1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
|
package IO::Compress::Deflate ;
require 5.006 ;
use strict ;
use warnings;
use bytes;
require Exporter ;
use IO::Compress::RawDeflate 2.048 ();
use IO::Compress::Adapter::Deflate 2.048 ;
use IO::Compress::Zlib::Constants 2.048 ;
use IO::Compress::Base::Common 2.048 qw(createSelfTiedObject);
our ($VERSION, @ISA, @EXPORT_OK, %EXPORT_TAGS, %DEFLATE_CONSTANTS, $DeflateError);
$VERSION = '2.048';
$DeflateError = '';
@ISA = qw(Exporter IO::Compress::RawDeflate);
@EXPORT_OK = qw( $DeflateError deflate ) ;
%EXPORT_TAGS = %IO::Compress::RawDeflate::DEFLATE_CONSTANTS ;
push @{ $EXPORT_TAGS{all} }, @EXPORT_OK ;
Exporter::export_ok_tags('all');
sub new
{
my $class = shift ;
my $obj = createSelfTiedObject($class, \$DeflateError);
return $obj->_create(undef, @_);
}
sub deflate
{
my $obj = createSelfTiedObject(undef, \$DeflateError);
return $obj->_def(@_);
}
sub bitmask($$$$)
{
my $into = shift ;
my $value = shift ;
my $offset = shift ;
my $mask = shift ;
return $into | (($value & $mask) << $offset ) ;
}
sub mkDeflateHdr($$$;$)
{
my $method = shift ;
my $cinfo = shift;
my $level = shift;
my $fdict_adler = shift ;
my $cmf = 0;
my $flg = 0;
my $fdict = 0;
$fdict = 1 if defined $fdict_adler;
$cmf = bitmask($cmf, $method, ZLIB_CMF_CM_OFFSET, ZLIB_CMF_CM_BITS);
$cmf = bitmask($cmf, $cinfo, ZLIB_CMF_CINFO_OFFSET, ZLIB_CMF_CINFO_BITS);
$flg = bitmask($flg, $fdict, ZLIB_FLG_FDICT_OFFSET, ZLIB_FLG_FDICT_BITS);
$flg = bitmask($flg, $level, ZLIB_FLG_LEVEL_OFFSET, ZLIB_FLG_LEVEL_BITS);
my $fcheck = 31 - ($cmf * 256 + $flg) % 31 ;
$flg = bitmask($flg, $fcheck, ZLIB_FLG_FCHECK_OFFSET, ZLIB_FLG_FCHECK_BITS);
my $hdr = pack("CC", $cmf, $flg) ;
$hdr .= pack("N", $fdict_adler) if $fdict ;
return $hdr;
}
sub mkHeader
{
my $self = shift ;
my $param = shift ;
my $level = $param->value('Level');
my $strategy = $param->value('Strategy');
my $lflag ;
$level = 6
if $level == Z_DEFAULT_COMPRESSION ;
if (ZLIB_VERNUM >= 0x1210)
{
if ($strategy >= Z_HUFFMAN_ONLY || $level < 2)
{ $lflag = ZLIB_FLG_LEVEL_FASTEST }
elsif ($level < 6)
{ $lflag = ZLIB_FLG_LEVEL_FAST }
elsif ($level == 6)
{ $lflag = ZLIB_FLG_LEVEL_DEFAULT }
else
{ $lflag = ZLIB_FLG_LEVEL_SLOWEST }
}
else
{
$lflag = ($level - 1) >> 1 ;
$lflag = 3 if $lflag > 3 ;
}
#my $wbits = (MAX_WBITS - 8) << 4 ;
my $wbits = 7;
mkDeflateHdr(ZLIB_CMF_CM_DEFLATED, $wbits, $lflag);
}
sub ckParams
{
my $self = shift ;
my $got = shift;
$got->value('ADLER32' => 1);
return 1 ;
}
sub mkTrailer
{
my $self = shift ;
return pack("N", *$self->{Compress}->adler32()) ;
}
sub mkFinalTrailer
{
return '';
}
#sub newHeader
#{
# my $self = shift ;
# return *$self->{Header};
#}
sub getExtraParams
{
my $self = shift ;
return $self->getZlibParams(),
}
sub getInverseClass
{
return ('IO::Uncompress::Inflate',
\$IO::Uncompress::Inflate::InflateError);
}
sub getFileInfo
{
my $self = shift ;
my $params = shift;
my $file = shift ;
}
1;
__END__
=head1 NAME
IO::Compress::Deflate - Write RFC 1950 files/buffers
=head1 SYNOPSIS
use IO::Compress::Deflate qw(deflate $DeflateError) ;
my $status = deflate $input => $output [,OPTS]
or die "deflate failed: $DeflateError\n";
my $z = new IO::Compress::Deflate $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 ;
=head1 DESCRIPTION
This module provides a Perl interface that allows writing compressed
data to files or buffer as defined in RFC 1950.
