1IO::Compress::Zstd(3) User Contributed Perl DocumentationIO::Compress::Zstd(3)
2
3
4

NAME

6       IO::Compress::Zstd - Write zstd files/buffers
7

SYNOPSIS

9           use IO::Compress::Zstd qw(zstd $ZstdError) ;
10
11           my $status = zstd $input => $output [,OPTS]
12               or die "zstd failed: $ZstdError\n";
13
14           my $z = IO::Compress::Zstd->new( $output [,OPTS] )
15               or die "zstd failed: $ZstdError\n";
16
17           $z->print($string);
18           $z->printf($format, $string);
19           $z->write($string);
20           $z->syswrite($string [, $length, $offset]);
21           $z->flush();
22           $z->tell();
23           $z->eof();
24           $z->seek($position, $whence);
25           $z->binmode();
26           $z->fileno();
27           $z->opened();
28           $z->autoflush();
29           $z->input_line_number();
30           $z->newStream( [OPTS] );
31
32           $z->close() ;
33
34           $ZstdError ;
35
36           # IO::File mode
37
38           print $z $string;
39           printf $z $format, $string;
40           tell $z
41           eof $z
42           seek $z, $position, $whence
43           binmode $z
44           fileno $z
45           close $z ;
46

DESCRIPTION

48       This module provides a Perl interface that allows writing zstd
49       compressed data to files or buffer.
50
51       For reading zstd files/buffers, see the companion module
52       IO::Uncompress::UnZstd.
53

