IO::Uncompress::Inflate(3pm)

1IO::Uncompress::Inflate(P3eprml)Programmers Reference GIuOi:d:eUncompress::Inflate(3pm)
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4

NAME

6       IO::Uncompress::Inflate - Read RFC 1950 files/buffers
7

SYNOPSIS

9           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
10
11           my $status = inflate $input => $output [,OPTS]
12               or die "inflate failed: $InflateError\n";
13
14           my $z = new IO::Uncompress::Inflate $input [OPTS]
15               or die "inflate failed: $InflateError\n";
16
17           $status = $z->read($buffer)
18           $status = $z->read($buffer, $length)
19           $status = $z->read($buffer, $length, $offset)
20           $line = $z->getline()
21           $char = $z->getc()
22           $char = $z->ungetc()
23           $char = $z->opened()
24
25           $status = $z->inflateSync()
26
27           $data = $z->trailingData()
28           $status = $z->nextStream()
29           $data = $z->getHeaderInfo()
30           $z->tell()
31           $z->seek($position, $whence)
32           $z->binmode()
33           $z->fileno()
34           $z->eof()
35           $z->close()
36
37           $InflateError ;
38
39           # IO::File mode
40
41           <$z>
42           read($z, $buffer);
43           read($z, $buffer, $length);
44           read($z, $buffer, $length, $offset);
45           tell($z)
46           seek($z, $position, $whence)
47           binmode($z)
48           fileno($z)
49           eof($z)
50           close($z)
51

DESCRIPTION

53       This module provides a Perl interface that allows the reading of
54       files/buffers that conform to RFC 1950.
55
56       For writing RFC 1950 files/buffers, see the companion module
57       IO::Compress::Deflate.
58

