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1 /* zlib.d: modified from zlib.h by Walter Bright */
2 /* updated from 1.2.1 to 1.2.3 by Thomas Kuehne */
3 /* updated from 1.2.3 to 1.2.8 by Dmitry Atamanov */
4 /* updated from 1.2.8 to 1.2.11 by Iain Buclaw */
5 /* updated from 1.2.11 to 1.2.12 by Brian Callahan */
11 /* zlib.h -- interface of the 'zlib' general purpose compression library
12 version 1.2.12, March 11th, 2022
14 Copyright (C) 1995-2022 Jean-loup Gailly and Mark Adler
16 This software is provided 'as-is', without any express or implied
17 warranty. In no event will the authors be held liable for any damages
18 arising from the use of this software.
20 Permission is granted to anyone to use this software for any purpose,
21 including commercial applications, and to alter it and redistribute it
22 freely, subject to the following restrictions:
24 1. The origin of this software must not be misrepresented; you must not
25 claim that you wrote the original software. If you use this software
26 in a product, an acknowledgment in the product documentation would be
27 appreciated but is not required.
28 2. Altered source versions must be plainly marked as such, and must not be
29 misrepresented as being the original software.
30 3. This notice may not be removed or altered from any source distribution.
32 Jean-loup Gailly Mark Adler
33 jloup@gzip.org madler@alumni.caltech.edu
36 The data format used by the zlib library is described by RFCs (Request for
37 Comments) 1950 to 1952 in the files http://tools.ietf.org/html/rfc1950
38 (zlib format), rfc1951 (deflate format) and rfc1952 (gzip format).
39 */
45 // Those are extern(D) as they should be mangled
49 /*
50 The 'zlib' compression library provides in-memory compression and
51 decompression functions, including integrity checks of the uncompressed data.
52 This version of the library supports only one compression method (deflation)
53 but other algorithms will be added later and will have the same stream
54 interface.
56 Compression can be done in a single step if the buffers are large enough,
57 or can be done by repeated calls of the compression function. In the latter
58 case, the application must provide more input and/or consume the output
59 (providing more output space) before each call.
61 The compressed data format used by default by the in-memory functions is
62 the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
63 around a deflate stream, which is itself documented in RFC 1951.
65 The library also supports reading and writing files in gzip (.gz) format
66 with an interface similar to that of stdio using the functions that start
67 with "gz". The gzip format is different from the zlib format. gzip is a
68 gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
70 This library can optionally read and write gzip and raw deflate streams in
71 memory as well.
73 The zlib format was designed to be compact and fast for use in memory
74 and on communications channels. The gzip format was designed for single-
75 file compression on file systems, has a larger header than zlib to maintain
76 directory information, and uses a different, slower check method than zlib.
78 The library does not install any signal handler. The decoder checks
79 the consistency of the compressed data, so the library should never crash
80 even in the case of corrupted input.
81 */
86 struct z_stream
87 {
104 for deflate, or the decoding state for inflate */
107 }
111 /*
112 gzip header information passed to and from zlib routines. See RFC 1952
113 for more details on the meanings of these fields.
114 */
115 struct gz_header
116 {
130 when writing a gzip file) */
131 }
135 /*
136 The application must update next_in and avail_in when avail_in has dropped
137 to zero. It must update next_out and avail_out when avail_out has dropped
138 to zero. The application must initialize zalloc, zfree and opaque before
139 calling the init function. All other fields are set by the compression
140 library and must not be updated by the application.
142 The opaque value provided by the application will be passed as the first
143 parameter for calls of zalloc and zfree. This can be useful for custom
144 memory management. The compression library attaches no meaning to the
145 opaque value.
147 zalloc must return Z_NULL if there is not enough memory for the object.
148 If zlib is used in a multi-threaded application, zalloc and zfree must be
149 thread safe. In that case, zlib is thread-safe. When zalloc and zfree are
150 Z_NULL on entry to the initialization function, they are set to internal
151 routines that use the standard library functions malloc() and free().
153 On 16-bit systems, the functions zalloc and zfree must be able to allocate
154 exactly 65536 bytes, but will not be required to allocate more than this if
155 the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS, pointers
156 returned by zalloc for objects of exactly 65536 bytes *must* have their
157 offset normalized to zero. The default allocation function provided by this
158 library ensures this (see zutil.c). To reduce memory requirements and avoid
159 any allocation of 64K objects, at the expense of compression ratio, compile
160 the library with -DMAX_WBITS=14 (see zconf.h).
162 The fields total_in and total_out can be used for statistics or progress
163 reports. After compression, total_in holds the total size of the
164 uncompressed data and may be saved for use by the decompressor (particularly
165 if the decompressor wants to decompress everything in a single step).
166 */
168 /* constants */
170 enum
171 {
179 }
180 /* Allowed flush values; see deflate() and inflate() below for details */
182 enum
183 {
193 }
194 /* Return codes for the compression/decompression functions. Negative
195 * values are errors, positive values are used for special but normal events.
196 */
198 enum
199 {
204 }
205 /* compression levels */
207 enum
208 {
214 }
215 /* compression strategy; see deflateInit2() below for details */
217 enum
218 {
223 Z_ASCII = Z_TEXT
224 }
225 /* Possible values of the data_type field for deflate() */
227 enum
228 {
230 }
231 /* The deflate compression method (the only one supported in this version) */
233 /// for initializing zalloc, zfree, opaque (extern(D) for mangling)
236 /* basic functions */
239 /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
240 If the first character differs, the library code actually used is not
241 compatible with the zlib.h header file used by the application. This check
242 is automatically made by deflateInit and inflateInit.
243 */
246 {
248 }
249 /*
250 Initializes the internal stream state for compression. The fields
251 zalloc, zfree and opaque must be initialized before by the caller. If
252 zalloc and zfree are set to Z_NULL, deflateInit updates them to use default
253 allocation functions.
255 The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
256 1 gives best speed, 9 gives best compression, 0 gives no compression at all
257 (the input data is simply copied a block at a time). Z_DEFAULT_COMPRESSION
258 requests a default compromise between speed and compression (currently
259 equivalent to level 6).
261 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
262 memory, Z_STREAM_ERROR if level is not a valid compression level, or
263 Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
264 with the version assumed by the caller (ZLIB_VERSION). msg is set to null
265 if there is no error message. deflateInit does not perform any compression:
266 this will be done by deflate().
267 */
271 /*
272 deflate compresses as much data as possible, and stops when the input
273 buffer becomes empty or the output buffer becomes full. It may introduce
274 some output latency (reading input without producing any output) except when
275 forced to flush.
277 The detailed semantics are as follows. deflate performs one or both of the
278 following actions:
280 - Compress more input starting at next_in and update next_in and avail_in
281 accordingly. If not all input can be processed (because there is not
282 enough room in the output buffer), next_in and avail_in are updated and
283 processing will resume at this point for the next call of deflate().
285 - Generate more output starting at next_out and update next_out and avail_out
286 accordingly. This action is forced if the parameter flush is non zero.
287 Forcing flush frequently degrades the compression ratio, so this parameter
288 should be set only when necessary. Some output may be provided even if
289 flush is zero.
291 Before the call of deflate(), the application should ensure that at least
292 one of the actions is possible, by providing more input and/or consuming more
293 output, and updating avail_in or avail_out accordingly; avail_out should
294 never be zero before the call. The application can consume the compressed
295 output when it wants, for example when the output buffer is full (avail_out
296 == 0), or after each call of deflate(). If deflate returns Z_OK and with
297 zero avail_out, it must be called again after making room in the output
298 buffer because there might be more output pending. See deflatePending(),
299 which can be used if desired to determine whether or not there is more ouput
300 in that case.
302 Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
303 decide how much data to accumulate before producing output, in order to
304 maximize compression.
306 If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
307 flushed to the output buffer and the output is aligned on a byte boundary, so
308 that the decompressor can get all input data available so far. (In
309 particular avail_in is zero after the call if enough output space has been
310 provided before the call.) Flushing may degrade compression for some
311 compression algorithms and so it should be used only when necessary. This
312 completes the current deflate block and follows it with an empty stored block
313 that is three bits plus filler bits to the next byte, followed by four bytes
314 (00 00 ff ff).
316 If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
317 output buffer, but the output is not aligned to a byte boundary. All of the
318 input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
319 This completes the current deflate block and follows it with an empty fixed
320 codes block that is 10 bits long. This assures that enough bytes are output
321 in order for the decompressor to finish the block before the empty fixed
322 codes block.