For reading RFC 1950 files/buffers, see the companion module
L<IO::Uncompress::Inflate|IO::Uncompress::Inflate>.
=head1 Functional Interface
A top-level function, C<deflate>, is provided to carry out
"one-shot" compression between buffers and/or files. For finer
control over the compression process, see the L</"OO Interface">
section.
use IO::Compress::Deflate qw(deflate $DeflateError) ;
deflate $input => $output [,OPTS]
or die "deflate failed: $DeflateError\n";
The functional interface needs Perl5.005 or better.
=head2 deflate $input => $output [, OPTS]
C<deflate> expects at least two parameters, C<$input> and C<$output>.
=head3 The C<$input> parameter
The parameter, C<$input>, is used to define the source of
the uncompressed data.
It can take one of the following forms:
=over 5
=item A filename
If the C<$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.
=item A filehandle
If the C<$input> parameter is a filehandle, the input data will be
read from it.
The string '-' can be used as an alias for standard input.
=item A scalar reference
If C<$input> is a scalar reference, the input data will be read
from C<$$input>.
=item An array reference
If C<$input> is an array reference, each element in the array must be a
filename.
The input data will be read from each file in turn.
The complete array will be walked to ensure that it only
contains valid filenames before any data is compressed.
=item An Input FileGlob string
If C<$input> is a string that is delimited by the characters "<" and ">"
C<deflate> will assume that it is an I<input fileglob string>. The
input is the list of files that match the fileglob.
See L<File::GlobMapper|File::GlobMapper> for more details.
=back
If the C<$input> parameter is any other type, C<undef> will be returned.
=head3 The C<$output> parameter
The parameter C<$output> is used to control the destination of the
compressed data. This parameter can take one of these forms.
=over 5
=item A filename
If the C<$output> parameter is a simple scalar, it is assumed to be a
filename. This file will be opened for writing and the compressed
data will be written to it.
=item A filehandle
If the C<$output> parameter is a filehandle, the compressed data
will be written to it.
The string '-' can be used as an alias for standard output.
=item A scalar reference
If C<$output> is a scalar reference, the compressed data will be
stored in C<$$output>.
=item An Array Reference
If C<$output> is an array reference, the compressed data will be
pushed onto the array.
=item An Output FileGlob
If C<$output> is a string that is delimited by the characters "<" and ">"
C<deflate> will assume that it is an I<output fileglob string>. The
output is the list of files that match the fileglob.
When C<$output> is an fileglob string, C<$input> must also be a fileglob
string. Anything else is an error.
See L<File::GlobMapper|File::GlobMapper> for more details.
=back
If the C<$output> parameter is any other type, C<undef> will be returned.
=head2 Notes
When C<$input> maps to multiple files/buffers and C<$output> is a single
file/buffer the input files/buffers will be stored
in C<$output> as a concatenated series of compressed data streams.
=head2 Optional Parameters
Unless specified below, the optional parameters for C<deflate>,
C<OPTS>, are the same as those used with the OO interface defined in the
L</"Constructor Options"> section below.
