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   OneShot 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       The constructor takes one mandatory parameter, $input, defined below,
317       and zero or more "OPTS", defined in "Constructor Options".
318
319       Returns an "IO::Uncompress::Inflate" object on success and undef on
320       failure.  The variable $InflateError will contain an error message on
321       failure.
322
323       If you are running Perl 5.005 or better the object, $z, returned from
324       IO::Uncompress::Inflate can be used exactly like an IO::File
325       filehandle.  This means that all normal input file operations can be
326       carried out with $z.  For example, to read a line from a compressed
327       file/buffer you can use either of these forms
328
329           $line = $z->getline();
330           $line = <$z>;
331
332       Below is a simple exaple of using the OO interface to read the
333       compressed file "myfile.1950" and write its contents to stdout.
334
335           my $filename = "myfile.1950";
336           my $z = IO::Uncompress::Inflate->new($filename)
337               or die "IO::Uncompress::Inflate failed: $InflateError\n";
338
339           while (<$z>) {
340               print $_;
341           }
342           $z->close();
343
344       See "EXAMPLES" for further examples
345
346       The mandatory parameter $input is used to determine the source of the
347       compressed data. This parameter can take one of three forms.
348
349       A filename
350            If the $input parameter is a scalar, it is assumed to be a
351            filename. This file will be opened for reading and the compressed
352            data will be read from it.
353
354       A filehandle
355            If the $input parameter is a filehandle, the compressed data will
356            be read from it.  The string '-' can be used as an alias for
357            standard input.
358
359       A scalar reference
360            If $input is a scalar reference, the compressed data will be read
361            from $$input.
362
363   Constructor Options
364       The option names defined below are case insensitive and can be
365       optionally prefixed by a '-'.  So all of the following are valid
366
367           -AutoClose
368           -autoclose
369           AUTOCLOSE
370           autoclose
371
372       OPTS is a combination of the following options:
373
374       "AutoClose => 0|1"
375            This option is only valid when the $input parameter is a
376            filehandle. If specified, and the value is true, it will result in
377            the file being closed once either the "close" method is called or
378            the IO::Uncompress::Inflate object is destroyed.
379
380            This parameter defaults to 0.
381
382       "MultiStream => 0|1"
383            Allows multiple concatenated compressed streams to be treated as a
384            single compressed stream. Decompression will stop once either the
385            end of the file/buffer is reached, an error is encountered
386            (premature eof, corrupt compressed data) or the end of a stream is
387            not immediately followed by the start of another stream.
388
389            This parameter defaults to 0.
390
391       "Prime => $string"
392            This option will uncompress the contents of $string before
393            processing the input file/buffer.
394
395            This option can be useful when the compressed data is embedded in
396            another file/data structure and it is not possible to work out
397            where the compressed data begins without having to read the first
398            few bytes. If this is the case, the uncompression can be primed
399            with these bytes using this option.
400
401       "Transparent => 0|1"
402            If this option is set and the input file/buffer is not compressed
403            data, the module will allow reading of it anyway.
404
405            In addition, if the input file/buffer does contain compressed data
406            and there is non-compressed data immediately following it, setting
407            this option will make this module treat the whole file/buffer as a
408            single data stream.
409
410            This option defaults to 1.
411
412       "BlockSize => $num"
413            When reading the compressed input data, IO::Uncompress::Inflate
414            will read it in blocks of $num bytes.
415
416            This option defaults to 4096.
417
418       "InputLength => $size"
419            When present this option will limit the number of compressed bytes
420            read from the input file/buffer to $size. This option can be used
421            in the situation where there is useful data directly after the
422            compressed data stream and you know beforehand the exact length of
423            the compressed data stream.
424
425            This option is mostly used when reading from a filehandle, in
426            which case the file pointer will be left pointing to the first
427            byte directly after the compressed data stream.
428
429            This option defaults to off.
430
431       "Append => 0|1"
432            This option controls what the "read" method does with uncompressed
433            data.
434
435            If set to 1, all uncompressed data will be appended to the output
436            parameter of the "read" method.
437
438            If set to 0, the contents of the output parameter of the "read"
439            method will be overwritten by the uncompressed data.
440
441            Defaults to 0.
442
443       "Strict => 0|1"
444            This option controls whether the extra checks defined below are
445            used when carrying out the decompression. When Strict is on, the
446            extra tests are carried out, when Strict is off they are not.
447
448            The default for this option is off.
449
450            1.   The ADLER32 checksum field must be present.
451
452            2.   The value of the ADLER32 field read must match the adler32
453                 value of the uncompressed data actually contained in the
454                 file.
455

