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 IO::Com‐
57       press::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
73       "inflate" expects at least two parameters, $input and $output.
74
75       The $input parameter
76
77       The parameter, $input, is used to define the source of the compressed
78       data.
79
80       It can take one of the following forms:
81
82       A filename
83            If the $input parameter is a simple scalar, it is assumed to be a
84            filename. This file will be opened for reading and the input data
85            will be read from it.
86
87       A filehandle
88            If the $input parameter is a filehandle, the input data will be
89            read from it.  The string '-' can be used as an alias for standard
90            input.
91
92       A scalar reference
93            If $input is a scalar reference, the input data will be read from
94            $$input.
95
96       An array reference
97            If $input is an array reference, each element in the array must be
98            a filename.
99
100            The input data will be read from each file in turn.
101
102            The complete array will be walked to ensure that it only contains
103            valid filenames before any data is uncompressed.
104
105       An Input FileGlob string
106            If $input is a string that is delimited by the characters "<" and
107            ">" "inflate" will assume that it is an input fileglob string. The
108            input is the list of files that match the fileglob.
109
110            If the fileglob does not match any files ...
111
112            See File::GlobMapper for more details.
113
114       If the $input parameter is any other type, "undef" will be returned.
115
116       The $output parameter
117
118       The parameter $output is used to control the destination of the uncom‐
119       pressed data. This parameter can take one of these forms.
120
121       A filename
122            If the $output parameter is a simple scalar, it is assumed to be a
123            filename.  This file will be opened for writing and the uncom‐
124            pressed data will be written to it.
125
126       A filehandle
127            If the $output parameter is a filehandle, the uncompressed data
128            will be written to it.  The string '-' can be used as an alias for
129            standard output.
130
131       A scalar reference
132            If $output is a scalar reference, the uncompressed data will be
133            stored in $$output.
134
135       An Array Reference
136            If $output is an array reference, the uncompressed data will be
137            pushed onto the array.
138
139       An Output FileGlob
140            If $output is a string that is delimited by the characters "<" and
141            ">" "inflate" will assume that it is an output fileglob string.
142            The output is the list of files that match the fileglob.
143
144            When $output is an fileglob string, $input must also be a fileglob
145            string. Anything else is an error.
146
147       If the $output parameter is any other type, "undef" will be returned.
148
149       Notes
150
151       When $input maps to multiple compressed files/buffers and $output is a
152       single file/buffer, after uncompression $output will contain a concate‐
153       nation of all the uncompressed data from each of the input files/buf‐
154       fers.
155
156       Optional Parameters
157
158       Unless specified below, the optional parameters for "inflate", "OPTS",
159       are the same as those used with the OO interface defined in the "Con‐
160       structor Options" section below.
161
162       "AutoClose => 0⎪1"
163            This option applies to any input or output data streams to
164            "inflate" that are filehandles.
165
166            If "AutoClose" is specified, and the value is true, it will result
167            in all input and/or output filehandles being closed once "inflate"
168            has completed.
169
170            This parameter defaults to 0.
171
172       "BinModeOut => 0⎪1"
173            When writing to a file or filehandle, set "binmode" before writing
174            to the file.
175
176            Defaults to 0.
177
178       "Append => 0⎪1"
179            TODO
180
181       "MultiStream => 0⎪1"
182            If the input file/buffer contains multiple compressed data
183            streams, this option will uncompress the whole lot as a single
184            data stream.
185
186            Defaults to 0.
187
188       "TrailingData => $scalar"
189            Returns the data, if any, that is present immediately after the
190            compressed data stream once uncompression is complete.
191
192            This option can be used when there is useful information immedi‐
193            ately following the compressed data stream, and you don't know the
194            length of the compressed data stream.
195
196            If the input is a buffer, "trailingData" will return everything
197            from the end of the compressed data stream to the end of the buf‐
198            fer.
199
200            If the input is a filehandle, "trailingData" will return the data
201            that is left in the filehandle input buffer once the end of the
202            compressed data stream has been reached. You can then use the
203            filehandle to read the rest of the input file.
204
205            Don't bother using "trailingData" if the input is a filename.
206
207            If you know the length of the compressed data stream before you
208            start uncompressing, you can avoid having to use "trailingData" by
209            setting the "InputLength" option.
210
211       Examples
212
213       To read the contents of the file "file1.txt.1950" and write the com‐
214       pressed data to the file "file1.txt".
215
216           use strict ;
217           use warnings ;
218           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
219
220           my $input = "file1.txt.1950";
221           my $output = "file1.txt";
222           inflate $input => $output
223               or die "inflate failed: $InflateError\n";
224
225       To read from an existing Perl filehandle, $input, and write the uncom‐
226       pressed data to a buffer, $buffer.
227
228           use strict ;
229           use warnings ;
230           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
231           use IO::File ;
232
233           my $input = new IO::File "<file1.txt.1950"
234               or die "Cannot open 'file1.txt.1950': $!\n" ;
235           my $buffer ;
236           inflate $input => \$buffer
237               or die "inflate failed: $InflateError\n";
238
239       To uncompress all files in the directory "/my/home" that match
240       "*.txt.1950" and store the compressed data in the same directory
241
242           use strict ;
243           use warnings ;
244           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
245
246           inflate '</my/home/*.txt.1950>' => '</my/home/#1.txt>'
247               or die "inflate failed: $InflateError\n";
248
249       and if you want to compress each file one at a time, this will do the
250       trick
251
252           use strict ;
253           use warnings ;
254           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
255
256           for my $input ( glob "/my/home/*.txt.1950" )
257           {
258               my $output = $input;
259               $output =~ s/.1950// ;
260               inflate $input => $output
261                   or die "Error compressing '$input': $InflateError\n";
262           }
263

