1IO::Uncompress::Gunzip(U3s)er Contributed Perl DocumentatIiOo:n:Uncompress::Gunzip(3)
2
6 IO::Uncompress::Gunzip - Read RFC 1952 files/buffers
7
9 use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
10 my $status = gunzip $input => $output [,OPTS]
12 or die "gunzip failed: $GunzipError\n";
13 my $z = new IO::Uncompress::Gunzip $input [OPTS]
15 or die "gunzip failed: $GunzipError\n";
16 $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 $status = $z->inflateSync()
26 $data = $z->trailingData()
28 $status = $z->nextStream()
29 $data = $z->getHeaderInfo()
30 $z->tell()
31 $z->seek($position, $whence)
32 $z->binmode()
33 $z->fileno()
34 $z->eof()
35 $z->close()
36 $GunzipError ;
38 # IO::File mode
40 <$z>
42 read($z, $buffer);
43 read($z, $buffer, $length);
44 read($z, $buffer, $length, $offset);
45 tell($z)
46 seek($z, $position, $whence)
47 binmode($z)
48 fileno($z)
49 eof($z)
50 close($z)
51
53 This module provides a Perl interface that allows the reading of
54 files/buffers that conform to RFC 1952.
55 For writing RFC 1952 files/buffers, see the companion module
57 IO::Compress::Gzip.
58
60 A top-level function, "gunzip", is provided to carry out "one-shot"
61 uncompression between buffers and/or files. For finer control over the
62 uncompression process, see the "OO Interface" section.
63 use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
65 gunzip $input_filename_or_reference => $output_filename_or_reference [,OPTS]
67 or die "gunzip failed: $GunzipError\n";
68 The functional interface needs Perl5.005 or better.
70 gunzip $input_filename_or_reference => $output_filename_or_reference [,
72 OPTS]
73 "gunzip" expects at least two parameters, $input_filename_or_reference
74 and $output_filename_or_reference and zero or more optional parameters
75 (see "Optional Parameters")
76 The $input_filename_or_reference parameter
78 The parameter, $input_filename_or_reference, is used to define the
80 source of the compressed data.
81 It can take one of the following forms:
83 A filename
85 If the $input_filename_or_reference parameter is a simple scalar,
86 it is assumed to be a filename. This file will be opened for
87 reading and the input data will be read from it.
88 A filehandle
90 If the $input_filename_or_reference parameter is a filehandle, the
91 input data will be read from it. The string '-' can be used as an
92 alias for standard input.
93 A scalar reference
95 If $input_filename_or_reference is a scalar reference, the input
96 data will be read from $$input_filename_or_reference.
97 An array reference
99 If $input_filename_or_reference is an array reference, each
100 element in the array must be a filename.
101 The input data will be read from each file in turn.
103 The complete array will be walked to ensure that it only contains
105 valid filenames before any data is uncompressed.
106 An Input FileGlob string
108 If $input_filename_or_reference is a string that is delimited by
109 the characters "<" and ">" "gunzip" will assume that it is an
110 input fileglob string. The input is the list of files that match
111 the fileglob.
112 See File::GlobMapper for more details.
114 If the $input_filename_or_reference parameter is any other type,
116 "undef" will be returned.
117 The $output_filename_or_reference parameter
119 The parameter $output_filename_or_reference is used to control the
121 destination of the uncompressed data. This parameter can take one of
122 these forms.
123 A filename
125 If the $output_filename_or_reference parameter is a simple scalar,
126 it is assumed to be a filename. This file will be opened for
127 writing and the uncompressed data will be written to it.
128 A filehandle
130 If the $output_filename_or_reference parameter is a filehandle,
131 the uncompressed data will be written to it. The string '-' can
132 be used as an alias for standard output.
133 A scalar reference
135 If $output_filename_or_reference is a scalar reference, the
136 uncompressed data will be stored in
137 $$output_filename_or_reference.
138 An Array Reference
140 If $output_filename_or_reference is an array reference, the
141 uncompressed data will be pushed onto the array.
142 An Output FileGlob
144 If $output_filename_or_reference is a string that is delimited by
145 the characters "<" and ">" "gunzip" will assume that it is an
146 output fileglob string. The output is the list of files that match
147 the fileglob.
148 When $output_filename_or_reference is an fileglob string,
150 $input_filename_or_reference must also be a fileglob string.
151 Anything else is an error.
152 See File::GlobMapper for more details.
154 If the $output_filename_or_reference parameter is any other type,
156 "undef" will be returned.
