IO::Uncompress::Inflate(3pm)

1IO::Uncompress::InflateU(s3e)r Contributed Perl DocumentaItOi:o:nUncompress::Inflate(3)
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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_filename_or_reference => $output_filename_or_reference [,OPTS]
67               or die "inflate failed: $InflateError\n";
68
69       The functional interface needs Perl5.005 or better.
70
71   inflate $input_filename_or_reference => $output_filename_or_reference [,
72       OPTS]
73       "inflate" expects at least two parameters, $input_filename_or_reference
74       and $output_filename_or_reference.
75
76       The $input_filename_or_reference parameter
77
78       The parameter, $input_filename_or_reference, is used to define the
79       source of the compressed data.
80
81       It can take one of the following forms:
82
83       A filename
84            If the <$input_filename_or_reference> parameter is a simple
85            scalar, it is assumed to be a filename. This file will be opened
86            for reading and the input data will be read from it.
87
88       A filehandle
89            If the $input_filename_or_reference parameter is a filehandle, the
90            input data will be read from it.  The string '-' can be used as an
91            alias for standard input.
92
93       A scalar reference
94            If $input_filename_or_reference is a scalar reference, the input
95            data will be read from $$input_filename_or_reference.
96
97       An array reference
98            If $input_filename_or_reference is an array reference, each
99            element in the array must be a filename.
100
101            The input data will be read from each file in turn.
102
103            The complete array will be walked to ensure that it only contains
104            valid filenames before any data is uncompressed.
105
106       An Input FileGlob string
107            If $input_filename_or_reference is a string that is delimited by
108            the characters "<" and ">" "inflate" will assume that it is an
109            input fileglob string. The input is the list of files that match
110            the fileglob.
111
112            See File::GlobMapper for more details.
113
114       If the $input_filename_or_reference parameter is any other type,
115       "undef" will be returned.
116
117       The $output_filename_or_reference parameter
118
119       The parameter $output_filename_or_reference is used to control the
120       destination of the uncompressed data. This parameter can take one of
121       these forms.
122
123       A filename
124            If the $output_filename_or_reference parameter is a simple scalar,
125            it is assumed to be a filename.  This file will be opened for
126            writing and the uncompressed data will be written to it.
127
128       A filehandle
129            If the $output_filename_or_reference parameter is a filehandle,
130            the uncompressed data will be written to it.  The string '-' can
131            be used as an alias for standard output.
132
133       A scalar reference
134            If $output_filename_or_reference is a scalar reference, the
135            uncompressed data will be stored in
136            $$output_filename_or_reference.
137
138       An Array Reference
139            If $output_filename_or_reference is an array reference, the
140            uncompressed data will be pushed onto the array.
141
142       An Output FileGlob
143            If $output_filename_or_reference is a string that is delimited by
144            the characters "<" and ">" "inflate" will assume that it is an
145            output fileglob string. The output is the list of files that match
146            the fileglob.
147
148            When $output_filename_or_reference is an fileglob string,
149            $input_filename_or_reference must also be a fileglob string.
150            Anything else is an error.
151
152            See File::GlobMapper for more details.
153
154       If the $output_filename_or_reference parameter is any other type,
155       "undef" will be returned.
156
157   Notes
158       When $input_filename_or_reference maps to multiple compressed
159       files/buffers and $output_filename_or_reference is a single
160       file/buffer, after uncompression $output_filename_or_reference will
161       contain a concatenation of all the uncompressed data from each of the
162       input files/buffers.
163
164   Optional Parameters
165       Unless specified below, the optional parameters for "inflate", "OPTS",
166       are the same as those used with the OO interface defined in the
167       "Constructor Options" section below.
168
169       "AutoClose => 0|1"
170            This option applies to any input or output data streams to
171            "inflate" that are filehandles.
172
173            If "AutoClose" is specified, and the value is true, it will result
174            in all input and/or output filehandles being closed once "inflate"
175            has completed.
176
177            This parameter defaults to 0.
178
179       "BinModeOut => 0|1"
180            When writing to a file or filehandle, set "binmode" before writing
181            to the file.
182
183            Defaults to 0.
184
185       "Append => 0|1"