324 If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
325 for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
326 seven bits of the current block are held to be written as the next byte after
327 the next deflate block is completed. In this case, the decompressor may not
328 be provided enough bits at this point in order to complete decompression of
329 the data provided so far to the compressor. It may need to wait for the next
330 block to be emitted. This is for advanced applications that need to control
331 the emission of deflate blocks.
333 If flush is set to Z_FULL_FLUSH, all output is flushed as with
334 Z_SYNC_FLUSH, and the compression state is reset so that decompression can
335 restart from this point if previous compressed data has been damaged or if
336 random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
337 compression.
339 If deflate returns with avail_out == 0, this function must be called again
340 with the same value of the flush parameter and more output space (updated
341 avail_out), until the flush is complete (deflate returns with non-zero
342 avail_out). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
343 avail_out is greater than six to avoid repeated flush markers due to
344 avail_out == 0 on return.
346 If the parameter flush is set to Z_FINISH, pending input is processed,
347 pending output is flushed and deflate returns with Z_STREAM_END if there was
348 enough output space. If deflate returns with Z_OK or Z_BUF_ERROR, this
349 function must be called again with Z_FINISH and more output space (updated
350 avail_out) but no more input data, until it returns with Z_STREAM_END or an
351 error. After deflate has returned Z_STREAM_END, the only possible operations
352 on the stream are deflateReset or deflateEnd.
354 Z_FINISH can be used in the first deflate call after deflateInit if all the
355 compression is to be done in a single step. In order to complete in one
356 call, avail_out must be at least the value returned by deflateBound (see
357 below). Then deflate is guaranteed to return Z_STREAM_END. If not enough
358 output space is provided, deflate will not return Z_STREAM_END, and it must
359 be called again as described above.
361 deflate() sets strm->adler to the Adler-32 checksum of all input read
362 so far (that is, total_in bytes). If a gzip stream is being generated, then
363 strm->adler will be the CRC-32 checksum of the input read so far. (See
364 deflateInit2 below.)
366 deflate() may update strm->data_type if it can make a good guess about
367 the input data type (Z_BINARY or Z_TEXT). If in doubt, the data is
368 considered binary. This field is only for information purposes and does not
369 affect the compression algorithm in any manner.
371 deflate() returns Z_OK if some progress has been made (more input
372 processed or more output produced), Z_STREAM_END if all input has been
373 consumed and all output has been produced (only when flush is set to
374 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
375 if next_in or next_out was Z_NULL or the state was inadvertently written over
376 by the application), or Z_BUF_ERROR if no progress is possible (for example
377 avail_in or avail_out was zero). Note that Z_BUF_ERROR is not fatal, and
378 deflate() can be called again with more input and more output space to
379 continue compressing.
380 */
384 /*
385 All dynamically allocated data structures for this stream are freed.
386 This function discards any unprocessed input and does not flush any pending
387 output.
389 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
390 stream state was inconsistent, Z_DATA_ERROR if the stream was freed
391 prematurely (some input or output was discarded). In the error case, msg
392 may be set but then points to a static string (which must not be
393 deallocated).
394 */
398 {
400 }
401 /*
402 Initializes the internal stream state for decompression. The fields
403 next_in, avail_in, zalloc, zfree and opaque must be initialized before by
404 the caller. In the current version of inflate, the provided input is not
405 read or consumed. The allocation of a sliding window will be deferred to
406 the first call of inflate (if the decompression does not complete on the
407 first call). If zalloc and zfree are set to Z_NULL, inflateInit updates
408 them to use default allocation functions.
410 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not enough
411 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
412 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
413 invalid, such as a null pointer to the structure. msg is set to null if
414 there is no error message. inflateInit does not perform any decompression.
415 Actual decompression will be done by inflate(). So next_in, and avail_in,
416 next_out, and avail_out are unused and unchanged. The current
417 implementation of inflateInit() does not process any header information --
418 that is deferred until inflate() is called.
419 */
423 /*
424 inflate decompresses as much data as possible, and stops when the input
425 buffer becomes empty or the output buffer becomes full. It may introduce
426 some output latency (reading input without producing any output) except when
427 forced to flush.
429 The detailed semantics are as follows. inflate performs one or both of the
430 following actions:
432 - Decompress more input starting at next_in and update next_in and avail_in
433 accordingly. If not all input can be processed (because there is not
434 enough room in the output buffer), then next_in and avail_in are updated
435 accordingly, and processing will resume at this point for the next call of
436 inflate().
438 - Generate more output starting at next_out and update next_out and avail_out
439 accordingly. inflate() provides as much output as possible, until there is
440 no more input data or no more space in the output buffer (see below about
441 the flush parameter).
443 Before the call of inflate(), the application should ensure that at least
444 one of the actions is possible, by providing more input and/or consuming more
445 output, and updating the next_* and avail_* values accordingly. If the
446 caller of inflate() does not provide both available input and available
447 output space, it is possible that there will be no progress made. The
448 application can consume the uncompressed output when it wants, for example
449 when the output buffer is full (avail_out == 0), or after each call of
450 inflate(). If inflate returns Z_OK and with zero avail_out, it must be
451 called again after making room in the output buffer because there might be
452 more output pending.
454 The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
455 Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
456 output as possible to the output buffer. Z_BLOCK requests that inflate()
457 stop if and when it gets to the next deflate block boundary. When decoding
458 the zlib or gzip format, this will cause inflate() to return immediately
459 after the header and before the first block. When doing a raw inflate,
460 inflate() will go ahead and process the first block, and will return when it
461 gets to the end of that block, or when it runs out of data.
463 The Z_BLOCK option assists in appending to or combining deflate streams.
464 To assist in this, on return inflate() always sets strm->data_type to the
465 number of unused bits in the last byte taken from strm->next_in, plus 64 if
466 inflate() is currently decoding the last block in the deflate stream, plus
467 128 if inflate() returned immediately after decoding an end-of-block code or
468 decoding the complete header up to just before the first byte of the deflate
469 stream. The end-of-block will not be indicated until all of the uncompressed
470 data from that block has been written to strm->next_out. The number of
471 unused bits may in general be greater than seven, except when bit 7 of
472 data_type is set, in which case the number of unused bits will be less than
473 eight. data_type is set as noted here every time inflate() returns for all
474 flush options, and so can be used to determine the amount of currently
475 consumed input in bits.
477 The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
478 end of each deflate block header is reached, before any actual data in that
479 block is decoded. This allows the caller to determine the length of the
480 deflate block header for later use in random access within a deflate block.
481 256 is added to the value of strm->data_type when inflate() returns
482 immediately after reaching the end of the deflate block header.
484 inflate() should normally be called until it returns Z_STREAM_END or an
485 error. However if all decompression is to be performed in a single step (a
486 single call of inflate), the parameter flush should be set to Z_FINISH. In
487 this case all pending input is processed and all pending output is flushed;
488 avail_out must be large enough to hold all of the uncompressed data for the
489 operation to complete. (The size of the uncompressed data may have been
490 saved by the compressor for this purpose.) The use of Z_FINISH is not
491 required to perform an inflation in one step. However it may be used to
492 inform inflate that a faster approach can be used for the single inflate()
493 call. Z_FINISH also informs inflate to not maintain a sliding window if the
494 stream completes, which reduces inflate's memory footprint. If the stream
495 does not complete, either because not all of the stream is provided or not
496 enough output space is provided, then a sliding window will be allocated and
497 inflate() can be called again to continue the operation as if Z_NO_FLUSH had
498 been used.
500 In this implementation, inflate() always flushes as much output as
501 possible to the output buffer, and always uses the faster approach on the
502 first call. So the effects of the flush parameter in this implementation are
503 on the return value of inflate() as noted below, when inflate() returns early
504 when Z_BLOCK or Z_TREES is used, and when inflate() avoids the allocation of
505 memory for a sliding window when Z_FINISH is used.
507 If a preset dictionary is needed after this call (see inflateSetDictionary
508 below), inflate sets strm->adler to the Adler-32 checksum of the dictionary
509 chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
510 strm->adler to the Adler-32 checksum of all output produced so far (that is,
511 total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
512 below. At the end of the stream, inflate() checks that its computed Adler-32
513 checksum is equal to that saved by the compressor and returns Z_STREAM_END
514 only if the checksum is correct.
516 inflate() can decompress and check either zlib-wrapped or gzip-wrapped
517 deflate data. The header type is detected automatically, if requested when
518 initializing with inflateInit2(). Any information contained in the gzip
519 header is not retained unless inflateGetHeader() is used. When processing
520 gzip-wrapped deflate data, strm->adler32 is set to the CRC-32 of the output
521 produced so far. The CRC-32 is checked against the gzip trailer, as is the
522 uncompressed length, modulo 2^32.