Functional Interface

60       A top-level function, "inflate", is provided to carry out "one-shot"
61       uncompression between buffers and/or files. For finer control over the
62       uncompression process, see the "OO Interface" section.
63
64           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
65
66           inflate $input => $output [,OPTS]
67               or die "inflate failed: $InflateError\n";
68
69       The functional interface needs Perl5.005 or better.
70
71   inflate $input => $output [, OPTS]
72       "inflate" expects at least two parameters, $input and $output.
73
74       The $input parameter
75
76       The parameter, $input, is used to define the source of the compressed
77       data.
78
79       It can take one of the following forms:
80
81       A filename
82            If the $input parameter is a simple scalar, it is assumed to be a
83            filename. This file will be opened for reading and the input data
84            will be read from it.
85
86       A filehandle
87            If the $input parameter is a filehandle, the input data will be
88            read from it.  The string '-' can be used as an alias for standard
89            input.
90
91       A scalar reference
92            If $input is a scalar reference, the input data will be read from
93            $$input.
94
95       An array reference
96            If $input is an array reference, each element in the array must be
97            a filename.
98
99            The input data will be read from each file in turn.
100
101            The complete array will be walked to ensure that it only contains
102            valid filenames before any data is uncompressed.
103
104       An Input FileGlob string
105            If $input is a string that is delimited by the characters "<" and
106            ">" "inflate" will assume that it is an input fileglob string. The
107            input is the list of files that match the fileglob.
108
109            If the fileglob does not match any files ...
110
111            See File::GlobMapper for more details.
112
113       If the $input parameter is any other type, "undef" will be returned.
114
115       The $output parameter
116
117       The parameter $output is used to control the destination of the
118       uncompressed data. This parameter can take one of these forms.
119
120       A filename
121            If the $output parameter is a simple scalar, it is assumed to be a
122            filename.  This file will be opened for writing and the
123            uncompressed data will be written to it.
124
125       A filehandle
126            If the $output parameter is a filehandle, the uncompressed data
127            will be written to it.  The string '-' can be used as an alias for
128            standard output.
129
130       A scalar reference
131            If $output is a scalar reference, the uncompressed data will be
132            stored in $$output.
133
134       An Array Reference
135            If $output is an array reference, the uncompressed data will be
136            pushed onto the array.
137
138       An Output FileGlob
139            If $output is a string that is delimited by the characters "<" and
140            ">" "inflate" will assume that it is an output fileglob string.
141            The output is the list of files that match the fileglob.
142
143            When $output is an fileglob string, $input must also be a fileglob
144            string. Anything else is an error.
145
146       If the $output parameter is any other type, "undef" will be returned.
147
148   Notes
149       When $input maps to multiple compressed files/buffers and $output is a
150       single file/buffer, after uncompression $output will contain a
151       concatenation of all the uncompressed data from each of the input
152       files/buffers.
153
154   Optional Parameters
155       Unless specified below, the optional parameters for "inflate", "OPTS",
156       are the same as those used with the OO interface defined in the
157       "Constructor Options" section below.
158
159       "AutoClose => 0|1"
160            This option applies to any input or output data streams to
161            "inflate" that are filehandles.
162
163            If "AutoClose" is specified, and the value is true, it will result
164            in all input and/or output filehandles being closed once "inflate"
165            has completed.
166
167            This parameter defaults to 0.
168
169       "BinModeOut => 0|1"
170            When writing to a file or filehandle, set "binmode" before writing
171            to the file.
172
173            Defaults to 0.
174
175       "Append => 0|1"
176            The behaviour of this option is dependent on the type of output
177            data stream.
178
179            ·    A Buffer
180
181                 If "Append" is enabled, all uncompressed data will be append
182                 to the end of the output buffer. Otherwise the output buffer
