2 ChangeLog file for zlib
4 Changes in 1.1.3 (9 July 1998)
5 - fix "an inflate input buffer bug that shows up on rare but persistent
7 - fix gzread and gztell for concatenated .gz files (Didier Le Botlan)
8 - fix gzseek(..., SEEK_SET) in write mode
9 - fix crc check after a gzeek (Frank Faubert)
10 - fix miniunzip when the last entry in a zip file is itself a zip file
12 - add contrib/asm586 and contrib/asm686 (Brian Raiter)
13 See http://www.muppetlabs.com/~breadbox/software/assembly.html
14 - add support for Delphi 3 in contrib/delphi (Bob Dellaca)
15 - add support for C++Builder 3 and Delphi 3 in contrib/delphi2 (Davide Moretti)
16 - do not exit prematurely in untgz if 0 at start of block (Magnus Holmgren)
17 - use macro EXTERN instead of extern to support DLL for BeOS (Sander Stoks)
20 - Support gzdopen on Mac with Metrowerks (Jason Linhart)
21 - Do not redefine Byte on Mac (Brad Pettit & Jason Linhart)
22 - define SEEK_END too if SEEK_SET is not defined (Albert Chin-A-Young)
23 - avoid some warnings with Borland C (Tom Tanner)
24 - fix a problem in contrib/minizip/zip.c for 16-bit MSDOS (Gilles Vollant)
25 - emulate utime() for WIN32 in contrib/untgz (Gilles Vollant)
26 - allow several arguments to configure (Tim Mooney, Frodo Looijaard)
27 - use libdir and includedir in Makefile.in (Tim Mooney)
28 - support shared libraries on OSF1 V4 (Tim Mooney)
29 - remove so_locations in "make clean" (Tim Mooney)
30 - fix maketree.c compilation error (Glenn, Mark)
31 - Python interface to zlib now in Python 1.5 (Jeremy Hylton)
32 - new Makefile.riscos (Rich Walker)
33 - initialize static descriptors in trees.c for embedded targets (Nick Smith)
34 - use "foo-gz" in example.c for RISCOS and VMS (Nick Smith)
35 - add the OS/2 files in Makefile.in too (Andrew Zabolotny)
36 - fix fdopen and halloc macros for Microsoft C 6.0 (Tom Lane)
37 - fix maketree.c to allow clean compilation of inffixed.h (Mark)
38 - fix parameter check in deflateCopy (Gunther Nikl)
39 - cleanup trees.c, use compressed_len only in debug mode (Christian Spieler)
40 - Many portability patches by Christian Spieler:
41 . zutil.c, zutil.h: added "const" for zmem*
42 . Make_vms.com: fixed some typos
43 . Make_vms.com: msdos/Makefile.*: removed zutil.h from some dependency lists
44 . msdos/Makefile.msc: remove "default rtl link library" info from obj files
45 . msdos/Makefile.*: use model-dependent name for the built zlib library
46 . msdos/Makefile.emx, nt/Makefile.emx, nt/Makefile.gcc:
47 new makefiles, for emx (DOS/OS2), emx&rsxnt and mingw32 (Windows 9x / NT)
48 - use define instead of typedef for Bytef also for MSC small/medium (Tom Lane)
49 - replace __far with _far for better portability (Christian Spieler, Tom Lane)
50 - fix test for errno.h in configure (Tim Newsham)
52 Changes in 1.1.2 (19 March 98)
53 - added contrib/minzip, mini zip and unzip based on zlib (Gilles Vollant)
54 See http://www.winimage.com/zLibDll/unzip.html
55 - preinitialize the inflate tables for fixed codes, to make the code
56 completely thread safe (Mark)
57 - some simplifications and slight speed-up to the inflate code (Mark)
58 - fix gzeof on non-compressed files (Allan Schrum)
59 - add -std1 option in configure for OSF1 to fix gzprintf (Martin Mokrejs)
60 - use default value of 4K for Z_BUFSIZE for 16-bit MSDOS (Tim Wegner + Glenn)
61 - added os2/Makefile.def and os2/zlib.def (Andrew Zabolotny)
62 - add shared lib support for UNIX_SV4.2MP (MATSUURA Takanori)
63 - do not wrap extern "C" around system includes (Tom Lane)
64 - mention zlib binding for TCL in README (Andreas Kupries)
65 - added amiga/Makefile.pup for Amiga powerUP SAS/C PPC (Andreas Kleinert)
66 - allow "make install prefix=..." even after configure (Glenn Randers-Pehrson)
67 - allow "configure --prefix $HOME" (Tim Mooney)
68 - remove warnings in example.c and gzio.c (Glenn Randers-Pehrson)
69 - move Makefile.sas to amiga/Makefile.sas
71 Changes in 1.1.1 (27 Feb 98)
72 - fix macros _tr_tally_* in deflate.h for debug mode (Glenn Randers-Pehrson)
73 - remove block truncation heuristic which had very marginal effect for zlib
74 (smaller lit_bufsize than in gzip 1.2.4) and degraded a little the
75 compression ratio on some files. This also allows inlining _tr_tally for
76 matches in deflate_slow.
