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 = IO::Uncompress::UnXz->new( $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       This module provides a Perl interface that allows the reading of lzma
52       files/buffers.
53
54       For writing xz files/buffers, see the companion module
55       IO::Compress::Xz.
56

Functional Interface

58       A top-level function, "unxz", 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::UnXz qw(unxz $UnXzError) ;
63
64           unxz $input_filename_or_reference => $output_filename_or_reference [,OPTS]
65               or die "unxz failed: $UnXzError\n";
66
67       The functional interface needs Perl5.005 or better.
68
69   unxz $input_filename_or_reference => $output_filename_or_reference [, OPTS]
70       "unxz" expects at least two parameters, $input_filename_or_reference
71       and $output_filename_or_reference and zero or more optional parameters
72       (see "Optional Parameters")
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 scalar,
83            it is assumed to be a filename. This file will be opened for
84            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 $$input_filename_or_reference.
94
95       An array reference
96            If $input_filename_or_reference is an array reference, each
97            element in the array must be a filename.
98
99            The input data will be read from each file in turn.
100
101            The complete array will be walked to ensure that it only contains
102            valid filenames before any data is uncompressed.
103
104       An Input FileGlob string
105            If $input_filename_or_reference is a string that is delimited by
106            the characters "<" and ">" "unxz" will assume that it is an input
107            fileglob string. The input is the list of files that match the
108            fileglob.
109
110            See File::GlobMapper for more details.
111
112       If the $input_filename_or_reference parameter is any other type,
113       "undef" will be returned.
114
115       The $output_filename_or_reference parameter
116
117       The parameter $output_filename_or_reference is used to control the
118       destination of the uncompressed data. This parameter can take one of
119       these forms.
120
121       A filename
122            If the $output_filename_or_reference parameter is a simple scalar,
123            it is assumed to be a filename.  This file will be opened for
124            writing and the uncompressed data will be written to it.
125
126       A filehandle
127            If the $output_filename_or_reference parameter is a filehandle,
128            the uncompressed data will be written to it.  The string '-' can
129            be used as an alias for standard output.
130
131       A scalar reference
132            If $output_filename_or_reference is a scalar reference, the
133            uncompressed data will be stored in
134            $$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 ">" "unxz" will assume that it is an output
143            fileglob string. The output is the list of files that match the
144            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       The optional parameters for the one-shot function "unxz" are (for the
164       most part) identical to those used with the OO interface defined in the
165       "Constructor Options" section. The exceptions are listed below
166
167       "AutoClose => 0|1"
168            This option applies to any input or output data streams to "unxz"
169            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 "unxz"
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   OneShot 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::UnXz qw(unxz $UnXzError) ;
260
261           my $input = "file1.txt.xz";
262           my $output = "file1.txt";
263           unxz $input => $output
264               or die "unxz failed: $UnXzError\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::UnXz qw(unxz $UnXzError) ;
272           use IO::File ;
273
274           my $input = IO::File->new( "<file1.txt.xz" )
275               or die "Cannot open 'file1.txt.xz': $!\n" ;
276           my $buffer ;
277           unxz $input => \$buffer
278               or die "unxz failed: $UnXzError\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::UnXz qw(unxz $UnXzError) ;
286
287           unxz '</my/home/*.txt.xz>' => '</my/home/#1.txt>'
288               or die "unxz failed: $UnXzError\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::UnXz qw(unxz $UnXzError) ;
296
297           for my $input ( glob "/my/home/*.txt.xz" )
298           {
299               my $output = $input;
300               $output =~ s/.xz// ;
301               unxz $input => $output
302                   or die "Error compressing '$input': $UnXzError\n";
303           }
304

