IO::Uncompress::UnLzip(3pm)

1IO::Uncompress::UnLzip(U3s)er Contributed Perl DocumentatIiOo:n:Uncompress::UnLzip(3)
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NAME

6       IO::Uncompress::UnLzip - Read lzip files/buffers
7

SYNOPSIS

9           use IO::Uncompress::UnLzip qw(unlzip $UnLzipError) ;
10
11           my $status = unlzip $input => $output [,OPTS]
12               or die "unlzip failed: $UnLzipError\n";
13
14           my $z = new IO::Uncompress::UnLzip $input [OPTS]
15               or die "unlzip failed: $UnLzipError\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           $UnLzipError ;
36
37           # IO::File mode
38
39           <$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 lzma
52       files/buffers.
53
54       For writing lzip files/buffers, see the companion module
55       IO::Compress::Lzip.
56

Functional Interface

58       A top-level function, "unlzip", 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::UnLzip qw(unlzip $UnLzipError) ;
63
64           unlzip $input_filename_or_reference => $output_filename_or_reference [,OPTS]
65               or die "unlzip failed: $UnLzipError\n";
66
67       The functional interface needs Perl5.005 or better.
68
69   unlzip $input_filename_or_reference => $output_filename_or_reference [,
70       OPTS]
71       "unlzip" 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 $$input_filename_or_reference.
94
95       An array reference
96            If $input_filename_or_reference is an array reference, each
97            element in the array must be a filename.
98
99            The input data will be read from each file in turn.
100
101            The complete array will be walked to ensure that it only contains
102            valid filenames before any data is uncompressed.
103
104       An Input FileGlob string
105            If $input_filename_or_reference is a string that is delimited by
106            the characters "<" and ">" "unlzip" will assume that it is an
107            input fileglob string. The input is the list of files that match
108            the fileglob.
109
110            See File::GlobMapper for more details.
111
112       If the $input_filename_or_reference parameter is any other type,
113       "undef" will be returned.
114
115       The $output_filename_or_reference parameter
116
117       The parameter $output_filename_or_reference is used to control the
118       destination of the uncompressed data. This parameter can take one of
119       these forms.
120
121       A filename
122            If the $output_filename_or_reference parameter is a simple scalar,
123            it is assumed to be a filename.  This file will be opened for
124            writing and the uncompressed data will be written to it.
125
126       A filehandle
127            If the $output_filename_or_reference parameter is a filehandle,
128            the uncompressed data will be written to it.  The string '-' can
129            be used as an alias for standard output.
130
131       A scalar reference
132            If $output_filename_or_reference is a scalar reference, the
133            uncompressed data will be stored in
134            $$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 ">" "unlzip" 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 "unlzip", "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            "unlzip" 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 "unlzip"
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.xz" and write the
255       uncompressed data to the file "file1.txt".
256
257           use strict ;
258           use warnings ;
259           use IO::Uncompress::UnLzip qw(unlzip $UnLzipError) ;
260
261           my $input = "file1.txt.xz";
262           my $output = "file1.txt";
263           unlzip $input => $output
264               or die "unlzip failed: $UnLzipError\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::UnLzip qw(unlzip $UnLzipError) ;
272           use IO::File ;
273
274           my $input = new IO::File "<file1.txt.xz"
275               or die "Cannot open 'file1.txt.xz': $!\n" ;
276           my $buffer ;
277           unlzip $input => \$buffer
278               or die "unlzip failed: $UnLzipError\n";
279
280       To uncompress all files in the directory "/my/home" that match
281       "*.txt.xz" and store the compressed data in the same directory
282
283           use strict ;
284           use warnings ;
285           use IO::Uncompress::UnLzip qw(unlzip $UnLzipError) ;
286
287           unlzip '</my/home/*.txt.xz>' => '</my/home/#1.txt>'
288               or die "unlzip failed: $UnLzipError\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::UnLzip qw(unlzip $UnLzipError) ;
296
297           for my $input ( glob "/my/home/*.txt.xz" )
298           {
299               my $output = $input;
300               $output =~ s/.xz// ;
301               unlzip $input => $output
302                   or die "Error compressing '$input': $UnLzipError\n";
303           }
304