157 Notes
159 When $input_filename_or_reference maps to multiple compressed
160 files/buffers and $output_filename_or_reference is a single
161 file/buffer, after uncompression $output_filename_or_reference will
162 contain a concatenation of all the uncompressed data from each of the
163 input files/buffers.
164 Optional Parameters
166 The optional parameters for the one-shot function "gunzip" are (for the
167 most part) identical to those used with the OO interface defined in the
168 "Constructor Options" section. The exceptions are listed below
169 "AutoClose => 0|1"
171 This option applies to any input or output data streams to
172 "gunzip" that are filehandles.
173 If "AutoClose" is specified, and the value is true, it will result
175 in all input and/or output filehandles being closed once "gunzip"
176 has completed.
177 This parameter defaults to 0.
179 "BinModeOut => 0|1"
181 This option is now a no-op. All files will be written in binmode.
182 "Append => 0|1"
184 The behaviour of this option is dependent on the type of output
185 data stream.
186 · A Buffer
188 If "Append" is enabled, all uncompressed data will be append
190 to the end of the output buffer. Otherwise the output buffer
191 will be cleared before any uncompressed data is written to
192 it.
193 · A Filename
195 If "Append" is enabled, the file will be opened in append
197 mode. Otherwise the contents of the file, if any, will be
198 truncated before any uncompressed data is written to it.
199 · A Filehandle
201 If "Append" is enabled, the filehandle will be positioned to
203 the end of the file via a call to "seek" before any
204 uncompressed data is written to it. Otherwise the file
205 pointer will not be moved.
206 When "Append" is specified, and set to true, it will append all
208 uncompressed data to the output data stream.
209 So when the output is a filehandle it will carry out a seek to the
211 eof before writing any uncompressed data. If the output is a
212 filename, it will be opened for appending. If the output is a
213 buffer, all uncompressed data will be appended to the existing
214 buffer.
215 Conversely when "Append" is not specified, or it is present and is
217 set to false, it will operate as follows.
218 When the output is a filename, it will truncate the contents of
220 the file before writing any uncompressed data. If the output is a
221 filehandle its position will not be changed. If the output is a
222 buffer, it will be wiped before any uncompressed data is output.
223 Defaults to 0.
225 "MultiStream => 0|1"
227 If the input file/buffer contains multiple compressed data
228 streams, this option will uncompress the whole lot as a single
229 data stream.
230 Defaults to 0.
232 "TrailingData => $scalar"
234 Returns the data, if any, that is present immediately after the
235 compressed data stream once uncompression is complete.
236 This option can be used when there is useful information
238 immediately following the compressed data stream, and you don't
239 know the length of the compressed data stream.
240 If the input is a buffer, "trailingData" will return everything
242 from the end of the compressed data stream to the end of the
243 buffer.
244 If the input is a filehandle, "trailingData" will return the data
246 that is left in the filehandle input buffer once the end of the
247 compressed data stream has been reached. You can then use the
248 filehandle to read the rest of the input file.
249 Don't bother using "trailingData" if the input is a filename.
251 If you know the length of the compressed data stream before you
253 start uncompressing, you can avoid having to use "trailingData" by
254 setting the "InputLength" option.
255 Examples
257 To read the contents of the file "file1.txt.gz" and write the
258 uncompressed data to the file "file1.txt".
259 use strict ;
261 use warnings ;
262 use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
263 my $input = "file1.txt.gz";
265 my $output = "file1.txt";
266 gunzip $input => $output
267 or die "gunzip failed: $GunzipError\n";
268 To read from an existing Perl filehandle, $input, and write the
270 uncompressed data to a buffer, $buffer.
271 use strict ;
273 use warnings ;
274 use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
275 use IO::File ;
276 my $input = new IO::File "<file1.txt.gz"
278 or die "Cannot open 'file1.txt.gz': $!\n" ;
279 my $buffer ;
280 gunzip $input => \$buffer
281 or die "gunzip failed: $GunzipError\n";
282 To uncompress all files in the directory "/my/home" that match
284 "*.txt.gz" and store the compressed data in the same directory
285 use strict ;
287 use warnings ;
288 use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
289 gunzip '</my/home/*.txt.gz>' => '</my/home/#1.txt>'
291 or die "gunzip failed: $GunzipError\n";
292 and if you want to compress each file one at a time, this will do the
294 trick
295 use strict ;
297 use warnings ;
298 use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
299 for my $input ( glob "/my/home/*.txt.gz" )
301 {
302 my $output = $input;
303 $output =~ s/.gz// ;
304 gunzip $input => $output
305 or die "Error compressing '$input': $GunzipError\n";
306 }
307
309 Constructor
310 The format of the constructor for IO::Uncompress::Gunzip is shown below
311 my $z = new IO::Uncompress::Gunzip $input [OPTS]
313 or die "IO::Uncompress::Gunzip failed: $GunzipError\n";
314 Returns an "IO::Uncompress::Gunzip" object on success and undef on
316 failure. The variable $GunzipError will contain an error message on
317 failure.
