NAME

IO::Uncompress::Inflate - Perl interface to read RFC 1950 files/buffers

SYNOPSIS

use IO::Uncompress::Inflate qw(inflate $InflateError) ;

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

my $z = new IO::Uncompress::Inflate $input [OPTS] 
    or die "inflate failed: $InflateError\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()

$InflateError ;

# 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 1950.

For writing RFC 1950 files/buffers, see the companion module IO::Compress::Deflate.

Functional Interface

A top-level function, inflate, 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::Inflate qw(inflate $InflateError) ;

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

The functional interface needs Perl5.005 or better.

inflate $input => $output [, OPTS]

inflate 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 ">" inflate 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 ">" inflate 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 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 inflate, 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 inflate 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 inflate 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

Creates a new stream after each file.

Defaults to 1.

Examples

To read the contents of the file file1.txt.1950 and write the compressed data to the file file1.txt.

use strict ;
use warnings ;
use IO::Uncompress::Inflate qw(inflate $InflateError) ;

my $input = "file1.txt.1950";
my $output = "file1.txt";
inflate $input => $output
    or die "inflate failed: $InflateError\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::Inflate qw(inflate $InflateError) ;
use IO::File ;

my $input = new IO::File "<file1.txt.1950"
    or die "Cannot open 'file1.txt.1950': $!\n" ;
my $buffer ;
inflate $input => \$buffer 
    or die "inflate failed: $InflateError\n";

To uncompress all files in the directory "/my/home" that match "*.txt.1950" and store the compressed data in the same directory

use strict ;
use warnings ;
use IO::Uncompress::Inflate qw(inflate $InflateError) ;

inflate '</my/home/*.txt.1950>' => '</my/home/#1.txt>'
    or die "inflate failed: $InflateError\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::Inflate qw(inflate $InflateError) ;

for my $input ( glob "/my/home/*.txt.1950" )
{
    my $output = $input;
    $output =~ s/.1950// ;
    inflate $input => $output 
        or die "Error compressing '$input': $InflateError\n";
}

OO Interface

Constructor

The format of the constructor for IO::Uncompress::Inflate is shown below

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

Returns an IO::Uncompress::Inflate object on success and undef on failure. The variable $InflateError will contain an error message on failure.

If you are running Perl 5.005 or better the object, $z, returned from IO::Uncompress::Inflate 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::Inflate 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 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::Uncompress::Inflate 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 controls whether the extra checks defined below are used when carrying out the decompression. When Strict is on, the extra tests are carried out, when Strict is off they are not.

The default for this option is off.

The ADLER32 checksum field must be present.
The value of the ADLER32 field read must match the adler32 value of the uncompressed data actually contained in the file.

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();
@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.

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::Uncompress::Inflate 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::Inflate 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::Uncompress::Inflate at present.

:all

Imports inflate and $InflateError. Same as doing this

use IO::Uncompress::Inflate qw(inflate $InflateError) ;

EXAMPLES

AUTHOR

The IO::Uncompress::Inflate 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

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cpanm

cpanm Env

CPAN shell

perl -MCPAN -e shell
install Env

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

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NAME

SYNOPSIS

DESCRIPTION

Functional Interface

inflate $input => $output [, OPTS]

The $input parameter

The $output parameter

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