OO Interface

306   Constructor
307       The format of the constructor for IO::Uncompress::UnLzip is shown below
308
309           my $z = new IO::Uncompress::UnLzip $input [OPTS]
310               or die "IO::Uncompress::UnLzip failed: $UnLzipError\n";
311
312       Returns an "IO::Uncompress::UnLzip" object on success and undef on
313       failure.  The variable $UnLzipError will contain an error message on
314       failure.
315
316       If you are running Perl 5.005 or better the object, $z, returned from
317       IO::Uncompress::UnLzip can be used exactly like an IO::File filehandle.
318       This means that all normal input file operations can be carried out
319       with $z.  For example, to read a line from a compressed file/buffer you
320       can use either of these forms
321
322           $line = $z->getline();
323           $line = <$z>;
324
325       The mandatory parameter $input is used to determine the source of the
326       compressed data. This parameter can take one of three forms.
327
328       A filename
329            If the $input parameter is a scalar, it is assumed to be a
330            filename. This file will be opened for reading and the compressed
331            data will be read from it.
332
333       A filehandle
334            If the $input parameter is a filehandle, the compressed data will
335            be read from it.  The string '-' can be used as an alias for
336            standard input.
337
338       A scalar reference
339            If $input is a scalar reference, the compressed data will be read
340            from $$input.
341
342   Constructor Options
343       The option names defined below are case insensitive and can be
344       optionally prefixed by a '-'.  So all of the following are valid
345
346           -AutoClose
347           -autoclose
348           AUTOCLOSE
349           autoclose
350
351       OPTS is a combination of the following options:
352
353       "AutoClose => 0|1"
354            This option is only valid when the $input parameter is a
355            filehandle. If specified, and the value is true, it will result in
356            the file being closed once either the "close" method is called or
357            the IO::Uncompress::UnLzip object is destroyed.
358
359            This parameter defaults to 0.
360
361       "MultiStream => 0|1"
362            Allows multiple concatenated compressed streams to be treated as a
363            single compressed stream. Decompression will stop once either the
364            end of the file/buffer is reached, an error is encountered
365            (premature eof, corrupt compressed data) or the end of a stream is
366            not immediately followed by the start of another stream.
367
368            This parameter defaults to 0.
369
370       "Prime => $string"
371            This option will uncompress the contents of $string before
372            processing the input file/buffer.
373
374            This option can be useful when the compressed data is embedded in
375            another file/data structure and it is not possible to work out
376            where the compressed data begins without having to read the first
377            few bytes. If this is the case, the uncompression can be primed
378            with these bytes using this option.
379
380       "Transparent => 0|1"
381            If this option is set and the input file/buffer is not compressed
382            data, the module will allow reading of it anyway.
383
384            In addition, if the input file/buffer does contain compressed data
385            and there is non-compressed data immediately following it, setting
386            this option will make this module treat the whole file/buffer as a
387            single data stream.
388
389            This option defaults to 1.
390
391       "BlockSize => $num"
392            When reading the compressed input data, IO::Uncompress::UnLzip
393            will read it in blocks of $num bytes.
394
395            This option defaults to 4096.
396
397       "InputLength => $size"
398            When present this option will limit the number of compressed bytes
399            read from the input file/buffer to $size. This option can be used
400            in the situation where there is useful data directly after the
401            compressed data stream and you know beforehand the exact length of
402            the compressed data stream.
403
404            This option is mostly used when reading from a filehandle, in
405            which case the file pointer will be left pointing to the first
406            byte directly after the compressed data stream.
407
408            This option defaults to off.
409
410       "Append => 0|1"
411            This option controls what the "read" method does with uncompressed
412            data.
413
414            If set to 1, all uncompressed data will be appended to the output
415            parameter of the "read" method.
416
417            If set to 0, the contents of the output parameter of the "read"
418            method will be overwritten by the uncompressed data.
419
420            Defaults to 0.
421
422       "Strict => 0|1"
423            This option controls whether the extra checks defined below are
424            used when carrying out the decompression. When Strict is on, the
425            extra tests are carried out, when Strict is off they are not.
426
427            The default for this option is off.
428
429   Examples
430       TODO
431

