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            This option is now a no-op. All files will be written  in binmode.
181
182       "Append => 0|1"
183            The behaviour of this option is dependent on the type of output
184            data stream.
185
186            ·    A Buffer
187
188                 If "Append" is enabled, all uncompressed data will be append
189                 to the end of the output buffer. Otherwise the output buffer
190                 will be cleared before any uncompressed data is written to
191                 it.
192
193            ·    A Filename
194
195                 If "Append" is enabled, the file will be opened in append
196                 mode. Otherwise the contents of the file, if any, will be
197                 truncated before any uncompressed data is written to it.
198
199            ·    A Filehandle
200
201                 If "Append" is enabled, the filehandle will be positioned to
202                 the end of the file via a call to "seek" before any
203                 uncompressed data is written to it.  Otherwise the file
204                 pointer will not be moved.
205
206            When "Append" is specified, and set to true, it will append all
207            uncompressed data to the output data stream.
208
209            So when the output is a filehandle it will carry out a seek to the
210            eof before writing any uncompressed data. If the output is a
211            filename, it will be opened for appending. If the output is a
212            buffer, all uncompressed data will be appended to the existing
213            buffer.
214
215            Conversely when "Append" is not specified, or it is present and is
216            set to false, it will operate as follows.
217
218            When the output is a filename, it will truncate the contents of
219            the file before writing any uncompressed data. If the output is a
220            filehandle its position will not be changed. If the output is a
221            buffer, it will be wiped before any uncompressed data is output.
222
223            Defaults to 0.
224
225       "MultiStream => 0|1"
226            If the input file/buffer contains multiple compressed data
227            streams, this option will uncompress the whole lot as a single
228            data stream.
229
230            Defaults to 0.
231
232       "TrailingData => $scalar"
233            Returns the data, if any, that is present immediately after the
234            compressed data stream once uncompression is complete.
235
236            This option can be used when there is useful information
237            immediately following the compressed data stream, and you don't
238            know the length of the compressed data stream.
239
240            If the input is a buffer, "trailingData" will return everything
241            from the end of the compressed data stream to the end of the
242            buffer.
243
244            If the input is a filehandle, "trailingData" will return the data
245            that is left in the filehandle input buffer once the end of the
246            compressed data stream has been reached. You can then use the
247            filehandle to read the rest of the input file.
248
249            Don't bother using "trailingData" if the input is a filename.
250
251            If you know the length of the compressed data stream before you
252            start uncompressing, you can avoid having to use "trailingData" by
253            setting the "InputLength" option.
254
255   Examples
256       To read the contents of the file "file1.txt.1950" and write the
257       uncompressed data to the file "file1.txt".
258
259           use strict ;
260           use warnings ;
261           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
262
263           my $input = "file1.txt.1950";
264           my $output = "file1.txt";
265           inflate $input => $output
266               or die "inflate failed: $InflateError\n";
267
268       To read from an existing Perl filehandle, $input, and write the
269       uncompressed data to a buffer, $buffer.
270
271           use strict ;
272           use warnings ;
273           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
274           use IO::File ;
275
276           my $input = new IO::File "<file1.txt.1950"
277               or die "Cannot open 'file1.txt.1950': $!\n" ;
278           my $buffer ;
279           inflate $input => \$buffer
280               or die "inflate failed: $InflateError\n";
281
282       To uncompress all files in the directory "/my/home" that match
283       "*.txt.1950" and store the compressed data in the same directory
284
285           use strict ;
286           use warnings ;
287           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
288
289           inflate '</my/home/*.txt.1950>' => '</my/home/#1.txt>'
290               or die "inflate failed: $InflateError\n";
291
292       and if you want to compress each file one at a time, this will do the
293       trick
294
295           use strict ;
296           use warnings ;
297           use IO::Uncompress::Inflate qw(inflate $InflateError) ;
298
299           for my $input ( glob "/my/home/*.txt.1950" )
300           {
301               my $output = $input;
302               $output =~ s/.1950// ;
303               inflate $input => $output
304                   or die "Error compressing '$input': $InflateError\n";
305           }
306