524 inflate() returns Z_OK if some progress has been made (more input processed
525 or more output produced), Z_STREAM_END if the end of the compressed data has
526 been reached and all uncompressed output has been produced, Z_NEED_DICT if a
527 preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
528 corrupted (input stream not conforming to the zlib format or incorrect check
529 value, in which case strm->msg points to a string with a more specific
530 error), Z_STREAM_ERROR if the stream structure was inconsistent (for example
531 next_in or next_out was Z_NULL, or the state was inadvertently written over
532 by the application), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR
533 if no progress was possible or if there was not enough room in the output
534 buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
535 inflate() can be called again with more input and more output space to
536 continue decompressing. If Z_DATA_ERROR is returned, the application may
537 then call inflateSync() to look for a good compression block if a partial
538 recovery of the data is to be attempted.
539 */
543 /*
544 All dynamically allocated data structures for this stream are freed.
545 This function discards any unprocessed input and does not flush any pending
546 output.
548 inflateEnd returns Z_OK if success, or Z_STREAM_ERROR if the stream state
549 was inconsistent.
550 */
552 /* Advanced functions */
554 /*
555 The following functions are needed only in some special applications.
556 */
564 {
567 }
568 /*
569 This is another version of deflateInit with more compression options. The
570 fields zalloc, zfree and opaque must be initialized before by the caller.
572 The method parameter is the compression method. It must be Z_DEFLATED in
573 this version of the library.
575 The windowBits parameter is the base two logarithm of the window size
576 (the size of the history buffer). It should be in the range 8 .. 15 for this
577 version of the library. Larger values of this parameter result in better
578 compression at the expense of memory usage. The default value is 15 if
579 deflateInit is used instead.
581 For the current implementation of deflate(), a windowBits value of 8 (a
582 window size of 256 bytes) is not supported. As a result, a request for 8
583 will result in 9 (a 512-byte window). In that case, providing 8 to
584 inflateInit2() will result in an error when the zlib header with 9 is
585 checked against the initialization of inflate(). The remedy is to not use 8
586 with deflateInit2() with this initialization, or at least in that case use 9
587 with inflateInit2().
589 windowBits can also be -8 .. -15 for raw deflate. In this case, -windowBits
590 determines the window size. deflate() will then generate raw deflate data
591 with no zlib header or trailer, and will not compute a check value.
593 windowBits can also be greater than 15 for optional gzip encoding. Add
594 16 to windowBits to write a simple gzip header and trailer around the
595 compressed data instead of a zlib wrapper. The gzip header will have no
596 file name, no extra data, no comment, no modification time (set to zero), no
597 header crc, and the operating system will be set to the appropriate value,
598 if the operating system was determined at compile time. If a gzip stream is
599 being written, strm->adler is a CRC-32 instead of an Adler-32.
601 For raw deflate or gzip encoding, a request for a 256-byte window is
602 rejected as invalid, since only the zlib header provides a means of
603 transmitting the window size to the decompressor.
605 The memLevel parameter specifies how much memory should be allocated
606 for the internal compression state. memLevel=1 uses minimum memory but is
607 slow and reduces compression ratio; memLevel=9 uses maximum memory for
608 optimal speed. The default value is 8. See zconf.h for total memory usage
609 as a function of windowBits and memLevel.
611 The strategy parameter is used to tune the compression algorithm. Use the
612 value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
613 filter (or predictor), Z_HUFFMAN_ONLY to force Huffman encoding only (no
614 string match), or Z_RLE to limit match distances to one (run-length
615 encoding). Filtered data consists mostly of small values with a somewhat
616 random distribution. In this case, the compression algorithm is tuned to
617 compress them better. The effect of Z_FILTERED is to force more Huffman
618 coding and less string matching; it is somewhat intermediate between
619 Z_DEFAULT_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
620 fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
621 strategy parameter only affects the compression ratio but not the
622 correctness of the compressed output even if it is not set appropriately.
623 Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
624 decoder for special applications.
626 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
627 memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
628 method), or Z_VERSION_ERROR if the zlib library version (zlib_version) is
629 incompatible with the version assumed by the caller (ZLIB_VERSION). msg is
630 set to null if there is no error message. deflateInit2 does not perform any
631 compression: this will be done by deflate().
632 */
635 /*
636 Initializes the compression dictionary from the given byte sequence
637 without producing any compressed output. When using the zlib format, this
638 function must be called immediately after deflateInit, deflateInit2 or
639 deflateReset, and before any call of deflate. When doing raw deflate, this
640 function must be called either before any call of deflate, or immediately
641 after the completion of a deflate block, i.e. after all input has been
642 consumed and all output has been delivered when using any of the flush
643 options Z_BLOCK, Z_PARTIAL_FLUSH, Z_SYNC_FLUSH, or Z_FULL_FLUSH. The
644 compressor and decompressor must use exactly the same dictionary (see
645 inflateSetDictionary).
647 The dictionary should consist of strings (byte sequences) that are likely
648 to be encountered later in the data to be compressed, with the most commonly
649 used strings preferably put towards the end of the dictionary. Using a
650 dictionary is most useful when the data to be compressed is short and can be
651 predicted with good accuracy; the data can then be compressed better than
652 with the default empty dictionary.
654 Depending on the size of the compression data structures selected by
655 deflateInit or deflateInit2, a part of the dictionary may in effect be
656 discarded, for example if the dictionary is larger than the window size
657 provided in deflateInit or deflateInit2. Thus the strings most likely to be
658 useful should be put at the end of the dictionary, not at the front. In
659 addition, the current implementation of deflate will use at most the window
660 size minus 262 bytes of the provided dictionary.
662 Upon return of this function, strm->adler is set to the Adler-32 value
663 of the dictionary; the decompressor may later use this value to determine
664 which dictionary has been used by the compressor. (The Adler-32 value
665 applies to the whole dictionary even if only a subset of the dictionary is
666 actually used by the compressor.) If a raw deflate was requested, then the
667 Adler-32 value is not computed and strm->adler is not set.
669 deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
670 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
671 inconsistent (for example if deflate has already been called for this stream
672 or if not at a block boundary for raw deflate). deflateSetDictionary does
673 not perform any compression: this will be done by deflate().
674 */
677 /*
678 Returns the sliding dictionary being maintained by deflate. dictLength is
679 set to the number of bytes in the dictionary, and that many bytes are copied
680 to dictionary. dictionary must have enough space, where 32768 bytes is
681 always enough. If deflateGetDictionary() is called with dictionary equal to
682 Z_NULL, then only the dictionary length is returned, and nothing is copied.
683 Similary, if dictLength is Z_NULL, then it is not set.
685 deflateGetDictionary() may return a length less than the window size, even
686 when more than the window size in input has been provided. It may return up
687 to 258 bytes less in that case, due to how zlib's implementation of deflate
688 manages the sliding window and lookahead for matches, where matches can be
689 up to 258 bytes long. If the application needs the last window-size bytes of
690 input, then that would need to be saved by the application outside of zlib.
692 deflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
693 stream state is inconsistent.
694 */
697 /*
698 Sets the destination stream as a complete copy of the source stream.
700 This function can be useful when several compression strategies will be
701 tried, for example when there are several ways of pre-processing the input
702 data with a filter. The streams that will be discarded should then be freed
703 by calling deflateEnd. Note that deflateCopy duplicates the internal
704 compression state which can be quite large, so this strategy is slow and can
705 consume lots of memory.
707 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
708 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
709 (such as zalloc being Z_NULL). msg is left unchanged in both source and
710 destination.
711 */
714 /*
715 This function is equivalent to deflateEnd followed by deflateInit, but
716 does not free and reallocate the internal compression state. The stream
717 will leave the compression level and any other attributes that may have been
718 set unchanged.
720 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
721 stream state was inconsistent (such as zalloc or state being Z_NULL).
722 */
725 /*
726 Dynamically update the compression level and compression strategy. The
727 interpretation of level and strategy is as in deflateInit2(). This can be
728 used to switch between compression and straight copy of the input data, or
729 to switch to a different kind of input data requiring a different strategy.
730 If the compression approach (which is a function of the level) or the
731 strategy is changed, and if there have been any deflate() calls since the
732 state was initialized or reset, then the input available so far is
733 compressed with the old level and strategy using deflate(strm, Z_BLOCK).