Methods

457   read
458       Usage is
459
460           $status = $z->read($buffer)
461
462       Reads a block of compressed data (the size of the compressed block is
463       determined by the "Buffer" option in the constructor), uncompresses it
464       and writes any uncompressed data into $buffer. If the "Append"
465       parameter is set in the constructor, the uncompressed data will be
466       appended to the $buffer parameter. Otherwise $buffer will be
467       overwritten.
468
469       Returns the number of uncompressed bytes written to $buffer, zero if
470       eof or a negative number on error.
471
472   read
473       Usage is
474
475           $status = $z->read($buffer, $length)
476           $status = $z->read($buffer, $length, $offset)
477
478           $status = read($z, $buffer, $length)
479           $status = read($z, $buffer, $length, $offset)
480
481       Attempt to read $length bytes of uncompressed data into $buffer.
482
483       The main difference between this form of the "read" method and the
484       previous one, is that this one will attempt to return exactly $length
485       bytes. The only circumstances that this function will not is if end-of-
486       file or an IO error is encountered.
487
488       Returns the number of uncompressed bytes written to $buffer, zero if
489       eof or a negative number on error.
490
491   getline
492       Usage is
493
494           $line = $z->getline()
495           $line = <$z>
496
497       Reads a single line.
498
499       This method fully supports the use of the variable $/ (or
500       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
501       what constitutes an end of line. Paragraph mode, record mode and file
502       slurp mode are all supported.
503
504   getc
505       Usage is
506
507           $char = $z->getc()
508
509       Read a single character.
510
511   ungetc
512       Usage is
513
514           $char = $z->ungetc($string)
515
516   inflateSync
517       Usage is
518
519           $status = $z->inflateSync()
520
521       TODO
522
523   getHeaderInfo
524       Usage is
525
526           $hdr  = $z->getHeaderInfo();
527           @hdrs = $z->getHeaderInfo();
528
529       This method returns either a hash reference (in scalar context) or a
530       list or hash references (in array context) that contains information
531       about each of the header fields in the compressed data stream(s).
532
533   tell
534       Usage is
535
536           $z->tell()
537           tell $z
538
539       Returns the uncompressed file offset.
540
541   eof
542       Usage is
543
544           $z->eof();
545           eof($z);
546
547       Returns true if the end of the compressed input stream has been
548       reached.
549
550   seek
551           $z->seek($position, $whence);
552           seek($z, $position, $whence);
553
554       Provides a sub-set of the "seek" functionality, with the restriction
555       that it is only legal to seek forward in the input file/buffer.  It is
556       a fatal error to attempt to seek backward.
557
558       Note that the implementation of "seek" in this module does not provide
559       true random access to a compressed file/buffer. It  works by
560       uncompressing data from the current offset in the file/buffer until it
561       reaches the uncompressed offset specified in the parameters to "seek".
562       For very small files this may be acceptable behaviour. For large files
563       it may cause an unacceptable delay.
564
565       The $whence parameter takes one the usual values, namely SEEK_SET,
566       SEEK_CUR or SEEK_END.
567
568       Returns 1 on success, 0 on failure.
569
570   binmode
571       Usage is
572
573           $z->binmode
574           binmode $z ;
575
576       This is a noop provided for completeness.
577
578   opened
579           $z->opened()
580
581       Returns true if the object currently refers to a opened file/buffer.
582
583   autoflush
584           my $prev = $z->autoflush()
585           my $prev = $z->autoflush(EXPR)
586
587       If the $z object is associated with a file or a filehandle, this method
588       returns the current autoflush setting for the underlying filehandle. If
589       "EXPR" is present, and is non-zero, it will enable flushing after every
590       write/print operation.
591
592       If $z is associated with a buffer, this method has no effect and always
593       returns "undef".
594
595       Note that the special variable $| cannot be used to set or retrieve the
596       autoflush setting.
597
598   input_line_number