OO Interface

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

Methods

442   read
443       Usage is
444
445           $status = $z->read($buffer)
446
447       Reads a block of compressed data (the size of the compressed block is
448       determined by the "Buffer" option in the constructor), uncompresses it
449       and writes any uncompressed data into $buffer. If the "Append"
450       parameter is set in the constructor, the uncompressed data will be
451       appended to the $buffer parameter. Otherwise $buffer will be
452       overwritten.
453
454       Returns the number of uncompressed bytes written to $buffer, zero if
455       eof or a negative number on error.
456
457   read
458       Usage is
459
460           $status = $z->read($buffer, $length)
461           $status = $z->read($buffer, $length, $offset)
462
463           $status = read($z, $buffer, $length)
464           $status = read($z, $buffer, $length, $offset)
465
466       Attempt to read $length bytes of uncompressed data into $buffer.
467
468       The main difference between this form of the "read" method and the
469       previous one, is that this one will attempt to return exactly $length
470       bytes. The only circumstances that this function will not is if end-of-
471       file or an IO error is encountered.
472
473       Returns the number of uncompressed bytes written to $buffer, zero if
474       eof or a negative number on error.
475
476   getline
477       Usage is
478
479           $line = $z->getline()
480           $line = <$z>
481
482       Reads a single line.
483
484       This method fully supports the use of the variable $/ (or
485       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
486       what constitutes an end of line. Paragraph mode, record mode and file
487       slurp mode are all supported.
488
489   getc
490       Usage is
491
492           $char = $z->getc()
493
494       Read a single character.
495
496   ungetc
497       Usage is
498
499           $char = $z->ungetc($string)
500
501   inflateSync
502       Usage is
503
504           $status = $z->inflateSync()
505
506       TODO
507
508   getHeaderInfo
509       Usage is
510
511           $hdr  = $z->getHeaderInfo();
512           @hdrs = $z->getHeaderInfo();
513
514       This method returns either a hash reference (in scalar context) or a
515       list or hash references (in array context) that contains information
516       about each of the header fields in the compressed data stream(s).
517
518   tell
519       Usage is
520
521           $z->tell()
522           tell $z
523
524       Returns the uncompressed file offset.
525
526   eof
527       Usage is
528
529           $z->eof();
530           eof($z);
531
532       Returns true if the end of the compressed input stream has been
533       reached.
534
535   seek
536           $z->seek($position, $whence);
537           seek($z, $position, $whence);
538
539       Provides a sub-set of the "seek" functionality, with the restriction
540       that it is only legal to seek forward in the input file/buffer.  It is
541       a fatal error to attempt to seek backward.
542
543       Note that the implementation of "seek" in this module does not provide
544       true random access to a compressed file/buffer. It  works by
545       uncompressing data from the current offset in the file/buffer until it
546       reaches the uncompressed offset specified in the parameters to "seek".
547       For very small files this may be acceptable behaviour. For large files
548       it may cause an unacceptable delay.
549
550       The $whence parameter takes one the usual values, namely SEEK_SET,
551       SEEK_CUR or SEEK_END.
552
553       Returns 1 on success, 0 on failure.
554
555   binmode
556       Usage is
557
558           $z->binmode
559           binmode $z ;
560
561       This is a noop provided for completeness.
562
563   opened
564           $z->opened()
565
566       Returns true if the object currently refers to a opened file/buffer.
567
568   autoflush
569           my $prev = $z->autoflush()
570           my $prev = $z->autoflush(EXPR)
571
572       If the $z object is associated with a file or a filehandle, this method
573       returns the current autoflush setting for the underlying filehandle. If
574       "EXPR" is present, and is non-zero, it will enable flushing after every
575       write/print operation.
576
577       If $z is associated with a buffer, this method has no effect and always
578       returns "undef".
579
580       Note that the special variable $| cannot be used to set or retrieve the
581       autoflush setting.
582
583   input_line_number
584           $z->input_line_number()
585           $z->input_line_number(EXPR)
586
587       Returns the current uncompressed line number. If "EXPR" is present it
588       has the effect of setting the line number. Note that setting the line
589       number does not change the current position within the file/buffer
590       being read.
591
592       The contents of $/ are used to determine what constitutes a line
593       terminator.
594
595   fileno
596           $z->fileno()
597           fileno($z)
598
599       If the $z object is associated with a file or a filehandle, "fileno"
600       will return the underlying file descriptor. Once the "close" method is
601       called "fileno" will return "undef".
602
603       If the $z object is associated with a buffer, this method will return
604       "undef".
605
606   close
607           $z->close() ;
608           close $z ;
609
610       Closes the output file/buffer.
611
612       For most versions of Perl this method will be automatically invoked if
613       the IO::Uncompress::Inflate object is destroyed (either explicitly or
614       by the variable with the reference to the object going out of scope).
615       The exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In
616       these cases, the "close" method will be called automatically, but not
617       until global destruction of all live objects when the program is
618       terminating.
619
620       Therefore, if you want your scripts to be able to run on all versions
621       of Perl, you should call "close" explicitly and not rely on automatic
622       closing.
623
624       Returns true on success, otherwise 0.
625
626       If the "AutoClose" option has been enabled when the
627       IO::Uncompress::Inflate object was created, and the object is
628       associated with a file, the underlying file will also be closed.
629
630   nextStream
631       Usage is
632
633           my $status = $z->nextStream();
634
635       Skips to the next compressed data stream in the input file/buffer. If a
636       new compressed data stream is found, the eof marker will be cleared and
637       $.  will be reset to 0.
638
639       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
640       error was encountered.
641
642   trailingData
643       Usage is
644
645           my $data = $z->trailingData();
646
647       Returns the data, if any, that is present immediately after the
648       compressed data stream once uncompression is complete. It only makes
649       sense to call this method once the end of the compressed data stream
650       has been encountered.
651
652       This option can be used when there is useful information immediately
653       following the compressed data stream, and you don't know the length of
654       the compressed data stream.
655
656       If the input is a buffer, "trailingData" will return everything from
657       the end of the compressed data stream to the end of the buffer.
658
659       If the input is a filehandle, "trailingData" will return the data that
660       is left in the filehandle input buffer once the end of the compressed
661       data stream has been reached. You can then use the filehandle to read
662       the rest of the input file.
663
664       Don't bother using "trailingData" if the input is a filename.
665
666       If you know the length of the compressed data stream before you start
667       uncompressing, you can avoid having to use "trailingData" by setting
668       the "InputLength" option in the constructor.
669

Importing

671       No symbolic constants are required by this IO::Uncompress::Inflate at
672       present.
673
674       :all Imports "inflate" and $InflateError.  Same as doing this
675
676                use IO::Uncompress::Inflate qw(inflate $InflateError) ;
677

EXAMPLES

679   Working with Net::FTP
680       See IO::Compress::FAQ
681

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) 2005-2019 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 v5.30.0                      2019-08-12        IO::Uncompress::Inflate(3)