318 If you are running Perl 5.005 or better the object, $z, returned from
320 IO::Uncompress::Gunzip 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 $line = $z->getline();
326 $line = <$z>;
327 The mandatory parameter $input is used to determine the source of the
329 compressed data. This parameter can take one of three forms.
330 A filename
332 If the $input parameter is a scalar, it is assumed to be a
333 filename. This file will be opened for reading and the compressed
334 data will be read from it.
335 A filehandle
337 If the $input parameter is a filehandle, the compressed data will
338 be read from it. The string '-' can be used as an alias for
339 standard input.
340 A scalar reference
342 If $input is a scalar reference, the compressed data will be read
343 from $$input.
344 Constructor Options
346 The option names defined below are case insensitive and can be
347 optionally prefixed by a '-'. So all of the following are valid
348 -AutoClose
350 -autoclose
351 AUTOCLOSE
352 autoclose
353 OPTS is a combination of the following options:
355 "AutoClose => 0|1"
357 This option is only valid when the $input parameter is a
358 filehandle. If specified, and the value is true, it will result in
359 the file being closed once either the "close" method is called or
360 the IO::Uncompress::Gunzip object is destroyed.
361 This parameter defaults to 0.
363 "MultiStream => 0|1"
365 Allows multiple concatenated compressed streams to be treated as a
366 single compressed stream. Decompression will stop once either the
367 end of the file/buffer is reached, an error is encountered
368 (premature eof, corrupt compressed data) or the end of a stream is
369 not immediately followed by the start of another stream.
370 This parameter defaults to 0.
372 "Prime => $string"
374 This option will uncompress the contents of $string before
375 processing the input file/buffer.
376 This option can be useful when the compressed data is embedded in
378 another file/data structure and it is not possible to work out
379 where the compressed data begins without having to read the first
380 few bytes. If this is the case, the uncompression can be primed
381 with these bytes using this option.
382 "Transparent => 0|1"
384 If this option is set and the input file/buffer is not compressed
385 data, the module will allow reading of it anyway.
386 In addition, if the input file/buffer does contain compressed data
388 and there is non-compressed data immediately following it, setting
389 this option will make this module treat the whole file/buffer as a
390 single data stream.
391 This option defaults to 1.
393 "BlockSize => $num"
395 When reading the compressed input data, IO::Uncompress::Gunzip
396 will read it in blocks of $num bytes.
397 This option defaults to 4096.
399 "InputLength => $size"
401 When present this option will limit the number of compressed bytes
402 read from the input file/buffer to $size. This option can be used
403 in the situation where there is useful data directly after the
404 compressed data stream and you know beforehand the exact length of
405 the compressed data stream.
406 This option is mostly used when reading from a filehandle, in
408 which case the file pointer will be left pointing to the first
409 byte directly after the compressed data stream.
410 This option defaults to off.
412 "Append => 0|1"
414 This option controls what the "read" method does with uncompressed
415 data.
416 If set to 1, all uncompressed data will be appended to the output
418 parameter of the "read" method.
419 If set to 0, the contents of the output parameter of the "read"
421 method will be overwritten by the uncompressed data.
422 Defaults to 0.
424 "Strict => 0|1"
426 This option controls whether the extra checks defined below are
427 used when carrying out the decompression. When Strict is on, the
428 extra tests are carried out, when Strict is off they are not.
429 The default for this option is off.
431 1. If the FHCRC bit is set in the gzip FLG header byte, the
433 CRC16 bytes in the header must match the crc16 value of the
434 gzip header actually read.
435 2. If the gzip header contains a name field (FNAME) it consists
437 solely of ISO 8859-1 characters.
438 3. If the gzip header contains a comment field (FCOMMENT) it
440 consists solely of ISO 8859-1 characters plus line-feed.
441 4. If the gzip FEXTRA header field is present it must conform to
443 the sub-field structure as defined in RFC 1952.
444 5. The CRC32 and ISIZE trailer fields must be present.
446 6. The value of the CRC32 field read must match the crc32 value
448 of the uncompressed data actually contained in the gzip file.
449 7. The value of the ISIZE fields read must match the length of
451 the uncompressed data actually read from the file.