183                 will be cleared before any uncompressed data is written to
184                 it.
185
186            ·    A Filename
187
188                 If "Append" is enabled, the file will be opened in append
189                 mode. Otherwise the contents of the file, if any, will be
190                 truncated before any uncompressed data is written to it.
191
192            ·    A Filehandle
193
194                 If "Append" is enabled, the filehandle will be positioned to
195                 the end of the file via a call to "seek" before any
196                 uncompressed data is written to it.  Otherwise the file
197                 pointer will not be moved.
198
199            When "Append" is specified, and set to true, it will append all
200            uncompressed data to the output data stream.
201
202            So when the output is a filehandle it will carry out a seek to the
203            eof before writing any uncompressed data. If the output is a
204            filename, it will be opened for appending. If the output is a
205            buffer, all uncompressed data will be appened to the existing
206            buffer.
207
208            Conversely when "Append" is not specified, or it is present and is
209            set to false, it will operate as follows.
210
211            When the output is a filename, it will truncate the contents of
212            the file before writing any uncompressed data. If the output is a
213            filehandle its position will not be changed. If the output is a
214            buffer, it will be wiped before any uncompressed data is output.
215
216            Defaults to 0.
217
218       "MultiStream => 0|1"
219            If the input file/buffer contains multiple compressed data
220            streams, this option will uncompress the whole lot as a single
221            data stream.
222
223            Defaults to 0.
224
225       "TrailingData => $scalar"
226            Returns the data, if any, that is present immediately after the
227            compressed data stream once uncompression is complete.
228
229            This option can be used when there is useful information
230            immediately following the compressed data stream, and you don't
231            know the length of the compressed data stream.
232
233            If the input is a buffer, "trailingData" will return everything
234            from the end of the compressed data stream to the end of the
235            buffer.
236
237            If the input is a filehandle, "trailingData" will return the data
238            that is left in the filehandle input buffer once the end of the
239            compressed data stream has been reached. You can then use the
240            filehandle to read the rest of the input file.
241
242            Don't bother using "trailingData" if the input is a filename.
243
244            If you know the length of the compressed data stream before you
245            start uncompressing, you can avoid having to use "trailingData" by
246            setting the "InputLength" option.
247
248   Examples
249       To read the contents of the file "file1.txt.1950" and write the
250       uncompressed data to the file "file1.txt".
251
252           use strict ;
253           use warnings ;
254           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
255
256           my $input = "file1.txt.1950";
257           my $output = "file1.txt";
258           inflate $input => $output
259               or die "inflate failed: $InflateError\n";
260
261       To read from an existing Perl filehandle, $input, and write the
262       uncompressed data to a buffer, $buffer.
263
264           use strict ;
265           use warnings ;
266           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
267           use IO::File ;
268
269           my $input = new IO::File "<file1.txt.1950"
270               or die "Cannot open 'file1.txt.1950': $!\n" ;
271           my $buffer ;
272           inflate $input => \$buffer
273               or die "inflate failed: $InflateError\n";
274
275       To uncompress all files in the directory "/my/home" that match
276       "*.txt.1950" and store the compressed data in the same directory
277
278           use strict ;
279           use warnings ;
280           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
281
282           inflate '</my/home/*.txt.1950>' => '</my/home/#1.txt>'
283               or die "inflate failed: $InflateError\n";
284
285       and if you want to compress each file one at a time, this will do the
286       trick
287
288           use strict ;
289           use warnings ;
290           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
291
292           for my $input ( glob "/my/home/*.txt.1950" )
293           {
294               my $output = $input;
295               $output =~ s/.1950// ;
296               inflate $input => $output
297                   or die "Error compressing '$input': $InflateError\n";
298           }
299