OO Interface

306   Constructor
307       The format of the constructor for IO::Uncompress::UnXz is shown below
308
309           my $z = IO::Uncompress::UnXz->new( $input [OPTS] )
310               or die "IO::Uncompress::UnXz failed: $UnXzError\n";
311
312       The constructor takes one mandatory parameter, $input, defined below,
313       and zero or more "OPTS", defined in "Constructor Options".
314
315       Returns an "IO::Uncompress::UnXz" object on success and undef on
316       failure.  The variable $UnXzError will contain an error message on
317       failure.
318
319       If you are running Perl 5.005 or better the object, $z, returned from
320       IO::Uncompress::UnXz can be used exactly like an IO::File filehandle.
321       This means that all normal input file operations can be carried out
322       with $z.  For example, to read a line from a compressed file/buffer you
323       can use either of these forms
324
325           $line = $z->getline();
326           $line = <$z>;
327
328       Below is a simple exaple of using the OO interface to read the
329       compressed file "myfile.xz" and write its contents to stdout.
330
331           my $filename = "myfile.xz";
332           my $z = IO::Uncompress::UnXz->new($filename)
333               or die "IO::Uncompress::UnXz failed: $UnXzError\n";
334
335           while (<$z>) {
336               print $_;
337           }
338           $z->close();
339
340       See "EXAMPLES" for further examples
341
342       The mandatory parameter $input is used to determine the source of the
343       compressed data. This parameter can take one of three forms.
344
345       A filename
346            If the $input parameter is a scalar, it is assumed to be a
347            filename. This file will be opened for reading and the compressed
348            data will be read from it.
349
350       A filehandle
351            If the $input parameter is a filehandle, the compressed data will
352            be read from it.  The string '-' can be used as an alias for
353            standard input.
354
355       A scalar reference
356            If $input is a scalar reference, the compressed data will be read
357            from $$input.
358
359   Constructor Options
360       The option names defined below are case insensitive and can be
361       optionally prefixed by a '-'.  So all of the following are valid
362
363           -AutoClose
364           -autoclose
365           AUTOCLOSE
366           autoclose
367
368       OPTS is a combination of the following options:
369
370       "AutoClose => 0|1"
371            This option is only valid when the $input parameter is a
372            filehandle. If specified, and the value is true, it will result in
373            the file being closed once either the "close" method is called or
374            the IO::Uncompress::UnXz object is destroyed.
375
376            This parameter defaults to 0.
377
378       "MultiStream => 0|1"
379            Allows multiple concatenated compressed streams to be treated as a
380            single compressed stream. Decompression will stop once either the
381            end of the file/buffer is reached, an error is encountered
382            (premature eof, corrupt compressed data) or the end of a stream is
383            not immediately followed by the start of another stream.
384
385            This parameter defaults to 0.
386
387       "Prime => $string"
388            This option will uncompress the contents of $string before
389            processing the input file/buffer.
390
391            This option can be useful when the compressed data is embedded in
392            another file/data structure and it is not possible to work out
393            where the compressed data begins without having to read the first
394            few bytes. If this is the case, the uncompression can be primed
395            with these bytes using this option.
396
397       "Transparent => 0|1"
398            If this option is set and the input file/buffer is not compressed
399            data, the module will allow reading of it anyway.
400
401            In addition, if the input file/buffer does contain compressed data
402            and there is non-compressed data immediately following it, setting
403            this option will make this module treat the whole file/buffer as a
404            single data stream.
405
406            This option defaults to 1.
407
408       "BlockSize => $num"
409            When reading the compressed input data, IO::Uncompress::UnXz will
410            read it in blocks of $num bytes.
411
412            This option defaults to 4096.
413
414       "InputLength => $size"
415            When present this option will limit the number of compressed bytes
416            read from the input file/buffer to $size. This option can be used
417            in the situation where there is useful data directly after the
418            compressed data stream and you know beforehand the exact length of
419            the compressed data stream.
420
421            This option is mostly used when reading from a filehandle, in
422            which case the file pointer will be left pointing to the first
423            byte directly after the compressed data stream.
424
425            This option defaults to off.
426
427       "Append => 0|1"
428            This option controls what the "read" method does with uncompressed
429            data.
430
431            If set to 1, all uncompressed data will be appended to the output
432            parameter of the "read" method.
433
434            If set to 0, the contents of the output parameter of the "read"
435            method will be overwritten by the uncompressed data.
436
437            Defaults to 0.
438
439       "Strict => 0|1"
440            This option controls whether the extra checks defined below are
441            used when carrying out the decompression. When Strict is on, the
442            extra tests are carried out, when Strict is off they are not.
443
444            The default for this option is off.
445
446       "MemLimit => $number"
447            Default is 128Meg.
448
449       "Flags => $flags"
450            Default is 0.
451

