IO::Uncompress::UnLzma(3pm)

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

6       IO::Uncompress::UnLzma - Read lzma files/buffers
7

SYNOPSIS

9           use IO::Uncompress::UnLzma qw(unlzma $UnLzmaError) ;
10
11           my $status = unlzma $input => $output [,OPTS]
12               or die "unlzma failed: $UnLzmaError\n";
13
14           my $z = IO::Uncompress::UnLzma->new( $input [OPTS] )
15               or die "unlzma failed: $UnLzmaError\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           $UnLzmaError ;
36
37           # IO::File mode
38
39           <$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 lzma files/buffers, see the companion module
55       IO::Compress::Lzma.
56

Functional Interface

58       A top-level function, "unlzma", 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::UnLzma qw(unlzma $UnLzmaError) ;
63
64           unlzma $input_filename_or_reference => $output_filename_or_reference [,OPTS]
65               or die "unlzma failed: $UnLzmaError\n";
66
67       The functional interface needs Perl5.005 or better.
68
69   unlzma $input_filename_or_reference => $output_filename_or_reference [,
70       OPTS]
71       "unlzma" expects at least two parameters, $input_filename_or_reference
72       and $output_filename_or_reference and zero or more optional parameters
73       (see "Optional Parameters")
74
75       The $input_filename_or_reference parameter
76
77       The parameter, $input_filename_or_reference, is used to define the
78       source of the compressed data.
79
80       It can take one of the following forms:
81
82       A filename
83            If the $input_filename_or_reference parameter is a simple scalar,
84            it is assumed to be a filename. This file will be opened for
85            reading and the input data will be read from it.
86
87       A filehandle
88            If the $input_filename_or_reference parameter is a filehandle, the
89            input data will be read from it.  The string '-' can be used as an
90            alias for standard input.
91
92       A scalar reference
93            If $input_filename_or_reference is a scalar reference, the input
94            data will be read from $$input_filename_or_reference.
95
96       An array reference
97            If $input_filename_or_reference is an array reference, each
98            element in the array must be a filename.
99
100            The input data will be read from each file in turn.
101
102            The complete array will be walked to ensure that it only contains
103            valid filenames before any data is uncompressed.
104
105       An Input FileGlob string
106            If $input_filename_or_reference is a string that is delimited by
107            the characters "<" and ">" "unlzma" will assume that it is an
108            input fileglob string. The input is the list of files that match
109            the fileglob.
110
111            See File::GlobMapper for more details.
112
113       If the $input_filename_or_reference parameter is any other type,
114       "undef" will be returned.
115
116       The $output_filename_or_reference parameter
117
118       The parameter $output_filename_or_reference is used to control the
119       destination of the uncompressed data. This parameter can take one of
120       these forms.
121
122       A filename
123            If the $output_filename_or_reference parameter is a simple scalar,
124            it is assumed to be a filename.  This file will be opened for
125            writing and the uncompressed data will be written to it.
126
127       A filehandle
128            If the $output_filename_or_reference parameter is a filehandle,
129            the uncompressed data will be written to it.  The string '-' can
130            be used as an alias for standard output.
131
132       A scalar reference
133            If $output_filename_or_reference is a scalar reference, the
134            uncompressed data will be stored in
135            $$output_filename_or_reference.
136
137       An Array Reference
138            If $output_filename_or_reference is an array reference, the
139            uncompressed data will be pushed onto the array.
140
141       An Output FileGlob
142            If $output_filename_or_reference is a string that is delimited by
143            the characters "<" and ">" "unlzma" will assume that it is an
144            output fileglob string. The output is the list of files that match
145            the fileglob.
146
147            When $output_filename_or_reference is an fileglob string,
148            $input_filename_or_reference must also be a fileglob string.
149            Anything else is an error.
150
151            See File::GlobMapper for more details.
152
153       If the $output_filename_or_reference parameter is any other type,
154       "undef" will be returned.
155
156   Notes
157       When $input_filename_or_reference maps to multiple compressed
158       files/buffers and $output_filename_or_reference is a single
159       file/buffer, after uncompression $output_filename_or_reference will
160       contain a concatenation of all the uncompressed data from each of the
161       input files/buffers.
162
163   Optional Parameters
164       The optional parameters for the one-shot function "unlzma" are (for the
165       most part) identical to those used with the OO interface defined in the
166       "Constructor Options" section. The exceptions are listed below
167
168       "AutoClose => 0|1"
169            This option applies to any input or output data streams to
170            "unlzma" that are filehandles.
171