Methods

433   read
434       Usage is
435
436           $status = $z->read($buffer)
437
438       Reads a block of compressed data (the size of the compressed block is
439       determined by the "Buffer" option in the constructor), uncompresses it
440       and writes any uncompressed data into $buffer. If the "Append"
441       parameter is set in the constructor, the uncompressed data will be
442       appended to the $buffer parameter. Otherwise $buffer will be
443       overwritten.
444
445       Returns the number of uncompressed bytes written to $buffer, zero if
446       eof or a negative number on error.
447
448   read
449       Usage is
450
451           $status = $z->read($buffer, $length)
452           $status = $z->read($buffer, $length, $offset)
453
454           $status = read($z, $buffer, $length)
455           $status = read($z, $buffer, $length, $offset)
456
457       Attempt to read $length bytes of uncompressed data into $buffer.
458
459       The main difference between this form of the "read" method and the
460       previous one, is that this one will attempt to return exactly $length
461       bytes. The only circumstances that this function will not is if end-of-
462       file or an IO error is encountered.
463
464       Returns the number of uncompressed bytes written to $buffer, zero if
465       eof or a negative number on error.
466
467   getline
468       Usage is
469
470           $line = $z->getline()
471           $line = <$z>
472
473       Reads a single line.
474
475       This method fully supports the use of the variable $/ (or
476       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
477       what constitutes an end of line. Paragraph mode, record mode and file
478       slurp mode are all supported.
479
480   getc
481       Usage is
482
483           $char = $z->getc()
484
485       Read a single character.
486
487   ungetc
488       Usage is
489
490           $char = $z->ungetc($string)
491
492   getHeaderInfo
493       Usage is
494
495           $hdr  = $z->getHeaderInfo();
496           @hdrs = $z->getHeaderInfo();
497
498       This method returns either a hash reference (in scalar context) or a
499       list or hash references (in array context) that contains information
500       about each of the header fields in the compressed data stream(s).
501
502   tell
503       Usage is
504
505           $z->tell()
506           tell $z
507
508       Returns the uncompressed file offset.
509
510   eof
511       Usage is
512
513           $z->eof();
514           eof($z);
515
516       Returns true if the end of the compressed input stream has been
517       reached.
518
519   seek
520           $z->seek($position, $whence);
521           seek($z, $position, $whence);
522
523       Provides a sub-set of the "seek" functionality, with the restriction
524       that it is only legal to seek forward in the input file/buffer.  It is
525       a fatal error to attempt to seek backward.
526
527       Note that the implementation of "seek" in this module does not provide
528       true random access to a compressed file/buffer. It  works by
529       uncompressing data from the current offset in the file/buffer until it
530       reaches the uncompressed offset specified in the parameters to "seek".
531       For very small files this may be acceptable behaviour. For large files
532       it may cause an unacceptable delay.
533
534       The $whence parameter takes one the usual values, namely SEEK_SET,
535       SEEK_CUR or SEEK_END.
536
537       Returns 1 on success, 0 on failure.
538
539   binmode
540       Usage is
541
542           $z->binmode
543           binmode $z ;
544
545       This is a noop provided for completeness.
546
547   opened
548           $z->opened()
549
550       Returns true if the object currently refers to a opened file/buffer.
551
552   autoflush
553           my $prev = $z->autoflush()
554           my $prev = $z->autoflush(EXPR)
555
556       If the $z object is associated with a file or a filehandle, this method
557       returns the current autoflush setting for the underlying filehandle. If
558       "EXPR" is present, and is non-zero, it will enable flushing after every
559       write/print operation.
560
561       If $z is associated with a buffer, this method has no effect and always
562       returns "undef".
563
