaults to 1.

$consumeInput

$small

To quote the bzip2 documentation

    If small is nonzero, the library will use an alternative decompression
    algorithm which uses less memory but at the cost of decompressing more
    slowly (roughly speaking, half the speed, but the maximum memory
    requirement drops to around 2300k).
    

Defaults to 0.

$limitOutput

The "LimitOutput" option changes the behavior of the "$i->bzinflate" 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 16k 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->bzinflate" 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.

$verbosity

This parameter is ignored.

Defaults to 0.

$status = $z->bzinflate($input, $output);¶

Uncompresses $input and writes the uncompressed data to $output.

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

If "consumeInput" is enabled in the constructor for the bunzip2 object, $input will have all compressed data removed from it after uncompression. On "BZ_OK" return this will mean that $input will be an empty string; when "BZ_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 bunzip2 object, the uncompressed data will be appended to $output. If not enabled, $output will be truncated before the uncompressed data is written to it.

my $version = Compress::Raw::Bzip2::bzlibversion();¶

Returns the version of the underlying bzip2 library.