IO::Uncompress::UnXz(3pm)

1IO::Uncompress::UnXz(3)User Contributed Perl DocumentatioInO::Uncompress::UnXz(3)
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NAME

6       IO::Uncompress::UnXz - Read xz files/buffers
7

SYNOPSIS

9           use IO::Uncompress::UnXz qw(unxz $UnXzError) ;
10
11           my $status = unxz $input => $output [,OPTS]
12               or die "unxz failed: $UnXzError\n";
13
14           my $z = new IO::Uncompress::UnXz $input [OPTS]
15               or die "unxz failed: $UnXzError\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           $UnXzError ;
36
37           # IO::File mode
38
39           <$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       WARNING -- This is a Beta release.
52
53       ·    DO NOT use in production code.
54
55       ·    The documentation is incomplete in places.
56
57       ·    Parts of the interface defined here are tentative.
58
59       ·    Please report any problems you find.
60
61       This module provides a Perl interface that allows the reading of lzma
62       files/buffers.
63
64       For writing xz files/buffers, see the companion module
65       IO::Compress::Xz.
66

Functional Interface

68       A top-level function, "unxz", is provided to carry out "one-shot"
69       uncompression between buffers and/or files. For finer control over the
70       uncompression process, see the "OO Interface" section.
71
72           use IO::Uncompress::UnXz qw(unxz $UnXzError) ;
73
74           unxz $input_filename_or_reference => $output_filename_or_reference [,OPTS]
75               or die "unxz failed: $UnXzError\n";
76
77       The functional interface needs Perl5.005 or better.
78
79   unxz $input_filename_or_reference => $output_filename_or_reference [, OPTS]
80       "unxz" expects at least two parameters, $input_filename_or_reference
81       and $output_filename_or_reference.
82
83       The $input_filename_or_reference parameter
84
85       The parameter, $input_filename_or_reference, is used to define the
86       source of the compressed data.
87
88       It can take one of the following forms:
89
90       A filename
91            If the <$input_filename_or_reference> parameter is a simple
92            scalar, it is assumed to be a filename. This file will be opened
93            for reading and the input data will be read from it.
94
95       A filehandle
96            If the $input_filename_or_reference parameter is a filehandle, the
97            input data will be read from it.  The string '-' can be used as an
98            alias for standard input.
99
100       A scalar reference
101            If $input_filename_or_reference is a scalar reference, the input
102            data will be read from $$input_filename_or_reference.
103
104       An array reference
105            If $input_filename_or_reference is an array reference, each
106            element in the array must be a filename.
107
108            The input data will be read from each file in turn.
109
110            The complete array will be walked to ensure that it only contains
111            valid filenames before any data is uncompressed.
112
113       An Input FileGlob string
114            If $input_filename_or_reference is a string that is delimited by
115            the characters "<" and ">" "unxz" will assume that it is an input
116            fileglob string. The input is the list of files that match the
117            fileglob.
118
119            See File::GlobMapper for more details.
120
121       If the $input_filename_or_reference parameter is any other type,
122       "undef" will be returned.
123
124       The $output_filename_or_reference parameter
125
126       The parameter $output_filename_or_reference is used to control the
127       destination of the uncompressed data. This parameter can take one of
128       these forms.
129
130       A filename
131            If the $output_filename_or_reference parameter is a simple scalar,
132            it is assumed to be a filename.  This file will be opened for
133            writing and the uncompressed data will be written to it.
134
135       A filehandle
136            If the $output_filename_or_reference parameter is a filehandle,
137            the uncompressed data will be written to it.  The string '-' can
138            be used as an alias for standard output.
139
140       A scalar reference
141            If $output_filename_or_reference is a scalar reference, the
142            uncompressed data will be stored in
143            $$output_filename_or_reference.
144
145       An Array Reference
146            If $output_filename_or_reference is an array reference, the
147            uncompressed data will be pushed onto the array.
148
149       An Output FileGlob
150            If $output_filename_or_reference is a string that is delimited by
151            the characters "<" and ">" "unxz" will assume that it is an output
152            fileglob string. The output is the list of files that match the
153            fileglob.
154
155            When $output_filename_or_reference is an fileglob string,
156            $input_filename_or_reference must also be a fileglob string.
157            Anything else is an error.
158
159            See File::GlobMapper for more details.
160
161       If the $output_filename_or_reference parameter is any other type,
162       "undef" will be returned.
163
164   Notes
165       When $input_filename_or_reference maps to multiple compressed
166       files/buffers and $output_filename_or_reference is a single
167       file/buffer, after uncompression $output_filename_or_reference will
168       contain a concatenation of all the uncompressed data from each of the
169       input files/buffers.
170
171   Optional Parameters
172       Unless specified below, the optional parameters for "unxz", "OPTS", are