564       Note that the special variable $| cannot be used to set or retrieve the
565       autoflush setting.
566
567   input_line_number
568           $z->input_line_number()
569           $z->input_line_number(EXPR)
570
571       Returns the current uncompressed line number. If "EXPR" is present it
572       has the effect of setting the line number. Note that setting the line
573       number does not change the current position within the file/buffer
574       being read.
575
576       The contents of $/ are used to determine what constitutes a line
577       terminator.
578
579   fileno
580           $z->fileno()
581           fileno($z)
582
583       If the $z object is associated with a file or a filehandle, "fileno"
584       will return the underlying file descriptor. Once the "close" method is
585       called "fileno" will return "undef".
586
587       If the $z object is associated with a buffer, this method will return
588       "undef".
589
590   close
591           $z->close() ;
592           close $z ;
593
594       Closes the output file/buffer.
595
596       For most versions of Perl this method will be automatically invoked if
597       the IO::Uncompress::UnLzip object is destroyed (either explicitly or by
598       the variable with the reference to the object going out of scope). The
599       exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In these
600       cases, the "close" method will be called automatically, but not until
601       global destruction of all live objects when the program is terminating.
602
603       Therefore, if you want your scripts to be able to run on all versions
604       of Perl, you should call "close" explicitly and not rely on automatic
605       closing.
606
607       Returns true on success, otherwise 0.
608
609       If the "AutoClose" option has been enabled when the
610       IO::Uncompress::UnLzip object was created, and the object is associated
611       with a file, the underlying file will also be closed.
612
613   nextStream
614       Usage is
615
616           my $status = $z->nextStream();
617
618       Skips to the next compressed data stream in the input file/buffer. If a
619       new compressed data stream is found, the eof marker will be cleared and
620       $.  will be reset to 0.
621
622       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
623       error was encountered.
624
625   trailingData
626       Usage is
627
628           my $data = $z->trailingData();
629
630       Returns the data, if any, that is present immediately after the
631       compressed data stream once uncompression is complete. It only makes
632       sense to call this method once the end of the compressed data stream
633       has been encountered.
634
635       This option can be used when there is useful information immediately
636       following the compressed data stream, and you don't know the length of
637       the compressed data stream.
638
639       If the input is a buffer, "trailingData" will return everything from
640       the end of the compressed data stream to the end of the buffer.
641
642       If the input is a filehandle, "trailingData" will return the data that
643       is left in the filehandle input buffer once the end of the compressed
644       data stream has been reached. You can then use the filehandle to read
645       the rest of the input file.
646
647       Don't bother using "trailingData" if the input is a filename.
648
649       If you know the length of the compressed data stream before you start
650       uncompressing, you can avoid having to use "trailingData" by setting
651       the "InputLength" option in the constructor.
652

Importing

654       No symbolic constants are required by this IO::Uncompress::UnLzip at
655       present.
656
657       :all Imports "unlzip" and $UnLzipError.  Same as doing this
658
659                use IO::Uncompress::UnLzip qw(unlzip $UnLzipError) ;
660

EXAMPLES

AUTHOR

678       This module was written by Paul Marquess, "pmqs@cpan.org".
679

MODIFICATION HISTORY

681       See the Changes file.
682

COPYRIGHT AND LICENSE

684       Copyright (c) 2005-2019 Paul Marquess. All rights reserved.
685
686       This program is free software; you can redistribute it and/or modify it
687       under the same terms as Perl itself.
688
689
690
691perl v5.28.1                      2019-01-05         IO::Uncompress::UnLzip(3)