734 There are three approaches for the compression levels 0, 1 .. 3, and 4 .. 9
735 respectively. The new level and strategy will take effect at the next call
736 of deflate().
738 If a deflate(strm, Z_BLOCK) is performed by deflateParams(), and it does
739 not have enough output space to complete, then the parameter change will not
740 take effect. In this case, deflateParams() can be called again with the
741 same parameters and more output space to try again.
743 In order to assure a change in the parameters on the first try, the
744 deflate stream should be flushed using deflate() with Z_BLOCK or other flush
745 request until strm.avail_out is not zero, before calling deflateParams().
746 Then no more input data should be provided before the deflateParams() call.
747 If this is done, the old level and strategy will be applied to the data
748 compressed before deflateParams(), and the new level and strategy will be
749 applied to the the data compressed after deflateParams().
751 deflateParams returns Z_OK on success, Z_STREAM_ERROR if the source stream
752 state was inconsistent or if a parameter was invalid, or Z_BUF_ERROR if
753 there was not enough output space to complete the compression of the
754 available input data before a change in the strategy or approach. Note that
755 in the case of a Z_BUF_ERROR, the parameters are not changed. A return
756 value of Z_BUF_ERROR is not fatal, in which case deflateParams() can be
757 retried with more output space.
758 */
762 /*
763 Fine tune deflate's internal compression parameters. This should only be
764 used by someone who understands the algorithm used by zlib's deflate for
765 searching for the best matching string, and even then only by the most
766 fanatic optimizer trying to squeeze out the last compressed bit for their
767 specific input data. Read the deflate.c source code for the meaning of the
768 max_lazy, good_length, nice_length, and max_chain parameters.
770 deflateTune() can be called after deflateInit() or deflateInit2(), and
771 returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
772 */
775 /*
776 deflateBound() returns an upper bound on the compressed size after
777 deflation of sourceLen bytes. It must be called after deflateInit() or
778 deflateInit2(), and after deflateSetHeader(), if used. This would be used
779 to allocate an output buffer for deflation in a single pass, and so would be
780 called before deflate(). If that first deflate() call is provided the
781 sourceLen input bytes, an output buffer allocated to the size returned by
782 deflateBound(), and the flush value Z_FINISH, then deflate() is guaranteed
783 to return Z_STREAM_END. Note that it is possible for the compressed size to
784 be larger than the value returned by deflateBound() if flush options other
785 than Z_FINISH or Z_NO_FLUSH are used.
786 */
789 /*
790 deflatePending() returns the number of bytes and bits of output that have
791 been generated, but not yet provided in the available output. The bytes not
792 provided would be due to the available output space having being consumed.
793 The number of bits of output not provided are between 0 and 7, where they
794 await more bits to join them in order to fill out a full byte. If pending
795 or bits are Z_NULL, then those values are not set.
797 deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
798 stream state was inconsistent.
799 */
802 /*
803 deflatePrime() inserts bits in the deflate output stream. The intent
804 is that this function is used to start off the deflate output with the bits
805 leftover from a previous deflate stream when appending to it. As such, this
806 function can only be used for raw deflate, and must be used before the first
807 deflate() call after a deflateInit2() or deflateReset(). bits must be less
808 than or equal to 16, and that many of the least significant bits of value
809 will be inserted in the output.
811 deflatePrime returns Z_OK if success, Z_BUF_ERROR if there was not enough
812 room in the internal buffer to insert the bits, or Z_STREAM_ERROR if the
813 source stream state was inconsistent.
814 */
817 /*
818 deflateSetHeader() provides gzip header information for when a gzip
819 stream is requested by deflateInit2(). deflateSetHeader() may be called
820 after deflateInit2() or deflateReset() and before the first call of
821 deflate(). The text, time, os, extra field, name, and comment information
822 in the provided gz_header structure are written to the gzip header (xflag is
823 ignored -- the extra flags are set according to the compression level). The
824 caller must assure that, if not Z_NULL, name and comment are terminated with
825 a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
826 available there. If hcrc is true, a gzip header crc is included. Note that
827 the current versions of the command-line version of gzip (up through version
828 1.3.x) do not support header crc's, and will report that it is a "multi-part
829 gzip file" and give up.
831 If deflateSetHeader is not used, the default gzip header has text false,
832 the time set to zero, and os set to 255, with no extra, name, or comment
833 fields. The gzip header is returned to the default state by deflateReset().
835 deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
836 stream state was inconsistent.
837 */
840 {
842 }
843 /*
844 This is another version of inflateInit with an extra parameter. The
845 fields next_in, avail_in, zalloc, zfree and opaque must be initialized
846 before by the caller.
848 The windowBits parameter is the base two logarithm of the maximum window
849 size (the size of the history buffer). It should be in the range 8 .. 15 for
850 this version of the library. The default value is 15 if inflateInit is used
851 instead. windowBits must be greater than or equal to the windowBits value
852 provided to deflateInit2() while compressing, or it must be equal to 15 if
853 deflateInit2() was not used. If a compressed stream with a larger window
854 size is given as input, inflate() will return with the error code
855 Z_DATA_ERROR instead of trying to allocate a larger window.
857 windowBits can also be zero to request that inflate use the window size in
858 the zlib header of the compressed stream.
860 windowBits can also be -8 .. -15 for raw inflate. In this case, -windowBits
861 determines the window size. inflate() will then process raw deflate data,
862 not looking for a zlib or gzip header, not generating a check value, and not
863 looking for any check values for comparison at the end of the stream. This
864 is for use with other formats that use the deflate compressed data format
865 such as zip. Those formats provide their own check values. If a custom
866 format is developed using the raw deflate format for compressed data, it is
867 recommended that a check value such as an Adler-32 or a CRC-32 be applied to
868 the uncompressed data as is done in the zlib, gzip, and zip formats. For
869 most applications, the zlib format should be used as is. Note that comments
870 above on the use in deflateInit2() applies to the magnitude of windowBits.
872 windowBits can also be greater than 15 for optional gzip decoding. Add
873 32 to windowBits to enable zlib and gzip decoding with automatic header
874 detection, or add 16 to decode only the gzip format (the zlib format will
875 return a Z_DATA_ERROR). If a gzip stream is being decoded, strm->adler is a
876 CRC-32 instead of an Adler-32. Unlike the gunzip utility and gzread() (see
877 below), inflate() will *not* automatically decode concatenated gzip members.
878 inflate() will return Z_STREAM_END at the end of the gzip member. The state
879 would need to be reset to continue decoding a subsequent gzip member. This
880 *must* be done if there is more data after a gzip member, in order for the
881 decompression to be compliant with the gzip standard (RFC 1952).
883 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
884 memory, Z_VERSION_ERROR if the zlib library version is incompatible with the
885 version assumed by the caller, or Z_STREAM_ERROR if the parameters are
886 invalid, such as a null pointer to the structure. msg is set to null if
887 there is no error message. inflateInit2 does not perform any decompression
888 apart from possibly reading the zlib header if present: actual decompression
889 will be done by inflate(). (So next_in and avail_in may be modified, but
890 next_out and avail_out are unused and unchanged.) The current implementation
891 of inflateInit2() does not process any header information -- that is
892 deferred until inflate() is called.
893 */
896 /*
897 Initializes the decompression dictionary from the given uncompressed byte
898 sequence. This function must be called immediately after a call of inflate,
899 if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
900 can be determined from the Adler-32 value returned by that call of inflate.
901 The compressor and decompressor must use exactly the same dictionary (see
902 deflateSetDictionary). For raw inflate, this function can be called at any
903 time to set the dictionary. If the provided dictionary is smaller than the
904 window and there is already data in the window, then the provided dictionary
905 will amend what's there. The application must insure that the dictionary
906 that was used for compression is provided.
908 inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
909 parameter is invalid (e.g. dictionary being Z_NULL) or the stream state is
910 inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
911 expected one (incorrect Adler-32 value). inflateSetDictionary does not
912 perform any decompression: this will be done by subsequent calls of
913 inflate().
914 */
917 /*
918 Returns the sliding dictionary being maintained by inflate. dictLength is
919 set to the number of bytes in the dictionary, and that many bytes are copied
920 to dictionary. dictionary must have enough space, where 32768 bytes is
921 always enough. If inflateGetDictionary() is called with dictionary equal to
922 Z_NULL, then only the dictionary length is returned, and nothing is copied.
923 Similary, if dictLength is Z_NULL, then it is not set.
925 inflateGetDictionary returns Z_OK on success, or Z_STREAM_ERROR if the
926 stream state is inconsistent.