173       the same as those used with the OO interface defined in the
174       "Constructor Options" section below.
175
176       "AutoClose => 0|1"
177            This option applies to any input or output data streams to "unxz"
178            that are filehandles.
179
180            If "AutoClose" is specified, and the value is true, it will result
181            in all input and/or output filehandles being closed once "unxz"
182            has completed.
183
184            This parameter defaults to 0.
185
186       "BinModeOut => 0|1"
187            This option is now a no-op. All files will be written  in binmode.
188
189       "Append => 0|1"
190            The behaviour of this option is dependent on the type of output
191            data stream.
192
193            ·    A Buffer
194
195                 If "Append" is enabled, all uncompressed data will be append
196                 to the end of the output buffer. Otherwise the output buffer
197                 will be cleared before any uncompressed data is written to
198                 it.
199
200            ·    A Filename
201
202                 If "Append" is enabled, the file will be opened in append
203                 mode. Otherwise the contents of the file, if any, will be
204                 truncated before any uncompressed data is written to it.
205
206            ·    A Filehandle
207
208                 If "Append" is enabled, the filehandle will be positioned to
209                 the end of the file via a call to "seek" before any
210                 uncompressed data is written to it.  Otherwise the file
211                 pointer will not be moved.
212
213            When "Append" is specified, and set to true, it will append all
214            uncompressed data to the output data stream.
215
216            So when the output is a filehandle it will carry out a seek to the
217            eof before writing any uncompressed data. If the output is a
218            filename, it will be opened for appending. If the output is a
219            buffer, all uncompressed data will be appended to the existing
220            buffer.
221
222            Conversely when "Append" is not specified, or it is present and is
223            set to false, it will operate as follows.
224
225            When the output is a filename, it will truncate the contents of
226            the file before writing any uncompressed data. If the output is a
227            filehandle its position will not be changed. If the output is a
228            buffer, it will be wiped before any uncompressed data is output.
229
230            Defaults to 0.
231
232       "MultiStream => 0|1"
233            If the input file/buffer contains multiple compressed data
234            streams, this option will uncompress the whole lot as a single
235            data stream.
236
237            Defaults to 0.
238
239       "TrailingData => $scalar"
240            Returns the data, if any, that is present immediately after the
241            compressed data stream once uncompression is complete.
242
243            This option can be used when there is useful information
244            immediately following the compressed data stream, and you don't
245            know the length of the compressed data stream.
246
247            If the input is a buffer, "trailingData" will return everything
248            from the end of the compressed data stream to the end of the
249            buffer.
250
251            If the input is a filehandle, "trailingData" will return the data
252            that is left in the filehandle input buffer once the end of the
253            compressed data stream has been reached. You can then use the
254            filehandle to read the rest of the input file.
255
256            Don't bother using "trailingData" if the input is a filename.
257
258            If you know the length of the compressed data stream before you
259            start uncompressing, you can avoid having to use "trailingData" by
260            setting the "InputLength" option.
261
262   Examples
263       To read the contents of the file "file1.txt.xz" and write the
264       uncompressed data to the file "file1.txt".
265
266           use strict ;
267           use warnings ;
268           use IO::Uncompress::UnXz qw(unxz $UnXzError) ;
269
270           my $input = "file1.txt.xz";
271           my $output = "file1.txt";
272           unxz $input => $output
273               or die "unxz failed: $UnXzError\n";
274
275       To read from an existing Perl filehandle, $input, and write the
276       uncompressed data to a buffer, $buffer.
277
278           use strict ;
279           use warnings ;
280           use IO::Uncompress::UnXz qw(unxz $UnXzError) ;
281           use IO::File ;
282
283           my $input = new IO::File "<file1.txt.xz"
284               or die "Cannot open 'file1.txt.xz': $!\n" ;
285           my $buffer ;
286           unxz $input => \$buffer
287               or die "unxz failed: $UnXzError\n";
288
289       To uncompress all files in the directory "/my/home" that match
290       "*.txt.xz" and store the compressed data in the same directory
291
292           use strict ;
293           use warnings ;
294           use IO::Uncompress::UnXz qw(unxz $UnXzError) ;
295
296           unxz '</my/home/*.txt.xz>' => '</my/home/#1.txt>'
297               or die "unxz failed: $UnXzError\n";
298
299       and if you want to compress each file one at a time, this will do the
300       trick
301
302           use strict ;
303           use warnings ;
304           use IO::Uncompress::UnXz qw(unxz $UnXzError) ;
305
306           for my $input ( glob "/my/home/*.txt.xz" )
307           {
308               my $output = $input;
309               $output =~ s/.xz// ;
310               unxz $input => $output
311                   or die "Error compressing '$input': $UnXzError\n";
312           }
313