172            If "AutoClose" is specified, and the value is true, it will result
173            in all input and/or output filehandles being closed once "unlzma"
174            has completed.
175
176            This parameter defaults to 0.
177
178       "BinModeOut => 0|1"
179            This option is now a no-op. All files will be written  in binmode.
180
181       "Append => 0|1"
182            The behaviour of this option is dependent on the type of output
183            data stream.
184
185            •    A Buffer
186
187                 If "Append" is enabled, all uncompressed data will be append
188                 to the end of the output buffer. Otherwise the output buffer
189                 will be cleared before any uncompressed data is written to
190                 it.
191
192            •    A Filename
193
194                 If "Append" is enabled, the file will be opened in append
195                 mode. Otherwise the contents of the file, if any, will be
196                 truncated before any uncompressed data is written to it.
197
198            •    A Filehandle
199
200                 If "Append" is enabled, the filehandle will be positioned to
201                 the end of the file via a call to "seek" before any
202                 uncompressed data is written to it.  Otherwise the file
203                 pointer will not be moved.
204
205            When "Append" is specified, and set to true, it will append all
206            uncompressed data to the output data stream.
207
208            So when the output is a filehandle it will carry out a seek to the
209            eof before writing any uncompressed data. If the output is a
210            filename, it will be opened for appending. If the output is a
211            buffer, all uncompressed data will be appended to the existing
212            buffer.
213
214            Conversely when "Append" is not specified, or it is present and is
215            set to false, it will operate as follows.
216
217            When the output is a filename, it will truncate the contents of
218            the file before writing any uncompressed data. If the output is a
219            filehandle its position will not be changed. If the output is a
220            buffer, it will be wiped before any uncompressed data is output.
221
222            Defaults to 0.
223
224       "MultiStream => 0|1"
225            If the input file/buffer contains multiple compressed data
226            streams, this option will uncompress the whole lot as a single
227            data stream.
228
229            Defaults to 0.
230
231       "TrailingData => $scalar"
232            Returns the data, if any, that is present immediately after the
233            compressed data stream once uncompression is complete.
234
235            This option can be used when there is useful information
236            immediately following the compressed data stream, and you don't
237            know the length of the compressed data stream.
238
239            If the input is a buffer, "trailingData" will return everything
240            from the end of the compressed data stream to the end of the
241            buffer.
242
243            If the input is a filehandle, "trailingData" will return the data
244            that is left in the filehandle input buffer once the end of the
245            compressed data stream has been reached. You can then use the
246            filehandle to read the rest of the input file.
247
248            Don't bother using "trailingData" if the input is a filename.
249
250            If you know the length of the compressed data stream before you
251            start uncompressing, you can avoid having to use "trailingData" by
252            setting the "InputLength" option.
253
254   Examples
255       To read the contents of the file "file1.txt.lzma" and write the
256       uncompressed data to the file "file1.txt".
257
258           use strict ;
259           use warnings ;
260           use IO::Uncompress::UnLzma qw(unlzma $UnLzmaError) ;
261
262           my $input = "file1.txt.lzma";
263           my $output = "file1.txt";
264           unlzma $input => $output
265               or die "unlzma failed: $UnLzmaError\n";
266
267       To read from an existing Perl filehandle, $input, and write the
268       uncompressed data to a buffer, $buffer.
269
270           use strict ;
271           use warnings ;
272           use IO::Uncompress::UnLzma qw(unlzma $UnLzmaError) ;
273           use IO::File ;
274
275           my $input = IO::File->new( "<file1.txt.lzma" )
276               or die "Cannot open 'file1.txt.lzma': $!\n" ;
277           my $buffer ;
278           unlzma $input => \$buffer
279               or die "unlzma failed: $UnLzmaError\n";
280
281       To uncompress all files in the directory "/my/home" that match
282       "*.txt.lzma" and store the compressed data in the same directory
283
284           use strict ;
285           use warnings ;
286           use IO::Uncompress::UnLzma qw(unlzma $UnLzmaError) ;
287
288           unlzma '</my/home/*.txt.lzma>' => '</my/home/#1.txt>'
289               or die "unlzma failed: $UnLzmaError\n";
290
291       and if you want to compress each file one at a time, this will do the
292       trick
293
294           use strict ;
295           use warnings ;
296           use IO::Uncompress::UnLzma qw(unlzma $UnLzmaError) ;
297
298           for my $input ( glob "/my/home/*.txt.lzma" )
299           {
300               my $output = $input;
301               $output =~ s/.lzma// ;
302               unlzma $input => $output
303                   or die "Error compressing '$input': $UnLzmaError\n";
304           }
305