927 */
930 /*
931 Skips invalid compressed data until a possible full flush point (see above
932 for the description of deflate with Z_FULL_FLUSH) can be found, or until all
933 available input is skipped. No output is provided.
935 inflateSync searches for a 00 00 FF FF pattern in the compressed data.
936 All full flush points have this pattern, but not all occurrences of this
937 pattern are full flush points.
939 inflateSync returns Z_OK if a possible full flush point has been found,
940 Z_BUF_ERROR if no more input was provided, Z_DATA_ERROR if no flush point
941 has been found, or Z_STREAM_ERROR if the stream structure was inconsistent.
942 In the success case, the application may save the current current value of
943 total_in which indicates where valid compressed data was found. In the
944 error case, the application may repeatedly call inflateSync, providing more
945 input each time, until success or end of the input data.
946 */
949 /*
950 Sets the destination stream as a complete copy of the source stream.
952 This function can be useful when randomly accessing a large stream. The
953 first pass through the stream can periodically record the inflate state,
954 allowing restarting inflate at those points when randomly accessing the
955 stream.
957 inflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
958 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
959 (such as zalloc being Z_NULL). msg is left unchanged in both source and
960 destination.
961 */
964 /*
965 This function is equivalent to inflateEnd followed by inflateInit,
966 but does not free and reallocate the internal decompression state. The
967 stream will keep attributes that may have been set by inflateInit2.
969 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
970 stream state was inconsistent (such as zalloc or state being Z_NULL).
971 */
974 /*
975 This function is the same as inflateReset, but it also permits changing
976 the wrap and window size requests. The windowBits parameter is interpreted
977 the same as it is for inflateInit2. If the window size is changed, then the
978 memory allocated for the window is freed, and the window will be reallocated
979 by inflate() if needed.
981 inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
982 stream state was inconsistent (such as zalloc or state being Z_NULL), or if
983 the windowBits parameter is invalid.
984 */
987 /*
988 This function inserts bits in the inflate input stream. The intent is
989 that this function is used to start inflating at a bit position in the
990 middle of a byte. The provided bits will be used before any bytes are used
991 from next_in. This function should only be used with raw inflate, and
992 should be used before the first inflate() call after inflateInit2() or
993 inflateReset(). bits must be less than or equal to 16, and that many of the
994 least significant bits of value will be inserted in the input.
996 If bits is negative, then the input stream bit buffer is emptied. Then
997 inflatePrime() can be called again to put bits in the buffer. This is used
998 to clear out bits leftover after feeding inflate a block description prior
999 to feeding inflate codes.
1001 inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
1002 stream state was inconsistent.
1003 */
1006 /*
1007 This function returns two values, one in the lower 16 bits of the return
1008 value, and the other in the remaining upper bits, obtained by shifting the
1009 return value down 16 bits. If the upper value is -1 and the lower value is
1010 zero, then inflate() is currently decoding information outside of a block.
1011 If the upper value is -1 and the lower value is non-zero, then inflate is in
1012 the middle of a stored block, with the lower value equaling the number of
1013 bytes from the input remaining to copy. If the upper value is not -1, then
1014 it is the number of bits back from the current bit position in the input of
1015 the code (literal or length/distance pair) currently being processed. In
1016 that case the lower value is the number of bytes already emitted for that
1017 code.
1019 A code is being processed if inflate is waiting for more input to complete
1020 decoding of the code, or if it has completed decoding but is waiting for
1021 more output space to write the literal or match data.
1023 inflateMark() is used to mark locations in the input data for random
1024 access, which may be at bit positions, and to note those cases where the
1025 output of a code may span boundaries of random access blocks. The current
1026 location in the input stream can be determined from avail_in and data_type
1027 as noted in the description for the Z_BLOCK flush parameter for inflate.
1029 inflateMark returns the value noted above, or -65536 if the provided
1030 source stream state was inconsistent.
1031 */
1034 /*
1035 inflateGetHeader() requests that gzip header information be stored in the
1036 provided gz_header structure. inflateGetHeader() may be called after
1037 inflateInit2() or inflateReset(), and before the first call of inflate().
1038 As inflate() processes the gzip stream, head->done is zero until the header
1039 is completed, at which time head->done is set to one. If a zlib stream is
1040 being decoded, then head->done is set to -1 to indicate that there will be
1041 no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be
1042 used to force inflate() to return immediately after header processing is
1043 complete and before any actual data is decompressed.
1045 The text, time, xflags, and os fields are filled in with the gzip header
1046 contents. hcrc is set to true if there is a header CRC. (The header CRC
1047 was valid if done is set to one.) If extra is not Z_NULL, then extra_max
1048 contains the maximum number of bytes to write to extra. Once done is true,
1049 extra_len contains the actual extra field length, and extra contains the
1050 extra field, or that field truncated if extra_max is less than extra_len.
1051 If name is not Z_NULL, then up to name_max characters are written there,
1052 terminated with a zero unless the length is greater than name_max. If
1053 comment is not Z_NULL, then up to comm_max characters are written there,
1054 terminated with a zero unless the length is greater than comm_max. When any
1055 of extra, name, or comment are not Z_NULL and the respective field is not
1056 present in the header, then that field is set to Z_NULL to signal its
1057 absence. This allows the use of deflateSetHeader() with the returned
1058 structure to duplicate the header. However if those fields are set to
1059 allocated memory, then the application will need to save those pointers
1060 elsewhere so that they can be eventually freed.
1062 If inflateGetHeader is not used, then the header information is simply
1063 discarded. The header is always checked for validity, including the header
1064 CRC if present. inflateReset() will reset the process to discard the header
1065 information. The application would need to call inflateGetHeader() again to
1066 retrieve the header from the next gzip stream.
1068 inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
1069 stream state was inconsistent.
1070 */
1074 {
1076 }
1077 /*
1078 Initialize the internal stream state for decompression using inflateBack()
1079 calls. The fields zalloc, zfree and opaque in strm must be initialized
1080 before the call. If zalloc and zfree are Z_NULL, then the default library-
1081 derived memory allocation routines are used. windowBits is the base two
1082 logarithm of the window size, in the range 8 .. 15. window is a caller
1083 supplied buffer of that size. Except for special applications where it is
1084 assured that deflate was used with small window sizes, windowBits must be 15
1085 and a 32K byte window must be supplied to be able to decompress general
1086 deflate streams.
1088 See inflateBack() for the usage of these routines.
1090 inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
1091 the parameters are invalid, Z_MEM_ERROR if the internal state could not be
1092 allocated, or Z_VERSION_ERROR if the version of the library does not match
1093 the version of the header file.
1094 */
1100 in_func f_in,
1102 out_func f_out,
1104 /*
1105 inflateBack() does a raw inflate with a single call using a call-back
1106 interface for input and output. This is potentially more efficient than
1107 inflate() for file i/o applications, in that it avoids copying between the
1108 output and the sliding window by simply making the window itself the output
1109 buffer. inflate() can be faster on modern CPUs when used with large
1110 buffers. inflateBack() trusts the application to not change the output
1111 buffer passed by the output function, at least until inflateBack() returns.
1113 inflateBackInit() must be called first to allocate the internal state
1114 and to initialize the state with the user-provided window buffer.
1115 inflateBack() may then be used multiple times to inflate a complete, raw
1116 deflate stream with each call. inflateBackEnd() is then called to free the
1117 allocated state.
1119 A raw deflate stream is one with no zlib or gzip header or trailer.
1120 This routine would normally be used in a utility that reads zip or gzip
1121 files and writes out uncompressed files. The utility would decode the
1122 header and process the trailer on its own, hence this routine expects only
1123 the raw deflate stream to decompress. This is different from the default
1124 behavior of inflate(), which expects a zlib header and trailer around the
1125 deflate stream.
1127 inflateBack() uses two subroutines supplied by the caller that are then
1128 called by inflateBack() for input and output. inflateBack() calls those
1129 routines until it reads a complete deflate stream and writes out all of the
1130 uncompressed data, or until it encounters an error. The function's
1131 parameters and return types are defined above in the in_func and out_func
1132 typedefs. inflateBack() will call in(in_desc, &buf) which should return the
1133 number of bytes of provided input, and a pointer to that input in buf. If
1134 there is no input available, in() must return zero -- buf is ignored in that
1135 case -- and inflateBack() will return a buffer error. inflateBack() will
1136 call out(out_desc, buf, len) to write the uncompressed data buf[0 .. len-1].
