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IO::Compress::RawDeflaUser)Contributed Perl DocumenIO::Compress::RawDeflate(3)



NAME
       IO::Compress::RawDeflate - Write RFC 1951 files/buffers

SYNOPSIS
           use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;

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

           my $z = new IO::Compress::RawDeflate $output [,OPTS]
               or die "rawdeflate failed: $RawDeflateError\n";

           $z->print($string);
           $z->printf($format, $string);
           $z->write($string);
           $z->syswrite($string [, $length, $offset]);
           $z->flush();
           $z->tell();
           $z->eof();
           $z->seek($position, $whence);
           $z->binmode();
           $z->fileno();
           $z->opened();
           $z->autoflush();
           $z->input_line_number();
           $z->newStream( [OPTS] );

           $z->deflateParams();

           $z->close() ;

           $RawDeflateError ;

           # IO::File mode

           print $z $string;
           printf $z $format, $string;
           tell $z
           eof $z
           seek $z, $position, $whence
           binmode $z
           fileno $z
           close $z ;

DESCRIPTION
       This module provides a Perl interface that allows writing compressed data to files or buffer as defined in RFC
       1951.

       Note that RFC 1951 data is not a good choice of compression format to use in isolation, especially if you want
       to auto-detect it.

       For reading RFC 1951 files/buffers, see the companion module IO::Uncompress::RawInflate.

Functional Interface
       A top-level function, "rawdeflate", is provided to carry out "one-shot" compression between buffers and/or
       files. For finer control over the compression process, see the "OO Interface" section.

           use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;

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

       The functional interface needs Perl5.005 or better.

       rawdeflate $input => $output [, OPTS]

       "rawdeflate" expects at least two parameters, $input and $output.

       The $input parameter

       The parameter, $input, is used to define the source of the uncompressed 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 com-
            pressed.

       An Input FileGlob string
            If $input is a string that is delimited by the characters "<" and ">" "rawdeflate" 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 compressed 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 compressed data will be written to it.

       A filehandle
            If the $output parameter is a filehandle, the compressed 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 compressed data will be stored in $$output.

       An Array Reference
            If $output is an array reference, the compressed data will be pushed onto the array.

       An Output FileGlob
            If $output is a string that is delimited by the characters "<" and ">" "rawdeflate" 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 input files/buffers will be
       stored in $output as a concatenated series of compressed data streams.

       Optional Parameters

       Unless specified below, the optional parameters for "rawdeflate", "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 "rawdeflate" 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 "rawdeflate" has completed.

            This parameter defaults to 0.

       "BinModeIn => 0|1"
            When reading from a file or filehandle, set "binmode" before reading.

            Defaults to 0.

       "Append => 0|1"
            TODO

       Examples

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

           use strict ;
           use warnings ;
           use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;

           my $input = "file1.txt";
           rawdeflate $input => "$input.1951"
               or die "rawdeflate failed: $RawDeflateError\n";

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

           use strict ;
           use warnings ;
           use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;
           use IO::File ;

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

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

           use strict ;
           use warnings ;
           use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;

           rawdeflate '</my/home/*.txt>' => '<*.1951>'
               or die "rawdeflate failed: $RawDeflateError\n";

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

           use strict ;
           use warnings ;
           use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;

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

OO Interface
       Constructor

       The format of the constructor for "IO::Compress::RawDeflate" is shown below

           my $z = new IO::Compress::RawDeflate $output [,OPTS]
               or die "IO::Compress::RawDeflate failed: $RawDeflateError\n";

       It returns an "IO::Compress::RawDeflate" object on success and undef on failure.  The variable $RawDeflateError
       will contain an error message on failure.

       If you are running Perl 5.005 or better the object, $z, returned from IO::Compress::RawDeflate can be used
       exactly like an IO::File filehandle.  This means that all normal output file operations can be carried out with
       $z.  For example, to write to a compressed file/buffer you can use either of these forms

           $z->print("hello world\n");
           print $z "hello world\n";

       The mandatory parameter $output is used to control the destination of the compressed 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 compressed data will be written to it.

       A filehandle
            If the $output parameter is a filehandle, the compressed 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 compressed data will be stored in $$output.

       If the $output parameter is any other type, "IO::Compress::RawDeflate"::new will return undef.

