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1 | # File : Zlib.pm |
2 | # Author : Paul Marquess | |
5993747c PM |
3 | # Created : 12 August 2005 |
4 | # Version : 1.37 | |
f4c6fd49 RGS |
5 | # |
6 | # Copyright (c) 1995-2005 Paul Marquess. All rights reserved. | |
7 | # This program is free software; you can redistribute it and/or | |
8 | # modify it under the same terms as Perl itself. | |
9 | # | |
10 | ||
11 | package Compress::Zlib; | |
12 | ||
13 | require 5.004 ; | |
14 | require Exporter; | |
f4c6fd49 RGS |
15 | use AutoLoader; |
16 | use Carp ; | |
17 | use IO::Handle ; | |
18 | ||
19 | use strict ; | |
8aa25532 RGS |
20 | use warnings ; |
21 | our ($VERSION, @ISA, @EXPORT, $AUTOLOAD); | |
22 | our ($deflateDefault, $deflateParamsDefault, $inflateDefault); | |
f4c6fd49 | 23 | |
5993747c | 24 | $VERSION = "1.37" ; |
f4c6fd49 | 25 | |
06edba15 | 26 | @ISA = qw(Exporter); |
f4c6fd49 RGS |
27 | # Items to export into callers namespace by default. Note: do not export |
28 | # names by default without a very good reason. Use EXPORT_OK instead. | |
29 | # Do not simply export all your public functions/methods/constants. | |
30 | @EXPORT = qw( | |
31 | deflateInit | |
32 | inflateInit | |
33 | ||
34 | compress | |
35 | uncompress | |
36 | ||
37 | gzip gunzip | |
38 | ||
39 | gzopen | |
40 | $gzerrno | |
41 | ||
42 | adler32 | |
43 | crc32 | |
44 | ||
45 | ZLIB_VERSION | |
06edba15 | 46 | ZLIB_VERNUM |
f4c6fd49 RGS |
47 | |
48 | DEF_WBITS | |
49 | OS_CODE | |
50 | ||
51 | MAX_MEM_LEVEL | |
52 | MAX_WBITS | |
53 | ||
54 | Z_ASCII | |
55 | Z_BEST_COMPRESSION | |
56 | Z_BEST_SPEED | |
57 | Z_BINARY | |
58 | Z_BUF_ERROR | |
59 | Z_DATA_ERROR | |
60 | Z_DEFAULT_COMPRESSION | |
61 | Z_DEFAULT_STRATEGY | |
62 | Z_DEFLATED | |
63 | Z_ERRNO | |
64 | Z_FILTERED | |
65 | Z_FINISH | |
66 | Z_FULL_FLUSH | |
67 | Z_HUFFMAN_ONLY | |
68 | Z_MEM_ERROR | |
69 | Z_NEED_DICT | |
70 | Z_NO_COMPRESSION | |
71 | Z_NO_FLUSH | |
72 | Z_NULL | |
73 | Z_OK | |
74 | Z_PARTIAL_FLUSH | |
75 | Z_STREAM_END | |
76 | Z_STREAM_ERROR | |
77 | Z_SYNC_FLUSH | |
78 | Z_UNKNOWN | |
79 | Z_VERSION_ERROR | |
80 | ); | |
81 | ||
82 | ||
83 | ||
84 | sub AUTOLOAD { | |
85 | my($constname); | |
86 | ($constname = $AUTOLOAD) =~ s/.*:://; | |
87 | my ($error, $val) = constant($constname); | |
88 | Carp::croak $error if $error; | |
89 | no strict 'refs'; | |
90 | *{$AUTOLOAD} = sub { $val }; | |
91 | goto &{$AUTOLOAD}; | |
92 | } | |
93 | ||
06edba15 PM |
94 | eval { |
95 | require XSLoader; | |
96 | XSLoader::load('Compress::Zlib', $VERSION); | |
97 | } or do { | |
98 | require DynaLoader; | |
99 | local @ISA = qw(DynaLoader); | |
100 | bootstrap Compress::Zlib $VERSION ; | |
101 | } ; | |
f4c6fd49 RGS |
102 | |
103 | # Preloaded methods go here. | |
104 | ||
105 | sub isaFilehandle($) | |
106 | { | |
107 | my $fh = shift ; | |
108 | ||
109 | return ((UNIVERSAL::isa($fh,'GLOB') or UNIVERSAL::isa(\$fh,'GLOB')) | |
110 | and defined fileno($fh) ) | |
111 | ||
112 | } | |
113 | ||
114 | sub isaFilename($) | |
115 | { | |
116 | my $name = shift ; | |
117 | ||
118 | return (! ref $name and UNIVERSAL::isa(\$name, 'SCALAR')) ; | |
119 | } | |
120 | ||
121 | sub gzopen($$) | |
122 | { | |
123 | my ($file, $mode) = @_ ; | |
124 | ||
125 | if (isaFilehandle $file) { | |
126 | IO::Handle::flush($file) ; | |
127 | my $offset = tell($file) ; | |
128 | gzdopen_(fileno($file), $mode, $offset) ; | |
129 | } | |
130 | elsif (isaFilename $file) { | |
131 | gzopen_($file, $mode) | |
132 | } | |
133 | else { | |
134 | croak "gzopen: file parameter is not a filehandle or filename" | |
135 | } | |
136 | } | |
137 | ||
138 | sub ParseParameters($@) | |
139 | { | |
140 | my ($default, @rest) = @_ ; | |
141 | my (%got) = %$default ; | |
142 | my (@Bad) ; | |
143 | my ($key, $value) ; | |
144 | my $sub = (caller(1))[3] ; | |
145 | my %options = () ; | |
146 | ||
147 | # allow the options to be passed as a hash reference or | |
148 | # as the complete hash. | |
149 | if (@rest == 1) { | |
150 | ||
151 | croak "$sub: parameter is not a reference to a hash" | |
152 | if ref $rest[0] ne "HASH" ; | |
153 | ||
154 | %options = %{ $rest[0] } ; | |
155 | } | |
156 | elsif (@rest >= 2) { | |
157 | my $count = @rest; | |
158 | croak "$sub: Expected even number of parameters, got $count" | |
159 | if @rest % 2 != 0 ; | |
160 | %options = @rest ; | |
161 | } | |
162 | ||
163 | while (($key, $value) = each %options) | |
164 | { | |
165 | $key =~ s/^-// ; | |
166 | ||
167 | if (exists $default->{$key}) | |
168 | { $got{$key} = $value } | |
169 | else | |
170 | { push (@Bad, $key) } | |
171 | } | |
172 | ||
173 | if (@Bad) { | |
174 | my ($bad) = join(", ", @Bad) ; | |
175 | croak "unknown key value(s) @Bad" ; | |
176 | } | |
177 | ||
178 | return \%got ; | |
179 | } | |
180 | ||
181 | $deflateDefault = { | |
182 | 'Level' => Z_DEFAULT_COMPRESSION(), | |
183 | 'Method' => Z_DEFLATED(), | |
184 | 'WindowBits' => MAX_WBITS(), | |
185 | 'MemLevel' => MAX_MEM_LEVEL(), | |
186 | 'Strategy' => Z_DEFAULT_STRATEGY(), | |
187 | 'Bufsize' => 4096, | |
188 | 'Dictionary' => "", | |
189 | } ; | |
190 | ||
191 | $deflateParamsDefault = { | |
192 | 'Level' => undef, | |
193 | 'Strategy' => undef, | |
194 | 'Bufsize' => undef, | |
195 | } ; | |
196 | ||
197 | $inflateDefault = { | |
198 | 'WindowBits' => MAX_WBITS(), | |
199 | 'Bufsize' => 4096, | |
200 | 'Dictionary' => "", | |
201 | } ; | |
202 | ||
203 | ||
