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            This option is now a no-op. All files will be written  in binmode.
179
180       "Append => 0|1"
181            The behaviour of this option is dependent on the type of output
182            data stream.
183
184            ·    A Buffer
185
186                 If "Append" is enabled, all uncompressed data will be append
187                 to the end of the output buffer. Otherwise the output buffer
188                 will be cleared before any uncompressed data is written to
189                 it.
190
191            ·    A Filename
192
193                 If "Append" is enabled, the file will be opened in append
194                 mode. Otherwise the contents of the file, if any, will be
195                 truncated before any uncompressed data is written to it.
196
197            ·    A Filehandle
198
199                 If "Append" is enabled, the filehandle will be positioned to
200                 the end of the file via a call to "seek" before any
201                 uncompressed data is written to it.  Otherwise the file
202                 pointer will not be moved.
203
204            When "Append" is specified, and set to true, it will append all
205            uncompressed data to the output data stream.
206
207            So when the output is a filehandle it will carry out a seek to the
208            eof before writing any uncompressed data. If the output is a
209            filename, it will be opened for appending. If the output is a
210            buffer, all uncompressed data will be appended to the existing
211            buffer.
212
213            Conversely when "Append" is not specified, or it is present and is
214            set to false, it will operate as follows.
215
216            When the output is a filename, it will truncate the contents of
217            the file before writing any uncompressed data. If the output is a
218            filehandle its position will not be changed. If the output is a
219            buffer, it will be wiped before any uncompressed data is output.
220
221            Defaults to 0.
222
223       "MultiStream => 0|1"
224            If the input file/buffer contains multiple compressed data
225            streams, this option will uncompress the whole lot as a single
226            data stream.
227
228            Defaults to 0.
229
230       "TrailingData => $scalar"
231            Returns the data, if any, that is present immediately after the
232            compressed data stream once uncompression is complete.
233
234            This option can be used when there is useful information
235            immediately following the compressed data stream, and you don't
236            know the length of the compressed data stream.
237
238            If the input is a buffer, "trailingData" will return everything
239            from the end of the compressed data stream to the end of the
240            buffer.
241
242            If the input is a filehandle, "trailingData" will return the data
243            that is left in the filehandle input buffer once the end of the
244            compressed data stream has been reached. You can then use the
245            filehandle to read the rest of the input file.
246
247            Don't bother using "trailingData" if the input is a filename.
248
249            If you know the length of the compressed data stream before you
250            start uncompressing, you can avoid having to use "trailingData" by
251            setting the "InputLength" option.
252
253   Examples
254       To read the contents of the file "file1.txt.bz2" and write the
255       uncompressed data to the file "file1.txt".
256
257           use strict ;
258           use warnings ;
259           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
260
261           my $input = "file1.txt.bz2";
262           my $output = "file1.txt";
263           bunzip2 $input => $output
264               or die "bunzip2 failed: $Bunzip2Error\n";
265
266       To read from an existing Perl filehandle, $input, and write the
267       uncompressed data to a buffer, $buffer.
268
269           use strict ;
270           use warnings ;
271           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
272           use IO::File ;
273
274           my $input = new IO::File "<file1.txt.bz2"
275               or die "Cannot open 'file1.txt.bz2': $!\n" ;
276           my $buffer ;
277           bunzip2 $input => \$buffer
278               or die "bunzip2 failed: $Bunzip2Error\n";
279
280       To uncompress all files in the directory "/my/home" that match
281       "*.txt.bz2" and store the compressed data in the same directory
282
283           use strict ;
284           use warnings ;
285           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
286
287           bunzip2 '</my/home/*.txt.bz2>' => '</my/home/#1.txt>'
288               or die "bunzip2 failed: $Bunzip2Error\n";
289
290       and if you want to compress each file one at a time, this will do the
291       trick
292
293           use strict ;
294           use warnings ;
295           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
296
297           for my $input ( glob "/my/home/*.txt.bz2" )
298           {
299               my $output = $input;
300               $output =~ s/.bz2// ;
301               bunzip2 $input => $output
302                   or die "Error compressing '$input': $Bunzip2Error\n";
303           }
304