OO Interface

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

Methods

434   read
435       Usage is
436
437           $status = $z->read($buffer)
438
439       Reads a block of compressed data (the size of the compressed block is
440       determined by the "Buffer" option in the constructor), uncompresses it
441       and writes any uncompressed data into $buffer. If the "Append"
442       parameter is set in the constructor, the uncompressed data will be
443       appended to the $buffer parameter. Otherwise $buffer will be
444       overwritten.
445
446       Returns the number of uncompressed bytes written to $buffer, zero if
447       eof or a negative number on error.
448
449   read
450       Usage is
451
452           $status = $z->read($buffer, $length)
453           $status = $z->read($buffer, $length, $offset)
454
455           $status = read($z, $buffer, $length)
456           $status = read($z, $buffer, $length, $offset)
457
458       Attempt to read $length bytes of uncompressed data into $buffer.
459
460       The main difference between this form of the "read" method and the
461       previous one, is that this one will attempt to return exactly $length
462       bytes. The only circumstances that this function will not is if end-of-
463       file or an IO error is encountered.
464
465       Returns the number of uncompressed bytes written to $buffer, zero if
466       eof or a negative number on error.
467
468   getline
469       Usage is
470
471           $line = $z->getline()
472           $line = <$z>
473
474       Reads a single line.
475
476       This method fully supports the use of the variable $/ (or
477       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
478       what constitutes an end of line. Paragraph mode, record mode and file
479       slurp mode are all supported.
480
481   getc
482       Usage is
483
484           $char = $z->getc()
485
486       Read a single character.
487
488   ungetc
489       Usage is
490
491           $char = $z->ungetc($string)
492
493   getHeaderInfo
494       Usage is
495
496           $hdr  = $z->getHeaderInfo();
497           @hdrs = $z->getHeaderInfo();
498
499       This method returns either a hash reference (in scalar context) or a
500       list or hash references (in array context) that contains information
501       about each of the header fields in the compressed data stream(s).
502
503   tell
504       Usage is
505
506           $z->tell()
507           tell $z
508
509       Returns the uncompressed file offset.
510
511   eof
512       Usage is
513
514           $z->eof();
515           eof($z);
516
517       Returns true if the end of the compressed input stream has been
518       reached.
519
520   seek
521           $z->seek($position, $whence);
522           seek($z, $position, $whence);
523
524       Provides a sub-set of the "seek" functionality, with the restriction
525       that it is only legal to seek forward in the input file/buffer.  It is
526       a fatal error to attempt to seek backward.
527
528       Note that the implementation of "seek" in this module does not provide
529       true random access to a compressed file/buffer. It  works by
530       uncompressing data from the current offset in the file/buffer until it
531       reaches the uncompressed offset specified in the parameters to "seek".
532       For very small files this may be acceptable behaviour. For large files
533       it may cause an unacceptable delay.
534
535       The $whence parameter takes one the usual values, namely SEEK_SET,
536       SEEK_CUR or SEEK_END.
537
538       Returns 1 on success, 0 on failure.
539
540   binmode
541       Usage is
542
543           $z->binmode
544           binmode $z ;
545
546       This is a noop provided for completeness.
547
548   opened
549           $z->opened()
550
551       Returns true if the object currently refers to a opened file/buffer.
552
553   autoflush
554           my $prev = $z->autoflush()
555           my $prev = $z->autoflush(EXPR)
556
557       If the $z object is associated with a file or a filehandle, this method
558       returns the current autoflush setting for the underlying filehandle. If
559       "EXPR" is present, and is non-zero, it will enable flushing after every
560       write/print operation.
561
562       If $z is associated with a buffer, this method has no effect and always
563       returns "undef".
564
565       Note that the special variable $| cannot be used to set or retrieve the
566       autoflush setting.
567
