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 IO::Com‐
55       press::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 => $output [,OPTS]
65               or die "bunzip2 failed: $Bunzip2Error\n";
66
67       The functional interface needs Perl5.005 or better.
68
69       bunzip2 $input => $output [, OPTS]
70
71       "bunzip2" expects at least two parameters, $input and $output.
72
73       The $input parameter
74
75       The parameter, $input, is used to define the source of the compressed
76       data.
77
78       It can take one of the following forms:
79
80       A filename
81            If the $input parameter is a simple scalar, it is assumed to be a
82            filename. This file will be opened for reading and the input data
83            will be read from it.
84
85       A filehandle
86            If the $input parameter is a filehandle, the input data will be
87            read from it.  The string '-' can be used as an alias for standard
88            input.
89
90       A scalar reference
91            If $input is a scalar reference, the input data will be read from
92            $$input.
93
94       An array reference
95            If $input is an array reference, each element in the array must be
96            a filename.
97
98            The input data will be read from each file in turn.
99
100            The complete array will be walked to ensure that it only contains
101            valid filenames before any data is uncompressed.
102
103       An Input FileGlob string
104            If $input is a string that is delimited by the characters "<" and
105            ">" "bunzip2" will assume that it is an input fileglob string. The
106            input is the list of files that match the fileglob.
107
108            If the fileglob does not match any files ...
109
110            See File::GlobMapper for more details.
111
112       If the $input parameter is any other type, "undef" will be returned.
113
114       The $output parameter
115
116       The parameter $output is used to control the destination of the uncom‐
117       pressed data. This parameter can take one of these forms.
118
119       A filename
120            If the $output parameter is a simple scalar, it is assumed to be a
121            filename.  This file will be opened for writing and the uncom‐
122            pressed data will be written to it.
123
124       A filehandle
125            If the $output parameter is a filehandle, the uncompressed data
126            will be written to it.  The string '-' can be used as an alias for
127            standard output.
128
129       A scalar reference
130            If $output is a scalar reference, the uncompressed data will be
131            stored in $$output.
132
133       An Array Reference
134            If $output is an array reference, the uncompressed data will be
135            pushed onto the array.
136
137       An Output FileGlob
138            If $output is a string that is delimited by the characters "<" and
139            ">" "bunzip2" will assume that it is an output fileglob string.
140            The output is the list of files that match the fileglob.
141
142            When $output is an fileglob string, $input must also be a fileglob
143            string. Anything else is an error.
144
145       If the $output parameter is any other type, "undef" will be returned.
146
147       Notes
148
149       When $input maps to multiple compressed files/buffers and $output is a
150       single file/buffer, after uncompression $output will contain a concate‐
151       nation of all the uncompressed data from each of the input files/buf‐
152       fers.
153
154       Optional Parameters
155
156       Unless specified below, the optional parameters for "bunzip2", "OPTS",
157       are the same as those used with the OO interface defined in the "Con‐
158       structor Options" section below.
159
160       "AutoClose => 0⎪1"
161            This option applies to any input or output data streams to "bun‐
162            zip2" that are filehandles.
163
164            If "AutoClose" is specified, and the value is true, it will result
165            in all input and/or output filehandles being closed once "bunzip2"
166            has completed.
167
168            This parameter defaults to 0.
169
170       "BinModeOut => 0⎪1"
171            When writing to a file or filehandle, set "binmode" before writing
172            to the file.
173
174            Defaults to 0.
175
176       "Append => 0⎪1"
177            TODO
178
179       "MultiStream => 0⎪1"
180            If the input file/buffer contains multiple compressed data
181            streams, this option will uncompress the whole lot as a single
182            data stream.
183
184            Defaults to 0.
185
186       "TrailingData => $scalar"
187            Returns the data, if any, that is present immediately after the
188            compressed data stream once uncompression is complete.
189
190            This option can be used when there is useful information immedi‐
191            ately following the compressed data stream, and you don't know the
192            length of the compressed data stream.
193
194            If the input is a buffer, "trailingData" will return everything
195            from the end of the compressed data stream to the end of the buf‐
196            fer.
197
198            If the input is a filehandle, "trailingData" will return the data
199            that is left in the filehandle input buffer once the end of the
200            compressed data stream has been reached. You can then use the
201            filehandle to read the rest of the input file.
202
203            Don't bother using "trailingData" if the input is a filename.
204
205            If you know the length of the compressed data stream before you
206            start uncompressing, you can avoid having to use "trailingData" by
207            setting the "InputLength" option.
208
209       Examples
210
211       To read the contents of the file "file1.txt.bz2" and write the com‐
212       pressed data to the file "file1.txt".
213
214           use strict ;
215           use warnings ;
216           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
217
218           my $input = "file1.txt.bz2";
219           my $output = "file1.txt";
220           bunzip2 $input => $output
221               or die "bunzip2 failed: $Bunzip2Error\n";
222
223       To read from an existing Perl filehandle, $input, and write the uncom‐
224       pressed data to a buffer, $buffer.
225
226           use strict ;
227           use warnings ;
228           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
229           use IO::File ;
230
231           my $input = new IO::File "<file1.txt.bz2"
232               or die "Cannot open 'file1.txt.bz2': $!\n" ;
233           my $buffer ;
234           bunzip2 $input => \$buffer
235               or die "bunzip2 failed: $Bunzip2Error\n";
236
237       To uncompress all files in the directory "/my/home" that match
238       "*.txt.bz2" and store the compressed data in the same directory
239
240           use strict ;
241           use warnings ;
242           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
243
244           bunzip2 '</my/home/*.txt.bz2>' => '</my/home/#1.txt>'
245               or die "bunzip2 failed: $Bunzip2Error\n";
246
247       and if you want to compress each file one at a time, this will do the
248       trick
249
250           use strict ;
251           use warnings ;
252           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
253
254           for my $input ( glob "/my/home/*.txt.bz2" )
255           {
256               my $output = $input;
257               $output =~ s/.bz2// ;
258               bunzip2 $input => $output
259                   or die "Error compressing '$input': $Bunzip2Error\n";
260           }
261