599           $z->input_line_number()
600           $z->input_line_number(EXPR)
601
602       Returns the current uncompressed line number. If "EXPR" is present it
603       has the effect of setting the line number. Note that setting the line
604       number does not change the current position within the file/buffer
605       being read.
606
607       The contents of $/ are used to determine what constitutes a line
608       terminator.
609
610   fileno
611           $z->fileno()
612           fileno($z)
613
614       If the $z object is associated with a file or a filehandle, "fileno"
615       will return the underlying file descriptor. Once the "close" method is
616       called "fileno" will return "undef".
617
618       If the $z object is associated with a buffer, this method will return
619       "undef".
620
621   close
622           $z->close() ;
623           close $z ;
624
625       Closes the output file/buffer.
626
627       For most versions of Perl this method will be automatically invoked if
628       the IO::Uncompress::Inflate object is destroyed (either explicitly or
629       by the variable with the reference to the object going out of scope).
630       The exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In
631       these cases, the "close" method will be called automatically, but not
632       until global destruction of all live objects when the program is
633       terminating.
634
635       Therefore, if you want your scripts to be able to run on all versions
636       of Perl, you should call "close" explicitly and not rely on automatic
637       closing.
638
639       Returns true on success, otherwise 0.
640
641       If the "AutoClose" option has been enabled when the
642       IO::Uncompress::Inflate object was created, and the object is
643       associated with a file, the underlying file will also be closed.
644
645   nextStream
646       Usage is
647
648           my $status = $z->nextStream();
649
650       Skips to the next compressed data stream in the input file/buffer. If a
651       new compressed data stream is found, the eof marker will be cleared and
652       $.  will be reset to 0.
653
654       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
655       error was encountered.
656
657   trailingData
658       Usage is
659
660           my $data = $z->trailingData();
661
662       Returns the data, if any, that is present immediately after the
663       compressed data stream once uncompression is complete. It only makes
664       sense to call this method once the end of the compressed data stream
665       has been encountered.
666
667       This option can be used when there is useful information immediately
668       following the compressed data stream, and you don't know the length of
669       the compressed data stream.
670
671       If the input is a buffer, "trailingData" will return everything from
672       the end of the compressed data stream to the end of the buffer.
673
674       If the input is a filehandle, "trailingData" will return the data that
675       is left in the filehandle input buffer once the end of the compressed
676       data stream has been reached. You can then use the filehandle to read
677       the rest of the input file.
678
679       Don't bother using "trailingData" if the input is a filename.
680
681       If you know the length of the compressed data stream before you start
682       uncompressing, you can avoid having to use "trailingData" by setting
683       the "InputLength" option in the constructor.
684

Importing

686       No symbolic constants are required by IO::Uncompress::Inflate at
687       present.
688
689       :all Imports "inflate" and $InflateError.  Same as doing this
690
691                use IO::Uncompress::Inflate qw(inflate $InflateError) ;
692

EXAMPLES

694   Working with Net::FTP
695       See IO::Compress::FAQ
696

SUPPORT

698       General feedback/questions/bug reports should be sent to
699       <https://github.com/pmqs/IO-Compress/issues> (preferred) or
700       <https://rt.cpan.org/Public/Dist/Display.html?Name=IO-Compress>.
701

AUTHOR

734       This module was written by Paul Marquess, "pmqs@cpan.org".
735

MODIFICATION HISTORY

737       See the Changes file.
738

COPYRIGHT AND LICENSE

740       Copyright (c) 2005-2023 Paul Marquess. All rights reserved.
741
742       This program is free software; you can redistribute it and/or modify it
743       under the same terms as Perl itself.
744
745
746
747perl v5.38.0                      2023-07-26        IO::Uncompress::Inflate(3)