77 - added msdos/Makefile.w32 for WIN32 Microsoft Visual C++ (Bob Frazier)
79 Changes in 1.1.0 (24 Feb 98)
80 - do not return STREAM_END prematurely in inflate (John Bowler)
81 - revert to the zlib 1.0.8 inflate to avoid the gcc 2.8.0 bug (Jeremy Buhler)
82 - compile with -DFASTEST to get compression code optimized for speed only
83 - in minigzip, try mmap'ing the input file first (Miguel Albrecht)
84 - increase size of I/O buffers in minigzip.c and gzio.c (not a big gain
85 on Sun but significant on HP)
87 - add a pointer to experimental unzip library in README (Gilles Vollant)
88 - initialize variable gcc in configure (Chris Herborth)
90 Changes in 1.0.9 (17 Feb 1998)
91 - added gzputs and gzgets functions
92 - do not clear eof flag in gzseek (Mark Diekhans)
93 - fix gzseek for files in transparent mode (Mark Diekhans)
94 - do not assume that vsprintf returns the number of bytes written (Jens Krinke)
95 - replace EXPORT with ZEXPORT to avoid conflict with other programs
96 - added compress2 in zconf.h, zlib.def, zlib.dnt
97 - new asm code from Gilles Vollant in contrib/asm386
98 - simplify the inflate code (Mark):
99 . Replace ZALLOC's in huft_build() with single ZALLOC in inflate_blocks_new()
100 . ZALLOC the length list in inflate_trees_fixed() instead of using stack
101 . ZALLOC the value area for huft_build() instead of using stack
102 . Simplify Z_FINISH check in inflate()
104 - Avoid gcc 2.8.0 comparison bug a little differently than zlib 1.0.8
105 - in inftrees.c, avoid cc -O bug on HP (Farshid Elahi)
106 - in zconf.h move the ZLIB_DLL stuff earlier to avoid problems with
107 the declaration of FAR (Gilles VOllant)
108 - install libz.so* with mode 755 (executable) instead of 644 (Marc Lehmann)
109 - read_buf buf parameter of type Bytef* instead of charf*
110 - zmemcpy parameters are of type Bytef*, not charf* (Joseph Strout)
111 - do not redeclare unlink in minigzip.c for WIN32 (John Bowler)
112 - fix check for presence of directories in "make install" (Ian Willis)
114 Changes in 1.0.8 (27 Jan 1998)
115 - fixed offsets in contrib/asm386/gvmat32.asm (Gilles Vollant)
116 - fix gzgetc and gzputc for big endian systems (Markus Oberhumer)
117 - added compress2() to allow setting the compression level
118 - include sys/types.h to get off_t on some systems (Marc Lehmann & QingLong)
119 - use constant arrays for the static trees in trees.c instead of computing
120 them at run time (thanks to Ken Raeburn for this suggestion). To create
121 trees.h, compile with GEN_TREES_H and run "make test".