204 | sub deflateInit(@) | |
205 | { | |
206 | my ($got) = ParseParameters($deflateDefault, @_) ; | |
8aa25532 | 207 | no warnings; |
f4c6fd49 RGS |
208 | croak "deflateInit: Bufsize must be >= 1, you specified $got->{Bufsize}" |
209 | unless $got->{Bufsize} >= 1; | |
210 | _deflateInit($got->{Level}, $got->{Method}, $got->{WindowBits}, | |
211 | $got->{MemLevel}, $got->{Strategy}, $got->{Bufsize}, | |
212 | $got->{Dictionary}) ; | |
213 | ||
214 | } | |
215 | ||
216 | sub inflateInit(@) | |
217 | { | |
218 | my ($got) = ParseParameters($inflateDefault, @_) ; | |
8aa25532 | 219 | no warnings; |
f4c6fd49 RGS |
220 | croak "inflateInit: Bufsize must be >= 1, you specified $got->{Bufsize}" |
221 | unless $got->{Bufsize} >= 1; | |
222 | _inflateInit($got->{WindowBits}, $got->{Bufsize}, $got->{Dictionary}); | |
223 | ||
224 | } | |
225 | ||
226 | sub Compress::Zlib::deflateStream::deflateParams | |
227 | { | |
228 | my $self = shift ; | |
229 | my ($got) = ParseParameters($deflateParamsDefault, @_) ; | |
230 | croak "deflateParams needs Level and/or Strategy" | |
231 | unless defined $got->{Level} || defined $got->{Strategy}; | |
8aa25532 | 232 | no warnings; |
f4c6fd49 RGS |
233 | croak "deflateParams: Bufsize must be >= 1, you specified $got->{Bufsize}" |
234 | unless !defined $got->{Bufsize} || $got->{Bufsize} >= 1; | |
235 | ||
236 | my $flags = 0; | |
237 | if (defined $got->{Level}) | |
238 | { $flags |= 1 } | |
239 | else | |
240 | { $got->{Level} = 0 } | |
241 | ||
242 | if (defined $got->{Strategy}) | |
243 | { $flags |= 2 } | |
244 | else | |
245 | { $got->{Strategy} = 0 } | |
246 | ||
247 | $got->{Bufsize} = 0 | |
248 | if !defined $got->{Bufsize}; | |
249 | ||
250 | $self->_deflateParams($flags, $got->{Level}, $got->{Strategy}, | |
251 | $got->{Bufsize}); | |
252 | ||
253 | } | |
254 | ||
255 | sub compress($;$) | |
256 | { | |
257 | my ($x, $output, $out, $err, $in) ; | |
258 | ||
259 | if (ref $_[0] ) { | |
260 | $in = $_[0] ; | |
261 | croak "not a scalar reference" unless ref $in eq 'SCALAR' ; | |
262 | } | |
263 | else { | |
264 | $in = \$_[0] ; | |
265 | } | |
266 | ||
267 | my $level = (@_ == 2 ? $_[1] : Z_DEFAULT_COMPRESSION() ); | |
268 | ||
269 | ||
270 | if ( (($x, $err) = deflateInit(Level => $level))[1] == Z_OK()) { | |
271 | ||
272 | ($output, $err) = $x->deflate($in) ; | |
273 | return undef unless $err == Z_OK() ; | |
274 | ||
275 | ($out, $err) = $x->flush() ; | |
276 | return undef unless $err == Z_OK() ; | |
277 | ||
278 | return ($output . $out) ; | |
279 | ||
280 | } | |
281 | ||
282 | return undef ; | |
283 | } | |
284 | ||
285 | ||
286 | sub uncompress($) | |
287 | { | |
288 | my ($x, $output, $err, $in) ; | |
289 | ||
290 | if (ref $_[0] ) { | |
291 | $in = $_[0] ; | |
292 | croak "not a scalar reference" unless ref $in eq 'SCALAR' ; | |
293 | } | |
294 | else { | |
295 | $in = \$_[0] ; | |
296 | } | |
297 | ||
298 | if ( (($x, $err) = inflateInit())[1] == Z_OK()) { | |
299 | ||
300 | ($output, $err) = $x->__unc_inflate($in) ; | |
301 | return undef unless $err == Z_STREAM_END() ; | |
302 | ||
303 | return $output ; | |
304 | } | |
305 | ||
306 | return undef ; | |
307 | } | |
308 | ||
309 | ||
310 | # Constants | |
311 | use constant MAGIC1 => 0x1f ; | |
312 | use constant MAGIC2 => 0x8b ; | |
313 | use constant OSCODE => 3 ; | |
314 | ||
315 | use constant FTEXT => 1 ; | |
316 | use constant FHCRC => 2 ; | |
317 | use constant FEXTRA => 4 ; | |
318 | use constant FNAME => 8 ; | |
319 | use constant FCOMMENT => 16 ; | |
320 | use constant NULL => pack("C", 0) ; | |
321 | use constant RESERVED => 0xE0 ; | |
322 | ||
323 | use constant MIN_HDR_SIZE => 10 ; # minimum gzip header size | |
324 | ||
325 | sub memGzip($) | |
326 | { | |
327 | my $x = deflateInit( | |
328 | -Level => Z_BEST_COMPRESSION(), | |
329 | -WindowBits => - MAX_WBITS(), | |
330 | ) | |
331 | or return undef ; | |
332 | ||
333 | # write a minimal gzip header | |
334 | my(@m); | |
335 | push @m, pack("C" . MIN_HDR_SIZE, | |
336 | MAGIC1, MAGIC2, Z_DEFLATED(), 0,0,0,0,0,0, OSCODE) ; | |
337 | ||
338 | # if the deflation buffer isn't a reference, make it one | |
339 | my $string = (ref $_[0] ? $_[0] : \$_[0]) ; | |
340 | ||
341 | my ($output, $status) = $x->deflate($string) ; | |
342 | push @m, $output ; | |
343 | $status == Z_OK() | |
344 | or return undef ; | |
345 | ||
346 | ($output, $status) = $x->flush() ; | |
347 | push @m, $output ; | |
348 | $status == Z_OK() | |
349 | or return undef ; | |
350 | ||
351 | push @m, pack("V V", crc32($string), $x->total_in()); | |
352 | ||
353 | return join "", @m; | |
354 | } | |
355 | ||
356 | sub _removeGzipHeader($) | |
357 | { | |
358 | my $string = shift ; | |
359 | ||
360 | return Z_DATA_ERROR() | |
361 | if length($$string) < MIN_HDR_SIZE ; | |
362 | ||
363 | my ($magic1, $magic2, $method, $flags, $time, $xflags, $oscode) = | |
364 | unpack ('CCCCVCC', $$string); | |
365 | ||
366 | return Z_DATA_ERROR() | |
367 | unless $magic1 == MAGIC1 and $magic2 == MAGIC2 and | |
368 | $method == Z_DEFLATED() and !($flags & RESERVED()) ; | |
369 | substr($$string, 0, MIN_HDR_SIZE) = '' ; | |
370 | ||
371 | # skip extra field | |
372 | if ($flags & FEXTRA) | |
373 | { | |
374 | return Z_DATA_ERROR() | |
375 | if length($$string) < 2 ; | |
376 | ||
377 | my ($extra_len) = unpack ('v', $$string); | |
378 | $extra_len += 2; | |
379 | return Z_DATA_ERROR() | |
380 | if length($$string) < $extra_len ; | |