=over 5
=item C<< AutoClose => 0|1 >>
This option applies to any input or output data streams to
C<deflate> that are filehandles.
If C<AutoClose> is specified, and the value is true, it will result in all
input and/or output filehandles being closed once C<deflate> has
completed.
This parameter defaults to 0.
=item C<< BinModeIn => 0|1 >>
When reading from a file or filehandle, set C<binmode> before reading.
Defaults to 0.
=item C<< Append => 0|1 >>
The behaviour of this option is dependent on the type of output data
stream.
=over 5
=item * A Buffer
If C<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.
=item * A Filename
If C<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.
=item * A Filehandle
If C<Append> is enabled, the filehandle will be positioned to the end of
the file via a call to C<seek> before any compressed data is
written to it. Otherwise the file pointer will not be moved.
=back
When C<Append> is specified, and set to true, it will I<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 C<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.
=back
=head2 Examples
To read the contents of the file C<file1.txt> and write the compressed
data to the file C<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: $DeflateError\n";
To read from an existing Perl filehandle, C<$input>, and write the
compressed data to a buffer, C<$buffer>.
use strict ;
use warnings ;
use IO::Compress::Deflate qw(deflate $DeflateError) ;
use IO::File ;
my $input = new IO::File "<file1.txt"
or die "Cannot open 'file1.txt': $!\n" ;
my $buffer ;
deflate $input => \$buffer
or die "deflate failed: $DeflateError\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::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";
}
=head1 OO Interface
=head2 Constructor
The format of the constructor for C<IO::Compress::Deflate> is shown below
my $z = new IO::Compress::Deflate $output [,OPTS]
or die "IO::Compress::Deflate failed: $DeflateError\n";
It returns an C<IO::Compress::Deflate> object on success and undef on failure.
The variable C<$DeflateError> will contain an error message on failure.
If you are running Perl 5.005 or better the object, C<$z>, returned from
IO::Compress::Deflate can be used exactly like an L<IO::File|IO::File> filehandle.
This means that all normal output file operations can be carried out
with C<$z>.
For example, to write to a compressed file/buffer you can use either of
these forms
$z->print("hello world\n");
print $z "hello world\n";
The mandatory parameter C<$output> is used to control the destination
of the compressed data. This parameter can take one of these forms.
=over 5
=item A filename
If the C<$output> parameter is a simple scalar, it is assumed to be a
filename. This file will be opened for writing and the compressed data
will be written to it.
=item A filehandle
If the C<$output> parameter is a filehandle, the compressed data will be
written to it.
The string '-' can be used as an alias for standard output.
=item A scalar reference
If C<$output> is a scalar reference, the compressed data will be stored
in C<$$output>.
=back
If the C<$output> parameter is any other type, C<IO::Compress::Deflate>::new will
return undef.
=head2 Constructor Options
C<OPTS> is any combination of the following options:
=over 5
=item C<< AutoClose => 0|1 >>
This option is only valid when the C<$output> parameter is a filehandle. If
specified, and the value is true, it will result in the C<$output> being
closed once either the C<close> method is called or the C<IO::Compress::Deflate>
object is destroyed.
This parameter defaults to 0.
=item C<< Append => 0|1 >>
Opens C<$output> in append mode.
The behaviour of this option is dependent on the type of C<$output>.
=over 5
=item * A Buffer
If C<$output> is a buffer and C<Append> is enabled, all compressed data
will be append to the end of C<$output>. Otherwise C<$output> will be
cleared before any data is written to it.
=item * A Filename
If C<$output> is a filename and C<Append> is enabled, the file will be
opened in append mode. Otherwise the contents of the file, if any, will be
truncated before any compressed data is written to it.
=item * A Filehandle
If C<$output> is a filehandle, the file pointer will be positioned to the
end of the file via a call to C<seek> before any compressed data is written
to it. Otherwise the file pointer will not be moved.
=back
This parameter defaults to 0.