OO Interface

301   Constructor
302       The format of the constructor for IO::Uncompress::Inflate is shown
303       below
304
305           my $z = new IO::Uncompress::Inflate $input [OPTS]
306               or die "IO::Uncompress::Inflate failed: $InflateError\n";
307
308       Returns an "IO::Uncompress::Inflate" object on success and undef on
309       failure.  The variable $InflateError will contain an error message on
310       failure.
311
312       If you are running Perl 5.005 or better the object, $z, returned from
313       IO::Uncompress::Inflate can be used exactly like an IO::File
314       filehandle.  This means that all normal input file operations can be
315       carried out with $z.  For example, to read a line from a compressed
316       file/buffer you can use either of these forms
317
318           $line = $z->getline();
319           $line = <$z>;
320
321       The mandatory parameter $input is used to determine the source of the
322       compressed data. This parameter can take one of three forms.
323
324       A filename
325            If the $input parameter is a scalar, it is assumed to be a
326            filename. This file will be opened for reading and the compressed
327            data will be read from it.
328
329       A filehandle
330            If the $input parameter is a filehandle, the compressed data will
331            be read from it.  The string '-' can be used as an alias for
332            standard input.
333
334       A scalar reference
335            If $input is a scalar reference, the compressed data will be read
336            from $$output.
337
338   Constructor Options
339       The option names defined below are case insensitive and can be
340       optionally prefixed by a '-'.  So all of the following are valid
341
342           -AutoClose
343           -autoclose
344           AUTOCLOSE
345           autoclose
346
347       OPTS is a combination of the following options:
348
349       "AutoClose => 0|1"
350            This option is only valid when the $input parameter is a
351            filehandle. If specified, and the value is true, it will result in
352            the file being closed once either the "close" method is called or
353            the IO::Uncompress::Inflate object is destroyed.
354
355            This parameter defaults to 0.
356
357       "MultiStream => 0|1"
358            Allows multiple concatenated compressed streams to be treated as a
359            single compressed stream. Decompression will stop once either the
360            end of the file/buffer is reached, an error is encountered
361            (premature eof, corrupt compressed data) or the end of a stream is
362            not immediately followed by the start of another stream.
363
364            This parameter defaults to 0.
365
366       "Prime => $string"
367            This option will uncompress the contents of $string before
368            processing the input file/buffer.
369
370            This option can be useful when the compressed data is embedded in
371            another file/data structure and it is not possible to work out
372            where the compressed data begins without having to read the first
373            few bytes. If this is the case, the uncompression can be primed
374            with these bytes using this option.
375
376       "Transparent => 0|1"
377            If this option is set and the input file/buffer is not compressed
378            data, the module will allow reading of it anyway.
379
380            In addition, if the input file/buffer does contain compressed data
381            and there is non-compressed data immediately following it, setting
382            this option will make this module treat the whole file/bufffer as
383            a single data stream.
384
385            This option defaults to 1.
386
387       "BlockSize => $num"
388            When reading the compressed input data, IO::Uncompress::Inflate
389            will read it in blocks of $num bytes.
390
391            This option defaults to 4096.
392
393       "InputLength => $size"
394            When present this option will limit the number of compressed bytes
395            read from the input file/buffer to $size. This option can be used
396            in the situation where there is useful data directly after the
397            compressed data stream and you know beforehand the exact length of
398            the compressed data stream.
399
400            This option is mostly used when reading from a filehandle, in
401            which case the file pointer will be left pointing to the first
402            byte directly after the compressed data stream.
403
404            This option defaults to off.
405
406       "Append => 0|1"
407            This option controls what the "read" method does with uncompressed
408            data.
409
410            If set to 1, all uncompressed data will be appended to the output
411            parameter of the "read" method.
412
413            If set to 0, the contents of the output parameter of the "read"
414            method will be overwritten by the uncompressed data.
415
416            Defaults to 0.
417
418       "Strict => 0|1"
419            This option controls whether the extra checks defined below are
420            used when carrying out the decompression. When Strict is on, the
421            extra tests are carried out, when Strict is off they are not.
422
423            The default for this option is off.
424
425            1.   The ADLER32 checksum field must be present.
426
427            2.   The value of the ADLER32 field read must match the adler32
428                 value of the uncompressed data actually contained in the
429                 file.
430
431   Examples
432       TODO
433