OO Interface

306   Constructor
307       The format of the constructor for IO::Uncompress::Bunzip2 is shown
308       below
309
310           my $z = new IO::Uncompress::Bunzip2 $input [OPTS]
311               or die "IO::Uncompress::Bunzip2 failed: $Bunzip2Error\n";
312
313       Returns an "IO::Uncompress::Bunzip2" object on success and undef on
314       failure.  The variable $Bunzip2Error will contain an error message on
315       failure.
316
317       If you are running Perl 5.005 or better the object, $z, returned from
318       IO::Uncompress::Bunzip2 can be used exactly like an IO::File
319       filehandle.  This means that all normal input file operations can be
320       carried out with $z.  For example, to read a line from a compressed
321       file/buffer you can use either of these forms
322
323           $line = $z->getline();
324           $line = <$z>;
325
326       The mandatory parameter $input is used to determine the source of the
327       compressed data. This parameter can take one of three forms.
328
329       A filename
330            If the $input parameter is a scalar, it is assumed to be a
331            filename. This file will be opened for reading and the compressed
332            data will be read from it.
333
334       A filehandle
335            If the $input parameter is a filehandle, the compressed data will
336            be read from it.  The string '-' can be used as an alias for
337            standard input.
338
339       A scalar reference
340            If $input is a scalar reference, the compressed data will be read
341            from $$input.
342
343   Constructor Options
344       The option names defined below are case insensitive and can be
345       optionally prefixed by a '-'.  So all of the following are valid
346
347           -AutoClose
348           -autoclose
349           AUTOCLOSE
350           autoclose
351
352       OPTS is a combination of the following options:
353
354       "AutoClose => 0|1"
355            This option is only valid when the $input parameter is a
356            filehandle. If specified, and the value is true, it will result in
357            the file being closed once either the "close" method is called or
358            the IO::Uncompress::Bunzip2 object is destroyed.
359
360            This parameter defaults to 0.
361
362       "MultiStream => 0|1"
363            Allows multiple concatenated compressed streams to be treated as a
364            single compressed stream. Decompression will stop once either the
365            end of the file/buffer is reached, an error is encountered
366            (premature eof, corrupt compressed data) or the end of a stream is
367            not immediately followed by the start of another stream.
368
369            This parameter defaults to 0.
370
371       "Prime => $string"
372            This option will uncompress the contents of $string before
373            processing the input file/buffer.
374
375            This option can be useful when the compressed data is embedded in
376            another file/data structure and it is not possible to work out
377            where the compressed data begins without having to read the first
378            few bytes. If this is the case, the uncompression can be primed
379            with these bytes using this option.
380
381       "Transparent => 0|1"
382            If this option is set and the input file/buffer is not compressed
383            data, the module will allow reading of it anyway.
384
385            In addition, if the input file/buffer does contain compressed data
386            and there is non-compressed data immediately following it, setting
387            this option will make this module treat the whole file/buffer as a
388            single data stream.
389
390            This option defaults to 1.
391
392       "BlockSize => $num"
393            When reading the compressed input data, IO::Uncompress::Bunzip2
394            will read it in blocks of $num bytes.
395
396            This option defaults to 4096.
397
398       "InputLength => $size"
399            When present this option will limit the number of compressed bytes
400            read from the input file/buffer to $size. This option can be used
401            in the situation where there is useful data directly after the
402            compressed data stream and you know beforehand the exact length of
403            the compressed data stream.
404
405            This option is mostly used when reading from a filehandle, in
406            which case the file pointer will be left pointing to the first
407            byte directly after the compressed data stream.
408
409            This option defaults to off.
410
411       "Append => 0|1"
412            This option controls what the "read" method does with uncompressed
413            data.
414
415            If set to 1, all uncompressed data will be appended to the output
416            parameter of the "read" method.
417
418            If set to 0, the contents of the output parameter of the "read"
419            method will be overwritten by the uncompressed data.
420
421            Defaults to 0.
422
423       "Strict => 0|1"
424            This option is a no-op.
425
426       "Small => 0|1"
427            When non-zero this options will make bzip2 use a decompression
428            algorithm that uses less memory at the expense of increasing the
429            amount of time taken for decompression.
430
431            Default is 0.
432
433   Examples
434       TODO
435