OO Interface

265       Constructor
266
267       The format of the constructor for IO::Uncompress::Inflate is shown
268       below
269
270           my $z = new IO::Uncompress::Inflate $input [OPTS]
271               or die "IO::Uncompress::Inflate failed: $InflateError\n";
272
273       Returns an "IO::Uncompress::Inflate" object on success and undef on
274       failure.  The variable $InflateError will contain an error message on
275       failure.
276
277       If you are running Perl 5.005 or better the object, $z, returned from
278       IO::Uncompress::Inflate can be used exactly like an IO::File filehan‐
279       dle.  This means that all normal input file operations can be carried
280       out with $z.  For example, to read a line from a compressed file/buffer
281       you can use either of these forms
282
283           $line = $z->getline();
284           $line = <$z>;
285
286       The mandatory parameter $input is used to determine the source of the
287       compressed data. This parameter can take one of three forms.
288
289       A filename
290            If the $input parameter is a scalar, it is assumed to be a file‐
291            name. This file will be opened for reading and the compressed data
292            will be read from it.
293
294       A filehandle
295            If the $input parameter is a filehandle, the compressed data will
296            be read from it.  The string '-' can be used as an alias for stan‐
297            dard input.
298
299       A scalar reference
300            If $input is a scalar reference, the compressed data will be read
301            from $$output.
302
303       Constructor Options
304
305       The option names defined below are case insensitive and can be option‐
306       ally prefixed by a '-'.  So all of the following are valid
307
308           -AutoClose
309           -autoclose
310           AUTOCLOSE
311           autoclose
312
313       OPTS is a combination of the following options:
314
315       "AutoClose => 0⎪1"
316            This option is only valid when the $input parameter is a filehan‐
317            dle. If specified, and the value is true, it will result in the
318            file being closed once either the "close" method is called or the
319            IO::Uncompress::Inflate object is destroyed.
320
321            This parameter defaults to 0.
322
323       "MultiStream => 0⎪1"
324            Allows multiple concatenated compressed streams to be treated as a
325            single compressed stream. Decompression will stop once either the
326            end of the file/buffer is reached, an error is encountered (prema‐
327            ture eof, corrupt compressed data) or the end of a stream is not
328            immediately followed by the start of another stream.
329
330            This parameter defaults to 0.
331
332       "Prime => $string"
333            This option will uncompress the contents of $string before pro‐
334            cessing the input file/buffer.
335
336            This option can be useful when the compressed data is embedded in
337            another file/data structure and it is not possible to work out
338            where the compressed data begins without having to read the first
339            few bytes. If this is the case, the uncompression can be primed
340            with these bytes using this option.
341
342       "Transparent => 0⎪1"
343            If this option is set and the input file/buffer is not compressed
344            data, the module will allow reading of it anyway.
345
346            In addition, if the input file/buffer does contain compressed data
347            and there is non-compressed data immediately following it, setting
348            this option will make this module treat the whole file/bufffer as
349            a single data stream.
350
351            This option defaults to 1.
352
353       "BlockSize => $num"
354            When reading the compressed input data, IO::Uncompress::Inflate
355            will read it in blocks of $num bytes.
356
357            This option defaults to 4096.
358
359       "InputLength => $size"
360            When present this option will limit the number of compressed bytes
361            read from the input file/buffer to $size. This option can be used
362            in the situation where there is useful data directly after the
363            compressed data stream and you know beforehand the exact length of
364            the compressed data stream.
365
366            This option is mostly used when reading from a filehandle, in
367            which case the file pointer will be left pointing to the first
368            byte directly after the compressed data stream.
369
370            This option defaults to off.
371
372       "Append => 0⎪1"
373            This option controls what the "read" method does with uncompressed
374            data.
375
376            If set to 1, all uncompressed data will be appended to the output
377            parameter of the "read" method.
378
379            If set to 0, the contents of the output parameter of the "read"
380            method will be overwritten by the uncompressed data.
381
382            Defaults to 0.
383
384       "Strict => 0⎪1"
385            This option controls whether the extra checks defined below are
386            used when carrying out the decompression. When Strict is on, the
387            extra tests are carried out, when Strict is off they are not.
388
389            The default for this option is off.
390
391            1    The ADLER32 checksum field must be present.
392
393            2    The value of the ADLER32 field read must match the adler32
394                 value of the uncompressed data actually contained in the
395                 file.
396
397       Examples
398
399       TODO
400

