use IO::Compress::Deflate qw(deflate $DeflateError) ;
my $status = deflate $input => $output [,OPTS]
or die "deflate failed: $DeflateError\n";
my $z = IO::Compress::Deflate->new( $output [,OPTS] )
or die "deflate failed: $DeflateError\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() ;
$DeflateError ;
# IO::File mode
print $z $string;
printf $z $format, $string;
tell $z
eof $z
seek $z, $position, $whence
binmode $z
fileno $z
close $z ;
For reading RFC 1950 files/buffers, see the companion module IO::Uncompress::Inflate.
use IO::Compress::Deflate qw(deflate $DeflateError) ;
deflate $input_filename_or_reference => $output_filename_or_reference [,OPTS]
or die "deflate failed: $DeflateError\n";
The functional interface needs Perl5.005 or better.
The $input_filename_or_reference parameter
The parameter, $input_filename_or_reference, is used to define the source of the uncompressed data.
It can take one of the following forms:
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.
See File::GlobMapper for more details.
If the $input_filename_or_reference parameter is any other type, "undef" will be returned.
The $output_filename_or_reference parameter
The parameter $output_filename_or_reference is used to control the destination of the compressed data. This parameter can take one of these forms.
When $output_filename_or_reference is an fileglob string, $input_filename_or_reference must also be a fileglob string. Anything else is an error.
See File::GlobMapper for more details.
If the $output_filename_or_reference parameter is any other type, "undef" will be returned.
If "AutoClose" is specified, and the value is true, it will result in all input and/or output filehandles being closed once "deflate" has completed.
This parameter defaults to 0.
If "Append" is enabled, all compressed data will be append to the end of the output buffer. Otherwise the output buffer will be cleared before any compressed data is written to it.
If "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.
If "Append" is enabled, the filehandle 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.
When "Append" is specified, and set to true, it will append all compressed data to the output data stream.
So when the output is a filehandle it will carry out a seek to the eof before writing any compressed data. If the output is a filename, it will be opened for appending. If the output is a buffer, all compressed data will be appended to the existing buffer.
Conversely when "Append" is not specified, or it is present and is set to false, it will operate as follows.
When the output is a filename, it will truncate the contents of the file before writing any compressed data. If the output is a filehandle its position will not be changed. If the output is a buffer, it will be wiped before any compressed data is output.
Defaults to 0.
Streaming
This very simple command line example demonstrates the streaming capabilities of the module. The code reads data from STDIN, compresses it, and writes the compressed data to STDOUT.
$ echo hello world | perl -MIO::Compress::Deflate=deflate -e 'deflate \*STDIN => \*STDOUT' >output.1950
The special filename ``-'' can be used as a standin for both "\*STDIN" and "\*STDOUT", so the above can be rewritten as
$ echo hello world | perl -MIO::Compress::Deflate=deflate -e 'deflate "-" => "-"' >output.1950
Compressing a file from the filesystem
To read the contents of the file "file1.txt" and write the compressed data to the file "file1.txt.1950".
use strict ;
use warnings ;
use IO::Compress::Deflate qw(deflate $DeflateError) ;
my $input = "file1.txt";
deflate $input => "$input.1950"
or die "deflate failed: $DeflateError\n";
Reading from a Filehandle and writing to an in-memory buffer
To read from an existing Perl filehandle, $input, and write the compressed data to a buffer, $buffer.
use strict ;
use warnings ;
use IO::Compress::Deflate qw(deflate $DeflateError) ;
use IO::File ;
my $input = IO::File->new( "<file1.txt" )
or die "Cannot open 'file1.txt': $!\n" ;
my $buffer ;
deflate $input => \$buffer
or die "deflate failed: $DeflateError\n";
Compressing multiple files
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::Deflate qw(deflate $DeflateError) ;
deflate '</my/home/*.txt>' => '<*.1950>'
or die "deflate failed: $DeflateError\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::Deflate qw(deflate $DeflateError) ;
for my $input ( glob "/my/home/*.txt" )
{
my $output = "$input.1950" ;
deflate $input => $output
or die "Error compressing '$input': $DeflateError\n";
}
my $z = IO::Compress::Deflate->new( $output [,OPTS] )
or die "IO::Compress::Deflate failed: $DeflateError\n";
It returns an "IO::Compress::Deflate" object on success and undef on failure. The variable $DeflateError will contain an error message on failure.
If you are running Perl 5.005 or better the object, $z, returned from IO::Compress::Deflate 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.
If the $output parameter is any other type, "IO::Compress::Deflate"::new will return undef.
This parameter defaults to 0.
The behaviour of this option is dependent on the type of $output.
If $output is a buffer and "Append" is enabled, all compressed data will be append to the end of $output. Otherwise $output will be cleared before any data is written to it.
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.
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.
It is a fatal error to attempt to use this option when $output is not an RFC 1950 data stream.
There are a number of other limitations with the "Merge" option:
This parameter defaults to 0.
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::Deflate" by default.
use IO::Compress::Deflate qw(:strategy);
use IO::Compress::Deflate qw(:constants);
use IO::Compress::Deflate qw(:all);
Z_FILTERED Z_HUFFMAN_ONLY Z_RLE Z_FIXED Z_DEFAULT_STRATEGY
The default is Z_DEFAULT_STRATEGY.
$z->print($data)
print $z $data
Compresses and outputs the contents of the $data parameter. This has the same behaviour as the "print" built-in.
$z->printf($format, $data)
printf $z $format, $data
Compresses and outputs the contents of the $data parameter.
$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.
$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.
$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.
$z->tell()
tell $z
Returns the uncompressed file offset.
$z->eof();
eof($z);
Returns true if the "close" method has been called.
$z->seek($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.
$z->binmode
binmode $z ;
This is a noop provided for completeness.
$z->opened()
Returns true if the object currently refers to a opened file/buffer.
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.
$z->input_line_number()
$z->input_line_number(EXPR)
This method always returns "undef" when compressing.
$z->fileno()
fileno($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 associated with a buffer, this method will return "undef".
$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::Deflate 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::Deflate object was created, and the object is associated with a file, the underlying file will also be closed.
$z->newStream( [OPTS] )
Closes the current compressed data stream and starts a new one.
OPTS consists of any of the options that are available when creating the $z object.
See the ``Constructor Options'' section for more details.
$z->deflateParams
use IO::Compress::Deflate qw(deflate $DeflateError :constants) ;
use IO::Compress::Deflate qw(:flush :level :strategy) ;
Z_NO_FLUSH
Z_PARTIAL_FLUSH
Z_SYNC_FLUSH
Z_FULL_FLUSH
Z_FINISH
Z_BLOCK
Z_NO_COMPRESSION
Z_BEST_SPEED
Z_BEST_COMPRESSION
Z_DEFAULT_COMPRESSION
Z_FILTERED
Z_HUFFMAN_ONLY
Z_RLE
Z_FIXED
Z_DEFAULT_STRATEGY
IO::Compress::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 "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>.
The primary site for gzip is <http://www.gzip.org>.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.