IO::Uncompress::Bunzip2(3pm)

1IO::Uncompress::Bunzip2U(s3e)r Contributed Perl DocumentaItOi:o:nUncompress::Bunzip2(3)
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NAME

6       IO::Uncompress::Bunzip2 - Read bzip2 files/buffers
7

SYNOPSIS

9           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
10
11           my $status = bunzip2 $input => $output [,OPTS]
12               or die "bunzip2 failed: $Bunzip2Error\n";
13
14           my $z = new IO::Uncompress::Bunzip2 $input [OPTS]
15               or die "bunzip2 failed: $Bunzip2Error\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           $data = $z->trailingData()
26           $status = $z->nextStream()
27           $data = $z->getHeaderInfo()
28           $z->tell()
29           $z->seek($position, $whence)
30           $z->binmode()
31           $z->fileno()
32           $z->eof()
33           $z->close()
34
35           $Bunzip2Error ;
36
37           # IO::File mode
38
39           <$z>
40           read($z, $buffer);
41           read($z, $buffer, $length);
42           read($z, $buffer, $length, $offset);
43           tell($z)
44           seek($z, $position, $whence)
45           binmode($z)
46           fileno($z)
47           eof($z)
48           close($z)
49

DESCRIPTION

51       This module provides a Perl interface that allows the reading of bzip2
52       files/buffers.
53
54       For writing bzip2 files/buffers, see the companion module
55       IO::Compress::Bzip2.
56

Functional Interface

58       A top-level function, "bunzip2", is provided to carry out "one-shot"
59       uncompression between buffers and/or files. For finer control over the
60       uncompression process, see the "OO Interface" section.
61
62           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
63
64           bunzip2 $input_filename_or_reference => $output_filename_or_reference [,OPTS]
65               or die "bunzip2 failed: $Bunzip2Error\n";
66
67       The functional interface needs Perl5.005 or better.
68
69   bunzip2 $input_filename_or_reference => $output_filename_or_reference [,
70       OPTS]
71       "bunzip2" expects at least two parameters, $input_filename_or_reference
72       and $output_filename_or_reference.
73
74       The $input_filename_or_reference parameter
75
76       The parameter, $input_filename_or_reference, is used to define the
77       source of the compressed data.
78
79       It can take one of the following forms:
80
81       A filename
82            If the <$input_filename_or_reference> parameter is a simple
83            scalar, it is assumed to be a filename. This file will be opened
84            for reading and the input data will be read from it.
85
86       A filehandle
87            If the $input_filename_or_reference parameter is a filehandle, the
88            input data will be read from it.  The string '-' can be used as an
89            alias for standard input.
90
91       A scalar reference
92            If $input_filename_or_reference is a scalar reference, the input
93            data will be read from $$input_filename_or_reference.
94
95       An array reference
96            If $input_filename_or_reference is an array reference, each
97            element in the array must be a filename.
98
99            The input data will be read from each file in turn.
100
101            The complete array will be walked to ensure that it only contains
102            valid filenames before any data is uncompressed.
103
104       An Input FileGlob string
105            If $input_filename_or_reference is a string that is delimited by
106            the characters "<" and ">" "bunzip2" will assume that it is an
107            input fileglob string. The input is the list of files that match
108            the fileglob.
109
110            See File::GlobMapper for more details.
111
112       If the $input_filename_or_reference parameter is any other type,
113       "undef" will be returned.
114
115       The $output_filename_or_reference parameter
116
117       The parameter $output_filename_or_reference is used to control the
118       destination of the uncompressed data. This parameter can take one of
119       these forms.
120
121       A filename
122            If the $output_filename_or_reference parameter is a simple scalar,
123            it is assumed to be a filename.  This file will be opened for
124            writing and the uncompressed data will be written to it.
125
126       A filehandle
127            If the $output_filename_or_reference parameter is a filehandle,
128            the uncompressed data will be written to it.  The string '-' can
129            be used as an alias for standard output.
130
131       A scalar reference
132            If $output_filename_or_reference is a scalar reference, the
133            uncompressed data will be stored in
134            $$output_filename_or_reference.
135
136       An Array Reference
137            If $output_filename_or_reference is an array reference, the
138            uncompressed data will be pushed onto the array.
139
140       An Output FileGlob
141            If $output_filename_or_reference is a string that is delimited by
142            the characters "<" and ">" "bunzip2" will assume that it is an
143            output fileglob string. The output is the list of files that match
144            the fileglob.
145
146            When $output_filename_or_reference is an fileglob string,
147            $input_filename_or_reference must also be a fileglob string.
148            Anything else is an error.
149
150            See File::GlobMapper for more details.
151
152       If the $output_filename_or_reference parameter is any other type,
153       "undef" will be returned.
154
155   Notes
156       When $input_filename_or_reference maps to multiple compressed
157       files/buffers and $output_filename_or_reference is a single
158       file/buffer, after uncompression $output_filename_or_reference will
159       contain a concatenation of all the uncompressed data from each of the
160       input files/buffers.
161
162   Optional Parameters
163       Unless specified below, the optional parameters for "bunzip2", "OPTS",
164       are the same as those used with the OO interface defined in the
165       "Constructor Options" section below.
166
167       "AutoClose => 0|1"
168            This option applies to any input or output data streams to
169            "bunzip2" that are filehandles.
170
171            If "AutoClose" is specified, and the value is true, it will result
172            in all input and/or output filehandles being closed once "bunzip2"
173            has completed.
174
175            This parameter defaults to 0.
176
177       "BinModeOut => 0|1"
178            When writing to a file or filehandle, set "binmode" before writing
179            to the file.
180
181            Defaults to 0.
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.bz2" and write the
258       uncompressed data to the file "file1.txt".
259
260           use strict ;
261           use warnings ;
262           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
263
264           my $input = "file1.txt.bz2";
265           my $output = "file1.txt";
266           bunzip2 $input => $output
267               or die "bunzip2 failed: $Bunzip2Error\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::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
275           use IO::File ;
276
277           my $input = new IO::File "<file1.txt.bz2"
278               or die "Cannot open 'file1.txt.bz2': $!\n" ;
279           my $buffer ;
280           bunzip2 $input => \$buffer
281               or die "bunzip2 failed: $Bunzip2Error\n";
282
283       To uncompress all files in the directory "/my/home" that match
284       "*.txt.bz2" and store the compressed data in the same directory
285
286           use strict ;
287           use warnings ;
288           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
289
290           bunzip2 '</my/home/*.txt.bz2>' => '</my/home/#1.txt>'
291               or die "bunzip2 failed: $Bunzip2Error\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::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
299
300           for my $input ( glob "/my/home/*.txt.bz2" )
301           {
302               my $output = $input;
303               $output =~ s/.bz2// ;
304               bunzip2 $input => $output
305                   or die "Error compressing '$input': $Bunzip2Error\n";
306           }
307