1137 out() should return zero on success, or non-zero on failure. If out()
1138 returns non-zero, inflateBack() will return with an error. Neither in() nor
1139 out() are permitted to change the contents of the window provided to
1140 inflateBackInit(), which is also the buffer that out() uses to write from.
1141 The length written by out() will be at most the window size. Any non-zero
1142 amount of input may be provided by in().
1144 For convenience, inflateBack() can be provided input on the first call by
1145 setting strm->next_in and strm->avail_in. If that input is exhausted, then
1146 in() will be called. Therefore strm->next_in must be initialized before
1147 calling inflateBack(). If strm->next_in is Z_NULL, then in() will be called
1148 immediately for input. If strm->next_in is not Z_NULL, then strm->avail_in
1149 must also be initialized, and then if strm->avail_in is not zero, input will
1150 initially be taken from strm->next_in[0 .. strm->avail_in - 1].
1152 The in_desc and out_desc parameters of inflateBack() is passed as the
1153 first parameter of in() and out() respectively when they are called. These
1154 descriptors can be optionally used to pass any information that the caller-
1155 supplied in() and out() functions need to do their job.
1157 On return, inflateBack() will set strm->next_in and strm->avail_in to
1158 pass back any unused input that was provided by the last in() call. The
1159 return values of inflateBack() can be Z_STREAM_END on success, Z_BUF_ERROR
1160 if in() or out() returned an error, Z_DATA_ERROR if there was a format error
1161 in the deflate stream (in which case strm->msg is set to indicate the nature
1162 of the error), or Z_STREAM_ERROR if the stream was not properly initialized.
1163 In the case of Z_BUF_ERROR, an input or output error can be distinguished
1164 using strm->next_in which will be Z_NULL only if in() returned an error. If
1165 strm->next_in is not Z_NULL, then the Z_BUF_ERROR was due to out() returning
1166 non-zero. (in() will always be called before out(), so strm->next_in is
1167 assured to be defined if out() returns non-zero.) Note that inflateBack()
1168 cannot return Z_OK.
1169 */
1172 /*
1173 All memory allocated by inflateBackInit() is freed.
1175 inflateBackEnd() returns Z_OK on success, or Z_STREAM_ERROR if the stream
1176 state was inconsistent.
1177 */
1180 /* Return flags indicating compile-time options.
1182 Type sizes, two bits each, 00 = 16 bits, 01 = 32, 10 = 64, 11 = other:
1183 1.0: size of uInt
1184 3.2: size of uLong
1185 5.4: size of voidpf (pointer)
1186 7.6: size of z_off_t
1188 Compiler, assembler, and debug options:
1189 8: ZLIB_DEBUG
1190 9: ASMV or ASMINF -- use ASM code
1191 10: ZLIB_WINAPI -- exported functions use the WINAPI calling convention
1192 11: 0 (reserved)
1194 One-time table building (smaller code, but not thread-safe if true):
1195 12: BUILDFIXED -- build static block decoding tables when needed
1196 13: DYNAMIC_CRC_TABLE -- build CRC calculation tables when needed
1197 14,15: 0 (reserved)
1199 Library content (indicates missing functionality):
1200 16: NO_GZCOMPRESS -- gz* functions cannot compress (to avoid linking
1201 deflate code when not needed)
1202 17: NO_GZIP -- deflate can't write gzip streams, and inflate can't detect
1203 and decode gzip streams (to avoid linking crc code)
1204 18-19: 0 (reserved)
1206 Operation variations (changes in library functionality):
1207 20: PKZIP_BUG_WORKAROUND -- slightly more permissive inflate
1208 21: FASTEST -- deflate algorithm with only one, lowest compression level
1209 22,23: 0 (reserved)
1211 The sprintf variant used by gzprintf (zero is best):
1212 24: 0 = vs*, 1 = s* -- 1 means limited to 20 arguments after the format
1213 25: 0 = *nprintf, 1 = *printf -- 1 means gzprintf() not secure!
1214 26: 0 = returns value, 1 = void -- 1 means inferred string length returned
1216 Remainder:
1217 27-31: 0 (reserved)
1218 */
1220 /* utility functions */
1222 /*
1223 The following utility functions are implemented on top of the basic
1224 stream-oriented functions. To simplify the interface, some default options
1225 are assumed (compression level and memory usage, standard memory allocation
1226 functions). The source code of these utility functions can be modified if
1227 you need special options.
1228 */
1233 size_t sourceLen);
1234 /*
1235 Compresses the source buffer into the destination buffer. sourceLen is
1236 the byte length of the source buffer. Upon entry, destLen is the total size
1237 of the destination buffer, which must be at least the value returned by
1238 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1239 compressed data. compress() is equivalent to compress2() with a level
1240 parameter of Z_DEFAULT_COMPRESSION.
1242 compress returns Z_OK if success, Z_MEM_ERROR if there was not
1243 enough memory, Z_BUF_ERROR if there was not enough room in the output
1244 buffer.
1245 */
1250 size_t sourceLen,
1252 /*
1253 Compresses the source buffer into the destination buffer. The level
1254 parameter has the same meaning as in deflateInit. sourceLen is the byte
1255 length of the source buffer. Upon entry, destLen is the total size of the
1256 destination buffer, which must be at least the value returned by
1257 compressBound(sourceLen). Upon exit, destLen is the actual size of the
1258 compressed data.
1260 compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
1261 memory, Z_BUF_ERROR if there was not enough room in the output buffer,
1262 Z_STREAM_ERROR if the level parameter is invalid.
1263 */
1266 /*
1267 compressBound() returns an upper bound on the compressed size after
1268 compress() or compress2() on sourceLen bytes. It would be used before a
1269 compress() or compress2() call to allocate the destination buffer.
1270 */
1275 size_t sourceLen);
1276 /*
1277 Decompresses the source buffer into the destination buffer. sourceLen is
1278 the byte length of the source buffer. Upon entry, destLen is the total size
1279 of the destination buffer, which must be large enough to hold the entire
1280 uncompressed data. (The size of the uncompressed data must have been saved
1281 previously by the compressor and transmitted to the decompressor by some
1282 mechanism outside the scope of this compression library.) Upon exit, destLen
1283 is the actual size of the uncompressed data.
1285 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
1286 enough memory, Z_BUF_ERROR if there was not enough room in the output
1287 buffer, or Z_DATA_ERROR if the input data was corrupted or incomplete. In
1288 the case where there is not enough room, uncompress() will fill the output
1289 buffer with the uncompressed data up to that point.
1290 */
1296 /*
1297 Same as uncompress, except that sourceLen is a pointer, where the
1298 length of the source is *sourceLen. On return, *sourceLen is the number of
1299 source bytes consumed.
1300 */
1302 /* gzip file access functions */
1304 /*
1305 This library supports reading and writing files in gzip (.gz) format with
1306 an interface similar to that of stdio, using the functions that start with
1307 "gz". The gzip format is different from the zlib format. gzip is a gzip
1308 wrapper, documented in RFC 1952, wrapped around a deflate stream.
1309 */
1316 /*
1317 Open the gzip (.gz) file at path for reading and decompressing, or
1318 compressing and writing. The mode parameter is as in fopen ("rb" or "wb")
1319 but can also include a compression level ("wb9") or a strategy: 'f' for
1320 filtered data as in "wb6f", 'h' for Huffman-only compression as in "wb1h",
1321 'R' for run-length encoding as in "wb1R", or 'F' for fixed code compression
1322 as in "wb9F". (See the description of deflateInit2 for more information
1323 about the strategy parameter.) 'T' will request transparent writing or
1324 appending with no compression and not using the gzip format.
1326 "a" can be used instead of "w" to request that the gzip stream that will
1327 be written be appended to the file. "+" will result in an error, since
1328 reading and writing to the same gzip file is not supported. The addition of
1329 "x" when writing will create the file exclusively, which fails if the file
1330 already exists. On systems that support it, the addition of "e" when
1331 reading or writing will set the flag to close the file on an execve() call.
1333 These functions, as well as gzip, will read and decode a sequence of gzip
1334 streams in a file. The append function of gzopen() can be used to create
1335 such a file. (Also see gzflush() for another way to do this.) When
1336 appending, gzopen does not test whether the file begins with a gzip stream,
1337 nor does it look for the end of the gzip streams to begin appending. gzopen
1338 will simply append a gzip stream to the existing file.
1340 gzopen can be used to read a file which is not in gzip format; in this
1341 case gzread will directly read from the file without decompression. When
1342 reading, this will be detected automatically by looking for the magic two-
1343 byte gzip header.