Methods

435   read
436       Usage is
437
438           $status = $z->read($buffer)
439
440       Reads a block of compressed data (the size the the compressed block is
441       determined by the "Buffer" option in the constructor), uncompresses it
442       and writes any uncompressed data into $buffer. If the "Append"
443       parameter is set in the constructor, the uncompressed data will be
444       appended to the $buffer parameter. Otherwise $buffer will be
445       overwritten.
446
447       Returns the number of uncompressed bytes written to $buffer, zero if
448       eof or a negative number on error.
449
450   read
451       Usage is
452
453           $status = $z->read($buffer, $length)
454           $status = $z->read($buffer, $length, $offset)
455
456           $status = read($z, $buffer, $length)
457           $status = read($z, $buffer, $length, $offset)
458
459       Attempt to read $length bytes of uncompressed data into $buffer.
460
461       The main difference between this form of the "read" method and the
462       previous one, is that this one will attempt to return exactly $length
463       bytes. The only circumstances that this function will not is if end-of-
464       file or an IO error is encountered.
465
466       Returns the number of uncompressed bytes written to $buffer, zero if
467       eof or a negative number on error.
468
469   getline
470       Usage is
471
472           $line = $z->getline()
473           $line = <$z>
474
475       Reads a single line.
476
477       This method fully supports the use of of the variable $/ (or
478       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
479       what constitutes an end of line. Paragraph mode, record mode and file
480       slurp mode are all supported.
481
482   getc
483       Usage is
484
485           $char = $z->getc()
486
487       Read a single character.
488
489   ungetc
490       Usage is
491
492           $char = $z->ungetc($string)
493
494   inflateSync
495       Usage is
496
497           $status = $z->inflateSync()
498
499       TODO
500
501   getHeaderInfo
502       Usage is
503
504           $hdr  = $z->getHeaderInfo();
505           @hdrs = $z->getHeaderInfo();
506
507       This method returns either a hash reference (in scalar context) or a
508       list or hash references (in array context) that contains information
509       about each of the header fields in the compressed data stream(s).
510
511   tell
512       Usage is
513
514           $z->tell()
515           tell $z
516
517       Returns the uncompressed file offset.
518
519   eof
520       Usage is
521
522           $z->eof();
523           eof($z);
524
525       Returns true if the end of the compressed input stream has been
526       reached.
527
528   seek
529           $z->seek($position, $whence);
530           seek($z, $position, $whence);
531
532       Provides a sub-set of the "seek" functionality, with the restriction
533       that it is only legal to seek forward in the input file/buffer.  It is
534       a fatal error to attempt to seek backward.
535
536       The $whence parameter takes one the usual values, namely SEEK_SET,
537       SEEK_CUR or SEEK_END.
538
539       Returns 1 on success, 0 on failure.
540
541   binmode
542       Usage is
543
544           $z->binmode
545           binmode $z ;
546
547       This is a noop provided for completeness.
548
549   opened
550           $z->opened()
551
552       Returns true if the object currently refers to a opened file/buffer.
553
554   autoflush
555           my $prev = $z->autoflush()
556           my $prev = $z->autoflush(EXPR)
557
558       If the $z object is associated with a file or a filehandle, this method
559       returns the current autoflush setting for the underlying filehandle. If
560       "EXPR" is present, and is non-zero, it will enable flushing after every
561       write/print operation.
562
563       If $z is associated with a buffer, this method has no effect and always
564       returns "undef".
565
566       Note that the special variable $| cannot be used to set or retrieve the
567       autoflush setting.
568
569   input_line_number
570           $z->input_line_number()
571           $z->input_line_number(EXPR)
572
573       Returns the current uncompressed line number. If "EXPR" is present it
574       has the effect of setting the line number. Note that setting the line
575       number does not change the current position within the file/buffer
576       being read.
577
578       The contents of $/ are used to to determine what constitutes a line
579       terminator.
580
581   fileno
582           $z->fileno()
583           fileno($z)
584
585       If the $z object is associated with a file or a filehandle, "fileno"
586       will return the underlying file descriptor. Once the "close" method is
587       called "fileno" will return "undef".
588
589       If the $z object is is associated with a buffer, this method will
590       return "undef".
591
592   close
593           $z->close() ;
594           close $z ;
595
596       Closes the output file/buffer.
597
598       For most versions of Perl this method will be automatically invoked if
599       the IO::Uncompress::Inflate object is destroyed (either explicitly or
600       by the variable with the reference to the object going out of scope).
601       The exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In
602       these cases, the "close" method will be called automatically, but not
603       until global destruction of all live objects when the program is
604       terminating.
605
606       Therefore, if you want your scripts to be able to run on all versions
607       of Perl, you should call "close" explicitly and not rely on automatic
608       closing.
609
610       Returns true on success, otherwise 0.
611
612       If the "AutoClose" option has been enabled when the
613       IO::Uncompress::Inflate object was created, and the object is
614       associated with a file, the underlying file will also be closed.
615
616   nextStream
617       Usage is
618
619           my $status = $z->nextStream();
620
621       Skips to the next compressed data stream in the input file/buffer. If a
622       new compressed data stream is found, the eof marker will be cleared and
623       $.  will be reset to 0.
624
625       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
626       error was encountered.
627
628   trailingData
629       Usage is
630
631           my $data = $z->trailingData();
632
633       Returns the data, if any, that is present immediately after the
634       compressed data stream once uncompression is complete. It only makes
635       sense to call this method once the end of the compressed data stream
636       has been encountered.
637
638       This option can be used when there is useful information immediately
639       following the compressed data stream, and you don't know the length of
640       the compressed data stream.
641
642       If the input is a buffer, "trailingData" will return everything from
643       the end of the compressed data stream to the end of the buffer.
644
645       If the input is a filehandle, "trailingData" will return the data that
646       is left in the filehandle input buffer once the end of the compressed
647       data stream has been reached. You can then use the filehandle to read
648       the rest of the input file.
649
650       Don't bother using "trailingData" if the input is a filename.
651
652       If you know the length of the compressed data stream before you start
653       uncompressing, you can avoid having to use "trailingData" by setting
654       the "InputLength" option in the constructor.
655

Importing

657       No symbolic constants are required by this IO::Uncompress::Inflate at
658       present.
659
660       :all Imports "inflate" and $InflateError.  Same as doing this
661
662                use IO::Uncompress::Inflate qw(inflate $InflateError) ;
663

EXAMPLES

665   Working with Net::FTP
666       See IO::Uncompress::Inflate::FAQ
667

AUTHOR

694       This module was written by Paul Marquess, pmqs@cpan.org.
695

MODIFICATION HISTORY

697       See the Changes file.
698

COPYRIGHT AND LICENSE

700       Copyright (c) 2005-2010 Paul Marquess. All rights reserved.
701
702       This program is free software; you can redistribute it and/or modify it
703       under the same terms as Perl itself.
704
705
706
707perl v5.12.4                      2011-06-07      IO::Uncompress::Inflate(3pm)