122 - check return code of example in "make test" and display result
123 - pass minigzip command line options to file_compress
124 - simplifying code of inflateSync to avoid gcc 2.8 bug
126 - support CC="gcc -Wall" in configure -s (QingLong)
127 - avoid a flush caused by ftell in gzopen for write mode (Ken Raeburn)
128 - fix test for shared library support to avoid compiler warnings
129 - zlib.lib -> zlib.dll in msdos/zlib.rc (Gilles Vollant)
130 - check for TARGET_OS_MAC in addition to MACOS (Brad Pettit)
131 - do not use fdopen for Metrowerks on Mac (Brad Pettit))
132 - add checks for gzputc and gzputc in example.c
133 - avoid warnings in gzio.c and deflate.c (Andreas Kleinert)
134 - use const for the CRC table (Ken Raeburn)
135 - fixed "make uninstall" for shared libraries
136 - use Tracev instead of Trace in infblock.c
137 - in example.c use correct compressed length for test_sync
138 - suppress +vnocompatwarnings in configure for HPUX (not always supported)
140 Changes in 1.0.7 (20 Jan 1998)
141 - fix gzseek which was broken in write mode
142 - return error for gzseek to negative absolute position
143 - fix configure for Linux (Chun-Chung Chen)
144 - increase stack space for MSC (Tim Wegner)
145 - get_crc_table and inflateSyncPoint are EXPORTed (Gilles Vollant)
146 - define EXPORTVA for gzprintf (Gilles Vollant)
147 - added man page zlib.3 (Rick Rodgers)
148 - for contrib/untgz, fix makedir() and improve Makefile
150 - check gzseek in write mode in example.c
151 - allocate extra buffer for seeks only if gzseek is actually called
152 - avoid signed/unsigned comparisons (Tim Wegner, Gilles Vollant)
153 - add inflateSyncPoint in zconf.h
154 - fix list of exported functions in nt/zlib.dnt and mdsos/zlib.def
156 Changes in 1.0.6 (19 Jan 1998)
157 - add functions gzprintf, gzputc, gzgetc, gztell, gzeof, gzseek, gzrewind and
158 gzsetparams (thanks to Roland Giersig and Kevin Ruland for some of this code)
159 - Fix a deflate bug occuring only with compression level 0 (thanks to
160 Andy Buckler for finding this one).
161 - In minigzip, pass transparently also the first byte for .Z files.
162 - return Z_BUF_ERROR instead of Z_OK if output buffer full in uncompress()
163 - check Z_FINISH in inflate (thanks to Marc Schluper)
164 - Implement deflateCopy (thanks to Adam Costello)
165 - make static libraries by default in configure, add --shared option.
166 - move MSDOS or Windows specific files to directory msdos
167 - suppress the notion of partial flush to simplify the interface
168 (but the symbol Z_PARTIAL_FLUSH is kept for compatibility with 1.0.4)
169 - suppress history buffer provided by application to simplify the interface
170 (this feature was not implemented anyway in 1.0.4)
171 - next_in and avail_in must be initialized before calling inflateInit or
173 - add EXPORT in all exported functions (for Windows DLL)
174 - added Makefile.nt (thanks to Stephen Williams)
175 - added the unsupported "contrib" directory:
176 contrib/asm386/ by Gilles Vollant <info@winimage.com>
177 386 asm code replacing longest_match().
178 contrib/iostream/ by Kevin Ruland <kevin@rodin.wustl.edu>
179 A C++ I/O streams interface to the zlib gz* functions
180 contrib/iostream2/ by Tyge Løvset <Tyge.Lovset@cmr.no>
181 Another C++ I/O streams interface
182 contrib/untgz/ by "Pedro A. Aranda Guti\irrez" <paag@tid.es>
183 A very simple tar.gz file extractor using zlib
184 contrib/visual-basic.txt by Carlos Rios <c_rios@sonda.cl>
185 How to use compress(), uncompress() and the gz* functions from VB.
186 - pass params -f (filtered data), -h (huffman only), -1 to -9 (compression
187 level) in minigzip (thanks to Tom Lane)
189 - use const for rommable constants in deflate
190 - added test for gzseek and gztell in example.c
191 - add undocumented function inflateSyncPoint() (hack for Paul Mackerras)
192 - add undocumented function zError to convert error code to string
194 - Allow compilation of gzio with -DNO_DEFLATE to avoid the compression code.
195 - Use default memcpy for Symantec MSDOS compiler.