381 | ||
382 | substr($$string, 0, $extra_len) = ''; | |
383 | } | |
384 | ||
385 | # skip orig name | |
386 | if ($flags & FNAME) | |
387 | { | |
388 | my $name_end = index ($$string, NULL); | |
389 | return Z_DATA_ERROR() | |
390 | if $name_end == -1 ; | |
391 | substr($$string, 0, $name_end + 1) = ''; | |
392 | } | |
393 | ||
394 | # skip comment | |
395 | if ($flags & FCOMMENT) | |
396 | { | |
397 | my $comment_end = index ($$string, NULL); | |
398 | return Z_DATA_ERROR() | |
399 | if $comment_end == -1 ; | |
400 | substr($$string, 0, $comment_end + 1) = ''; | |
401 | } | |
402 | ||
403 | # skip header crc | |
404 | if ($flags & FHCRC) | |
405 | { | |
406 | return Z_DATA_ERROR() | |
407 | if length ($$string) < 2 ; | |
408 | substr($$string, 0, 2) = ''; | |
409 | } | |
410 | ||
411 | return Z_OK(); | |
412 | } | |
413 | ||
414 | ||
415 | sub memGunzip($) | |
416 | { | |
417 | # if the buffer isn't a reference, make it one | |
418 | my $string = (ref $_[0] ? $_[0] : \$_[0]); | |
419 | ||
420 | _removeGzipHeader($string) == Z_OK() | |
421 | or return undef; | |
422 | ||
423 | my $bufsize = length $$string > 4096 ? length $$string : 4096 ; | |
424 | my $x = inflateInit( -WindowBits => - MAX_WBITS(), | |
425 | -Bufsize => $bufsize) | |
426 | or return undef; | |
427 | my ($output, $status) = $x->inflate($string); | |
428 | return undef | |
429 | unless $status == Z_STREAM_END(); | |
430 | ||
431 | if (length $$string >= 8) | |
432 | { | |
433 | my ($crc, $len) = unpack ("VV", substr($$string, 0, 8)); | |
434 | substr($$string, 0, 8) = ''; | |
435 | return undef | |
436 | unless $len == length($output) and | |
437 | $crc == crc32($output); | |
438 | } | |
439 | else | |
440 | { | |
441 | $$string = ''; | |
442 | } | |
443 | ||
444 | return $output; | |
445 | } | |
446 | ||
447 | # Autoload methods go after __END__, and are processed by the autosplit program. | |
448 | ||
449 | 1; | |
450 | __END__ | |
451 | ||
452 | =cut | |
453 | ||
454 | =head1 NAME | |
455 | ||
456 | Compress::Zlib - Interface to zlib compression library | |
457 | ||
458 | =head1 SYNOPSIS | |
459 | ||
460 | use Compress::Zlib ; | |
461 | ||
462 | ($d, $status) = deflateInit( [OPT] ) ; | |
463 | ($out, $status) = $d->deflate($buffer) ; | |
464 | $status = $d->deflateParams([OPT]) ; | |
465 | ($out, $status) = $d->flush() ; | |
466 | $d->dict_adler() ; | |
467 | $d->total_in() ; | |
468 | $d->total_out() ; | |
469 | $d->msg() ; | |
470 | ||
471 | ($i, $status) = inflateInit( [OPT] ) ; | |
472 | ($out, $status) = $i->inflate($buffer) ; | |
473 | $status = $i->inflateSync($buffer) ; | |
474 | $i->dict_adler() ; | |
475 | $i->total_in() ; | |
476 | $i->total_out() ; | |
477 | $i->msg() ; | |
478 | ||
479 | $dest = compress($source, [$level]) ; | |
480 | $dest = uncompress($source) ; | |
481 | ||
482 | $gz = gzopen($filename or filehandle, $mode) ; | |
483 | $bytesread = $gz->gzread($buffer [,$size]) ; | |
484 | $bytesread = $gz->gzreadline($line) ; | |
485 | $byteswritten = $gz->gzwrite($buffer) ; | |
486 | $status = $gz->gzflush($flush) ; | |
487 | $status = $gz->gzclose() ; | |
488 | $status = $gz->gzeof() ; | |
489 | $status = $gz->gzsetparams($level, $strategy) ; | |
490 | $errstring = $gz->gzerror() ; | |
491 | $gzerrno | |
492 | ||
493 | $dest = Compress::Zlib::memGzip($buffer) ; | |
494 | $dest = Compress::Zlib::memGunzip($buffer) ; | |
495 | ||
496 | $crc = adler32($buffer [,$crc]) ; | |
497 | $crc = crc32($buffer [,$crc]) ; | |
498 | ||
499 | ZLIB_VERSION | |
500 | ||
501 | =head1 DESCRIPTION | |
502 | ||
503 | The I<Compress::Zlib> module provides a Perl interface to the I<zlib> | |
504 | compression library (see L</AUTHOR> for details about where to get | |
505 | I<zlib>). Most of the functionality provided by I<zlib> is available | |
506 | in I<Compress::Zlib>. | |
507 | ||
508 | The module can be split into two general areas of functionality, namely | |
509 | in-memory compression/decompression and read/write access to I<gzip> | |
510 | files. Each of these areas will be discussed separately below. | |
511 | ||
512 | =head1 DEFLATE | |
513 | ||
514 | The interface I<Compress::Zlib> provides to the in-memory I<deflate> | |
515 | (and I<inflate>) functions has been modified to fit into a Perl model. | |
516 | ||
517 | The main difference is that for both inflation and deflation, the Perl | |
518 | interface will I<always> consume the complete input buffer before | |
519 | returning. Also the output buffer returned will be automatically grown | |
520 | to fit the amount of output available. | |
521 | ||
522 | Here is a definition of the interface available: | |
523 | ||
524 | ||
525 | =head2 B<($d, $status) = deflateInit( [OPT] )> | |
526 | ||
527 | Initialises a deflation stream. | |
528 | ||
529 | It combines the features of the I<zlib> functions B<deflateInit>, | |
530 | B<deflateInit2> and B<deflateSetDictionary>. | |
531 | ||
532 | If successful, it will return the initialised deflation stream, B<$d> | |
533 | and B<$status> of C<Z_OK> in a list context. In scalar context it | |
534 | returns the deflation stream, B<$d>, only. | |
535 | ||
536 | If not successful, the returned deflation stream (B<$d>) will be | |
537 | I<undef> and B<$status> will hold the exact I<zlib> error code. | |
538 | ||
539 | The function optionally takes a number of named options specified as | |
540 | C<-Name=E<gt>value> pairs. This allows individual options to be | |
