IO::Inflate - Perl interface to read RFC 1950 files/buffers
use IO::Inflate qw(inflate $InflateError) ; my $status = inflate $input => $output [,OPTS] or die "inflate failed: $InflateError\n"; my $z = new IO::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)
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::Deflate.
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.
inflate
use IO::Inflate qw(inflate $InflateError) ; inflate $input => $output [,OPTS] or die "inflate failed: $InflateError\n"; inflate \%hash [,OPTS] or die "inflate failed: $InflateError\n";
The functional interface needs Perl5.005 or better.
If the first parameter is not a hash reference inflate expects at least two parameters, $input and $output.
$input
$output
The parameter, $input, is used to define the source of the compressed data.
It can take one of the following forms:
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.
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.
If $input is a scalar reference, the input data will be read from $$input.
$$input
If $input is an array reference, the input data will be read from each element of the array in turn. The action taken by inflate 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.
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.
undef
The parameter $output is used to control the destination of the uncompressed data. This parameter can take one of these forms.
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.
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.
If $output is a scalar reference, the uncompressed data will be stored in $$output.
$$output
If $output is a hash reference, the uncompressed data will be written to $output{$input} as a scalar reference.
$output{$input}
When $output is a hash reference, $input must be either a filename or list of filenames. Anything else is an error.
If $output is an array reference, the uncompressed data will be pushed onto the array.
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.
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
\%hash
If the value is undef the uncompressed data will be written to the value as a scalar reference.
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.
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.
If the value is a scalar reference, the uncompressed data will be stored in the buffer that is referenced by the scalar.
If the value is a hash reference, the uncompressed data will be written to $hash{$input} as a scalar reference.
$hash{$input}
Any other type is a error.
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.
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.
OPTS
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.
AutoClose
This parameter defaults to 0.
TODO
To read the contents of the file file1.txt.1950 and write the compressed data to the file file1.txt.
file1.txt.1950
file1.txt
use strict ; use warnings ; use IO::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.
$buffer
use strict ; use warnings ; use IO::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::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::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"; }
The format of the constructor for IO::Inflate is shown below
my $z = new IO::Inflate $input [OPTS] or die "IO::Inflate failed: $InflateError\n";
Returns an IO::Inflate object on success and undef on failure. The variable $InflateError will contain an error message on failure.
IO::Inflate
$InflateError
If you are running Perl 5.005 or better the object, $z, returned from IO::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
$z
$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.
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.
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.
If $input is a scalar reference, the compressed data will be read from $$output.
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:
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::Inflate object is destroyed.
close
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 option will uncompress the contents of $string before processing the input file/buffer.
$string
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.
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.
When reading the compressed input data, IO::Inflate will read it in blocks of $num bytes.
$num
This option defaults to 4096.
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.
$size
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.
This option controls what the read method does with uncompressed data.
read
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.
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.
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.
Buffer
Append
Returns the number of uncompressed bytes written to $buffer, zero if eof or a negative number on error.
$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.
$length
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.
$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.
$/
$INPUT_RECORD_SEPARATOR
$RS
English
$char = $z->getc()
Read a single character.
$char = $z->ungetc($string)
$status = $z->inflateSync()
$hdr = $z->getHeaderInfo()
This method returns a hash reference that contains the contents of each of the header fields defined in RFC1950.
$z->tell() tell $z
Returns the uncompressed file offset.
$z->eof(); eof($z);
Returns true if the end of the compressed input stream has been reached.
$z->seek($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.
seek
The $whence parameter takes one the usual values, namely SEEK_SET, SEEK_CUR or SEEK_END.
$whence
Returns 1 on success, 0 on failure.
$z->binmode binmode $z ;
This is a noop provided for completeness.
$z->fileno() fileno($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.
$z->close() ; close $z ;
Closes the output file/buffer.
For most versions of Perl this method will be automatically invoked if the IO::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::Inflate object was created, and the object is associated with a file, the underlying file will also be closed.
No symbolic constants are required by this IO::Inflate at present.
Imports inflate and $InflateError. Same as doing this
use IO::Inflate qw(inflate $InflateError) ;
Compress::Zlib, IO::Gzip, IO::Gunzip, IO::Deflate, IO::RawDeflate, IO::RawInflate, IO::AnyInflate
Compress::Zlib::FAQ
File::GlobMapper, Archive::Tar, IO::Zlib
For RFC 1950, 1951 and 1952 see http://www.faqs.org/rfcs/rfc1950.html, http://www.faqs.org/rfcs/rfc1951.html and http://www.faqs.org/rfcs/rfc1952.html
The primary site for the gzip program is http://www.gzip.org.
The IO::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.
See the Changes file.
Copyright (c) 2005 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.
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.