Methods

402       read
403
404       Usage is
405
406           $status = $z->read($buffer)
407
408       Reads a block of compressed data (the size the the compressed block is
409       determined by the "Buffer" option in the constructor), uncompresses it
410       and writes any uncompressed data into $buffer. If the "Append" parame‐
411       ter is set in the constructor, the uncompressed data will be appended
412       to the $buffer parameter. Otherwise $buffer will be overwritten.
413
414       Returns the number of uncompressed bytes written to $buffer, zero if
415       eof or a negative number on error.
416
417       read
418
419       Usage is
420
421           $status = $z->read($buffer, $length)
422           $status = $z->read($buffer, $length, $offset)
423
424           $status = read($z, $buffer, $length)
425           $status = read($z, $buffer, $length, $offset)
426
427       Attempt to read $length bytes of uncompressed data into $buffer.
428
429       The main difference between this form of the "read" method and the pre‐
430       vious one, is that this one will attempt to return exactly $length
431       bytes. The only circumstances that this function will not is if end-of-
432       file or an IO error is encountered.
433
434       Returns the number of uncompressed bytes written to $buffer, zero if
435       eof or a negative number on error.
436
437       getline
438
439       Usage is
440
441           $line = $z->getline()
442           $line = <$z>
443
444       Reads a single line.
445
446       This method fully supports the use of of the variable $/ (or
447       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
448       what constitutes an end of line. Paragraph mode, record mode and file
449       slurp mode are all supported.
450
451       getc
452
453       Usage is
454
455           $char = $z->getc()
456
457       Read a single character.
458
459       ungetc
460
461       Usage is
462
463           $char = $z->ungetc($string)
464
465       inflateSync
466
467       Usage is
468
469           $status = $z->inflateSync()
470
471       TODO
472
473       getHeaderInfo
474
475       Usage is
476
477           $hdr  = $z->getHeaderInfo();
478           @hdrs = $z->getHeaderInfo();
479
480       This method returns either a hash reference (in scalar context) or a
481       list or hash references (in array context) that contains information
482       about each of the header fields in the compressed data stream(s).
483
484       tell
485
486       Usage is
487
488           $z->tell()
489           tell $z
490
491       Returns the uncompressed file offset.
492
493       eof
494
495       Usage is
496
497           $z->eof();
498           eof($z);
499
500       Returns true if the end of the compressed input stream has been
501       reached.
502
503       seek
504
505           $z->seek($position, $whence);
506           seek($z, $position, $whence);
507
508       Provides a sub-set of the "seek" functionality, with the restriction
509       that it is only legal to seek forward in the input file/buffer.  It is
510       a fatal error to attempt to seek backward.
511
512       The $whence parameter takes one the usual values, namely SEEK_SET,
513       SEEK_CUR or SEEK_END.
514
515       Returns 1 on success, 0 on failure.
516
517       binmode
518
519       Usage is
520
521           $z->binmode
522           binmode $z ;
523
524       This is a noop provided for completeness.
525
526       opened
527
528           $z->opened()
529
530       Returns true if the object currently refers to a opened file/buffer.
531
532       autoflush
533
534           my $prev = $z->autoflush()
535           my $prev = $z->autoflush(EXPR)
536
537       If the $z object is associated with a file or a filehandle, this method
538       returns the current autoflush setting for the underlying filehandle. If
539       "EXPR" is present, and is non-zero, it will enable flushing after every
540       write/print operation.
541
542       If $z is associated with a buffer, this method has no effect and always
543       returns "undef".
544
545       Note that the special variable $⎪ cannot be used to set or retrieve the
546       autoflush setting.
547
548       input_line_number
549