541 | tailored without having to specify them all in the parameter list. | |
542 | ||
543 | For backward compatibility, it is also possible to pass the parameters | |
544 | as a reference to a hash containing the name=>value pairs. | |
545 | ||
546 | The function takes one optional parameter, a reference to a hash. The | |
547 | contents of the hash allow the deflation interface to be tailored. | |
548 | ||
549 | Here is a list of the valid options: | |
550 | ||
551 | =over 5 | |
552 | ||
553 | =item B<-Level> | |
554 | ||
555 | Defines the compression level. Valid values are 0 through 9, | |
556 | C<Z_NO_COMPRESSION>, C<Z_BEST_SPEED>, C<Z_BEST_COMPRESSION>, and | |
557 | C<Z_DEFAULT_COMPRESSION>. | |
558 | ||
559 | The default is C<-Level =E<gt>Z_DEFAULT_COMPRESSION>. | |
560 | ||
561 | =item B<-Method> | |
562 | ||
563 | Defines the compression method. The only valid value at present (and | |
564 | the default) is C<-Method =E<gt>Z_DEFLATED>. | |
565 | ||
566 | =item B<-WindowBits> | |
567 | ||
568 | For a definition of the meaning and valid values for B<WindowBits> | |
569 | refer to the I<zlib> documentation for I<deflateInit2>. | |
570 | ||
571 | Defaults to C<-WindowBits =E<gt>MAX_WBITS>. | |
572 | ||
573 | =item B<-MemLevel> | |
574 | ||
575 | For a definition of the meaning and valid values for B<MemLevel> | |
576 | refer to the I<zlib> documentation for I<deflateInit2>. | |
577 | ||
578 | Defaults to C<-MemLevel =E<gt>MAX_MEM_LEVEL>. | |
579 | ||
580 | =item B<-Strategy> | |
581 | ||
582 | Defines the strategy used to tune the compression. The valid values are | |
583 | C<Z_DEFAULT_STRATEGY>, C<Z_FILTERED> and C<Z_HUFFMAN_ONLY>. | |
584 | ||
585 | The default is C<-Strategy =E<gt>Z_DEFAULT_STRATEGY>. | |
586 | ||
587 | =item B<-Dictionary> | |
588 | ||
589 | When a dictionary is specified I<Compress::Zlib> will automatically | |
590 | call B<deflateSetDictionary> directly after calling B<deflateInit>. The | |
591 | Adler32 value for the dictionary can be obtained by calling the method | |
592 | C<$d->dict_adler()>. | |
593 | ||
594 | The default is no dictionary. | |
595 | ||
596 | =item B<-Bufsize> | |
597 | ||
598 | Sets the initial size for the deflation buffer. If the buffer has to be | |
599 | reallocated to increase the size, it will grow in increments of | |
600 | B<Bufsize>. | |
601 | ||
602 | The default is 4096. | |
603 | ||
604 | =back | |
605 | ||
606 | Here is an example of using the B<deflateInit> optional parameter list | |
607 | to override the default buffer size and compression level. All other | |
608 | options will take their default values. | |
609 | ||
610 | deflateInit( -Bufsize => 300, | |
611 | -Level => Z_BEST_SPEED ) ; | |
612 | ||
613 | ||
614 | =head2 B<($out, $status) = $d-E<gt>deflate($buffer)> | |
615 | ||
616 | ||
617 | Deflates the contents of B<$buffer>. The buffer can either be a scalar | |
618 | or a scalar reference. When finished, B<$buffer> will be | |
619 | completely processed (assuming there were no errors). If the deflation | |
620 | was successful it returns the deflated output, B<$out>, and a status | |
621 | value, B<$status>, of C<Z_OK>. | |
622 | ||
623 | On error, B<$out> will be I<undef> and B<$status> will contain the | |
624 | I<zlib> error code. | |
625 | ||
626 | In a scalar context B<deflate> will return B<$out> only. | |
627 | ||
628 | As with the I<deflate> function in I<zlib>, it is not necessarily the | |
629 | case that any output will be produced by this method. So don't rely on | |
630 | the fact that B<$out> is empty for an error test. | |
631 | ||
632 | ||
633 | =head2 B<($out, $status) = $d-E<gt>flush([flush_type])> | |
634 | ||
635 | Typically used to finish the deflation. Any pending output will be | |
636 | returned via B<$out>. | |
637 | B<$status> will have a value C<Z_OK> if successful. | |
638 | ||
639 | In a scalar context B<flush> will return B<$out> only. | |
640 | ||
641 | Note that flushing can seriously degrade the compression ratio, so it | |
642 | should only be used to terminate a decompression (using C<Z_FINISH>) or | |
643 | when you want to create a I<full flush point> (using C<Z_FULL_FLUSH>). | |
644 | ||
645 | By default the C<flush_type> used is C<Z_FINISH>. Other valid values | |
646 | for C<flush_type> are C<Z_NO_FLUSH>, C<Z_PARTIAL_FLUSH>, C<Z_SYNC_FLUSH> | |
647 | and C<Z_FULL_FLUSH>. It is strongly recommended that you only set the | |
648 | C<flush_type> parameter if you fully understand the implications of | |
649 | what it does. See the C<zlib> documentation for details. | |
650 | ||
651 | =head2 B<$status = $d-E<gt>deflateParams([OPT])> | |
652 | ||
653 | Change settings for the deflate stream C<$d>. | |
654 | ||
655 | The list of the valid options is shown below. Options not specified | |
656 | will remain unchanged. | |
657 | ||
658 | =over 5 | |
659 | ||
660 | =item B<-Level> | |
661 | ||
662 | Defines the compression level. Valid values are 0 through 9, | |
663 | C<Z_NO_COMPRESSION>, C<Z_BEST_SPEED>, C<Z_BEST_COMPRESSION>, and | |
664 | C<Z_DEFAULT_COMPRESSION>. | |
665 | ||
666 | =item B<-Strategy> | |
667 | ||
668 | Defines the strategy used to tune the compression. The valid values are | |
669 | C<Z_DEFAULT_STRATEGY>, C<Z_FILTERED> and C<Z_HUFFMAN_ONLY>. | |
670 | ||
671 | =back | |
672 | ||
673 | =head2 B<$d-E<gt>dict_adler()> | |
674 | ||
675 | Returns the adler32 value for the dictionary. | |