OO Interface

309   Constructor
310       The format of the constructor for IO::Uncompress::Bunzip2 is shown
311       below
312
313           my $z = new IO::Uncompress::Bunzip2 $input [OPTS]
314               or die "IO::Uncompress::Bunzip2 failed: $Bunzip2Error\n";
315
316       Returns an "IO::Uncompress::Bunzip2" object on success and undef on
317       failure.  The variable $Bunzip2Error 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::Bunzip2 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::Bunzip2 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::Bunzip2
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 is a no-op.
428
429       "Small => 0|1"
430            When non-zero this options will make bzip2 use a decompression
431            algorithm that uses less memory at the expense of increasing the
432            amount of time taken for decompression.
433
434            Default is 0.
435
436   Examples
437       TODO
438

Methods

440   read
441       Usage is
442
443           $status = $z->read($buffer)
444
445       Reads a block of compressed data (the size of the compressed block is
446       determined by the "Buffer" option in the constructor), uncompresses it
447       and writes any uncompressed data into $buffer. If the "Append"
448       parameter is set in the constructor, the uncompressed data will be
449       appended to the $buffer parameter. Otherwise $buffer will be
450       overwritten.
451
452       Returns the number of uncompressed bytes written to $buffer, zero if
453       eof or a negative number on error.
454
455   read
456       Usage is
457
458           $status = $z->read($buffer, $length)
459           $status = $z->read($buffer, $length, $offset)
460
461           $status = read($z, $buffer, $length)
462           $status = read($z, $buffer, $length, $offset)
463
464       Attempt to read $length bytes of uncompressed data into $buffer.
465
466       The main difference between this form of the "read" method and the
467       previous one, is that this one will attempt to return exactly $length
468       bytes. The only circumstances that this function will not is if end-of-
469       file or an IO error is encountered.
470
471       Returns the number of uncompressed bytes written to $buffer, zero if
472       eof or a negative number on error.
473
474   getline
475       Usage is
476
477           $line = $z->getline()
478           $line = <$z>
479
480       Reads a single line.
481
482       This method fully supports the use of the variable $/ (or
483       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
484       what constitutes an end of line. Paragraph mode, record mode and file
485       slurp mode are all supported.
486
487   getc
488       Usage is
489
490           $char = $z->getc()
491
492       Read a single character.
493
494   ungetc
495       Usage is
496
497           $char = $z->ungetc($string)
498
499   getHeaderInfo
500       Usage is
501
502           $hdr  = $z->getHeaderInfo();
503           @hdrs = $z->getHeaderInfo();
504
505       This method returns either a hash reference (in scalar context) or a
506       list or hash references (in array context) that contains information
507       about each of the header fields in the compressed data stream(s).
508
509   tell
510       Usage is
511
512           $z->tell()
513           tell $z
514
515       Returns the uncompressed file offset.
516
517   eof
518       Usage is
519
520           $z->eof();
521           eof($z);
522
523       Returns true if the end of the compressed input stream has been
524       reached.
525
526   seek
527           $z->seek($position, $whence);
528           seek($z, $position, $whence);
529
530       Provides a sub-set of the "seek" functionality, with the restriction
531       that it is only legal to seek forward in the input file/buffer.  It is
532       a fatal error to attempt to seek backward.
533
534       Note that the implementation of "seek" in this module does not provide
535       true random access to a compressed file/buffer. It  works by
536       uncompressing data from the current offset in the file/buffer until it
537       reaches the uncompressed offset specified in the parameters to "seek".
538       For very small files this may be acceptable behaviour. For large files
539       it may cause an unacceptable delay.
540
541       The $whence parameter takes one the usual values, namely SEEK_SET,
542       SEEK_CUR or SEEK_END.
543
544       Returns 1 on success, 0 on failure.
545
546   binmode
547       Usage is
548
549           $z->binmode
550           binmode $z ;
551
552       This is a noop provided for completeness.
553
554   opened
555           $z->opened()
556
557       Returns true if the object currently refers to a opened file/buffer.
558
559   autoflush
560           my $prev = $z->autoflush()
561           my $prev = $z->autoflush(EXPR)
