IO::Compress::RawDeflate(3) User Contributed Perl Documentation IO::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 $$input.
An array reference
If $input is an array reference, each element in the array must be a filename.
The input data will be read from each file in turn.
The complete array will be walked to ensure that it only contains valid filenames
before any data is compressed.
An Input FileGlob string
If $input is a string that is delimited by the characters "<" and ">" "rawdeflate"
will assume that it is an input fileglob string. The input is the list of files that
match the fileglob.
If the fileglob does not match any files ...
See File::GlobMapper for more details.
If the $input parameter is any other type, "undef" will be returned.
The $output parameter
The parameter $output is used to control the destination of the compressed data. This
parameter can take one of these forms.
A filename
If the $output parameter is a simple scalar, it is assumed to be a filename. This
file will be opened for writing and the compressed data will be written to it.
A filehandle
If the $output parameter is a filehandle, the compressed data will be written to it.
The string '-' can be used as an alias for standard output.
A scalar reference
If $output is a scalar reference, the compressed data will be stored in $$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 " \$buffer
or die "rawdeflate failed: $RawDeflateError\n";
To compress all files in the directory "/my/home" that match "*.txt" and store the com-
pressed data in the same directory
use strict ;
use warnings ;
use IO::Compress::RawDeflate qw(rawdeflate $RawDeflateError) ;
rawdeflate '' => '<*.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::RawDe-
flate 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::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.
* 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. Oth-
erwise 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 com-
pression 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 back-
ward.
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 cur-
rent 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 descriptor. 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::Com-
press::RawDeflate object is destroyed (either explicitly or by the variable with the ref-
erence 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 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.
Z_FILTERED
Z_HUFFMAN_ONLY
Z_RLE
Z_FIXED
Z_DEFAULT_STRATEGY
EXAMPLES
Apache::GZip Revisited
See IO::Compress::FAQ
Working with Net::FTP
See IO::Compress::FAQ
SEE ALSO
Compress::Zlib, IO::Compress::Gzip, IO::Uncompress::Gunzip, IO::Compress::Deflate,
IO::Uncompress::Inflate, IO::Uncompress::RawInflate, IO::Compress::Bzip2, IO::Uncom-
press::Bunzip2, IO::Compress::Lzop, IO::Uncompress::UnLzop, IO::Compress::Lzf, IO::Uncom-
press::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 and Mark
Adler .
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, .
MODIFICATION HISTORY
See the Changes file.
COPYRIGHT AND LICENSE
Copyright (c) 2005-2009 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 2009-03-28 IO::Compress::RawDeflate(3)
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