1345 gzopen returns NULL if the file could not be opened, if there was
1346 insufficient memory to allocate the gzFile state, or if an invalid mode was
1347 specified (an 'r', 'w', or 'a' was not provided, or '+' was provided).
1348 errno can be checked to determine if the reason gzopen failed was that the
1349 file could not be opened.
1350 */
1353 /*
1354 Associate a gzFile with the file descriptor fd. File descriptors are
1355 obtained from calls like open, dup, creat, pipe or fileno (if the file has
1356 been previously opened with fopen). The mode parameter is as in gzopen.
1358 The next call of gzclose on the returned gzFile will also close the file
1359 descriptor fd, just like fclose(fdopen(fd, mode)) closes the file descriptor
1360 fd. If you want to keep fd open, use fd = dup(fd_keep); gz = gzdopen(fd,
1361 mode);. The duplicated descriptor should be saved to avoid a leak, since
1362 gzdopen does not close fd if it fails. If you are using fileno() to get the
1363 file descriptor from a FILE *, then you will have to use dup() to avoid
1364 double-close()ing the file descriptor. Both gzclose() and fclose() will
1365 close the associated file descriptor, so they need to have different file
1366 descriptors.
1368 gzdopen returns NULL if there was insufficient memory to allocate the
1369 gzFile state, if an invalid mode was specified (an 'r', 'w', or 'a' was not
1370 provided, or '+' was provided), or if fd is -1. The file descriptor is not
1371 used until the next gz* read, write, seek, or close operation, so gzdopen
1372 will not detect if fd is invalid (unless fd is -1).
1373 */
1376 /*
1377 Set the internal buffer size used by this library's functions for file to
1378 size. The default buffer size is 8192 bytes. This function must be called
1379 after gzopen() or gzdopen(), and before any other calls that read or write
1380 the file. The buffer memory allocation is always deferred to the first read
1381 or write. Three times that size in buffer space is allocated. A larger
1382 buffer size of, for example, 64K or 128K bytes will noticeably increase the
1383 speed of decompression (reading).
1385 The new buffer size also affects the maximum length for gzprintf().
1387 gzbuffer() returns 0 on success, or -1 on failure, such as being called
1388 too late.
1389 */
1392 /*
1393 Dynamically update the compression level and strategy for file. See the
1394 description of deflateInit2 for the meaning of these parameters. Previously
1395 provided data is flushed before applying the parameter changes.
1397 gzsetparams returns Z_OK if success, Z_STREAM_ERROR if the file was not
1398 opened for writing, Z_ERRNO if there is an error writing the flushed data,
1399 or Z_MEM_ERROR if there is a memory allocation error.
1400 */
1403 /*
1404 Read and decompress up to len uncompressed bytes from file into buf. If
1405 the input file is not in gzip format, gzread copies the given number of
1406 bytes into the buffer directly from the file.
1408 After reaching the end of a gzip stream in the input, gzread will continue
1409 to read, looking for another gzip stream. Any number of gzip streams may be
1410 concatenated in the input file, and will all be decompressed by gzread().
1411 If something other than a gzip stream is encountered after a gzip stream,
1412 that remaining trailing garbage is ignored (and no error is returned).
1414 gzread can be used to read a gzip file that is being concurrently written.
1415 Upon reaching the end of the input, gzread will return with the available
1416 data. If the error code returned by gzerror is Z_OK or Z_BUF_ERROR, then
1417 gzclearerr can be used to clear the end of file indicator in order to permit
1418 gzread to be tried again. Z_OK indicates that a gzip stream was completed
1419 on the last gzread. Z_BUF_ERROR indicates that the input file ended in the
1420 middle of a gzip stream. Note that gzread does not return -1 in the event
1421 of an incomplete gzip stream. This error is deferred until gzclose(), which
1422 will return Z_BUF_ERROR if the last gzread ended in the middle of a gzip
1423 stream. Alternatively, gzerror can be used before gzclose to detect this
1424 case.
1426 gzread returns the number of uncompressed bytes actually read, less than
1427 len for end of file, or -1 for error. If len is too large to fit in an int,
1428 then nothing is read, -1 is returned, and the error state is set to
1429 Z_STREAM_ERROR.
1430 */
1433 /*
1434 Read and decompress up to nitems items of size size from file into buf,
1435 otherwise operating as gzread() does. This duplicates the interface of
1436 stdio's fread(), with size_t request and return types. If the library
1437 defines size_t, then z_size_t is identical to size_t. If not, then z_size_t
1438 is an unsigned integer type that can contain a pointer.
1440 gzfread() returns the number of full items read of size size, or zero if
1441 the end of the file was reached and a full item could not be read, or if
1442 there was an error. gzerror() must be consulted if zero is returned in
1443 order to determine if there was an error. If the multiplication of size and
1444 nitems overflows, i.e. the product does not fit in a z_size_t, then nothing
1445 is read, zero is returned, and the error state is set to Z_STREAM_ERROR.
1447 In the event that the end of file is reached and only a partial item is
1448 available at the end, i.e. the remaining uncompressed data length is not a
1449 multiple of size, then the final partial item is nevetheless read into buf
1450 and the end-of-file flag is set. The length of the partial item read is not
1451 provided, but could be inferred from the result of gztell(). This behavior
1452 is the same as the behavior of fread() implementations in common libraries,
1453 but it prevents the direct use of gzfread() to read a concurrently written
1454 file, reseting and retrying on end-of-file, when size is not 1.
1455 */
1458 /*
1459 Compress and write the len uncompressed bytes at buf to file. gzwrite
1460 returns the number of uncompressed bytes written or 0 in case of error.
1461 */
1464 /*
1465 Compress and write nitems items of size size from buf to file, duplicating
1466 the interface of stdio's fwrite(), with size_t request and return types. If
1467 the library defines size_t, then z_size_t is identical to size_t. If not,
1468 then z_size_t is an unsigned integer type that can contain a pointer.
1470 gzfwrite() returns the number of full items written of size size, or zero
1471 if there was an error. If the multiplication of size and nitems overflows,
1472 i.e. the product does not fit in a z_size_t, then nothing is written, zero
1473 is returned, and the error state is set to Z_STREAM_ERROR.
1474 */
1477 /*
1478 Convert, format, compress, and write the arguments (...) to file under
1479 control of the string format, as in fprintf. gzprintf returns the number of
1480 uncompressed bytes actually written, or a negative zlib error code in case
1481 of error. The number of uncompressed bytes written is limited to 8191, or
1482 one less than the buffer size given to gzbuffer(). The caller should assure
1483 that this limit is not exceeded. If it is exceeded, then gzprintf() will
1484 return an error (0) with nothing written. In this case, there may also be a
1485 buffer overflow with unpredictable consequences, which is possible only if
1486 zlib was compiled with the insecure functions sprintf() or vsprintf(),
1487 because the secure snprintf() or vsnprintf() functions were not available.
1488 This can be determined using zlibCompileFlags().
1489 */
1492 /*
1493 Compress and write the given null-terminated string s to file, excluding
1494 the terminating null character.
1496 gzputs returns the number of characters written, or -1 in case of error.
1497 */
1500 /*
1501 Read and decompress bytes from file into buf, until len-1 characters are
1502 read, or until a newline character is read and transferred to buf, or an
1503 end-of-file condition is encountered. If any characters are read or if len
1504 is one, the string is terminated with a null character. If no characters
1505 are read due to an end-of-file or len is less than one, then the buffer is
1506 left untouched.
1508 gzgets returns buf which is a null-terminated string, or it returns NULL
1509 for end-of-file or in case of error. If there was an error, the contents at
1510 buf are indeterminate.
1511 */
1514 /*
1515 Compress and write c, converted to an unsigned char, into file. gzputc
1516 returns the value that was written, or -1 in case of error.
1517 */
1520 /*
1521 Read and decompress one byte from file. gzgetc returns this byte or -1
1522 in case of end of file or error. This is implemented as a macro for speed.
1523 As such, it does not do all of the checking the other functions do. I.e.
1524 it does not check to see if file is NULL, nor whether the structure file
1525 points to has been clobbered or not.
1526 */
1529 /*
1530 Push c back onto the stream for file to be read as the first character on
1531 the next read. At least one character of push-back is always allowed.
1532 gzungetc() returns the character pushed, or -1 on failure. gzungetc() will
1533 fail if c is -1, and may fail if a character has been pushed but not read
1534 yet. If gzungetc is used immediately after gzopen or gzdopen, at least the
1535 output buffer size of pushed characters is allowed. (See gzbuffer above.)