568   input_line_number
569           $z->input_line_number()
570           $z->input_line_number(EXPR)
571
572       Returns the current uncompressed line number. If "EXPR" is present it
573       has the effect of setting the line number. Note that setting the line
574       number does not change the current position within the file/buffer
575       being read.
576
577       The contents of $/ are used to determine what constitutes a line
578       terminator.
579
580   fileno
581           $z->fileno()
582           fileno($z)
583
584       If the $z object is associated with a file or a filehandle, "fileno"
585       will return the underlying file descriptor. Once the "close" method is
586       called "fileno" will return "undef".
587
588       If the $z object is associated with a buffer, this method will return
589       "undef".
590
591   close
592           $z->close() ;
593           close $z ;
594
595       Closes the output file/buffer.
596
597       For most versions of Perl this method will be automatically invoked if
598       the IO::Uncompress::UnLzma object is destroyed (either explicitly or by
599       the variable with the reference to the object going out of scope). The
600       exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In these
601       cases, the "close" method will be called automatically, but not until
602       global destruction of all live objects when the program is terminating.
603
604       Therefore, if you want your scripts to be able to run on all versions
605       of Perl, you should call "close" explicitly and not rely on automatic
606       closing.
607
608       Returns true on success, otherwise 0.
609
610       If the "AutoClose" option has been enabled when the
611       IO::Uncompress::UnLzma object was created, and the object is associated
612       with a file, the underlying file will also be closed.
613
614   nextStream
615       Usage is
616
617           my $status = $z->nextStream();
618
619       Skips to the next compressed data stream in the input file/buffer. If a
620       new compressed data stream is found, the eof marker will be cleared and
621       $.  will be reset to 0.
622
623       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
624       error was encountered.
625
626   trailingData
627       Usage is
628
629           my $data = $z->trailingData();
630
631       Returns the data, if any, that is present immediately after the
632       compressed data stream once uncompression is complete. It only makes
633       sense to call this method once the end of the compressed data stream
634       has been encountered.
635
636       This option can be used when there is useful information immediately
637       following the compressed data stream, and you don't know the length of
638       the compressed data stream.
639
640       If the input is a buffer, "trailingData" will return everything from
641       the end of the compressed data stream to the end of the buffer.
642
643       If the input is a filehandle, "trailingData" will return the data that
644       is left in the filehandle input buffer once the end of the compressed
645       data stream has been reached. You can then use the filehandle to read
646       the rest of the input file.
647
648       Don't bother using "trailingData" if the input is a filename.
649
650       If you know the length of the compressed data stream before you start
651       uncompressing, you can avoid having to use "trailingData" by setting
652       the "InputLength" option in the constructor.
653

Importing

655       No symbolic constants are required by IO::Uncompress::UnLzma at
656       present.
657
658       :all Imports "unlzma" and $UnLzmaError.  Same as doing this
659
660                use IO::Uncompress::UnLzma qw(unlzma $UnLzmaError) ;
661

EXAMPLES

SUPPORT

664       General feedback/questions/bug reports should be sent to
665       <https://github.com/pmqs/IO-Compress-Lzma/issues> (preferred) or
666       <https://rt.cpan.org/Public/Dist/Display.html?Name=IO-Compress-Lzma>.
667

AUTHOR

684       This module was written by Paul Marquess, "pmqs@cpan.org".
685

MODIFICATION HISTORY

687       See the Changes file.
688

COPYRIGHT AND LICENSE

690       Copyright (c) 2005-2023 Paul Marquess. All rights reserved.
691
692       This program is free software; you can redistribute it and/or modify it
693       under the same terms as Perl itself.
694
695
696
697perl v5.36.0                      2023-02-09         IO::Uncompress::UnLzma(3)