550           $z->input_line_number()
551           $z->input_line_number(EXPR)
552
553       Returns the current uncompressed line number. If "EXPR" is present it
554       has the effect of setting the line number. Note that setting the line
555       number does not change the current position within the file/buffer
556       being read.
557
558       The contents of $/ are used to to determine what constitutes a line
559       terminator.
560
561       fileno
562
563           $z->fileno()
564           fileno($z)
565
566       If the $z object is associated with a file or a filehandle, this method
567       will return the underlying file descriptor.
568
569       If the $z object is is associated with a buffer, this method will
570       return undef.
571
572       close
573
574           $z->close() ;
575           close $z ;
576
577       Closes the output file/buffer.
578
579       For most versions of Perl this method will be automatically invoked if
580       the IO::Uncompress::Inflate object is destroyed (either explicitly or
581       by the variable with the reference to the object going out of scope).
582       The exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In
583       these cases, the "close" method will be called automatically, but not
584       until global destruction of all live objects when the program is termi‐
585       nating.
586
587       Therefore, if you want your scripts to be able to run on all versions
588       of Perl, you should call "close" explicitly and not rely on automatic
589       closing.
590
591       Returns true on success, otherwise 0.
592
593       If the "AutoClose" option has been enabled when the IO::Uncom‐
594       press::Inflate object was created, and the object is associated with a
595       file, the underlying file will also be closed.
596
597       nextStream
598
599       Usage is
600
601           my $status = $z->nextStream();
602
603       Skips to the next compressed data stream in the input file/buffer. If a
604       new compressed data stream is found, the eof marker will be cleared and
605       $.  will be reset to 0.
606
607       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
608       error was encountered.
609
610       trailingData
611
612       Usage is
613
614           my $data = $z->trailingData();
615
616       Returns the data, if any, that is present immediately after the com‐
617       pressed data stream once uncompression is complete. It only makes sense
618       to call this method once the end of the compressed data stream has been
619       encountered.
620
621       This option can be used when there is useful information immediately
622       following the compressed data stream, and you don't know the length of
623       the compressed data stream.
624
625       If the input is a buffer, "trailingData" will return everything from
626       the end of the compressed data stream to the end of the buffer.
627
628       If the input is a filehandle, "trailingData" will return the data that
629       is left in the filehandle input buffer once the end of the compressed
630       data stream has been reached. You can then use the filehandle to read
631       the rest of the input file.
632
633       Don't bother using "trailingData" if the input is a filename.
634
635       If you know the length of the compressed data stream before you start
636       uncompressing, you can avoid having to use "trailingData" by setting
637       the "InputLength" option in the constructor.
638

Importing

640       No symbolic constants are required by this IO::Uncompress::Inflate at
641       present.
642
643       :all Imports "inflate" and $InflateError.  Same as doing this
644
645                use IO::Uncompress::Inflate qw(inflate $InflateError) ;
646

EXAMPLES

AUTHOR

672       This module was written by Paul Marquess, pmqs@cpan.org.
673

MODIFICATION HISTORY

675       See the Changes file.
676

COPYRIGHT AND LICENSE

678       Copyright (c) 2005-2007 Paul Marquess. All rights reserved.
679
680       This program is free software; you can redistribute it and/or modify it
681       under the same terms as Perl itself.
682
683
684
685perl v5.8.8                       2007-06-18        IO::Uncompress::Inflate(3)