OO Interface

263       Constructor
264
265       The format of the constructor for IO::Uncompress::Bunzip2 is shown
266       below
267
268           my $z = new IO::Uncompress::Bunzip2 $input [OPTS]
269               or die "IO::Uncompress::Bunzip2 failed: $Bunzip2Error\n";
270
271       Returns an "IO::Uncompress::Bunzip2" object on success and undef on
272       failure.  The variable $Bunzip2Error will contain an error message on
273       failure.
274
275       If you are running Perl 5.005 or better the object, $z, returned from
276       IO::Uncompress::Bunzip2 can be used exactly like an IO::File filehan‐
277       dle.  This means that all normal input file operations can be carried
278       out with $z.  For example, to read a line from a compressed file/buffer
279       you can use either of these forms
280
281           $line = $z->getline();
282           $line = <$z>;
283
284       The mandatory parameter $input is used to determine the source of the
285       compressed data. This parameter can take one of three forms.
286
287       A filename
288            If the $input parameter is a scalar, it is assumed to be a file‐
289            name. This file will be opened for reading and the compressed data
290            will be read from it.
291
292       A filehandle
293            If the $input parameter is a filehandle, the compressed data will
294            be read from it.  The string '-' can be used as an alias for stan‐
295            dard input.
296
297       A scalar reference
298            If $input is a scalar reference, the compressed data will be read
299            from $$output.
300
301       Constructor Options
302
303       The option names defined below are case insensitive and can be option‐
304       ally prefixed by a '-'.  So all of the following are valid
305
306           -AutoClose
307           -autoclose
308           AUTOCLOSE
309           autoclose
310
311       OPTS is a combination of the following options:
312
313       "AutoClose => 0⎪1"
314            This option is only valid when the $input parameter is a filehan‐
315            dle. If specified, and the value is true, it will result in the
316            file being closed once either the "close" method is called or the
317            IO::Uncompress::Bunzip2 object is destroyed.
318
319            This parameter defaults to 0.
320
321       "MultiStream => 0⎪1"
322            Allows multiple concatenated compressed streams to be treated as a
323            single compressed stream. Decompression will stop once either the
324            end of the file/buffer is reached, an error is encountered (prema‐
325            ture eof, corrupt compressed data) or the end of a stream is not
326            immediately followed by the start of another stream.
327
328            This parameter defaults to 0.
329
330       "Prime => $string"
331            This option will uncompress the contents of $string before pro‐
332            cessing the input file/buffer.
333
334            This option can be useful when the compressed data is embedded in
335            another file/data structure and it is not possible to work out
336            where the compressed data begins without having to read the first
337            few bytes. If this is the case, the uncompression can be primed
338            with these bytes using this option.
339
340       "Transparent => 0⎪1"
341            If this option is set and the input file/buffer is not compressed
342            data, the module will allow reading of it anyway.
343
344            In addition, if the input file/buffer does contain compressed data
345            and there is non-compressed data immediately following it, setting
346            this option will make this module treat the whole file/bufffer as
347            a single data stream.
348
349            This option defaults to 1.
350
351       "BlockSize => $num"
352            When reading the compressed input data, IO::Uncompress::Bunzip2
353            will read it in blocks of $num bytes.
354
355            This option defaults to 4096.
356
357       "InputLength => $size"
358            When present this option will limit the number of compressed bytes
359            read from the input file/buffer to $size. This option can be used
360            in the situation where there is useful data directly after the
361            compressed data stream and you know beforehand the exact length of
362            the compressed data stream.
363
364            This option is mostly used when reading from a filehandle, in
365            which case the file pointer will be left pointing to the first
366            byte directly after the compressed data stream.
367
368            This option defaults to off.
369
370       "Append => 0⎪1"
371            This option controls what the "read" method does with uncompressed
372            data.
373
374            If set to 1, all uncompressed data will be appended to the output
375            parameter of the "read" method.
376
377            If set to 0, the contents of the output parameter of the "read"
378            method will be overwritten by the uncompressed data.
379
380            Defaults to 0.
381
382       "Strict => 0⎪1"
383            This option is a no-op.
384
385       "Small => 0⎪1"
386            When non-zero this options will make bzip2 use a decompression
387            algorithm that uses less memory at the expense of increasing the
388            amount of time taken for decompression.
389
390            Default is 0.
391
392       Examples
393
394       TODO
395