186            The behaviour of this option is dependent on the type of output
187            data stream.
188
189            ·    A Buffer
190
191                 If "Append" is enabled, all uncompressed data will be append
192                 to the end of the output buffer. Otherwise the output buffer
193                 will be cleared before any uncompressed data is written to
194                 it.
195
196            ·    A Filename
197
198                 If "Append" is enabled, the file will be opened in append
199                 mode. Otherwise the contents of the file, if any, will be
200                 truncated before any uncompressed data is written to it.
201
202            ·    A Filehandle
203
204                 If "Append" is enabled, the filehandle will be positioned to
205                 the end of the file via a call to "seek" before any
206                 uncompressed data is written to it.  Otherwise the file
207                 pointer will not be moved.
208
209            When "Append" is specified, and set to true, it will append all
210            uncompressed data to the output data stream.
211
212            So when the output is a filehandle it will carry out a seek to the
213            eof before writing any uncompressed data. If the output is a
214            filename, it will be opened for appending. If the output is a
215            buffer, all uncompressed data will be appended to the existing
216            buffer.
217
218            Conversely when "Append" is not specified, or it is present and is
219            set to false, it will operate as follows.
220
221            When the output is a filename, it will truncate the contents of
222            the file before writing any uncompressed data. If the output is a
223            filehandle its position will not be changed. If the output is a
224            buffer, it will be wiped before any uncompressed data is output.
225
226            Defaults to 0.
227
228       "MultiStream => 0|1"
229            If the input file/buffer contains multiple compressed data
230            streams, this option will uncompress the whole lot as a single
231            data stream.
232
233            Defaults to 0.
234
235       "TrailingData => $scalar"
236            Returns the data, if any, that is present immediately after the
237            compressed data stream once uncompression is complete.
238
239            This option can be used when there is useful information
240            immediately following the compressed data stream, and you don't
241            know the length of the compressed data stream.
242
243            If the input is a buffer, "trailingData" will return everything
244            from the end of the compressed data stream to the end of the
245            buffer.
246
247            If the input is a filehandle, "trailingData" will return the data
248            that is left in the filehandle input buffer once the end of the
249            compressed data stream has been reached. You can then use the
250            filehandle to read the rest of the input file.
251
252            Don't bother using "trailingData" if the input is a filename.
253
254            If you know the length of the compressed data stream before you
255            start uncompressing, you can avoid having to use "trailingData" by
256            setting the "InputLength" option.
257
258   Examples
259       To read the contents of the file "file1.txt.1950" and write the
260       uncompressed data to the file "file1.txt".
261
262           use strict ;
263           use warnings ;
264           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
265
266           my $input = "file1.txt.1950";
267           my $output = "file1.txt";
268           inflate $input => $output
269               or die "inflate failed: $InflateError\n";
270
271       To read from an existing Perl filehandle, $input, and write the
272       uncompressed data to a buffer, $buffer.
273
274           use strict ;
275           use warnings ;
276           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
277           use IO::File ;
278
279           my $input = new IO::File "<file1.txt.1950"
280               or die "Cannot open 'file1.txt.1950': $!\n" ;
281           my $buffer ;
282           inflate $input => \$buffer
283               or die "inflate failed: $InflateError\n";
284
285       To uncompress all files in the directory "/my/home" that match
286       "*.txt.1950" and store the compressed data in the same directory
287
288           use strict ;
289           use warnings ;
290           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
291
292           inflate '</my/home/*.txt.1950>' => '</my/home/#1.txt>'
293               or die "inflate failed: $InflateError\n";
294
295       and if you want to compress each file one at a time, this will do the
296       trick
297
298           use strict ;
299           use warnings ;
300           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
301
302           for my $input ( glob "/my/home/*.txt.1950" )
303           {
304               my $output = $input;
305               $output =~ s/.1950// ;
306               inflate $input => $output
307                   or die "Error compressing '$input': $InflateError\n";
308           }
309

