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man : IO::Compress::RawDeflate
IO::Compress::RawPerlaProgrammers RefIO::Compress::RawDeflate(3p)
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
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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 $$input.
An array reference
If $input is an array reference, each element in the
array must be a filename.
The input data will be read from each file in turn.
The complete array will be walked to ensure that it
only contains valid filenames before any data is
compressed.
An Input FileGlob string
If $input is a string that is delimited by the
characters "<" and ">" "rawdeflate" will assume that
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it is an input fileglob string. The input is the list
of files that match the fileglob.
If the fileglob does not match any files ...
See File::GlobMapper for more details.
If the $input parameter is any other type, "undef" will be
returned.
The $output parameter
The parameter $output is used to control the destination
of the compressed data. This parameter can take one of
these forms.
A filename
If the $output parameter is a simple scalar, it is
assumed to be a filename. This file will be opened
for writing and the compressed data will be written
to it.
A filehandle
If the $output parameter is a filehandle, the
compressed data will be written to it. The string
'-' can be used as an alias for standard output.
A scalar reference
If $output is a scalar reference, the compressed data
will be stored in $$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.
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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
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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
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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::Compress::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.
o 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.
o 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.
o 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
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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.
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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.
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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.
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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.
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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, this method will return the underlying file
descriptor.
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" explicitly
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
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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::Compress::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.
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Z_FILTERED
Z_HUFFMAN_ONLY
Z_RLE
Z_FIXED
Z_DEFAULT_STRATEGY
For
EXAMPLES
TODO
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::Uncompress::UnLzop,
IO::Compress::Lzf, IO::Uncompress::UnLzf,
IO::Uncompress::AnyInflate, IO::Uncompress::AnyUncompress
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) 2005-2007 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.
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