Functional Interface

55       A top-level function, "zstd", is provided to carry out "one-shot"
56       compression between buffers and/or files. For finer control over the
57       compression process, see the "OO Interface" section.
58
59           use IO::Compress::Zstd qw(zstd $ZstdError) ;
60
61           zstd $input_filename_or_reference => $output_filename_or_reference [,OPTS]
62               or die "zstd failed: $ZstdError\n";
63
64       The functional interface needs Perl5.005 or better.
65
66   zstd $input_filename_or_reference => $output_filename_or_reference [, OPTS]
67       "zstd" expects at least two parameters, $input_filename_or_reference
68       and $output_filename_or_reference and zero or more optional parameters
69       (see "Optional Parameters")
70
71       The $input_filename_or_reference parameter
72
73       The parameter, $input_filename_or_reference, is used to define the
74       source of the uncompressed data.
75
76       It can take one of the following forms:
77
78       A filename
79            If the $input_filename_or_reference parameter is a simple scalar,
80            it is assumed to be a filename. This file will be opened for
81            reading and the input data will be read from it.
82
83       A filehandle
84            If the $input_filename_or_reference parameter is a filehandle, the
85            input data will be read from it.  The string '-' can be used as an
86            alias for standard input.
87
88       A scalar reference
89            If $input_filename_or_reference is a scalar reference, the input
90            data will be read from $$input_filename_or_reference.
91
92       An array reference
93            If $input_filename_or_reference is an array reference, each
94            element in the array must be a filename.
95
96            The input data will be read from each file in turn.
97
98            The complete array will be walked to ensure that it only contains
99            valid filenames before any data is compressed.
100
101       An Input FileGlob string
102            If $input_filename_or_reference is a string that is delimited by
103            the characters "<" and ">" "zstd" will assume that it is an input
104            fileglob string. The input is the list of files that match the
105            fileglob.
106
107            See File::GlobMapper for more details.
108
109       If the $input_filename_or_reference parameter is any other type,
110       "undef" will be returned.
111
112       The $output_filename_or_reference parameter
113
114       The parameter $output_filename_or_reference is used to control the
115       destination of the compressed data. This parameter can take one of
116       these forms.
117
118       A filename
119            If the $output_filename_or_reference parameter is a simple scalar,
120            it is assumed to be a filename.  This file will be opened for
121            writing and the compressed data will be written to it.
122
123       A filehandle
124            If the $output_filename_or_reference parameter is a filehandle,
125            the compressed data will be written to it.  The string '-' can be
126            used as an alias for standard output.
127
128       A scalar reference
129            If $output_filename_or_reference is a scalar reference, the
130            compressed data will be stored in $$output_filename_or_reference.
131
132       An Array Reference
133            If $output_filename_or_reference is an array reference, the
134            compressed data will be pushed onto the array.
135
136       An Output FileGlob
137            If $output_filename_or_reference is a string that is delimited by
138            the characters "<" and ">" "zstd" will assume that it is an output
139            fileglob string. The output is the list of files that match the
140            fileglob.
141
142            When $output_filename_or_reference is an fileglob string,
143            $input_filename_or_reference must also be a fileglob string.
144            Anything else is an error.
145
146            See File::GlobMapper for more details.
147
148       If the $output_filename_or_reference parameter is any other type,
149       "undef" will be returned.
150
151   Notes
152       When $input_filename_or_reference maps to multiple files/buffers and
153       $output_filename_or_reference is a single file/buffer the input
154       files/buffers will be stored in $output_filename_or_reference as a
155       concatenated series of compressed data streams.
156
157   Optional Parameters
158       The optional parameters for the one-shot function "zstd" are (for the
159       most part) identical to those used with the OO interface defined in the
160       "Constructor Options" section. The exceptions are listed below
161
162       "AutoClose => 0|1"
163            This option applies to any input or output data streams to "zstd"
164            that are filehandles.
165
166            If "AutoClose" is specified, and the value is true, it will result
167            in all input and/or output filehandles being closed once "zstd"
168            has completed.
169
170            This parameter defaults to 0.
171
172       "BinModeIn => 0|1"
173            This option is now a no-op. All files will be read in binmode.
174
175       "Append => 0|1"
176            The behaviour of this option is dependent on the type of output
177            data stream.
178
179            •    A Buffer
180
181                 If "Append" is enabled, all compressed data will be append to
182                 the end of the output buffer. Otherwise the output buffer
183                 will be cleared before any compressed data is written to it.
184
185            •    A Filename
186
187                 If "Append" is enabled, the file will be opened in append
188                 mode. Otherwise the contents of the file, if any, will be
189                 truncated before any compressed data is written to it.
190
191            •    A Filehandle
192
193                 If "Append" is enabled, the filehandle will be positioned to
194                 the end of the file via a call to "seek" before any
195                 compressed data is written to it.  Otherwise the file pointer
196                 will not be moved.
197
198            When "Append" is specified, and set to true, it will append all
199            compressed data to the output data stream.
200
201            So when the output is a filehandle it will carry out a seek to the
202            eof before writing any compressed data. If the output is a
203            filename, it will be opened for appending. If the output is a
204            buffer, all compressed data will be appended to the existing
205            buffer.
206
207            Conversely when "Append" is not specified, or it is present and is
208            set to false, it will operate as follows.
209
210            When the output is a filename, it will truncate the contents of
211            the file before writing any compressed data. If the output is a
212            filehandle its position will not be changed. If the output is a
213            buffer, it will be wiped before any compressed data is output.
214
215            Defaults to 0.
216
217   Examples
218       Here are a few example that show the capabilities of the module.
219
220       Streaming
221
222       This very simple command line example demonstrates the streaming
223       capabilities of the module.  The code reads data from STDIN, compresses
224       it, and writes the compressed data to STDOUT.
225
226           $ echo hello world | perl -MIO::Compress::Zstd=zstd -e 'zstd \*STDIN => \*STDOUT' >output.zst
227
228       The special filename "-" can be used as a standin for both "\*STDIN"
229       and "\*STDOUT", so the above can be rewritten as
230
231           $ echo hello world | perl -MIO::Compress::Zstd=zstd -e 'zstd "-" => "-"' >output.zst
232
233       Compressing a file from the filesystem
234
235       To read the contents of the file "file1.txt" and write the compressed
236       data to the file "file1.txt.zst".
237
238           use strict ;
239           use warnings ;
240           use IO::Compress::Zstd qw(zstd $ZstdError) ;
241
242           my $input = "file1.txt";
243           zstd $input => "$input.zst"
244               or die "zstd failed: $ZstdError\n";
245
246       Reading from a Filehandle and writing to an in-memory buffer
247
248       To read from an existing Perl filehandle, $input, and write the
249       compressed data to a buffer, $buffer.
250
251           use strict ;
252           use warnings ;
253           use IO::Compress::Zstd qw(zstd $ZstdError) ;
254           use IO::File ;
255
256           my $input = IO::File->new( "<file1.txt" )
257               or die "Cannot open 'file1.txt': $!\n" ;
258           my $buffer ;
259           zstd $input => \$buffer
260               or die "zstd failed: $ZstdError\n";
261
262       Compressing multiple files
263
264       To compress all files in the directory "/my/home" that match "*.txt"
265       and store the compressed data in the same directory
266
267           use strict ;
268           use warnings ;
269           use IO::Compress::Zstd qw(zstd $ZstdError) ;
270
271           zstd '</my/home/*.txt>' => '<*.zst>'
272               or die "zstd failed: $ZstdError\n";
273
274       and if you want to compress each file one at a time, this will do the
275       trick
276
277           use strict ;
278           use warnings ;
279           use IO::Compress::Zstd qw(zstd $ZstdError) ;
280
281           for my $input ( glob "/my/home/*.txt" )
282           {
283               my $output = "$input.zst" ;
284               zstd $input => $output
285                   or die "Error compressing '$input': $ZstdError\n";
286           }
287