196 - Add EXPORT keyword for check_func (needed for Windows DLL)
197 - add current directory to LD_LIBRARY_PATH for "make test"
198 - create also a link for libz.so.1
199 - added support for FUJITSU UXP/DS (thanks to Toshiaki Nomura)
200 - use $(SHAREDLIB) instead of libz.so in Makefile.in (for HPUX)
201 - added -soname for Linux in configure (Chun-Chung Chen,
202 - assign numbers to the exported functions in zlib.def (for Windows DLL)
203 - add advice in zlib.h for best usage of deflateSetDictionary
204 - work around compiler bug on Atari (cast Z_NULL in call of s->checkfn)
205 - allow compilation with ANSI keywords only enabled for TurboC in large model
206 - avoid "versionString"[0] (Borland bug)
207 - add NEED_DUMMY_RETURN for Borland
208 - use variable z_verbose for tracing in debug mode (L. Peter Deutsch).
209 - allow compilation with CC
210 - defined STDC for OS/2 (David Charlap)
211 - limit external names to 8 chars for MVS (Thomas Lund)
212 - in minigzip.c, use static buffers only for 16-bit systems
213 - fix suffix check for "minigzip -d foo.gz"
214 - do not return an error for the 2nd of two consecutive gzflush() (Felix Lee)
215 - use _fdopen instead of fdopen for MSC >= 6.0 (Thomas Fanslau)
216 - added makelcc.bat for lcc-win32 (Tom St Denis)
217 - in Makefile.dj2, use copy and del instead of install and rm (Frank Donahoe)
218 - Avoid expanded $Id$. Use "rcs -kb" or "cvs admin -kb" to avoid Id expansion.
219 - check for unistd.h in configure (for off_t)
220 - remove useless check parameter in inflate_blocks_free
221 - avoid useless assignment of s->check to itself in inflate_blocks_new
222 - do not flush twice in gzclose (thanks to Ken Raeburn)
223 - rename FOPEN as F_OPEN to avoid clash with /usr/include/sys/file.h
224 - use NO_ERRNO_H instead of enumeration of operating systems with errno.h
225 - work around buggy fclose on pipes for HP/UX
226 - support zlib DLL with BORLAND C++ 5.0 (thanks to Glenn Randers-Pehrson)
227 - fix configure if CC is already equal to gcc
229 Changes in 1.0.5 (3 Jan 98)
230 - Fix inflate to terminate gracefully when fed corrupted or invalid data
231 - Use const for rommable constants in inflate
232 - Eliminate memory leaks on error conditions in inflate
233 - Removed some vestigial code in inflate
234 - Update web address in README
236 Changes in 1.0.4 (24 Jul 96)
237 - In very rare conditions, deflate(s, Z_FINISH) could fail to produce an EOF
238 bit, so the decompressor could decompress all the correct data but went
239 on to attempt decompressing extra garbage data. This affected minigzip too.
240 - zlibVersion and gzerror return const char* (needed for DLL)
241 - port to RISCOS (no fdopen, no multiple dots, no unlink, no fileno)
242 - use z_error only for DEBUG (avoid problem with DLLs)
244 Changes in 1.0.3 (2 Jul 96)
245 - use z_streamp instead of z_stream *, which is now a far pointer in MSDOS
246 small and medium models; this makes the library incompatible with previous
247 versions for these models. (No effect in large model or on other systems.)
248 - return OK instead of BUF_ERROR if previous deflate call returned with
249 avail_out as zero but there is nothing to do
250 - added memcmp for non STDC compilers
251 - define NO_DUMMY_DECL for more Mac compilers (.h files merged incorrectly)
252 - define __32BIT__ if __386__ or i386 is defined (pb. with Watcom and SCO)
253 - better check for 16-bit mode MSC (avoids problem with Symantec)
255 Changes in 1.0.2 (23 May 96)
256 - added Windows DLL support
257 - added a function zlibVersion (for the DLL support)
258 - fixed declarations using Bytef in infutil.c (pb with MSDOS medium model)
259 - Bytef is define's instead of typedef'd only for Borland C
260 - avoid reading uninitialized memory in example.c
261 - mention in README that the zlib format is now RFC1950
262 - updated Makefile.dj2
263 - added algorithm.doc
265 Changes in 1.0.1 (20 May 96) [1.0 skipped to avoid confusion]
266 - fix array overlay in deflate.c which sometimes caused bad compressed data
267 - fix inflate bug with empty stored block
268 - fix MSDOS medium model which was broken in 0.99
269 - fix deflateParams() which could generated bad compressed data.