676 | ||
677 | =head2 B<$d-E<gt>msg()> | |
678 | ||
679 | Returns the last error message generated by zlib. | |
680 | ||
681 | =head2 B<$d-E<gt>total_in()> | |
682 | ||
683 | Returns the total number of bytes uncompressed bytes input to deflate. | |
684 | ||
685 | =head2 B<$d-E<gt>total_out()> | |
686 | ||
687 | Returns the total number of compressed bytes output from deflate. | |
688 | ||
689 | =head2 Example | |
690 | ||
691 | ||
692 | Here is a trivial example of using B<deflate>. It simply reads standard | |
693 | input, deflates it and writes it to standard output. | |
694 | ||
695 | use strict ; | |
696 | use warnings ; | |
697 | ||
698 | use Compress::Zlib ; | |
699 | ||
700 | binmode STDIN; | |
701 | binmode STDOUT; | |
702 | my $x = deflateInit() | |
703 | or die "Cannot create a deflation stream\n" ; | |
704 | ||
705 | my ($output, $status) ; | |
706 | while (<>) | |
707 | { | |
708 | ($output, $status) = $x->deflate($_) ; | |
709 | ||
710 | $status == Z_OK | |
711 | or die "deflation failed\n" ; | |
712 | ||
713 | print $output ; | |
714 | } | |
715 | ||
716 | ($output, $status) = $x->flush() ; | |
717 | ||
718 | $status == Z_OK | |
719 | or die "deflation failed\n" ; | |
720 | ||
721 | print $output ; | |
722 | ||
723 | =head1 INFLATE | |
724 | ||
725 | Here is a definition of the interface: | |
726 | ||
727 | ||
728 | =head2 B<($i, $status) = inflateInit()> | |
729 | ||
730 | Initialises an inflation stream. | |
731 | ||
732 | In a list context it returns the inflation stream, B<$i>, and the | |
733 | I<zlib> status code (B<$status>). In a scalar context it returns the | |
734 | inflation stream only. | |
735 | ||
736 | If successful, B<$i> will hold the inflation stream and B<$status> will | |
737 | be C<Z_OK>. | |
738 | ||
739 | If not successful, B<$i> will be I<undef> and B<$status> will hold the | |
740 | I<zlib> error code. | |
741 | ||
742 | The function optionally takes a number of named options specified as | |
743 | C<-Name=E<gt>value> pairs. This allows individual options to be | |
744 | tailored without having to specify them all in the parameter list. | |
745 | ||
746 | For backward compatibility, it is also possible to pass the parameters | |
747 | as a reference to a hash containing the name=>value pairs. | |
748 | ||
749 | The function takes one optional parameter, a reference to a hash. The | |
750 | contents of the hash allow the deflation interface to be tailored. | |
751 | ||
752 | Here is a list of the valid options: | |
753 | ||
754 | =over 5 | |
755 | ||
756 | =item B<-WindowBits> | |
757 | ||
758 | For a definition of the meaning and valid values for B<WindowBits> | |
759 | refer to the I<zlib> documentation for I<inflateInit2>. | |
760 | ||
761 | Defaults to C<-WindowBits =E<gt>MAX_WBITS>. | |
762 | ||
763 | =item B<-Bufsize> | |
764 | ||
765 | Sets the initial size for the inflation buffer. If the buffer has to be | |
766 | reallocated to increase the size, it will grow in increments of | |
767 | B<Bufsize>. | |
768 | ||
769 | Default is 4096. | |
770 | ||
771 | =item B<-Dictionary> | |
772 | ||
773 | The default is no dictionary. | |
774 | ||
775 | =back | |
776 | ||
777 | Here is an example of using the B<inflateInit> optional parameter to | |
778 | override the default buffer size. | |
779 | ||
780 | inflateInit( -Bufsize => 300 ) ; | |
781 | ||
782 | =head2 B<($out, $status) = $i-E<gt>inflate($buffer)> | |
783 | ||
784 | Inflates the complete contents of B<$buffer>. The buffer can either be | |
785 | a scalar or a scalar reference. | |
786 | ||
787 | Returns C<Z_OK> if successful and C<Z_STREAM_END> if the end of the | |
788 | compressed data has been successfully reached. | |
789 | If not successful, B<$out> will be I<undef> and B<$status> will hold | |
790 | the I<zlib> error code. | |
791 | ||
792 | The C<$buffer> parameter is modified by C<inflate>. On completion it | |
793 | will contain what remains of the input buffer after inflation. This | |
794 | means that C<$buffer> will be an empty string when the return status is | |
795 | C<Z_OK>. When the return status is C<Z_STREAM_END> the C<$buffer> | |
796 | parameter will contains what (if anything) was stored in the input | |
797 | buffer after the deflated data stream. | |
798 | ||
799 | This feature is useful when processing a file format that encapsulates | |
800 | a compressed data stream (e.g. gzip, zip). | |
801 | ||
802 | =head2 B<$status = $i-E<gt>inflateSync($buffer)> | |
803 | ||
804 | Scans C<$buffer> until it reaches either a I<full flush point> or the | |
805 | end of the buffer. | |
806 | ||
807 | If a I<full flush point> is found, C<Z_OK> is returned and C<$buffer> | |
808 | will be have all data up to the flush point removed. This can then be | |
809 | passed to the C<deflate> method. | |
810 | ||
811 | Any other return code means that a flush point was not found. If more | |
812 | data is available, C<inflateSync> can be called repeatedly with more | |
813 | compressed data until the flush point is found. | |
814 | ||
815 | ||
816 | =head2 B<$i-E<gt>dict_adler()> | |
817 | ||
818 | Returns the adler32 value for the dictionary. | |
819 | ||
820 | =head2 B<$i-E<gt>msg()> | |
821 | ||
822 | Returns the last error message generated by zlib. | |
823 | ||
824 | =head2 B<$i-E<gt>total_in()> | |
825 | ||
826 | Returns the total number of bytes compressed bytes input to inflate. | |
827 | ||