OO Interface

311   Constructor
312       The format of the constructor for IO::Uncompress::Inflate is shown
313       below
314
315           my $z = new IO::Uncompress::Inflate $input [OPTS]
316               or die "IO::Uncompress::Inflate failed: $InflateError\n";
317
318       Returns an "IO::Uncompress::Inflate" object on success and undef on
319       failure.  The variable $InflateError will contain an error message on
320       failure.
321
322       If you are running Perl 5.005 or better the object, $z, returned from
323       IO::Uncompress::Inflate can be used exactly like an IO::File
324       filehandle.  This means that all normal input file operations can be
325       carried out with $z.  For example, to read a line from a compressed
326       file/buffer you can use either of these forms
327
328           $line = $z->getline();
329           $line = <$z>;
330
331       The mandatory parameter $input is used to determine the source of the
332       compressed data. This parameter can take one of three forms.
333
334       A filename
335            If the $input parameter is a scalar, it is assumed to be a
336            filename. This file will be opened for reading and the compressed
337            data will be read from it.
338
339       A filehandle
340            If the $input parameter is a filehandle, the compressed data will
341            be read from it.  The string '-' can be used as an alias for
342            standard input.
343
344       A scalar reference
345            If $input is a scalar reference, the compressed data will be read
346            from $$input.
347
348   Constructor Options
349       The option names defined below are case insensitive and can be
350       optionally prefixed by a '-'.  So all of the following are valid
351
352           -AutoClose
353           -autoclose
354           AUTOCLOSE
355           autoclose
356
357       OPTS is a combination of the following options:
358
359       "AutoClose => 0|1"
360            This option is only valid when the $input parameter is a
361            filehandle. If specified, and the value is true, it will result in
362            the file being closed once either the "close" method is called or
363            the IO::Uncompress::Inflate object is destroyed.
364
365            This parameter defaults to 0.
366
367       "MultiStream => 0|1"
368            Allows multiple concatenated compressed streams to be treated as a
369            single compressed stream. Decompression will stop once either the
370            end of the file/buffer is reached, an error is encountered
371            (premature eof, corrupt compressed data) or the end of a stream is
372            not immediately followed by the start of another stream.
373
374            This parameter defaults to 0.
375
376       "Prime => $string"
377            This option will uncompress the contents of $string before
378            processing the input file/buffer.
379
380            This option can be useful when the compressed data is embedded in
381            another file/data structure and it is not possible to work out
382            where the compressed data begins without having to read the first
383            few bytes. If this is the case, the uncompression can be primed
384            with these bytes using this option.
385
386       "Transparent => 0|1"
387            If this option is set and the input file/buffer is not compressed
388            data, the module will allow reading of it anyway.
389
390            In addition, if the input file/buffer does contain compressed data
391            and there is non-compressed data immediately following it, setting
392            this option will make this module treat the whole file/buffer as a
393            single data stream.
394
395            This option defaults to 1.
396
397       "BlockSize => $num"
398            When reading the compressed input data, IO::Uncompress::Inflate
399            will read it in blocks of $num bytes.
400
401            This option defaults to 4096.
402
403       "InputLength => $size"
404            When present this option will limit the number of compressed bytes
405            read from the input file/buffer to $size. This option can be used
406            in the situation where there is useful data directly after the
407            compressed data stream and you know beforehand the exact length of
408            the compressed data stream.
409
410            This option is mostly used when reading from a filehandle, in
411            which case the file pointer will be left pointing to the first
412            byte directly after the compressed data stream.
413
414            This option defaults to off.
415
416       "Append => 0|1"
417            This option controls what the "read" method does with uncompressed
418            data.
419
420            If set to 1, all uncompressed data will be appended to the output
421            parameter of the "read" method.
422
423            If set to 0, the contents of the output parameter of the "read"
424            method will be overwritten by the uncompressed data.
425
426            Defaults to 0.
427
428       "Strict => 0|1"
429            This option controls whether the extra checks defined below are
430            used when carrying out the decompression. When Strict is on, the
431            extra tests are carried out, when Strict is off they are not.
432
433            The default for this option is off.
434
435            1.   The ADLER32 checksum field must be present.
436
437            2.   The value of the ADLER32 field read must match the adler32
438                 value of the uncompressed data actually contained in the
439                 file.
440
441   Examples
442       TODO
443