270 - Bytef is define'd instead of typedef'ed (work around Borland bug)
271 - added an INDEX file
272 - new makefiles for DJGPP (Makefile.dj2), 32-bit Borland (Makefile.b32),
273 Watcom (Makefile.wat), Amiga SAS/C (Makefile.sas)
274 - speed up adler32 for modern machines without auto-increment
275 - added -ansi for IRIX in configure
276 - static_init_done in trees.c is an int
277 - define unlink as delete for VMS
278 - fix configure for QNX
279 - add configure branch for SCO and HPUX
280 - avoid many warnings (unused variables, dead assignments, etc...)
282 - fix the Watcom fix for 32 bit mode (define FAR as empty)
283 - removed redefinition of Byte for MKWERKS
284 - work around an MWKERKS bug (incorrect merge of all .h files)
286 Changes in 0.99 (27 Jan 96)
287 - allow preset dictionary shared between compressor and decompressor
288 - allow compression level 0 (no compression)
289 - add deflateParams in zlib.h: allow dynamic change of compression level
290 and compression strategy.
291 - test large buffers and deflateParams in example.c
292 - add optional "configure" to build zlib as a shared library
293 - suppress Makefile.qnx, use configure instead
294 - fixed deflate for 64-bit systems (detected on Cray)
295 - fixed inflate_blocks for 64-bit systems (detected on Alpha)
296 - declare Z_DEFLATED in zlib.h (possible parameter for deflateInit2)
297 - always return Z_BUF_ERROR when deflate() has nothing to do
298 - deflateInit and inflateInit are now macros to allow version checking
299 - prefix all global functions and types with z_ with -DZ_PREFIX
300 - make falloc completely reentrant (inftrees.c)
301 - fixed very unlikely race condition in ct_static_init
302 - free in reverse order of allocation to help memory manager
303 - use zlib-1.0/* instead of zlib/* inside the tar.gz
304 - make zlib warning-free with "gcc -O3 -Wall -Wwrite-strings -Wpointer-arith
305 -Wconversion -Wstrict-prototypes -Wmissing-prototypes"
306 - allow gzread on concatenated .gz files
307 - deflateEnd now returns Z_DATA_ERROR if it was premature
308 - deflate is finally (?) fully deterministic (no matches beyond end of input)
309 - Document Z_SYNC_FLUSH
310 - add uninstall in Makefile
311 - Check for __cpluplus in zlib.h
312 - Better test in ct_align for partial flush
313 - avoid harmless warnings for Borland C++
314 - initialize hash_head in deflate.c
315 - avoid warning on fdopen (gzio.c) for HP cc -Aa
316 - include stdlib.h for STDC compilers
317 - include errno.h for Cray
318 - ignore error if ranlib doesn't exist
319 - call ranlib twice for NeXTSTEP
320 - use exec_prefix instead of prefix for libz.a
321 - renamed ct_* as _tr_* to avoid conflict with applications
322 - clear z->msg in inflateInit2 before any error return
323 - initialize opaque in example.c, gzio.c, deflate.c and inflate.c
324 - fixed typo in zconf.h (_GNUC__ => __GNUC__)
325 - check for WIN32 in zconf.h and zutil.c (avoid farmalloc in 32-bit mode)
326 - fix typo in Make_vms.com (f$trnlnm -> f$getsyi)
327 - in fcalloc, normalize pointer if size > 65520 bytes
328 - don't use special fcalloc for 32 bit Borland C++
329 - use STDC instead of __GO32__ to avoid redeclaring exit, calloc, etc...
330 - use Z_BINARY instead of BINARY
331 - document that gzclose after gzdopen will close the file
332 - allow "a" as mode in gzopen.
333 - fix error checking in gzread
334 - allow skipping .gz extra-field on pipes
335 - added reference to Perl interface in README
336 - put the crc table in FAR data (I dislike more and more the medium model :)
337 - added get_crc_table
338 - added a dimension to all arrays (Borland C can't count).
339 - workaround Borland C bug in declaration of inflate_codes_new & inflate_fast
340 - guard against multiple inclusion of *.h (for precompiled header on Mac)
341 - Watcom C pretends to be Microsoft C small model even in 32 bit mode.