828 | =head2 B<$i-E<gt>total_out()> | |
829 | ||
830 | Returns the total number of uncompressed bytes output from inflate. | |
831 | ||
832 | =head2 Example | |
833 | ||
834 | Here is an example of using B<inflate>. | |
835 | ||
836 | use strict ; | |
837 | use warnings ; | |
838 | ||
839 | use Compress::Zlib ; | |
840 | ||
841 | my $x = inflateInit() | |
842 | or die "Cannot create a inflation stream\n" ; | |
843 | ||
844 | my $input = '' ; | |
845 | binmode STDIN; | |
846 | binmode STDOUT; | |
847 | ||
848 | my ($output, $status) ; | |
849 | while (read(STDIN, $input, 4096)) | |
850 | { | |
851 | ($output, $status) = $x->inflate(\$input) ; | |
852 | ||
853 | print $output | |
854 | if $status == Z_OK or $status == Z_STREAM_END ; | |
855 | ||
856 | last if $status != Z_OK ; | |
857 | } | |
858 | ||
859 | die "inflation failed\n" | |
860 | unless $status == Z_STREAM_END ; | |
861 | ||
862 | =head1 COMPRESS/UNCOMPRESS | |
863 | ||
864 | Two high-level functions are provided by I<zlib> to perform in-memory | |
bdd93743 PM |
865 | compression/uncompression of RFC1950 data streams. They are called |
866 | B<compress> and B<uncompress>. | |
867 | ||
868 | The two Perl subs defined below provide the equivalent | |
869 | functionality. | |
f4c6fd49 RGS |
870 | |
871 | =over 5 | |
872 | ||
873 | =item B<$dest = compress($source [, $level] ) ;> | |
874 | ||
875 | Compresses B<$source>. If successful it returns the | |
876 | compressed data. Otherwise it returns I<undef>. | |
877 | ||
878 | The source buffer can either be a scalar or a scalar reference. | |
879 | ||
5993747c | 880 | The B<$level> paramter defines the compression level. Valid values are |
f4c6fd49 RGS |
881 | 0 through 9, C<Z_NO_COMPRESSION>, C<Z_BEST_SPEED>, |
882 | C<Z_BEST_COMPRESSION>, and C<Z_DEFAULT_COMPRESSION>. | |
883 | If B<$level> is not specified C<Z_DEFAULT_COMPRESSION> will be used. | |
884 | ||
885 | ||
886 | =item B<$dest = uncompress($source) ;> | |
887 | ||
888 | Uncompresses B<$source>. If successful it returns the uncompressed | |
889 | data. Otherwise it returns I<undef>. | |
890 | ||
891 | The source buffer can either be a scalar or a scalar reference. | |
892 | ||
893 | =back | |
894 | ||
bdd93743 PM |
895 | Please note: the two functions defined above are I<not> compatible with |
896 | the Unix commands of the same name. | |
897 | ||
f4c6fd49 RGS |
898 | =head1 GZIP INTERFACE |
899 | ||
900 | A number of functions are supplied in I<zlib> for reading and writing | |
901 | I<gzip> files. This module provides an interface to most of them. In | |
902 | general the interface provided by this module operates identically to | |
903 | the functions provided by I<zlib>. Any differences are explained | |
904 | below. | |
905 | ||
906 | =over 5 | |
907 | ||
908 | =item B<$gz = gzopen(filename or filehandle, mode)> | |
909 | ||
910 | This function operates identically to the I<zlib> equivalent except | |
911 | that it returns an object which is used to access the other I<gzip> | |
912 | methods. | |
913 | ||
914 | As with the I<zlib> equivalent, the B<mode> parameter is used to | |
915 | specify both whether the file is opened for reading or writing and to | |
916 | optionally specify a a compression level. Refer to the I<zlib> | |
917 | documentation for the exact format of the B<mode> parameter. | |
918 | ||
919 | If a reference to an open filehandle is passed in place of the | |
920 | filename, gzdopen will be called behind the scenes. The third example | |
921 | at the end of this section, I<gzstream>, uses this feature. | |
922 | ||
923 | =item B<$bytesread = $gz-E<gt>gzread($buffer [, $size]) ;> | |
924 | ||
925 | Reads B<$size> bytes from the compressed file into B<$buffer>. If | |
926 | B<$size> is not specified, it will default to 4096. If the scalar | |
927 | B<$buffer> is not large enough, it will be extended automatically. | |
928 | ||
929 | Returns the number of bytes actually read. On EOF it returns 0 and in | |
930 | the case of an error, -1. | |
931 | ||
932 | =item B<$bytesread = $gz-E<gt>gzreadline($line) ;> | |
933 | ||
934 | Reads the next line from the compressed file into B<$line>. | |
935 | ||
936 | Returns the number of bytes actually read. On EOF it returns 0 and in | |
937 | the case of an error, -1. | |
938 | ||
939 | It is legal to intermix calls to B<gzread> and B<gzreadline>. | |
940 | ||
941 | At this time B<gzreadline> ignores the variable C<$/> | |
942 | (C<$INPUT_RECORD_SEPARATOR> or C<$RS> when C<English> is in use). The | |
943 | end of a line is denoted by the C character C<'\n'>. | |
944 | ||
945 | =item B<$byteswritten = $gz-E<gt>gzwrite($buffer) ;> | |
946 | ||
947 | Writes the contents of B<$buffer> to the compressed file. Returns the | |
948 | number of bytes actually written, or 0 on error. | |
949 | ||
950 | =item B<$status = $gz-E<gt>gzflush($flush) ;> | |
951 | ||
952 | Flushes all pending output to the compressed file. | |
953 | Works identically to the I<zlib> function it interfaces to. Note that | |
954 | the use of B<gzflush> can degrade compression. | |
955 | ||
956 | Returns C<Z_OK> if B<$flush> is C<Z_FINISH> and all output could be | |
957 | flushed. Otherwise the zlib error code is returned. | |
958 | ||
959 | Refer to the I<zlib> documentation for the valid values of B<$flush>. | |
960 | ||
961 | =item B<$status = $gz-E<gt>gzeof() ;> | |
962 | ||
963 | Returns 1 if the end of file has been detected while reading the input | |