OO Interface

315   Constructor
316       The format of the constructor for IO::Uncompress::UnXz is shown below
317
318           my $z = new IO::Uncompress::UnXz $input [OPTS]
319               or die "IO::Uncompress::UnXz failed: $UnXzError\n";
320
321       Returns an "IO::Uncompress::UnXz" object on success and undef on
322       failure.  The variable $UnXzError will contain an error message on
323       failure.
324
325       If you are running Perl 5.005 or better the object, $z, returned from
326       IO::Uncompress::UnXz can be used exactly like an IO::File filehandle.
327       This means that all normal input file operations can be carried out
328       with $z.  For example, to read a line from a compressed file/buffer you
329       can use either of these forms
330
331           $line = $z->getline();
332           $line = <$z>;
333
334       The mandatory parameter $input is used to determine the source of the
335       compressed data. This parameter can take one of three forms.
336
337       A filename
338            If the $input parameter is a scalar, it is assumed to be a
339            filename. This file will be opened for reading and the compressed
340            data will be read from it.
341
342       A filehandle
343            If the $input parameter is a filehandle, the compressed data will
344            be read from it.  The string '-' can be used as an alias for
345            standard input.
346
347       A scalar reference
348            If $input is a scalar reference, the compressed data will be read
349            from $$input.
350
351   Constructor Options
352       The option names defined below are case insensitive and can be
353       optionally prefixed by a '-'.  So all of the following are valid
354
355           -AutoClose
356           -autoclose
357           AUTOCLOSE
358           autoclose
359
360       OPTS is a combination of the following options:
361
362       "AutoClose => 0|1"
363            This option is only valid when the $input parameter is a
364            filehandle. If specified, and the value is true, it will result in
365            the file being closed once either the "close" method is called or
366            the IO::Uncompress::UnXz object is destroyed.
367
368            This parameter defaults to 0.
369
370       "MultiStream => 0|1"
371            Allows multiple concatenated compressed streams to be treated as a
372            single compressed stream. Decompression will stop once either the
373            end of the file/buffer is reached, an error is encountered
374            (premature eof, corrupt compressed data) or the end of a stream is
375            not immediately followed by the start of another stream.
376
377            This parameter defaults to 0.
378
379       "Prime => $string"
380            This option will uncompress the contents of $string before
381            processing the input file/buffer.
382
383            This option can be useful when the compressed data is embedded in
384            another file/data structure and it is not possible to work out
385            where the compressed data begins without having to read the first
386            few bytes. If this is the case, the uncompression can be primed
387            with these bytes using this option.
388
389       "Transparent => 0|1"
390            If this option is set and the input file/buffer is not compressed
391            data, the module will allow reading of it anyway.
392
393            In addition, if the input file/buffer does contain compressed data
394            and there is non-compressed data immediately following it, setting
395            this option will make this module treat the whole file/buffer as a
396            single data stream.
397
398            This option defaults to 1.
399
400       "BlockSize => $num"
401            When reading the compressed input data, IO::Uncompress::UnXz will
402            read it in blocks of $num bytes.
403
404            This option defaults to 4096.
405
406       "InputLength => $size"
407            When present this option will limit the number of compressed bytes
408            read from the input file/buffer to $size. This option can be used
409            in the situation where there is useful data directly after the
410            compressed data stream and you know beforehand the exact length of
411            the compressed data stream.
412
413            This option is mostly used when reading from a filehandle, in
414            which case the file pointer will be left pointing to the first
415            byte directly after the compressed data stream.
416
417            This option defaults to off.
418
419       "Append => 0|1"
420            This option controls what the "read" method does with uncompressed
421            data.
422
423            If set to 1, all uncompressed data will be appended to the output
424            parameter of the "read" method.
425
426            If set to 0, the contents of the output parameter of the "read"
427            method will be overwritten by the uncompressed data.
428
429            Defaults to 0.
430
431       "Strict => 0|1"
432            This option controls whether the extra checks defined below are
433            used when carrying out the decompression. When Strict is on, the
434            extra tests are carried out, when Strict is off they are not.
435
436            The default for this option is off.
437
438       "MemLimit => $number"
439            Default is 128Meg.
440
441       "Flags => $flags"
442            Default is 0.
443
444   Examples
445       TODO
446