Methods

453   read
454       Usage is
455
456           $status = $z->read($buffer)
457
458       Reads a block of compressed data (the size of the compressed block is
459       determined by the "Buffer" option in the constructor), uncompresses it
460       and writes any uncompressed data into $buffer. If the "Append"
461       parameter is set in the constructor, the uncompressed data will be
462       appended to the $buffer parameter. Otherwise $buffer will be
463       overwritten.
464
465       Returns the number of uncompressed bytes written to $buffer, zero if
466       eof or a negative number on error.
467
468   read
469       Usage is
470
471           $status = $z->read($buffer, $length)
472           $status = $z->read($buffer, $length, $offset)
473
474           $status = read($z, $buffer, $length)
475           $status = read($z, $buffer, $length, $offset)
476
477       Attempt to read $length bytes of uncompressed data into $buffer.
478
479       The main difference between this form of the "read" method and the
480       previous one, is that this one will attempt to return exactly $length
481       bytes. The only circumstances that this function will not is if end-of-
482       file or an IO error is encountered.
483
484       Returns the number of uncompressed bytes written to $buffer, zero if
485       eof or a negative number on error.
486
487   getline
488       Usage is
489
490           $line = $z->getline()
491           $line = <$z>
492
493       Reads a single line.
494
495       This method fully supports the use of the variable $/ (or
496       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
497       what constitutes an end of line. Paragraph mode, record mode and file
498       slurp mode are all supported.
499
500   getc
501       Usage is
502
503           $char = $z->getc()
504
505       Read a single character.
506
507   ungetc
508       Usage is
509
510           $char = $z->ungetc($string)
511
512   getHeaderInfo
513       Usage is
514
515           $hdr  = $z->getHeaderInfo();
516           @hdrs = $z->getHeaderInfo();
517
518       This method returns either a hash reference (in scalar context) or a
519       list or hash references (in array context) that contains information
520       about each of the header fields in the compressed data stream(s).
521
522   tell
523       Usage is
524
525           $z->tell()
526           tell $z
527
528       Returns the uncompressed file offset.
529
530   eof
531       Usage is
532
533           $z->eof();
534           eof($z);
535
536       Returns true if the end of the compressed input stream has been
537       reached.
538
539   seek
540           $z->seek($position, $whence);
541           seek($z, $position, $whence);
542
543       Provides a sub-set of the "seek" functionality, with the restriction
544       that it is only legal to seek forward in the input file/buffer.  It is
545       a fatal error to attempt to seek backward.
546
547       Note that the implementation of "seek" in this module does not provide
548       true random access to a compressed file/buffer. It  works by
549       uncompressing data from the current offset in the file/buffer until it
550       reaches the uncompressed offset specified in the parameters to "seek".
551       For very small files this may be acceptable behaviour. For large files
552       it may cause an unacceptable delay.
553
554       The $whence parameter takes one the usual values, namely SEEK_SET,
555       SEEK_CUR or SEEK_END.
556
557       Returns 1 on success, 0 on failure.
558
559   binmode
560       Usage is
561
562           $z->binmode
563           binmode $z ;
564
565       This is a noop provided for completeness.
566
567   opened
568           $z->opened()
569
570       Returns true if the object currently refers to a opened file/buffer.
571
572   autoflush
573           my $prev = $z->autoflush()
574           my $prev = $z->autoflush(EXPR)
575
576       If the $z object is associated with a file or a filehandle, this method
577       returns the current autoflush setting for the underlying filehandle. If
578       "EXPR" is present, and is non-zero, it will enable flushing after every
579       write/print operation.
580
581       If $z is associated with a buffer, this method has no effect and always
582       returns "undef".
583
584       Note that the special variable $| cannot be used to set or retrieve the
585       autoflush setting.
586
587   input_line_number