=item C<< Merge => 0|1 >>
This option is used to compress input data and append it to an existing
compressed data stream in C<$output>. The end result is a single compressed
data stream stored in C<$output>.
It is a fatal error to attempt to use this option when C<$output> is not an
RFC 1950 data stream.
There are a number of other limitations with the C<Merge> option:
=over 5
=item 1
This module needs to have been built with zlib 1.2.1 or better to work. A
fatal error will be thrown if C<Merge> is used with an older version of
zlib.
=item 2
If C<$output> is a file or a filehandle, it must be seekable.
=back
This parameter defaults to 0.
=item -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 C<IO::Compress::Deflate> by default.
use IO::Compress::Deflate qw(:strategy);
use IO::Compress::Deflate qw(:constants);
use IO::Compress::Deflate qw(:all);
=item -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.
=item C<< Strict => 0|1 >>
This is a placeholder option.
=back
=head2 Examples
TODO
=head1 Methods
=head2 print
Usage is
$z->print($data)
print $z $data
Compresses and outputs the contents of the C<$data> parameter. This
has the same behaviour as the C<print> built-in.
Returns true if successful.
=head2 printf
Usage is
$z->printf($format, $data)
printf $z $format, $data
Compresses and outputs the contents of the C<$data> parameter.
Returns true if successful.
=head2 syswrite
Usage is
$z->syswrite $data
$z->syswrite $data, $length
$z->syswrite $data, $length, $offset
Compresses and outputs the contents of the C<$data> parameter.
Returns the number of uncompressed bytes written, or C<undef> if
unsuccessful.
=head2 write
Usage is
$z->write $data
$z->write $data, $length
$z->write $data, $length, $offset
Compresses and outputs the contents of the C<$data> parameter.
Returns the number of uncompressed bytes written, or C<undef> if
unsuccessful.
=head2 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, C<$flush_type>, that controls
how the flushing will be carried out. By default the C<$flush_type>
used is C<Z_FINISH>. Other valid values for C<$flush_type> are
C<Z_NO_FLUSH>, C<Z_SYNC_FLUSH>, C<Z_FULL_FLUSH> and C<Z_BLOCK>. It is
strongly recommended that you only set the C<flush_type> parameter if
you fully understand the implications of what it does - overuse of C<flush>
can seriously degrade the level of compression achieved. See the C<zlib>
documentation for details.
Returns true on success.
=head2 tell
Usage is
$z->tell()
tell $z
Returns the uncompressed file offset.
=head2 eof
Usage is
$z->eof();
eof($z);
Returns true if the C<close> method has been called.
=head2 seek
$z->seek($position, $whence);
seek($z, $position, $whence);
Provides a sub-set of the C<seek> functionality, with the restriction
that it is only legal to seek forward in the output file/buffer.
It is a fatal error to attempt to seek backward.
Empty parts of the file/buffer will have NULL (0x00) bytes written to them.
The C<$whence> parameter takes one the usual values, namely SEEK_SET,
SEEK_CUR or SEEK_END.
Returns 1 on success, 0 on failure.
=head2 binmode
Usage is
$z->binmode
binmode $z ;
This is a noop provided for completeness.
=head2 opened
$z->opened()
Returns true if the object currently refers to a opened file/buffer.
=head2 autoflush
my $prev = $z->autoflush()
my $prev = $z->autoflush(EXPR)
If the C<$z> object is associated with a file or a filehandle, this method
returns the current autoflush setting for the underlying filehandle. If
C<EXPR> is present, and is non-zero, it will enable flushing after every
write/print operation.
If C<$z> is associated with a buffer, this method has no effect and always
returns C<undef>.
B<Note> that the special variable C<$|> B<cannot> be used to set or
retrieve the autoflush setting.
=head2 input_line_number
$z->input_line_number()
$z->input_line_number(EXPR)
This method always returns C<undef> when compressing.
=head2 fileno
$z->fileno()
fileno($z)
If the C<$z> object is associated with a file or a filehandle, C<fileno>
will return the underlying file descriptor. Once the C<close> method is
called C<fileno> will return C<undef>.