OO Interface

289   Constructor
290       The format of the constructor for "IO::Compress::Zstd" is shown below
291
292           my $z = IO::Compress::Zstd->new( $output [,OPTS] )
293               or die "IO::Compress::Zstd failed: $ZstdError\n";
294
295       It returns an "IO::Compress::Zstd" object on success and undef on
296       failure.  The variable $ZstdError will contain an error message on
297       failure.
298
299       If you are running Perl 5.005 or better the object, $z, returned from
300       IO::Compress::Zstd can be used exactly like an IO::File filehandle.
301       This means that all normal output file operations can be carried out
302       with $z.  For example, to write to a compressed file/buffer you can use
303       either of these forms
304
305           $z->print("hello world\n");
306           print $z "hello world\n";
307
308       The mandatory parameter $output is used to control the destination of
309       the compressed data. This parameter can take one of these forms.
310
311       A filename
312            If the $output parameter is a simple scalar, it is assumed to be a
313            filename. This file will be opened for writing and the compressed
314            data will be written to it.
315
316       A filehandle
317            If the $output parameter is a filehandle, the compressed data will
318            be written to it.  The string '-' can be used as an alias for
319            standard output.
320
321       A scalar reference
322            If $output is a scalar reference, the compressed data will be
323            stored in $$output.
324
325       If the $output parameter is any other type, "IO::Compress::Zstd"::new
326       will return undef.
327
328   Constructor Options
329       "OPTS" is any combination of zero or more the following options:
330
331       "AutoClose => 0|1"
332            This option is only valid when the $output parameter is a
333            filehandle. If specified, and the value is true, it will result in
334            the $output being closed once either the "close" method is called
335            or the "IO::Compress::Zstd" object is destroyed.
336
337            This parameter defaults to 0.
338
339       "Append => 0|1"
340            Opens $output in append mode.
341
342            The behaviour of this option is dependent on the type of $output.
343
344            •    A Buffer
345
346                 If $output is a buffer and "Append" is enabled, all
347                 compressed data will be append to the end of $output.
348                 Otherwise $output will be cleared before any data is written
349                 to it.
350
351            •    A Filename
352
353                 If $output is a filename and "Append" is enabled, the file
354                 will be opened in append mode. Otherwise the contents of the
355                 file, if any, will be truncated before any compressed data is
356                 written to it.
357
358            •    A Filehandle
359
360                 If $output is a filehandle, the file pointer will be
361                 positioned to the end of the file via a call to "seek" before
362                 any compressed data is written to it.  Otherwise the file
363                 pointer will not be moved.
364
365            This parameter defaults to 0.
366
367       "Level => number"
368            Defines the compression level used.
369
370            This gets passed to the ZSTD function ZSTD_initCStream.
371
372            Default is 3
373
374       "Strict => 0|1"
375            This is a placeholder option.
376
377   Examples
378       TODO
379