       Constructor Options

       "OPTS" is any combination of the following options:

       "AutoClose => 0|1"
            This option is only valid when the $output parameter is a filehandle. If specified, and the value is true,
            it will result in the $output being closed once either the "close" method is called or the "IO::Com-
            press::RawDeflate" object is destroyed.

            This parameter defaults to 0.

       "Append => 0|1"
            Opens $output in append mode.

            The behaviour of this option is dependent on the type of $output.

            * A Buffer
                 If $output is a buffer and "Append" is enabled, all compressed data will be append to the end if
                 $output. Otherwise $output will be cleared before any data is written to it.

            * A Filename
                 If $output is a filename and "Append" is enabled, the file will be opened in append mode. Otherwise
                 the contents of the file, if any, will be truncated before any compressed data is written to it.

            * A Filehandle
                 If $output is a filehandle, the file pointer will be positioned to the end of the file via a call to
                 "seek" before any compressed data is written to it.  Otherwise the file pointer will not be moved.

            This parameter defaults to 0.

       "Merge => 0|1"
            This option is used to compress input data and append it to an existing compressed data stream in $output.
            The end result is a single compressed data stream stored in $output.

            It is a fatal error to attempt to use this option when $output is not an RFC 1951 data stream.

            There are a number of other limitations with the "Merge" option:

            1    This module needs to have been built with zlib 1.2.1 or better to work. A fatal error will be thrown
                 if "Merge" is used with an older version of zlib.

            2    If $output is a file or a filehandle, it must be seekable.

            This parameter defaults to 0.

       -Level
            Defines the compression level used by zlib. The value should either be a number between 0 and 9 (0 means
            no compression and 9 is maximum compression), or one of the symbolic constants defined below.

               Z_NO_COMPRESSION
               Z_BEST_SPEED
               Z_BEST_COMPRESSION
               Z_DEFAULT_COMPRESSION

            The default is Z_DEFAULT_COMPRESSION.

            Note, these constants are not imported by "IO::Compress::RawDeflate" by default.

                use IO::Compress::RawDeflate qw(:strategy);
                use IO::Compress::RawDeflate qw(:constants);
                use IO::Compress::RawDeflate qw(:all);

       -Strategy
            Defines the strategy used to tune the compression. Use one of the symbolic constants defined below.

               Z_FILTERED
               Z_HUFFMAN_ONLY
               Z_RLE
               Z_FIXED
               Z_DEFAULT_STRATEGY

            The default is Z_DEFAULT_STRATEGY.

       "Strict => 0|1"
            This is a placeholder option.

       Examples

       TODO

Methods
       print

       Usage is

           $z->print($data)
           print $z $data

       Compresses and outputs the contents of the $data parameter. This has the same behaviour as the "print"
       built-in.

       Returns true if successful.

       printf

       Usage is

           $z->printf($format, $data)
           printf $z $format, $data

       Compresses and outputs the contents of the $data parameter.

       Returns true if successful.

       syswrite

       Usage is

           $z->syswrite $data
           $z->syswrite $data, $length
           $z->syswrite $data, $length, $offset

       Compresses and outputs the contents of the $data parameter.

       Returns the number of uncompressed bytes written, or "undef" if unsuccessful.

       write

       Usage is

           $z->write $data
           $z->write $data, $length
           $z->write $data, $length, $offset

       Compresses and outputs the contents of the $data parameter.

       Returns the number of uncompressed bytes written, or "undef" if unsuccessful.

       flush

       Usage is

           $z->flush;
           $z->flush($flush_type);

       Flushes any pending compressed data to the output file/buffer.

       This method takes an optional parameter, $flush_type, that controls how the flushing will be carried out. By
       default the $flush_type used is "Z_FINISH". Other valid values for $flush_type are "Z_NO_FLUSH",
       "Z_SYNC_FLUSH", "Z_FULL_FLUSH" and "Z_BLOCK". It is strongly recommended that you only set the "flush_type"
       parameter if you fully understand the implications of what it does - overuse of "flush" can seriously degrade
       the level of compression achieved. See the "zlib" documentation for details.

       Returns true on success.

       tell

       Usage is

           $z->tell()
           tell $z

       Returns the uncompressed file offset.

       eof

       Usage is

           $z->eof();
           eof($z);

       Returns true if the "close" method has been called.