Methods

445   read
446       Usage is
447
448           $status = $z->read($buffer)
449
450       Reads a block of compressed data (the size the the compressed block is
451       determined by the "Buffer" option in the constructor), uncompresses it
452       and writes any uncompressed data into $buffer. If the "Append"
453       parameter is set in the constructor, the uncompressed data will be
454       appended to the $buffer parameter. Otherwise $buffer will be
455       overwritten.
456
457       Returns the number of uncompressed bytes written to $buffer, zero if
458       eof or a negative number on error.
459
460   read
461       Usage is
462
463           $status = $z->read($buffer, $length)
464           $status = $z->read($buffer, $length, $offset)
465
466           $status = read($z, $buffer, $length)
467           $status = read($z, $buffer, $length, $offset)
468
469       Attempt to read $length bytes of uncompressed data into $buffer.
470
471       The main difference between this form of the "read" method and the
472       previous one, is that this one will attempt to return exactly $length
473       bytes. The only circumstances that this function will not is if end-of-
474       file or an IO error is encountered.
475
476       Returns the number of uncompressed bytes written to $buffer, zero if
477       eof or a negative number on error.
478
479   getline
480       Usage is
481
482           $line = $z->getline()
483           $line = <$z>
484
485       Reads a single line.
486
487       This method fully supports the use of of the variable $/ (or
488       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
489       what constitutes an end of line. Paragraph mode, record mode and file
490       slurp mode are all supported.
491
492   getc
493       Usage is
494
495           $char = $z->getc()
496
497       Read a single character.
498
499   ungetc
500       Usage is
501
502           $char = $z->ungetc($string)
503
504   inflateSync
505       Usage is
506
507           $status = $z->inflateSync()
508
509       TODO
510
511   getHeaderInfo
512       Usage is
513
514           $hdr  = $z->getHeaderInfo();
515           @hdrs = $z->getHeaderInfo();
516
517       This method returns either a hash reference (in scalar context) or a
518       list or hash references (in array context) that contains information
519       about each of the header fields in the compressed data stream(s).
520
521   tell
522       Usage is
523
524           $z->tell()
525           tell $z
526
527       Returns the uncompressed file offset.
528
529   eof
530       Usage is
531
532           $z->eof();
533           eof($z);
534
535       Returns true if the end of the compressed input stream has been
536       reached.
537
538   seek
539           $z->seek($position, $whence);
540           seek($z, $position, $whence);
541
542       Provides a sub-set of the "seek" functionality, with the restriction
543       that it is only legal to seek forward in the input file/buffer.  It is
544       a fatal error to attempt to seek backward.
545
546       Note that the implementation of "seek" in this module does not provide
547       true random access to a compressed file/buffer. It  works by
548       uncompressing data from the current offset in the file/buffer until it
549       reaches the ucompressed offset specified in the parameters to "seek".
550       For very small files this may be acceptable behaviour. For large files
551       it may cause an unacceptable delay.
552
553       The $whence parameter takes one the usual values, namely SEEK_SET,
554       SEEK_CUR or SEEK_END.
555
556       Returns 1 on success, 0 on failure.
557
558   binmode
559       Usage is
560
561           $z->binmode
562           binmode $z ;
563
564       This is a noop provided for completeness.
565
566   opened
567           $z->opened()
568
569       Returns true if the object currently refers to a opened file/buffer.
570
571   autoflush
572           my $prev = $z->autoflush()
573           my $prev = $z->autoflush(EXPR)
574
575       If the $z object is associated with a file or a filehandle, this method
576       returns the current autoflush setting for the underlying filehandle. If
577       "EXPR" is present, and is non-zero, it will enable flushing after every
578       write/print operation.
579
580       If $z is associated with a buffer, this method has no effect and always
581       returns "undef".
582