Methods

381   print
382       Usage is
383
384           $z->print($data)
385           print $z $data
386
387       Compresses and outputs the contents of the $data parameter. This has
388       the same behaviour as the "print" built-in.
389
390       Returns true if successful.
391
392   printf
393       Usage is
394
395           $z->printf($format, $data)
396           printf $z $format, $data
397
398       Compresses and outputs the contents of the $data parameter.
399
400       Returns true if successful.
401
402   syswrite
403       Usage is
404
405           $z->syswrite $data
406           $z->syswrite $data, $length
407           $z->syswrite $data, $length, $offset
408
409       Compresses and outputs the contents of the $data parameter.
410
411       Returns the number of uncompressed bytes written, or "undef" if
412       unsuccessful.
413
414   write
415       Usage is
416
417           $z->write $data
418           $z->write $data, $length
419           $z->write $data, $length, $offset
420
421       Compresses and outputs the contents of the $data parameter.
422
423       Returns the number of uncompressed bytes written, or "undef" if
424       unsuccessful.
425
426   flush
427       Usage is
428
429           $z->flush;
430
431       Flushes any pending compressed data to the output file/buffer.
432
433       Returns true on success.
434
435   tell
436       Usage is
437
438           $z->tell()
439           tell $z
440
441       Returns the uncompressed file offset.
442
443   eof
444       Usage is
445
446           $z->eof();
447           eof($z);
448
449       Returns true if the "close" method has been called.
450
451   seek
452           $z->seek($position, $whence);
453           seek($z, $position, $whence);
454
455       Provides a sub-set of the "seek" functionality, with the restriction
456       that it is only legal to seek forward in the output file/buffer.  It is
457       a fatal error to attempt to seek backward.
458
459       Empty parts of the file/buffer will have NULL (0x00) bytes written to
460       them.
461
462       The $whence parameter takes one the usual values, namely SEEK_SET,
463       SEEK_CUR or SEEK_END.
464
465       Returns 1 on success, 0 on failure.
466
467   binmode
468       Usage is
469
470           $z->binmode
471           binmode $z ;
472
473       This is a noop provided for completeness.
474
475   opened
476           $z->opened()
477
478       Returns true if the object currently refers to a opened file/buffer.
479
480   autoflush
481           my $prev = $z->autoflush()
482           my $prev = $z->autoflush(EXPR)
483
484       If the $z object is associated with a file or a filehandle, this method
485       returns the current autoflush setting for the underlying filehandle. If
486       "EXPR" is present, and is non-zero, it will enable flushing after every
487       write/print operation.
488
489       If $z is associated with a buffer, this method has no effect and always
490       returns "undef".
491
492       Note that the special variable $| cannot be used to set or retrieve the
493       autoflush setting.
494
495   input_line_number
496           $z->input_line_number()
497           $z->input_line_number(EXPR)
498
499       This method always returns "undef" when compressing.
500
501   fileno
502           $z->fileno()
503           fileno($z)
504
505       If the $z object is associated with a file or a filehandle, "fileno"
506       will return the underlying file descriptor. Once the "close" method is
507       called "fileno" will return "undef".
508
509       If the $z object is associated with a buffer, this method will return
510       "undef".
511
512   close
513           $z->close() ;
514           close $z ;
515
516       Flushes any pending compressed data and then closes the output
517       file/buffer.
518
519       For most versions of Perl this method will be automatically invoked if
520       the IO::Compress::Zstd object is destroyed (either explicitly or by the
521       variable with the reference to the object going out of scope). The
522       exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In these
523       cases, the "close" method will be called automatically, but not until
524       global destruction of all live objects when the program is terminating.
525
526       Therefore, if you want your scripts to be able to run on all versions
527       of Perl, you should call "close" explicitly and not rely on automatic
528       closing.
529
530       Returns true on success, otherwise 0.
531
532       If the "AutoClose" option has been enabled when the IO::Compress::Zstd
533       object was created, and the object is associated with a file, the
534       underlying file will also be closed.
535
536   newStream([OPTS])
537       Usage is
538
539           $z->newStream( [OPTS] )
540
541       Closes the current compressed data stream and starts a new one.
542
543       OPTS consists of any of the options that are available when creating
544       the $z object.
545
546       See the "Constructor Options" section for more details.
547

Importing

549       No symbolic constants are required by IO::Compress::Zstd at present.
550
551       :all Imports "zstd" and $ZstdError.  Same as doing this
552
553                use IO::Compress::Zstd qw(zstd $ZstdError) ;
554

EXAMPLES

SUPPORT

557       General feedback/questions/bug reports should be sent to
558       <https://github.com/pmqs/IO-Compress-Zstd/issues> (preferred) or
559       <https://rt.cpan.org/Public/Dist/Display.html?Name=IO-Compress-Zstd>.
560

SEE ALSO

562       Compress::Zlib, IO::Compress::Gzip, IO::Uncompress::Gunzip,
563       IO::Compress::Deflate, IO::Uncompress::Inflate,
564       IO::Compress::RawDeflate, IO::Uncompress::RawInflate,
565       IO::Compress::Bzip2, IO::Uncompress::Bunzip2, IO::Compress::Lzma,
566       IO::Uncompress::UnLzma, IO::Compress::Xz, IO::Uncompress::UnXz,
567       IO::Compress::Lzip, IO::Uncompress::UnLzip, IO::Compress::Lzop,
568       IO::Uncompress::UnLzop, IO::Compress::Lzf, IO::Uncompress::UnLzf,
569       IO::Uncompress::UnZstd, IO::Uncompress::AnyInflate,
570       IO::Uncompress::AnyUncompress
571
572       IO::Compress::FAQ
573
574       File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib
575

AUTHOR

577       This module was written by Paul Marquess, "pmqs@cpan.org".
578

MODIFICATION HISTORY

580       See the Changes file.
581
583       Copyright (c) 2019-2022 Paul Marquess. All rights reserved.
584
585       This program is free software; you can redistribute it and/or modify it
586       under the same terms as Perl itself.
587
588
589
590perl v5.36.0                      2022-07-22             IO::Compress::Zstd(3)
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