Methods

448   read
449       Usage is
450
451           $status = $z->read($buffer)
452
453       Reads a block of compressed data (the size of the compressed block is
454       determined by the "Buffer" option in the constructor), uncompresses it
455       and writes any uncompressed data into $buffer. If the "Append"
456       parameter is set in the constructor, the uncompressed data will be
457       appended to the $buffer parameter. Otherwise $buffer will be
458       overwritten.
459
460       Returns the number of uncompressed bytes written to $buffer, zero if
461       eof or a negative number on error.
462
463   read
464       Usage is
465
466           $status = $z->read($buffer, $length)
467           $status = $z->read($buffer, $length, $offset)
468
469           $status = read($z, $buffer, $length)
470           $status = read($z, $buffer, $length, $offset)
471
472       Attempt to read $length bytes of uncompressed data into $buffer.
473
474       The main difference between this form of the "read" method and the
475       previous one, is that this one will attempt to return exactly $length
476       bytes. The only circumstances that this function will not is if end-of-
477       file or an IO error is encountered.
478
479       Returns the number of uncompressed bytes written to $buffer, zero if
480       eof or a negative number on error.
481
482   getline
483       Usage is
484
485           $line = $z->getline()
486           $line = <$z>
487
488       Reads a single line.
489
490       This method fully supports the use of the variable $/ (or
491       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
492       what constitutes an end of line. Paragraph mode, record mode and file
493       slurp mode are all supported.
494
495   getc
496       Usage is
497
498           $char = $z->getc()
499
500       Read a single character.
501
502   ungetc
503       Usage is
504
505           $char = $z->ungetc($string)
506
507   getHeaderInfo
508       Usage is
509
510           $hdr  = $z->getHeaderInfo();
511           @hdrs = $z->getHeaderInfo();
512
513       This method returns either a hash reference (in scalar context) or a
514       list or hash references (in array context) that contains information
515       about each of the header fields in the compressed data stream(s).
516
517   tell
518       Usage is
519
520           $z->tell()
521           tell $z
522
523       Returns the uncompressed file offset.
524
525   eof
526       Usage is
527
528           $z->eof();
529           eof($z);
530
531       Returns true if the end of the compressed input stream has been
532       reached.
533
534   seek
535           $z->seek($position, $whence);
536           seek($z, $position, $whence);
537
538       Provides a sub-set of the "seek" functionality, with the restriction
539       that it is only legal to seek forward in the input file/buffer.  It is
540       a fatal error to attempt to seek backward.
541
542       Note that the implementation of "seek" in this module does not provide
543       true random access to a compressed file/buffer. It  works by
544       uncompressing data from the current offset in the file/buffer until it
545       reaches the uncompressed offset specified in the parameters to "seek".
546       For very small files this may be acceptable behaviour. For large files
547       it may cause an unacceptable delay.
548
549       The $whence parameter takes one the usual values, namely SEEK_SET,
550       SEEK_CUR or SEEK_END.
551
552       Returns 1 on success, 0 on failure.
553
554   binmode
555       Usage is
556
557           $z->binmode
558           binmode $z ;
559
560       This is a noop provided for completeness.
561
562   opened
563           $z->opened()
564
565       Returns true if the object currently refers to a opened file/buffer.
566
567   autoflush
568           my $prev = $z->autoflush()
569           my $prev = $z->autoflush(EXPR)
570
571       If the $z object is associated with a file or a filehandle, this method
572       returns the current autoflush setting for the underlying filehandle. If
573       "EXPR" is present, and is non-zero, it will enable flushing after every
574       write/print operation.
575
576       If $z is associated with a buffer, this method has no effect and always
577       returns "undef".
578