If the C<$z> object is associated with a buffer, this method will return
C<undef>.
=head2 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::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 C<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 C<close> explicitly and not rely on automatic
closing.
Returns true on success, otherwise 0.
If the C<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.
=head2 newStream([OPTS])
Usage is
$z->newStream( [OPTS] )
Closes the current compressed data stream and starts a new one.
OPTS consists of any of the the options that are available when creating
the C<$z> object.
See the L</"Constructor Options"> section for more details.
=head2 deflateParams
Usage is
$z->deflateParams
TODO
=head1 Importing
A number of symbolic constants are required by some methods in
C<IO::Compress::Deflate>. None are imported by default.
=over 5
=item :all
Imports C<deflate>, C<$DeflateError> and all symbolic
constants that can be used by C<IO::Compress::Deflate>. Same as doing this
use IO::Compress::Deflate qw(deflate $DeflateError :constants) ;
=item :constants
Import all symbolic constants. Same as doing this
use IO::Compress::Deflate qw(:flush :level :strategy) ;
=item :flush
These symbolic constants are used by the C<flush> method.
Z_NO_FLUSH
Z_PARTIAL_FLUSH
Z_SYNC_FLUSH
Z_FULL_FLUSH
Z_FINISH
Z_BLOCK
=item :level
These symbolic constants are used by the C<Level> option in the constructor.
Z_NO_COMPRESSION
Z_BEST_SPEED
Z_BEST_COMPRESSION
Z_DEFAULT_COMPRESSION
=item :strategy
These symbolic constants are used by the C<Strategy> option in the constructor.
Z_FILTERED
Z_HUFFMAN_ONLY
Z_RLE
Z_FIXED
Z_DEFAULT_STRATEGY
=back
=head1 EXAMPLES
=head2 Apache::GZip Revisited
See L<IO::Compress::FAQ|IO::Compress::FAQ/"Apache::GZip Revisited">
=head2 Working with Net::FTP
See L<IO::Compress::FAQ|IO::Compress::FAQ/"Compressed files and Net::FTP">
=head1 SEE ALSO
L<Compress::Zlib>, L<IO::Compress::Gzip>, L<IO::Uncompress::Gunzip>, L<IO::Uncompress::Inflate>, L<IO::Compress::RawDeflate>, L<IO::Uncompress::RawInflate>, L<IO::Compress::Bzip2>, L<IO::Uncompress::Bunzip2>, L<IO::Compress::Lzma>, L<IO::Uncompress::UnLzma>, L<IO::Compress::Xz>, L<IO::Uncompress::UnXz>, L<IO::Compress::Lzop>, L<IO::Uncompress::UnLzop>, L<IO::Compress::Lzf>, L<IO::Uncompress::UnLzf>, L<IO::Uncompress::AnyInflate>, L<IO::Uncompress::AnyUncompress>
L<IO::Compress::FAQ|IO::Compress::FAQ>
L<File::GlobMapper|File::GlobMapper>, L<Archive::Zip|Archive::Zip>,
L<Archive::Tar|Archive::Tar>,
L<IO::Zlib|IO::Zlib>
For RFC 1950, 1951 and 1952 see
F<http://www.faqs.org/rfcs/rfc1950.html>,
F<http://www.faqs.org/rfcs/rfc1951.html> and
F<http://www.faqs.org/rfcs/rfc1952.html>
The I<zlib> compression library was written by Jean-loup Gailly
F<gzip@prep.ai.mit.edu> and Mark Adler F<madler@alumni.caltech.edu>.
The primary site for the I<zlib> compression library is
F<http://www.zlib.org>.
The primary site for gzip is F<http://www.gzip.org>.
=head1 AUTHOR
This module was written by Paul Marquess, F<pmqs@cpan.org>.
=head1 MODIFICATION HISTORY
See the Changes file.
=head1 COPYRIGHT AND LICENSE
Copyright (c) 2005-2012 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.
|