NAME

IO::RawInflate - Perl interface to read RFC 1951 files/buffers

SYNOPSIS

use IO::RawInflate qw(rawinflate $RawInflateError) ;

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

my $z = new IO::RawInflate $input [OPTS] 
    or die "rawinflate failed: $RawInflateError\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()
$status = $z->inflateSync()
$z->trailingData()
$data = $z->getHeaderInfo()
$z->tell()
$z->seek($position, $whence)
$z->binmode()
$z->fileno()
$z->eof()
$z->close()

$RawInflateError ;

# 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

WARNING -- This is a Beta release.

DO NOT use in production code.
The documentation is incomplete in places.
Parts of the interface defined here are tentative.
Please report any problems you find.

This module provides a Perl interface that allows the reading of files/buffers that conform to RFC 1951.

For writing RFC 1951 files/buffers, see the companion module IO::RawDeflate.

Functional Interface

A top-level function, rawinflate, 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::RawInflate qw(rawinflate $RawInflateError) ;

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

rawinflate \%hash [,OPTS] 
    or die "rawinflate failed: $RawInflateError\n";

The functional interface needs Perl5.005 or better.

rawinflate $input => $output [, OPTS]

If the first parameter is not a hash reference rawinflate 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, the input data will be read from each element of the array in turn. The action taken by rawinflate with each element of the array will depend on the type of data stored in it. You can mix and match any of the types defined in this list, excluding other array or hash references. The complete array will be walked to ensure that it only contains valid data types before any data is uncompressed.

An Input FileGlob string

If $input is a string that is delimited by the characters "<" and ">" rawinflate 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.

A Hash Reference

If $output is a hash reference, the uncompressed data will be written to $output{$input} as a scalar reference.

When $output is a hash reference, $input must be either a filename or list of filenames. Anything else is an error.

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 ">" rawinflate 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.

rawinflate \%hash [, OPTS]

If the first parameter is a hash reference, \%hash, this will be used to define both the source of compressed data and to control where the uncompressed data is output. Each key/value pair in the hash defines a mapping between an input filename, stored in the key, and an output file/buffer, stored in the value. Although the input can only be a filename, there is more flexibility to control the destination of the uncompressed data. This is determined by the type of the value. Valid types are

undef: If the value is undef the uncompressed data will be written to the value as a scalar reference.
A filename: If the value 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 value 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 the value is a scalar reference, the uncompressed data will be stored in the buffer that is referenced by the scalar.
A Hash Reference: If the value is a hash reference, the uncompressed data will be written to $hash{$input} as a scalar reference.
An Array Reference: If $output is an array reference, the uncompressed data will be pushed onto the array.

Any other type is a error.

Notes

When $input maps to multiple files/buffers and $output is a single file/buffer the uncompressed input files/buffers will all be stored in $output as a single uncompressed stream.

Optional Parameters

Unless specified below, the optional parameters for rawinflate, 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 rawinflate 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 rawinflate has completed.

This parameter defaults to 0.

-Append => 0|1

TODO

Examples

To read the contents of the file file1.txt.1951 and write the compressed data to the file file1.txt.

use strict ;
use warnings ;
use IO::RawInflate qw(rawinflate $RawInflateError) ;

my $input = "file1.txt.1951";
my $output = "file1.txt";
rawinflate $input => $output
    or die "rawinflate failed: $RawInflateError\n";

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

use strict ;
use warnings ;
use IO::RawInflate qw(rawinflate $RawInflateError) ;
use IO::File ;

my $input = new IO::File "<file1.txt.1951"
    or die "Cannot open 'file1.txt.1951': $!\n" ;
my $buffer ;
rawinflate $input => \$buffer 
    or die "rawinflate failed: $RawInflateError\n";

To uncompress all files in the directory "/my/home" that match "*.txt.1951" and store the compressed data in the same directory

use strict ;
use warnings ;
use IO::RawInflate qw(rawinflate $RawInflateError) ;

rawinflate '</my/home/*.txt.1951>' => '</my/home/#1.txt>'
    or die "rawinflate failed: $RawInflateError\n";

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

use strict ;
use warnings ;
use IO::RawInflate qw(rawinflate $RawInflateError) ;

for my $input ( glob "/my/home/*.txt.1951" )
{
    my $output = $input;
    $output =~ s/.1951// ;
    rawinflate $input => $output 
        or die "Error compressing '$input': $RawInflateError\n";
}

OO Interface

Constructor

The format of the constructor for IO::RawInflate is shown below

my $z = new IO::RawInflate $input [OPTS]
    or die "IO::RawInflate failed: $RawInflateError\n";

Returns an IO::RawInflate object on success and undef on failure. The variable $RawInflateError will contain an error message on failure.

If you are running Perl 5.005 or better the object, $z, returned from IO::RawInflate 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::RawInflate object is destroyed.

This parameter defaults to 0.

-MultiStream => 0|1

This option is a no-op.

-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 or buffer is not compressed data, the module will allow reading of it anyway.

This option defaults to 1.

-BlockSize => $num

When reading the compressed input data, IO::RawInflate 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.

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. Both paragraph mode and file slurp mode are supported.

getc

Usage is

$char = $z->getc()

Read a single character.

ungetc

Usage is

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

inflateSync

Usage is

$status = $z->inflateSync()

TODO

getHeaderInfo

Usage is

$hdr = $z->getHeaderInfo()

TODO

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.

fileno

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

If the $z object is associated with a file, this method will return the underlying filehandle.

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::RawInflate 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::RawInflate object was created, and the object is associated with a file, the underlying file will also be closed.

Importing

No symbolic constants are required by this IO::RawInflate at present.

:all

Imports rawinflate and $RawInflateError. Same as doing this

use IO::RawInflate qw(rawinflate $RawInflateError) ;

EXAMPLES

AUTHOR

The IO::RawInflate module was written by Paul Marquess, pmqs@cpan.org. The latest copy of the module can be found on CPAN in modules/by-module/Compress/Compress-Zlib-x.x.tar.gz.

The zlib compression library was written by Jean-loup Gailly gzip@prep.ai.mit.edu and Mark Adler madler@alumni.caltech.edu.

The primary site for the zlib compression library is http://www.zlib.org.

MODIFICATION HISTORY

See the Changes file.

COPYRIGHT AND LICENSE

To install Compress::Zlib, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Compress::Zlib

CPAN shell

perl -MCPAN -e shell
install Compress::Zlib

For more information on module installation, please visit the detailed CPAN module installation guide.

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NAME

SYNOPSIS

DESCRIPTION

Functional Interface

rawinflate $input => $output [, OPTS]

The $input parameter

The $output parameter

rawinflate \%hash [, OPTS]

Notes

Optional Parameters

Examples

OO Interface

Constructor

Constructor Options

Examples

Methods

read

read

getline

getc

ungetc

inflateSync

getHeaderInfo

tell

eof

seek

binmode

fileno

close

Importing

EXAMPLES

SEE ALSO

AUTHOR

MODIFICATION HISTORY

COPYRIGHT AND LICENSE

Module Install Instructions

The `$input` parameter

The `$output` parameter