579       Note that the special variable $| cannot be used to set or retrieve the
580       autoflush setting.
581
582   input_line_number
583           $z->input_line_number()
584           $z->input_line_number(EXPR)
585
586       Returns the current uncompressed line number. If "EXPR" is present it
587       has the effect of setting the line number. Note that setting the line
588       number does not change the current position within the file/buffer
589       being read.
590
591       The contents of $/ are used to determine what constitutes a line
592       terminator.
593
594   fileno
595           $z->fileno()
596           fileno($z)
597
598       If the $z object is associated with a file or a filehandle, "fileno"
599       will return the underlying file descriptor. Once the "close" method is
600       called "fileno" will return "undef".
601
602       If the $z object is associated with a buffer, this method will return
603       "undef".
604
605   close
606           $z->close() ;
607           close $z ;
608
609       Closes the output file/buffer.
610
611       For most versions of Perl this method will be automatically invoked if
612       the IO::Uncompress::UnXz object is destroyed (either explicitly or by
613       the variable with the reference to the object going out of scope). The
614       exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In these
615       cases, the "close" method will be called automatically, but not until
616       global destruction of all live objects when the program is terminating.
617
618       Therefore, if you want your scripts to be able to run on all versions
619       of Perl, you should call "close" explicitly and not rely on automatic
620       closing.
621
622       Returns true on success, otherwise 0.
623
624       If the "AutoClose" option has been enabled when the
625       IO::Uncompress::UnXz object was created, and the object is associated
626       with a file, the underlying file will also be closed.
627
628   nextStream
629       Usage is
630
631           my $status = $z->nextStream();
632
633       Skips to the next compressed data stream in the input file/buffer. If a
634       new compressed data stream is found, the eof marker will be cleared and
635       $.  will be reset to 0.
636
637       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
638       error was encountered.
639
640   trailingData
641       Usage is
642
643           my $data = $z->trailingData();
644
645       Returns the data, if any, that is present immediately after the
646       compressed data stream once uncompression is complete. It only makes
647       sense to call this method once the end of the compressed data stream
648       has been encountered.
649
650       This option can be used when there is useful information immediately
651       following the compressed data stream, and you don't know the length of
652       the compressed data stream.
653
654       If the input is a buffer, "trailingData" will return everything from
655       the end of the compressed data stream to the end of the buffer.
656
657       If the input is a filehandle, "trailingData" will return the data that
658       is left in the filehandle input buffer once the end of the compressed
659       data stream has been reached. You can then use the filehandle to read
660       the rest of the input file.
661
662       Don't bother using "trailingData" if the input is a filename.
663
664       If you know the length of the compressed data stream before you start
665       uncompressing, you can avoid having to use "trailingData" by setting
666       the "InputLength" option in the constructor.
667

Importing

669       No symbolic constants are required by this IO::Uncompress::UnXz at
670       present.
671
672       :all Imports "unxz" and $UnXzError.  Same as doing this
673
674                use IO::Uncompress::UnXz qw(unxz $UnXzError) ;
675

EXAMPLES

AUTHOR

693       This module was written by Paul Marquess, "pmqs@cpan.org".
694

MODIFICATION HISTORY

696       See the Changes file.
697

COPYRIGHT AND LICENSE

699       Copyright (c) 2005-2019 Paul Marquess. All rights reserved.
700
701       This program is free software; you can redistribute it and/or modify it
702       under the same terms as Perl itself.
703
704
705
706perl v5.28.1                      2019-01-05           IO::Uncompress::UnXz(3)