964 | file, otherwise returns 0. | |
965 | ||
966 | =item B<$gz-E<gt>gzclose> | |
967 | ||
968 | Closes the compressed file. Any pending data is flushed to the file | |
969 | before it is closed. | |
970 | ||
971 | =item B<$gz-E<gt>gzsetparams($level, $strategy> | |
972 | ||
973 | Change settings for the deflate stream C<$gz>. | |
974 | ||
975 | The list of the valid options is shown below. Options not specified | |
976 | will remain unchanged. | |
977 | ||
978 | Note: This method is only available if you are running zlib 1.0.6 or better. | |
979 | ||
980 | =over 5 | |
981 | ||
982 | =item B<$level> | |
983 | ||
984 | Defines the compression level. Valid values are 0 through 9, | |
985 | C<Z_NO_COMPRESSION>, C<Z_BEST_SPEED>, C<Z_BEST_COMPRESSION>, and | |
986 | C<Z_DEFAULT_COMPRESSION>. | |
987 | ||
988 | =item B<$strategy> | |
989 | ||
990 | Defines the strategy used to tune the compression. The valid values are | |
991 | C<Z_DEFAULT_STRATEGY>, C<Z_FILTERED> and C<Z_HUFFMAN_ONLY>. | |
992 | ||
993 | =back | |
994 | ||
995 | =item B<$gz-E<gt>gzerror> | |
996 | ||
997 | Returns the I<zlib> error message or number for the last operation | |
998 | associated with B<$gz>. The return value will be the I<zlib> error | |
999 | number when used in a numeric context and the I<zlib> error message | |
1000 | when used in a string context. The I<zlib> error number constants, | |
1001 | shown below, are available for use. | |
1002 | ||
1003 | Z_OK | |
1004 | Z_STREAM_END | |
1005 | Z_ERRNO | |
1006 | Z_STREAM_ERROR | |
1007 | Z_DATA_ERROR | |
1008 | Z_MEM_ERROR | |
1009 | Z_BUF_ERROR | |
1010 | ||
1011 | =item B<$gzerrno> | |
1012 | ||
1013 | The B<$gzerrno> scalar holds the error code associated with the most | |
1014 | recent I<gzip> routine. Note that unlike B<gzerror()>, the error is | |
1015 | I<not> associated with a particular file. | |
1016 | ||
1017 | As with B<gzerror()> it returns an error number in numeric context and | |
1018 | an error message in string context. Unlike B<gzerror()> though, the | |
1019 | error message will correspond to the I<zlib> message when the error is | |
1020 | associated with I<zlib> itself, or the UNIX error message when it is | |
1021 | not (i.e. I<zlib> returned C<Z_ERRORNO>). | |
1022 | ||
1023 | As there is an overlap between the error numbers used by I<zlib> and | |
1024 | UNIX, B<$gzerrno> should only be used to check for the presence of | |
1025 | I<an> error in numeric context. Use B<gzerror()> to check for specific | |
1026 | I<zlib> errors. The I<gzcat> example below shows how the variable can | |
1027 | be used safely. | |
1028 | ||
1029 | =back | |
1030 | ||
1031 | ||
1032 | =head2 Examples | |
1033 | ||
1034 | Here is an example script which uses the interface. It implements a | |
1035 | I<gzcat> function. | |
1036 | ||
1037 | use strict ; | |
1038 | use warnings ; | |
1039 | ||
1040 | use Compress::Zlib ; | |
1041 | ||
1042 | die "Usage: gzcat file...\n" | |
1043 | unless @ARGV ; | |
1044 | ||
1045 | my $file ; | |
1046 | ||
1047 | foreach $file (@ARGV) { | |
1048 | my $buffer ; | |
1049 | ||
1050 | my $gz = gzopen($file, "rb") | |
1051 | or die "Cannot open $file: $gzerrno\n" ; | |
1052 | ||
1053 | print $buffer while $gz->gzread($buffer) > 0 ; | |
1054 | ||
1055 | die "Error reading from $file: $gzerrno" . ($gzerrno+0) . "\n" | |
1056 | if $gzerrno != Z_STREAM_END ; | |
1057 | ||
1058 | $gz->gzclose() ; | |
1059 | } | |
1060 | ||
1061 | Below is a script which makes use of B<gzreadline>. It implements a | |
1062 | very simple I<grep> like script. | |
1063 | ||
1064 | use strict ; | |
1065 | use warnings ; | |
1066 | ||
1067 | use Compress::Zlib ; | |
1068 | ||
1069 | die "Usage: gzgrep pattern file...\n" | |
1070 | unless @ARGV >= 2; | |
1071 | ||
1072 | my $pattern = shift ; | |
1073 | ||
1074 | my $file ; | |
1075 | ||
1076 | foreach $file (@ARGV) { | |
1077 | my $gz = gzopen($file, "rb") | |
1078 | or die "Cannot open $file: $gzerrno\n" ; | |
1079 | ||
1080 | while ($gz->gzreadline($_) > 0) { | |
1081 | print if /$pattern/ ; | |
1082 | } | |
1083 | ||
1084 | die "Error reading from $file: $gzerrno\n" | |
1085 | if $gzerrno != Z_STREAM_END ; | |
1086 | ||
1087 | $gz->gzclose() ; | |
1088 | } | |
1089 | ||
1090 | This script, I<gzstream>, does the opposite of the I<gzcat> script | |
1091 | above. It reads from standard input and writes a gzip file to standard | |
1092 | output. | |
1093 | ||
1094 | use strict ; | |
1095 | use warnings ; | |
1096 | ||
1097 | use Compress::Zlib ; | |
1098 | ||
1099 | binmode STDOUT; # gzopen only sets it on the fd | |
1100 | ||
1101 | my $gz = gzopen(\*STDOUT, "wb") | |
1102 | or die "Cannot open stdout: $gzerrno\n" ; | |
1103 | ||
1104 | while (<>) { | |
1105 | $gz->gzwrite($_) | |
1106 | or die "error writing: $gzerrno\n" ; | |
1107 | } | |
1108 | ||
1109 | $gz->gzclose ; | |
1110 | ||
1111 | =head2 Compress::Zlib::memGzip | |
1112 | ||
1113 | This function is used to create an in-memory gzip file. | |
1114 | It creates a minimal gzip header. | |
1115 | ||
1116 | $dest = Compress::Zlib::memGzip($buffer) ; | |
1117 | ||
1118 | If successful, it returns the in-memory gzip file, otherwise it returns | |
1119 | undef. | |
1120 | ||
1121 | The buffer parameter can either be a scalar or a scalar reference. | |
1122 | ||
1123 | =head2 Compress::Zlib::memGunzip | |
1124 | ||
1125 | This function is used to uncompress an in-memory gzip file. | |