Methods

437   read
438       Usage is
439
440           $status = $z->read($buffer)
441
442       Reads a block of compressed data (the size of the compressed block is
443       determined by the "Buffer" option in the constructor), uncompresses it
444       and writes any uncompressed data into $buffer. If the "Append"
445       parameter is set in the constructor, the uncompressed data will be
446       appended to the $buffer parameter. Otherwise $buffer will be
447       overwritten.
448
449       Returns the number of uncompressed bytes written to $buffer, zero if
450       eof or a negative number on error.
451
452   read
453       Usage is
454
455           $status = $z->read($buffer, $length)
456           $status = $z->read($buffer, $length, $offset)
457
458           $status = read($z, $buffer, $length)
459           $status = read($z, $buffer, $length, $offset)
460
461       Attempt to read $length bytes of uncompressed data into $buffer.
462
463       The main difference between this form of the "read" method and the
464       previous one, is that this one will attempt to return exactly $length
465       bytes. The only circumstances that this function will not is if end-of-
466       file or an IO error is encountered.
467
468       Returns the number of uncompressed bytes written to $buffer, zero if
469       eof or a negative number on error.
470
471   getline
472       Usage is
473
474           $line = $z->getline()
475           $line = <$z>
476
477       Reads a single line.
478
479       This method fully supports the use of the variable $/ (or
480       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
481       what constitutes an end of line. Paragraph mode, record mode and file
482       slurp mode are all supported.
483
484   getc
485       Usage is
486
487           $char = $z->getc()
488
489       Read a single character.
490
491   ungetc
492       Usage is
493
494           $char = $z->ungetc($string)
495
496   getHeaderInfo
497       Usage is
498
499           $hdr  = $z->getHeaderInfo();
500           @hdrs = $z->getHeaderInfo();
501
502       This method returns either a hash reference (in scalar context) or a
503       list or hash references (in array context) that contains information
504       about each of the header fields in the compressed data stream(s).
505
506   tell
507       Usage is
508
509           $z->tell()
510           tell $z
511
512       Returns the uncompressed file offset.
513
514   eof
515       Usage is
516
517           $z->eof();
518           eof($z);
519
520       Returns true if the end of the compressed input stream has been
521       reached.
522
523   seek
524           $z->seek($position, $whence);
525           seek($z, $position, $whence);
526
527       Provides a sub-set of the "seek" functionality, with the restriction
528       that it is only legal to seek forward in the input file/buffer.  It is
529       a fatal error to attempt to seek backward.
530
531       Note that the implementation of "seek" in this module does not provide
532       true random access to a compressed file/buffer. It  works by
533       uncompressing data from the current offset in the file/buffer until it
534       reaches the uncompressed offset specified in the parameters to "seek".
535       For very small files this may be acceptable behaviour. For large files
536       it may cause an unacceptable delay.
537
538       The $whence parameter takes one the usual values, namely SEEK_SET,
539       SEEK_CUR or SEEK_END.
540
541       Returns 1 on success, 0 on failure.
542
543   binmode
544       Usage is
545
546           $z->binmode
547           binmode $z ;
548
549       This is a noop provided for completeness.
550
551   opened
552           $z->opened()
553
554       Returns true if the object currently refers to a opened file/buffer.
555
556   autoflush
557           my $prev = $z->autoflush()
558           my $prev = $z->autoflush(EXPR)
559
560       If the $z object is associated with a file or a filehandle, this method
561       returns the current autoflush setting for the underlying filehandle. If
562       "EXPR" is present, and is non-zero, it will enable flushing after every
563       write/print operation.
564
565       If $z is associated with a buffer, this method has no effect and always
566       returns "undef".
567
568       Note that the special variable $| cannot be used to set or retrieve the