452 "ParseExtra => 0|1" If the gzip FEXTRA header field is present and this
454 option is set, it will force the module to check that it conforms to
455 the sub-field structure as defined in RFC 1952.
456 If the "Strict" is on it will automatically enable this option.
457 Defaults to 0.
459 Examples
461 TODO
462
464 read
465 Usage is
466 $status = $z->read($buffer)
468 Reads a block of compressed data (the size of the compressed block is
470 determined by the "Buffer" option in the constructor), uncompresses it
471 and writes any uncompressed data into $buffer. If the "Append"
472 parameter is set in the constructor, the uncompressed data will be
473 appended to the $buffer parameter. Otherwise $buffer will be
474 overwritten.
475 Returns the number of uncompressed bytes written to $buffer, zero if
477 eof or a negative number on error.
478 read
480 Usage is
481 $status = $z->read($buffer, $length)
483 $status = $z->read($buffer, $length, $offset)
484 $status = read($z, $buffer, $length)
486 $status = read($z, $buffer, $length, $offset)
487 Attempt to read $length bytes of uncompressed data into $buffer.
489 The main difference between this form of the "read" method and the
491 previous one, is that this one will attempt to return exactly $length
492 bytes. The only circumstances that this function will not is if end-of-
493 file or an IO error is encountered.
494 Returns the number of uncompressed bytes written to $buffer, zero if
496 eof or a negative number on error.
497 getline
499 Usage is
500 $line = $z->getline()
502 $line = <$z>
503 Reads a single line.
505 This method fully supports the use of the variable $/ (or
507 $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
508 what constitutes an end of line. Paragraph mode, record mode and file
509 slurp mode are all supported.
510 getc
512 Usage is
513 $char = $z->getc()
515 Read a single character.
517 ungetc
519 Usage is
520 $char = $z->ungetc($string)
522 inflateSync
524 Usage is
525 $status = $z->inflateSync()
527 TODO
529 getHeaderInfo
531 Usage is
532 $hdr = $z->getHeaderInfo();
534 @hdrs = $z->getHeaderInfo();
535 This method returns either a hash reference (in scalar context) or a
537 list or hash references (in array context) that contains information
538 about each of the header fields in the compressed data stream(s).
539 Name The contents of the Name header field, if present. If no name is
541 present, the value will be undef. Note this is different from a
542 zero length name, which will return an empty string.
543 Comment
545 The contents of the Comment header field, if present. If no
546 comment is present, the value will be undef. Note this is
547 different from a zero length comment, which will return an empty
548 string.
549 tell
551 Usage is
552 $z->tell()
554 tell $z
555 Returns the uncompressed file offset.
557 eof
559 Usage is
560 $z->eof();
562 eof($z);
563 Returns true if the end of the compressed input stream has been
565 reached.
566 seek
568 $z->seek($position, $whence);
569 seek($z, $position, $whence);
570 Provides a sub-set of the "seek" functionality, with the restriction
572 that it is only legal to seek forward in the input file/buffer. It is
573 a fatal error to attempt to seek backward.
574 Note that the implementation of "seek" in this module does not provide
576 true random access to a compressed file/buffer. It works by
577 uncompressing data from the current offset in the file/buffer until it
578 reaches the uncompressed offset specified in the parameters to "seek".
579 For very small files this may be acceptable behaviour. For large files
580 it may cause an unacceptable delay.
581 The $whence parameter takes one the usual values, namely SEEK_SET,
583 SEEK_CUR or SEEK_END.
584 Returns 1 on success, 0 on failure.
586 binmode
588 Usage is
589 $z->binmode
591 binmode $z ;
592 This is a noop provided for completeness.
594 opened
596 $z->opened()
597 Returns true if the object currently refers to a opened file/buffer.
599 autoflush
601 my $prev = $z->autoflush()
602 my $prev = $z->autoflush(EXPR)
603 If the $z object is associated with a file or a filehandle, this method
605 returns the current autoflush setting for the underlying filehandle. If
606 "EXPR" is present, and is non-zero, it will enable flushing after every
607 write/print operation.
608 If $z is associated with a buffer, this method has no effect and always
610 returns "undef".
611 Note that the special variable $| cannot be used to set or retrieve the
613 autoflush setting.
614 input_line_number
616 $z->input_line_number()
617 $z->input_line_number(EXPR)
618 Returns the current uncompressed line number. If "EXPR" is present it
620 has the effect of setting the line number. Note that setting the line
621 number does not change the current position within the file/buffer
622 being read.
623 The contents of $/ are used to determine what constitutes a line
625 terminator.