1126 | ||
1127 | $dest = Compress::Zlib::memGunzip($buffer) ; | |
1128 | ||
1129 | If successful, it returns the uncompressed gzip file, otherwise it | |
1130 | returns undef. | |
1131 | ||
1132 | The buffer parameter can either be a scalar or a scalar reference. The | |
1133 | contents of the buffer parameter are destroyed after calling this | |
1134 | function. | |
1135 | ||
1136 | =head1 CHECKSUM FUNCTIONS | |
1137 | ||
1138 | Two functions are provided by I<zlib> to calculate a checksum. For the | |
1139 | Perl interface, the order of the two parameters in both functions has | |
1140 | been reversed. This allows both running checksums and one off | |
1141 | calculations to be done. | |
1142 | ||
1143 | $crc = adler32($buffer [,$crc]) ; | |
1144 | $crc = crc32($buffer [,$crc]) ; | |
1145 | ||
1146 | The buffer parameters can either be a scalar or a scalar reference. | |
1147 | ||
1148 | If the $crc parameters is C<undef>, the crc value will be reset. | |
1149 | ||
5993747c PM |
1150 | =head1 FAQ |
1151 | ||
1152 | =head2 Compatibility with Unix compress/uncompress. | |
1153 | ||
1154 | Although C<Compress::Zlib> has a pair of functions called C<compress> | |
1155 | and C<uncompress>, they are I<not> the same as the Unix programs of the | |
1156 | same name. The C<Compress::Zlib> library is not compatable with Unix | |
1157 | C<compress>. | |
1158 | ||
1159 | If you have the C<uncompress> program available, you can use this to | |
1160 | read compressed files | |
1161 | ||
1162 | open F, "uncompress -c $filename |"; | |
1163 | while (<F>) | |
1164 | { | |
1165 | ... | |
1166 | ||
1167 | If you have the C<gunzip> program available, you can use this to read | |
1168 | compressed files | |
1169 | ||
1170 | open F, "gunzip -c $filename |"; | |
1171 | while (<F>) | |
1172 | { | |
1173 | ... | |
1174 | ||
1175 | and this to write compress files if you have the C<compress> program | |
1176 | available | |
1177 | ||
1178 | open F, "| compress -c $filename "; | |
1179 | print F "data"; | |
1180 | ... | |
1181 | close F ; | |
1182 | ||
1183 | =head2 Accessing .tar.Z files | |
1184 | ||
1185 | The C<Archive::Tar> module can optionally use C<Compress::Zlib> (via | |
1186 | the C<IO::Zlib> module) to access tar files that have been compressed | |
1187 | with C<gzip>. Unfortunately tar files compressed with the Unix C<compress> | |
1188 | utility cannot be read by C<Compress::Zlib> and so cannot be directly | |
1189 | accesses by C<Archive::Tar>. | |
1190 | ||
1191 | If the C<uncompress> or C<gunzip> programs are available, you can use | |
1192 | one of these workarounds to read C<.tar.Z> files from C<Archive::Tar> | |
1193 | ||
1194 | Firstly with C<uncompress> | |
1195 | ||
1196 | use strict; | |
1197 | use warnings; | |
1198 | use Archive::Tar; | |
1199 | ||
1200 | open F, "uncompress -c $filename |"; | |
1201 | my $tar = Archive::Tar->new(*F); | |
1202 | ... | |
1203 | ||
1204 | and this with C<gunzip> | |
1205 | ||
1206 | use strict; | |
1207 | use warnings; | |
1208 | use Archive::Tar; | |
1209 | ||
1210 | open F, "gunzip -c $filename |"; | |
1211 | my $tar = Archive::Tar->new(*F); | |
1212 | ... | |
1213 | ||
1214 | Similarly, if the C<compress> program is available, you can use this to | |
1215 | write a C<.tar.Z> file | |
1216 | ||
1217 | use strict; | |
1218 | use warnings; | |
1219 | use Archive::Tar; | |
1220 | use IO::File; | |
1221 | ||
1222 | my $fh = newIO::File "| compress -c >$filename"; | |
1223 | my $tar = Archive::Tar->new(); | |
1224 | ... | |
1225 | $tar->write($fh); | |
1226 | $fh->close ; | |
1227 | ||
1228 | =head2 Accessing ZIP Files | |
f4c6fd49 RGS |
1229 | |
1230 | Although it is possible to use this module to access .zip files, there | |
1231 | is a module on CPAN that will do all the hard work for you. Check out | |
1232 | ||
1233 | http://www.cpan.org/modules/by-module/Archive/Archive-Zip-*.tar.gz | |
1234 | ||
1235 | Assuming you don't want to use this module to access zip files there | |
1236 | are a number of undocumented features in the zlib library you need to | |
1237 | be aware of. | |
1238 | ||
1239 | =over 5 | |
1240 | ||
1241 | =item 1. | |
1242 | ||
1243 | When calling B<inflateInit> or B<deflateInit> the B<WindowBits> parameter | |
1244 | must be set to C<-MAX_WBITS>. This disables the creation of the zlib | |
1245 | header. | |
1246 | ||
1247 | =item 2. | |
1248 | ||
1249 | The zlib function B<inflate>, and so the B<inflate> method supplied in | |
1250 | this module, assume that there is at least one trailing byte after the | |
1251 | compressed data stream. Normally this isn't a problem because both | |
1252 | the gzip and zip file formats will guarantee that there is data directly | |
1253 | after the compressed data stream. | |
1254 | ||
1255 | =back | |
1256 | ||
1257 | =head1 CONSTANTS | |
1258 | ||
1259 | All the I<zlib> constants are automatically imported when you make use | |
1260 | of I<Compress::Zlib>. | |
1261 | ||
1262 | =head1 AUTHOR | |
1263 | ||
1264 | The I<Compress::Zlib> module was written by Paul Marquess, | |
1265 | F<pmqs@cpan.org>. The latest copy of the module can be | |
1266 | found on CPAN in F<modules/by-module/Compress/Compress-Zlib-x.x.tar.gz>. | |
1267 | ||
1268 | The primary site for the I<zlib> compression library is | |
1269 | F<http://www.zlib.org>. | |
1270 | ||
1271 | =head1 MODIFICATION HISTORY | |
1272 | ||
1273 | See the Changes file. |