569       autoflush setting.
570
571   input_line_number
572           $z->input_line_number()
573           $z->input_line_number(EXPR)
574
575       Returns the current uncompressed line number. If "EXPR" is present it
576       has the effect of setting the line number. Note that setting the line
577       number does not change the current position within the file/buffer
578       being read.
579
580       The contents of $/ are used to determine what constitutes a line
581       terminator.
582
583   fileno
584           $z->fileno()
585           fileno($z)
586
587       If the $z object is associated with a file or a filehandle, "fileno"
588       will return the underlying file descriptor. Once the "close" method is
589       called "fileno" will return "undef".
590
591       If the $z object is associated with a buffer, this method will return
592       "undef".
593
594   close
595           $z->close() ;
596           close $z ;
597
598       Closes the output file/buffer.
599
600       For most versions of Perl this method will be automatically invoked if
601       the IO::Uncompress::Bunzip2 object is destroyed (either explicitly or
602       by the variable with the reference to the object going out of scope).
603       The exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In
604       these cases, the "close" method will be called automatically, but not
605       until global destruction of all live objects when the program is
606       terminating.
607
608       Therefore, if you want your scripts to be able to run on all versions
609       of Perl, you should call "close" explicitly and not rely on automatic
610       closing.
611
612       Returns true on success, otherwise 0.
613
614       If the "AutoClose" option has been enabled when the
615       IO::Uncompress::Bunzip2 object was created, and the object is
616       associated with a file, the underlying file will also be closed.
617
618   nextStream
619       Usage is
620
621           my $status = $z->nextStream();
622
623       Skips to the next compressed data stream in the input file/buffer. If a
624       new compressed data stream is found, the eof marker will be cleared and
625       $.  will be reset to 0.
626
627       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
628       error was encountered.
629
630   trailingData
631       Usage is
632
633           my $data = $z->trailingData();
634
635       Returns the data, if any, that is present immediately after the
636       compressed data stream once uncompression is complete. It only makes
637       sense to call this method once the end of the compressed data stream
638       has been encountered.
639
640       This option can be used when there is useful information immediately
641       following the compressed data stream, and you don't know the length of
642       the compressed data stream.
643
644       If the input is a buffer, "trailingData" will return everything from
645       the end of the compressed data stream to the end of the buffer.
646
647       If the input is a filehandle, "trailingData" will return the data that
648       is left in the filehandle input buffer once the end of the compressed
649       data stream has been reached. You can then use the filehandle to read
650       the rest of the input file.
651
652       Don't bother using "trailingData" if the input is a filename.
653
654       If you know the length of the compressed data stream before you start
655       uncompressing, you can avoid having to use "trailingData" by setting
656       the "InputLength" option in the constructor.
657

Importing

659       No symbolic constants are required by this IO::Uncompress::Bunzip2 at
660       present.
661
662       :all Imports "bunzip2" and $Bunzip2Error.  Same as doing this
663
664                use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
665

EXAMPLES

667   Working with Net::FTP
668       See IO::Compress::FAQ
669

AUTHOR

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

MODIFICATION HISTORY

693       See the Changes file.
694

COPYRIGHT AND LICENSE

696       Copyright (c) 2005-2019 Paul Marquess. All rights reserved.
697
698       This program is free software; you can redistribute it and/or modify it
699       under the same terms as Perl itself.
700
701
702
703perl v5.28.1                      2019-01-05        IO::Uncompress::Bunzip2(3)