       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 output file/buffer.  It is a fatal error to attempt to seek backward.

       Empty parts of the file/buffer will have NULL (0x00) bytes written to them.

       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.

       opened

           $z->opened()

       Returns true if the object currently refers to a opened file/buffer.

       autoflush

           my $prev = $z->autoflush()
           my $prev = $z->autoflush(EXPR)

       If the $z object is associated with a file or a filehandle, this method returns the current autoflush setting
       for the underlying filehandle. If "EXPR" is present, and is non-zero, it will enable flushing after every
       write/print operation.

       If $z is associated with a buffer, this method has no effect and always returns "undef".

       Note that the special variable $| cannot be used to set or retrieve the autoflush setting.

       input_line_number

           $z->input_line_number()
           $z->input_line_number(EXPR)

       This method always returns "undef" when compressing.

       fileno

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

       If the $z object is associated with a file or a filehandle, "fileno" will return the underlying file descrip-
       tor. Once the "close" method is called "fileno" will return "undef".

       If the $z object is is associated with a buffer, this method will return "undef".

       close

           $z->close() ;
           close $z ;

       Flushes any pending compressed data and then closes the output file/buffer.

       For most versions of Perl this method will be automatically invoked if the IO::Compress::RawDeflate 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" explic-
       itly and not rely on automatic closing.

       Returns true on success, otherwise 0.

       If the "AutoClose" option has been enabled when the IO::Compress::RawDeflate object was created, and the object
       is associated with a file, the underlying file will also be closed.

       newStream([OPTS])

       Usage is

           $z->newStream( [OPTS] )

       Closes the current compressed data stream and starts a new one.

       OPTS consists of any of the the options that are available when creating the $z object.

       See the "Constructor Options" section for more details.

       deflateParams

       Usage is

           $z->deflateParams

       TODO

Importing
       A number of symbolic constants are required by some methods in "IO::Compress::RawDeflate". None are imported by
       default.

       :all Imports "rawdeflate", $RawDeflateError and all symbolic constants that can be used by "IO::Com-
            press::RawDeflate". Same as doing this

                use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError :constants) ;

       :constants
            Import all symbolic constants. Same as doing this

                use IO::Compress::RawDeflate qw(:flush :level :strategy) ;

       :flush
            These symbolic constants are used by the "flush" method.

                Z_NO_FLUSH
                Z_PARTIAL_FLUSH
                Z_SYNC_FLUSH
                Z_FULL_FLUSH
                Z_FINISH
                Z_BLOCK

       :level
            These symbolic constants are used by the "Level" option in the constructor.

                Z_NO_COMPRESSION
                Z_BEST_SPEED
                Z_BEST_COMPRESSION
                Z_DEFAULT_COMPRESSION

       :strategy
            These symbolic constants are used by the "Strategy" option in the constructor.

                Z_FILTERED
                Z_HUFFMAN_ONLY
                Z_RLE
                Z_FIXED
                Z_DEFAULT_STRATEGY

EXAMPLES
       Apache::GZip Revisited

       See IO::Compress::Zlib::FAQ

       Working with Net::FTP

       See IO::Compress::Zlib::FAQ

SEE ALSO
       Compress::Zlib, IO::Compress::Gzip, IO::Uncompress::Gunzip, IO::Compress::Deflate, IO::Uncompress::Inflate,
       IO::Uncompress::RawInflate, IO::Compress::Bzip2, IO::Uncompress::Bunzip2, IO::Compress::Lzop, IO::Uncom-
       press::UnLzop, IO::Compress::Lzf, IO::Uncompress::UnLzf, IO::Uncompress::AnyInflate, IO::Uncompress::AnyUncom-
       press

       Compress::Zlib::FAQ

       File::GlobMapper, Archive::Zip, 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 zlib compression library was written by Jean-loup Gailly gzipATprep.edu and Mark Adler
       madlerATalumni.edu.

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

       The primary site for gzip is http://www.gzip.org.

AUTHOR
       This module was written by Paul Marquess, pmqsATcpan.org.

MODIFICATION HISTORY
       See the Changes file.

COPYRIGHT AND LICENSE
       Copyright (c) 2005-2008 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.



perl v5.8.8                       2008-09-03       IO::Compress::RawDeflate(3)