626 fileno
628 $z->fileno()
629 fileno($z)
630 If the $z object is associated with a file or a filehandle, "fileno"
632 will return the underlying file descriptor. Once the "close" method is
633 called "fileno" will return "undef".
634 If the $z object is associated with a buffer, this method will return
636 "undef".
637 close
639 $z->close() ;
640 close $z ;
641 Closes the output file/buffer.
643 For most versions of Perl this method will be automatically invoked if
645 the IO::Uncompress::Gunzip object is destroyed (either explicitly or by
646 the variable with the reference to the object going out of scope). The
647 exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In these
648 cases, the "close" method will be called automatically, but not until
649 global destruction of all live objects when the program is terminating.
650 Therefore, if you want your scripts to be able to run on all versions
652 of Perl, you should call "close" explicitly and not rely on automatic
653 closing.
654 Returns true on success, otherwise 0.
656 If the "AutoClose" option has been enabled when the
658 IO::Uncompress::Gunzip object was created, and the object is associated
659 with a file, the underlying file will also be closed.
660 nextStream
662 Usage is
663 my $status = $z->nextStream();
665 Skips to the next compressed data stream in the input file/buffer. If a
667 new compressed data stream is found, the eof marker will be cleared and
668 $. will be reset to 0.
669 Returns 1 if a new stream was found, 0 if none was found, and -1 if an
671 error was encountered.
672 trailingData
674 Usage is
675 my $data = $z->trailingData();
677 Returns the data, if any, that is present immediately after the
679 compressed data stream once uncompression is complete. It only makes
680 sense to call this method once the end of the compressed data stream
681 has been encountered.
682 This option can be used when there is useful information immediately
684 following the compressed data stream, and you don't know the length of
685 the compressed data stream.
686 If the input is a buffer, "trailingData" will return everything from
688 the end of the compressed data stream to the end of the buffer.
689 If the input is a filehandle, "trailingData" will return the data that
691 is left in the filehandle input buffer once the end of the compressed
692 data stream has been reached. You can then use the filehandle to read
693 the rest of the input file.
694 Don't bother using "trailingData" if the input is a filename.
696 If you know the length of the compressed data stream before you start
698 uncompressing, you can avoid having to use "trailingData" by setting
699 the "InputLength" option in the constructor.
700
702 No symbolic constants are required by IO::Uncompress::Gunzip at
703 present.
704 :all Imports "gunzip" and $GunzipError. Same as doing this
706 use IO::Uncompress::Gunzip qw(gunzip $GunzipError) ;
708
710 Working with Net::FTP
711 See IO::Compress::FAQ
712
714 General feedback/questions/bug reports should be sent to
715 <https://github.com/pmqs/IO-Compress/issues> (preferred) or
716 <https://rt.cpan.org/Public/Dist/Display.html?Name=IO-Compress>.
717
719 Compress::Zlib, IO::Compress::Gzip, IO::Compress::Deflate,
720 IO::Uncompress::Inflate, IO::Compress::RawDeflate,
721 IO::Uncompress::RawInflate, IO::Compress::Bzip2,
722 IO::Uncompress::Bunzip2, IO::Compress::Lzma, IO::Uncompress::UnLzma,
723 IO::Compress::Xz, IO::Uncompress::UnXz, IO::Compress::Lzip,
724 IO::Uncompress::UnLzip, IO::Compress::Lzop, IO::Uncompress::UnLzop,
725 IO::Compress::Lzf, IO::Uncompress::UnLzf, IO::Compress::Zstd,
726 IO::Uncompress::UnZstd, IO::Uncompress::AnyInflate,
727 IO::Uncompress::AnyUncompress
728 IO::Compress::FAQ
730 File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib
732 For RFC 1950, 1951 and 1952 see
734 <http://www.faqs.org/rfcs/rfc1950.html>,
735 <http://www.faqs.org/rfcs/rfc1951.html> and
736 <http://www.faqs.org/rfcs/rfc1952.html>
737 The zlib compression library was written by Jean-loup Gailly
739 "gzip@prep.ai.mit.edu" and Mark Adler "madler@alumni.caltech.edu".
740 The primary site for the zlib compression library is
742 <http://www.zlib.org>.
743 The primary site for gzip is <http://www.gzip.org>.
745
747 This module was written by Paul Marquess, "pmqs@cpan.org".
748
750 See the Changes file.
751
753 Copyright (c) 2005-2020 Paul Marquess. All rights reserved.
754 This program is free software; you can redistribute it and/or modify it
756 under the same terms as Perl itself.
757perl v5.32.0 2020-08-01 IO::Uncompress::Gunzip(3)