583       Note that the special variable $| cannot be used to set or retrieve the
584       autoflush setting.
585
586   input_line_number
587           $z->input_line_number()
588           $z->input_line_number(EXPR)
589
590       Returns the current uncompressed line number. If "EXPR" is present it
591       has the effect of setting the line number. Note that setting the line
592       number does not change the current position within the file/buffer
593       being read.
594
595       The contents of $/ are used to to determine what constitutes a line
596       terminator.
597
598   fileno
599           $z->fileno()
600           fileno($z)
601
602       If the $z object is associated with a file or a filehandle, "fileno"
603       will return the underlying file descriptor. Once the "close" method is
604       called "fileno" will return "undef".
605
606       If the $z object is associated with a buffer, this method will return
607       "undef".
608
609   close
610           $z->close() ;
611           close $z ;
612
613       Closes the output file/buffer.
614
615       For most versions of Perl this method will be automatically invoked if
616       the IO::Uncompress::Inflate object is destroyed (either explicitly or
617       by the variable with the reference to the object going out of scope).
618       The exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In
619       these cases, the "close" method will be called automatically, but not
620       until global destruction of all live objects when the program is
621       terminating.
622
623       Therefore, if you want your scripts to be able to run on all versions
624       of Perl, you should call "close" explicitly and not rely on automatic
625       closing.
626
627       Returns true on success, otherwise 0.
628
629       If the "AutoClose" option has been enabled when the
630       IO::Uncompress::Inflate object was created, and the object is
631       associated with a file, the underlying file will also be closed.
632
633   nextStream
634       Usage is
635
636           my $status = $z->nextStream();
637
638       Skips to the next compressed data stream in the input file/buffer. If a
639       new compressed data stream is found, the eof marker will be cleared and
640       $.  will be reset to 0.
641
642       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
643       error was encountered.
644
645   trailingData
646       Usage is
647
648           my $data = $z->trailingData();
649
650       Returns the data, if any, that is present immediately after the
651       compressed data stream once uncompression is complete. It only makes
652       sense to call this method once the end of the compressed data stream
653       has been encountered.
654
655       This option can be used when there is useful information immediately
656       following the compressed data stream, and you don't know the length of
657       the compressed data stream.
658
659       If the input is a buffer, "trailingData" will return everything from
660       the end of the compressed data stream to the end of the buffer.
661
662       If the input is a filehandle, "trailingData" will return the data that
663       is left in the filehandle input buffer once the end of the compressed
664       data stream has been reached. You can then use the filehandle to read
665       the rest of the input file.
666
667       Don't bother using "trailingData" if the input is a filename.
668
669       If you know the length of the compressed data stream before you start
670       uncompressing, you can avoid having to use "trailingData" by setting
671       the "InputLength" option in the constructor.
672

Importing

674       No symbolic constants are required by this IO::Uncompress::Inflate at
675       present.
676
677       :all Imports "inflate" and $InflateError.  Same as doing this
678
679                use IO::Uncompress::Inflate qw(inflate $InflateError) ;
680

EXAMPLES

682   Working with Net::FTP
683       See IO::Compress::FAQ
684

AUTHOR

711       This module was written by Paul Marquess, pmqs@cpan.org.
712

MODIFICATION HISTORY

714       See the Changes file.
715

COPYRIGHT AND LICENSE

717       Copyright (c) 2005-2013 Paul Marquess. All rights reserved.
718
719       This program is free software; you can redistribute it and/or modify it
720       under the same terms as Perl itself.
721
722
723
724perl v5.16.3                      2013-05-19        IO::Uncompress::Inflate(3)