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

OO Interface

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

Methods

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

Importing

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

EXAMPLES

680   Working with Net::FTP
681       See IO::Compress::FAQ
682

SUPPORT

684       General feedback/questions/bug reports should be sent to
685       <https://github.com/pmqs/IO-Compress/issues> (preferred) or
686       <https://rt.cpan.org/Public/Dist/Display.html?Name=IO-Compress>.
687

AUTHOR

720       This module was written by Paul Marquess, "pmqs@cpan.org".
721

MODIFICATION HISTORY

723       See the Changes file.
724

COPYRIGHT AND LICENSE

726       Copyright (c) 2005-2022 Paul Marquess. All rights reserved.
727
728       This program is free software; you can redistribute it and/or modify it
729       under the same terms as Perl itself.
730
731
732
733perl v5.36.0                      2022-07-22        IO::Uncompress::Inflate(3)