588           $z->input_line_number()
589           $z->input_line_number(EXPR)
590
591       Returns the current uncompressed line number. If "EXPR" is present it
592       has the effect of setting the line number. Note that setting the line
593       number does not change the current position within the file/buffer
594       being read.
595
596       The contents of $/ are used to determine what constitutes a line
597       terminator.
598
599   fileno
600           $z->fileno()
601           fileno($z)
602
603       If the $z object is associated with a file or a filehandle, "fileno"
604       will return the underlying file descriptor. Once the "close" method is
605       called "fileno" will return "undef".
606
607       If the $z object is associated with a buffer, this method will return
608       "undef".
609
610   close
611           $z->close() ;
612           close $z ;
613
614       Closes the output file/buffer.
615
616       For most versions of Perl this method will be automatically invoked if
617       the IO::Uncompress::UnXz object is destroyed (either explicitly or by
618       the variable with the reference to the object going out of scope). The
619       exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In these
620       cases, the "close" method will be called automatically, but not until
621       global destruction of all live objects when the program is terminating.
622
623       Therefore, if you want your scripts to be able to run on all versions
624       of Perl, you should call "close" explicitly and not rely on automatic
625       closing.
626
627       Returns true on success, otherwise 0.
628
629       If the "AutoClose" option has been enabled when the
630       IO::Uncompress::UnXz object was created, and the object is associated
631       with a file, the underlying file will also be closed.
632
633   nextStream
634       Usage is
635
636           my $status = $z->nextStream();
637
638       Skips to the next compressed data stream in the input file/buffer. If a
639       new compressed data stream is found, the eof marker will be cleared and
640       $.  will be reset to 0.
641
642       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
643       error was encountered.
644
645   trailingData
646       Usage is
647
648           my $data = $z->trailingData();
649
650       Returns the data, if any, that is present immediately after the
651       compressed data stream once uncompression is complete. It only makes
652       sense to call this method once the end of the compressed data stream
653       has been encountered.
654
655       This option can be used when there is useful information immediately
656       following the compressed data stream, and you don't know the length of
657       the compressed data stream.
658
659       If the input is a buffer, "trailingData" will return everything from
660       the end of the compressed data stream to the end of the buffer.
661
662       If the input is a filehandle, "trailingData" will return the data that
663       is left in the filehandle input buffer once the end of the compressed
664       data stream has been reached. You can then use the filehandle to read
665       the rest of the input file.
666
667       Don't bother using "trailingData" if the input is a filename.
668
669       If you know the length of the compressed data stream before you start
670       uncompressing, you can avoid having to use "trailingData" by setting
671       the "InputLength" option in the constructor.
672

Importing

674       No symbolic constants are required by IO::Uncompress::UnXz at present.
675
676       :all Imports "unxz" and $UnXzError.  Same as doing this
677
678                use IO::Uncompress::UnXz qw(unxz $UnXzError) ;
679

EXAMPLES

SUPPORT

682       General feedback/questions/bug reports should be sent to
683       <https://github.com/pmqs/IO-Compress-Lzma/issues> (preferred) or
684       <https://rt.cpan.org/Public/Dist/Display.html?Name=IO-Compress-Lzma>.
685

AUTHOR

702       This module was written by Paul Marquess, "pmqs@cpan.org".
703

MODIFICATION HISTORY

705       See the Changes file.
706

COPYRIGHT AND LICENSE

708       Copyright (c) 2005-2023 Paul Marquess. All rights reserved.
709
710       This program is free software; you can redistribute it and/or modify it
711       under the same terms as Perl itself.
712
713
714
715perl v5.38.0                      2023-07-26           IO::Uncompress::UnXz(3)