Methods

397       read
398
399       Usage is
400
401           $status = $z->read($buffer)
402
403       Reads a block of compressed data (the size the the compressed block is
404       determined by the "Buffer" option in the constructor), uncompresses it
405       and writes any uncompressed data into $buffer. If the "Append" parame‐
406       ter is set in the constructor, the uncompressed data will be appended
407       to the $buffer parameter. Otherwise $buffer will be overwritten.
408
409       Returns the number of uncompressed bytes written to $buffer, zero if
410       eof or a negative number on error.
411
412       read
413
414       Usage is
415
416           $status = $z->read($buffer, $length)
417           $status = $z->read($buffer, $length, $offset)
418
419           $status = read($z, $buffer, $length)
420           $status = read($z, $buffer, $length, $offset)
421
422       Attempt to read $length bytes of uncompressed data into $buffer.
423
424       The main difference between this form of the "read" method and the pre‐
425       vious one, is that this one will attempt to return exactly $length
426       bytes. The only circumstances that this function will not is if end-of-
427       file or an IO error is encountered.
428
429       Returns the number of uncompressed bytes written to $buffer, zero if
430       eof or a negative number on error.
431
432       getline
433
434       Usage is
435
436           $line = $z->getline()
437           $line = <$z>
438
439       Reads a single line.
440
441       This method fully supports the use of of the variable $/ (or
442       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
443       what constitutes an end of line. Paragraph mode, record mode and file
444       slurp mode are all supported.
445
446       getc
447
448       Usage is
449
450           $char = $z->getc()
451
452       Read a single character.
453
454       ungetc
455
456       Usage is
457
458           $char = $z->ungetc($string)
459
460       getHeaderInfo
461
462       Usage is
463
464           $hdr  = $z->getHeaderInfo();
465           @hdrs = $z->getHeaderInfo();
466
467       This method returns either a hash reference (in scalar context) or a
468       list or hash references (in array context) that contains information
469       about each of the header fields in the compressed data stream(s).
470
471       tell
472
473       Usage is
474
475           $z->tell()
476           tell $z
477
478       Returns the uncompressed file offset.
479
480       eof
481
482       Usage is
483
484           $z->eof();
485           eof($z);
486
487       Returns true if the end of the compressed input stream has been
488       reached.
489
490       seek
491
492           $z->seek($position, $whence);
493           seek($z, $position, $whence);
494
495       Provides a sub-set of the "seek" functionality, with the restriction
496       that it is only legal to seek forward in the input file/buffer.  It is
497       a fatal error to attempt to seek backward.
498
499       The $whence parameter takes one the usual values, namely SEEK_SET,
500       SEEK_CUR or SEEK_END.
501
502       Returns 1 on success, 0 on failure.
503
504       binmode
505
506       Usage is
507
508           $z->binmode
509           binmode $z ;
510
511       This is a noop provided for completeness.
512
513       opened
514
515           $z->opened()
516
517       Returns true if the object currently refers to a opened file/buffer.
518
519       autoflush
520
521           my $prev = $z->autoflush()
522           my $prev = $z->autoflush(EXPR)
523
524       If the $z object is associated with a file or a filehandle, this method
525       returns the current autoflush setting for the underlying filehandle. If
526       "EXPR" is present, and is non-zero, it will enable flushing after every
527       write/print operation.
528
529       If $z is associated with a buffer, this method has no effect and always
530       returns "undef".
531
532       Note that the special variable $⎪ cannot be used to set or retrieve the
533       autoflush setting.
534
535       input_line_number
536
537           $z->input_line_number()
538           $z->input_line_number(EXPR)