1536 The pushed character will be discarded if the stream is repositioned with
1537 gzseek() or gzrewind().
1538 */
1541 /*
1542 Flush all pending output to file. The parameter flush is as in the
1543 deflate() function. The return value is the zlib error number (see function
1544 gzerror below). gzflush is only permitted when writing.
1546 If the flush parameter is Z_FINISH, the remaining data is written and the
1547 gzip stream is completed in the output. If gzwrite() is called again, a new
1548 gzip stream will be started in the output. gzread() is able to read such
1549 concatenated gzip streams.
1551 gzflush should be called only when strictly necessary because it will
1552 degrade compression if called too often.
1553 */
1556 /*
1557 Set the starting position to offset relative to whence for the next gzread
1558 or gzwrite on file. The offset represents a number of bytes in the
1559 uncompressed data stream. The whence parameter is defined as in lseek(2);
1560 the value SEEK_END is not supported.
1562 If the file is opened for reading, this function is emulated but can be
1563 extremely slow. If the file is opened for writing, only forward seeks are
1564 supported; gzseek then compresses a sequence of zeroes up to the new
1565 starting position.
1567 gzseek returns the resulting offset location as measured in bytes from
1568 the beginning of the uncompressed stream, or -1 in case of error, in
1569 particular if the file is opened for writing and the new starting position
1570 would be before the current position.
1571 */
1574 /*
1575 Rewind file. This function is supported only for reading.
1577 gzrewind(file) is equivalent to (int)gzseek(file, 0L, SEEK_SET).
1578 */
1581 /*
1582 Return the starting position for the next gzread or gzwrite on file.
1583 This position represents a number of bytes in the uncompressed data stream,
1584 and is zero when starting, even if appending or reading a gzip stream from
1585 the middle of a file using gzdopen().
1587 gztell(file) is equivalent to gzseek(file, 0L, SEEK_CUR)
1588 */
1591 /*
1592 Return the current compressed (actual) read or write offset of file. This
1593 offset includes the count of bytes that precede the gzip stream, for example
1594 when appending or when using gzdopen() for reading. When reading, the
1595 offset does not include as yet unused buffered input. This information can
1596 be used for a progress indicator. On error, gzoffset() returns -1.
1597 */
1600 /*
1601 Return true (1) if the end-of-file indicator for file has been set while
1602 reading, false (0) otherwise. Note that the end-of-file indicator is set
1603 only if the read tried to go past the end of the input, but came up short.
1604 Therefore, just like feof(), gzeof() may return false even if there is no
1605 more data to read, in the event that the last read request was for the exact
1606 number of bytes remaining in the input file. This will happen if the input
1607 file size is an exact multiple of the buffer size.
1609 If gzeof() returns true, then the read functions will return no more data,
1610 unless the end-of-file indicator is reset by gzclearerr() and the input file
1611 has grown since the previous end of file was detected.
1612 */
1615 /*
1616 Return true (1) if file is being copied directly while reading, or false
1617 (0) if file is a gzip stream being decompressed.
1619 If the input file is empty, gzdirect() will return true, since the input
1620 does not contain a gzip stream.
1622 If gzdirect() is used immediately after gzopen() or gzdopen() it will
1623 cause buffers to be allocated to allow reading the file to determine if it
1624 is a gzip file. Therefore if gzbuffer() is used, it should be called before
1625 gzdirect().
1627 When writing, gzdirect() returns true (1) if transparent writing was
1628 requested ("wT" for the gzopen() mode), or false (0) otherwise. (Note:
1629 gzdirect() is not needed when writing. Transparent writing must be
1630 explicitly requested, so the application already knows the answer. When
1631 linking statically, using gzdirect() will include all of the zlib code for
1632 gzip file reading and decompression, which may not be desired.)
1633 */
1636 /*
1637 Flush all pending output for file, if necessary, close file and
1638 deallocate the (de)compression state. Note that once file is closed, you
1639 cannot call gzerror with file, since its structures have been deallocated.
1640 gzclose must not be called more than once on the same file, just as free
1641 must not be called more than once on the same allocation.
1643 gzclose will return Z_STREAM_ERROR if file is not valid, Z_ERRNO on a
1644 file operation error, Z_MEM_ERROR if out of memory, Z_BUF_ERROR if the
1645 last read ended in the middle of a gzip stream, or Z_OK on success.
1646 */
1650 /*
1651 Same as gzclose(), but gzclose_r() is only for use when reading, and
1652 gzclose_w() is only for use when writing or appending. The advantage to
1653 using these instead of gzclose() is that they avoid linking in zlib
1654 compression or decompression code that is not used when only reading or only
1655 writing respectively. If gzclose() is used, then both compression and
1656 decompression code will be included the application when linking to a static
1657 zlib library.
1658 */
1661 /*
1662 Return the error message for the last error which occurred on file.
1663 errnum is set to zlib error number. If an error occurred in the file system
1664 and not in the compression library, errnum is set to Z_ERRNO and the
1665 application may consult errno to get the exact error code.
1667 The application must not modify the returned string. Future calls to
1668 this function may invalidate the previously returned string. If file is
1669 closed, then the string previously returned by gzerror will no longer be
1670 available.
1672 gzerror() should be used to distinguish errors from end-of-file for those
1673 functions above that do not distinguish those cases in their return values.
1674 */
1677 /*
1678 Clear the error and end-of-file flags for file. This is analogous to the
1679 clearerr() function in stdio. This is useful for continuing to read a gzip
1680 file that is being written concurrently.
1681 */
1683 /* checksum functions */
1685 /*
1686 These functions are not related to compression but are exported
1687 anyway because they might be useful in applications using the compression
1688 library.
1689 */
1692 /*
1693 Update a running Adler-32 checksum with the bytes buf[0 .. len-1] and
1694 return the updated checksum. An Adler-32 value is in the range of a 32-bit
1695 unsigned integer. If buf is Z_NULL, this function returns the required
1696 initial value for the checksum.
1698 An Adler-32 checksum is almost as reliable as a CRC-32 but can be computed
1699 much faster.
1701 Usage example:
1703 uLong adler = adler32(0L, Z_NULL, 0);
1705 while (read_buffer(buffer, length) != EOF)
1706 adler = adler32(adler, buffer, length);
1708 if (adler != original_adler) error();
1709 */
1712 /*
1713 Same as adler32(), but with a size_t length.
1714 */
1717 /*
1718 Combine two Adler-32 checksums into one. For two sequences of bytes, seq1
1719 and seq2 with lengths len1 and len2, Adler-32 checksums were calculated for
1720 each, adler1 and adler2. adler32_combine() returns the Adler-32 checksum of
1721 seq1 and seq2 concatenated, requiring only adler1, adler2, and len2. Note
1722 that the z_off_t type (like off_t) is a signed integer. If len2 is
1723 negative, the result has no meaning or utility.
1724 */
1727 /*
1728 Update a running CRC-32 with the bytes buf[0 .. len-1] and return the
1729 updated CRC-32. A CRC-32 value is in the range of a 32-bit unsigned integer.
1730 If buf is Z_NULL, this function returns the required initial value for the
1731 crc. Pre- and post-conditioning (one's complement) is performed within this
1732 function so it shouldn't be done by the application.
1734 Usage example:
1736 uLong crc = crc32(0L, Z_NULL, 0);
1738 while (read_buffer(buffer, length) != EOF)
1739 crc = crc32(crc, buffer, length);
1741 if (crc != original_crc) error();
1742 */
1745 /*
1746 Same as crc32(), but with a size_t length.
1747 */
1751 /*
1752 Combine two CRC-32 check values into one. For two sequences of bytes,
1753 seq1 and seq2 with lengths len1 and len2, CRC-32 check values were
1754 calculated for each, crc1 and crc2. crc32_combine() returns the CRC-32
1755 check value of seq1 and seq2 concatenated, requiring only crc1, crc2, and
1756 len2.
1757 */
1760 /*
1761 Return the operator corresponding to length len2, to be used with
1762 crc32_combine_op().
1763 */
1766 /*
1767 Give the same result as crc32_combine(), using op in place of len2. op is
1768 is generated from len2 by crc32_combine_gen(). This will be faster than
1769 crc32_combine() if the generated op is used more than once.
1770 */
1772 /* various hacks, don't look :) */
1774 /* deflateInit and inflateInit are macros to allow checking the zlib version
1775 * and the compiler's view of z_stream:
1776 */