562
563       If the $z object is associated with a file or a filehandle, this method
564       returns the current autoflush setting for the underlying filehandle. If
565       "EXPR" is present, and is non-zero, it will enable flushing after every
566       write/print operation.
567
568       If $z is associated with a buffer, this method has no effect and always
569       returns "undef".
570
571       Note that the special variable $| cannot be used to set or retrieve the
572       autoflush setting.
573
574   input_line_number
575           $z->input_line_number()
576           $z->input_line_number(EXPR)
577
578       Returns the current uncompressed line number. If "EXPR" is present it
579       has the effect of setting the line number. Note that setting the line
580       number does not change the current position within the file/buffer
581       being read.
582
583       The contents of $/ are used to determine what constitutes a line
584       terminator.
585
586   fileno
587           $z->fileno()
588           fileno($z)
589
590       If the $z object is associated with a file or a filehandle, "fileno"
591       will return the underlying file descriptor. Once the "close" method is
592       called "fileno" will return "undef".
593
594       If the $z object is associated with a buffer, this method will return
595       "undef".
596
597   close
598           $z->close() ;
599           close $z ;
600
601       Closes the output file/buffer.
602
603       For most versions of Perl this method will be automatically invoked if
604       the IO::Uncompress::Bunzip2 object is destroyed (either explicitly or
605       by the variable with the reference to the object going out of scope).
606       The exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In
607       these cases, the "close" method will be called automatically, but not
608       until global destruction of all live objects when the program is
609       terminating.
610
611       Therefore, if you want your scripts to be able to run on all versions
612       of Perl, you should call "close" explicitly and not rely on automatic
613       closing.
614
615       Returns true on success, otherwise 0.
616
617       If the "AutoClose" option has been enabled when the
618       IO::Uncompress::Bunzip2 object was created, and the object is
619       associated with a file, the underlying file will also be closed.
620
621   nextStream
622       Usage is
623
624           my $status = $z->nextStream();
625
626       Skips to the next compressed data stream in the input file/buffer. If a
627       new compressed data stream is found, the eof marker will be cleared and
628       $.  will be reset to 0.
629
630       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
631       error was encountered.
632
633   trailingData
634       Usage is
635
636           my $data = $z->trailingData();
637
638       Returns the data, if any, that is present immediately after the
639       compressed data stream once uncompression is complete. It only makes
640       sense to call this method once the end of the compressed data stream
641       has been encountered.
642
643       This option can be used when there is useful information immediately
644       following the compressed data stream, and you don't know the length of
645       the compressed data stream.
646
647       If the input is a buffer, "trailingData" will return everything from
648       the end of the compressed data stream to the end of the buffer.
649
650       If the input is a filehandle, "trailingData" will return the data that
651       is left in the filehandle input buffer once the end of the compressed
652       data stream has been reached. You can then use the filehandle to read
653       the rest of the input file.
654
655       Don't bother using "trailingData" if the input is a filename.
656
657       If you know the length of the compressed data stream before you start
658       uncompressing, you can avoid having to use "trailingData" by setting
659       the "InputLength" option in the constructor.
660

Importing

662       No symbolic constants are required by this IO::Uncompress::Bunzip2 at
663       present.
664
665       :all Imports "bunzip2" and $Bunzip2Error.  Same as doing this
666
667                use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
668

EXAMPLES

670   Working with Net::FTP
671       See IO::Compress::FAQ
672

AUTHOR

691       This module was written by Paul Marquess, "pmqs@cpan.org".
692

MODIFICATION HISTORY

694       See the Changes file.
695

COPYRIGHT AND LICENSE

697       Copyright (c) 2005-2018 Paul Marquess. All rights reserved.
698
699       This program is free software; you can redistribute it and/or modify it
700       under the same terms as Perl itself.
701
702
703
704perl v5.28.0                      2018-04-05        IO::Uncompress::Bunzip2(3)