539
540       Returns the current uncompressed line number. If "EXPR" is present it
541       has the effect of setting the line number. Note that setting the line
542       number does not change the current position within the file/buffer
543       being read.
544
545       The contents of $/ are used to to determine what constitutes a line
546       terminator.
547
548       fileno
549
550           $z->fileno()
551           fileno($z)
552
553       If the $z object is associated with a file or a filehandle, this method
554       will return the underlying file descriptor.
555
556       If the $z object is is associated with a buffer, this method will
557       return undef.
558
559       close
560
561           $z->close() ;
562           close $z ;
563
564       Closes the output file/buffer.
565
566       For most versions of Perl this method will be automatically invoked if
567       the IO::Uncompress::Bunzip2 object is destroyed (either explicitly or
568       by the variable with the reference to the object going out of scope).
569       The exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In
570       these cases, the "close" method will be called automatically, but not
571       until global destruction of all live objects when the program is termi‐
572       nating.
573
574       Therefore, if you want your scripts to be able to run on all versions
575       of Perl, you should call "close" explicitly and not rely on automatic
576       closing.
577
578       Returns true on success, otherwise 0.
579
580       If the "AutoClose" option has been enabled when the IO::Uncom‐
581       press::Bunzip2 object was created, and the object is associated with a
582       file, the underlying file will also be closed.
583
584       nextStream
585
586       Usage is
587
588           my $status = $z->nextStream();
589
590       Skips to the next compressed data stream in the input file/buffer. If a
591       new compressed data stream is found, the eof marker will be cleared and
592       $.  will be reset to 0.
593
594       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
595       error was encountered.
596
597       trailingData
598
599       Usage is
600
601           my $data = $z->trailingData();
602
603       Returns the data, if any, that is present immediately after the com‐
604       pressed data stream once uncompression is complete. It only makes sense
605       to call this method once the end of the compressed data stream has been
606       encountered.
607
608       This option can be used when there is useful information immediately
609       following the compressed data stream, and you don't know the length of
610       the compressed data stream.
611
612       If the input is a buffer, "trailingData" will return everything from
613       the end of the compressed data stream to the end of the buffer.
614
615       If the input is a filehandle, "trailingData" will return the data that
616       is left in the filehandle input buffer once the end of the compressed
617       data stream has been reached. You can then use the filehandle to read
618       the rest of the input file.
619
620       Don't bother using "trailingData" if the input is a filename.
621
622       If you know the length of the compressed data stream before you start
623       uncompressing, you can avoid having to use "trailingData" by setting
624       the "InputLength" option in the constructor.
625

Importing

627       No symbolic constants are required by this IO::Uncompress::Bunzip2 at
628       present.
629
630       :all Imports "bunzip2" and $Bunzip2Error.  Same as doing this
631
632                use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
633

EXAMPLES

AUTHOR

651       This module was written by Paul Marquess, pmqs@cpan.org.
652

MODIFICATION HISTORY

654       See the Changes file.
655

COPYRIGHT AND LICENSE

657       Copyright (c) 2005-2007 Paul Marquess. All rights reserved.
658
659       This program is free software; you can redistribute it and/or modify it
660       under the same terms as Perl itself.
661
662
663
664perl v5.8.8                       2007-06-18        IO::Uncompress::Bunzip2(3)