| IO::Compress::RawDeflate - Write RFC 1951 files/buffers |
newStream([OPTS])
IO::Compress::RawDeflate - Write RFC 1951 files/buffers
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 ;
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.
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_filename_or_reference => $output_filename_or_reference [,OPTS]
or die "rawdeflate failed: $RawDeflateError\n";
The functional interface needs Perl5.005 or better.
rawdeflate expects at least two parameters,
$input_filename_or_reference and $output_filename_or_reference.
$input_filename_or_reference parameterThe parameter, $input_filename_or_reference, is used to define the
source of the uncompressed data.
It can take one of the following forms:
$input_filename_or_reference parameter is a filehandle, the input
data will be read from it. The string '-' can be used as an alias for
standard input.
$input_filename_or_reference is a scalar reference, the input data
will be read from $$input_filename_or_reference.
$input_filename_or_reference is an array reference, each element in
the array must be a filename.
The input data will be read from each file in turn.
The complete array will be walked to ensure that it only contains valid filenames before any data is compressed.
$input_filename_or_reference is a string that is delimited by the
characters ``<'' and ``>'' rawdeflate will assume that it is an
input fileglob string. The input is the list of files that match the
fileglob.
See File::GlobMapper for more details.
If the $input_filename_or_reference parameter is any other type,
undef will be returned.
$output_filename_or_reference parameterThe parameter $output_filename_or_reference is used to control the
destination of the compressed data. This parameter can take one of
these forms.
$output_filename_or_reference parameter is a simple scalar, it is
assumed to be a filename. This file will be opened for writing and the
compressed data will be written to it.
$output_filename_or_reference parameter is a filehandle, the
compressed data will be written to it. The string '-' can be used as
an alias for standard output.
$output_filename_or_reference is a scalar reference, the
compressed data will be stored in $$output_filename_or_reference.
$output_filename_or_reference is an array reference,
the compressed data will be pushed onto the array.
$output_filename_or_reference 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_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.
When $input_filename_or_reference maps to multiple files/buffers and
$output_filename_or_reference is a single
file/buffer the input files/buffers will be stored
in $output_filename_or_reference as a concatenated series of compressed data streams.
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|1rawdeflate 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|1Append => 0|1Append 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.
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.
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.
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";
}
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.
$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.
$output parameter is a filehandle, the compressed data will be
written to it.
The string '-' can be used as an alias for standard output.
$output is a scalar reference, the compressed data will be stored
in $$output.
If the $output parameter is any other type, IO::Compress::RawDeflate::new will
return undef.
OPTS is any combination of the following options:
AutoClose => 0|1$output parameter is a filehandle. If
specified, and the value is true, it will result in the $output being
closed once either the close method is called or the IO::Compress::RawDeflate
object is destroyed.
This parameter defaults to 0.
Append => 0|1$output in append mode.
The behaviour of this option is dependent on the type of $output.
$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.
$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.
$output is a filehandle, the file pointer will be positioned to the
end of the file via a call to seek before any compressed data is written
to it. Otherwise the file pointer will not be moved.
This parameter defaults to 0.
Merge => 0|1$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:
Merge is used with an older version of
zlib.
If $output is a file or a filehandle, it must be seekable.
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::RawDeflate by default.
use IO::Compress::RawDeflate qw(:strategy);
use IO::Compress::RawDeflate qw(:constants);
use IO::Compress::RawDeflate qw(:all);
Z_FILTERED Z_HUFFMAN_ONLY Z_RLE Z_FIXED Z_DEFAULT_STRATEGY
The default is Z_DEFAULT_STRATEGY.
Strict => 0|1
TODO
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.
Usage is
$z->printf($format, $data)
printf $z $format, $data
Compresses and outputs the contents of the $data parameter.
Returns true if successful.
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.
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.
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.
Usage is
$z->tell()
tell $z
Returns the uncompressed file offset.
Usage is
$z->eof();
eof($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.
Usage is
$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::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 one.
OPTS consists of any of the options that are available when creating
the $z object.
See the Constructor Options section for more details.
Usage is
$z->deflateParams
TODO
A number of symbolic constants are required by some methods in
IO::Compress::RawDeflate. None are imported by default.
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) ;
use IO::Compress::RawDeflate qw(:flush :level :strategy) ;
flush method.
Z_NO_FLUSH
Z_PARTIAL_FLUSH
Z_SYNC_FLUSH
Z_FULL_FLUSH
Z_FINISH
Z_BLOCK
Level option in the constructor.
Z_NO_COMPRESSION
Z_BEST_SPEED
Z_BEST_COMPRESSION
Z_DEFAULT_COMPRESSION
Strategy option in the constructor.
Z_FILTERED
Z_HUFFMAN_ONLY
Z_RLE
Z_FIXED
Z_DEFAULT_STRATEGY
the Compress::Zlib manpage, the IO::Compress::Gzip manpage, the IO::Uncompress::Gunzip manpage, the IO::Compress::Deflate manpage, the IO::Uncompress::Inflate manpage, the IO::Uncompress::RawInflate manpage, the IO::Compress::Bzip2 manpage, the IO::Uncompress::Bunzip2 manpage, the IO::Compress::Lzma manpage, the IO::Uncompress::UnLzma manpage, the IO::Compress::Xz manpage, the IO::Uncompress::UnXz manpage, the IO::Compress::Lzip manpage, the IO::Uncompress::UnLzip manpage, the IO::Compress::Lzop manpage, the IO::Uncompress::UnLzop manpage, the IO::Compress::Lzf manpage, the IO::Uncompress::UnLzf manpage, the IO::Compress::Zstd manpage, the IO::Uncompress::UnZstd manpage, the IO::Uncompress::AnyInflate manpage, the IO::Uncompress::AnyUncompress manpage
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 module was written by Paul Marquess, pmqs@cpan.org.
See the Changes file.
Copyright (c) 2005-2019 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.
| IO::Compress::RawDeflate - Write RFC 1951 files/buffers |