342 - don't use unsized arrays to avoid silly warnings by Visual C++:
343 warning C4746: 'inflate_mask' : unsized array treated as '__far'
344 (what's wrong with far data in far model?).
345 - define enum out of inflate_blocks_state to allow compilation with C++
347 Changes in 0.95 (16 Aug 95)
348 - fix MSDOS small and medium model (now easier to adapt to any compiler)
350 - fix the final (:-) bug for deflate with flush (output was correct but
351 not completely flushed in rare occasions).
352 - default window size is same for compression and decompression
353 (it's now sufficient to set MAX_WBITS in zconf.h).
354 - voidp -> voidpf and voidnp -> voidp (for consistency with other
355 typedefs and because voidnp was not near in large model).
357 Changes in 0.94 (13 Aug 95)
358 - support MSDOS medium model
359 - fix deflate with flush (could sometimes generate bad output)
360 - fix deflateReset (zlib header was incorrectly suppressed)
361 - added support for VMS
362 - allow a compression level in gzopen()
363 - gzflush now calls fflush
364 - For deflate with flush, flush even if no more input is provided.
365 - rename libgz.a as libz.a
366 - avoid complex expression in infcodes.c triggering Turbo C bug
367 - work around a problem with gcc on Alpha (in INSERT_STRING)
368 - don't use inline functions (problem with some gcc versions)
369 - allow renaming of Byte, uInt, etc... with #define.
370 - avoid warning about (unused) pointer before start of array in deflate.c
371 - avoid various warnings in gzio.c, example.c, infblock.c, adler32.c, zutil.c
372 - avoid reserved word 'new' in trees.c
374 Changes in 0.93 (25 June 95)
375 - temporarily disable inline functions
376 - make deflate deterministic
377 - give enough lookahead for PARTIAL_FLUSH
378 - Set binary mode for stdin/stdout in minigzip.c for OS/2
379 - don't even use signed char in inflate (not portable enough)
380 - fix inflate memory leak for segmented architectures
382 Changes in 0.92 (3 May 95)
383 - don't assume that char is signed (problem on SGI)
384 - Clear bit buffer when starting a stored block
385 - no memcpy on Pyramid
386 - suppressed inftest.c
387 - optimized fill_window, put longest_match inline for gcc
388 - optimized inflate on stored blocks.
389 - untabify all sources to simplify patches
391 Changes in 0.91 (2 May 95)
392 - Default MEM_LEVEL is 8 (not 9 for Unix) as documented in zlib.h
393 - Document the memory requirements in zconf.h
394 - added "make install"
395 - fix sync search logic in inflateSync
396 - deflate(Z_FULL_FLUSH) now works even if output buffer too short
397 - after inflateSync, don't scare people with just "lo world"
398 - added support for DJGPP
400 Changes in 0.9 (1 May 95)
401 - don't assume that zalloc clears the allocated memory (the TurboC bug
402 was Mark's bug after all :)
403 - let again gzread copy uncompressed data unchanged (was working in 0.71)
404 - deflate(Z_FULL_FLUSH), inflateReset and inflateSync are now fully implemented
405 - added a test of inflateSync in example.c
406 - moved MAX_WBITS to zconf.h because users might want to change that.
407 - document explicitly that zalloc(64K) on MSDOS must return a normalized
408 pointer (zero offset)
409 - added Makefiles for Microsoft C, Turbo C, Borland C++
412 Changes in 0.8 (29 April 95)
413 - added fast inflate (inffast.c)
414 - deflate(Z_FINISH) now returns Z_STREAM_END when done. Warning: this
415 is incompatible with previous versions of zlib which returned Z_OK.
416 - work around a TurboC compiler bug (bad code for b << 0, see infutil.h)
417 (actually that was not a compiler bug, see 0.81 above)
418 - gzread no longer reads one extra byte in certain cases
419 - In gzio destroy(), don't reference a freed structure
420 - avoid many warnings for MSDOS
421 - avoid the ERROR symbol which is used by MS Windows
423 Changes in 0.71 (14 April 95)
424 - Fixed more MSDOS compilation problems :( There is still a bug with
427 Changes in 0.7 (14 April 95)
428 - Added full inflate support.
429 - Simplified the crc32() interface. The pre- and post-conditioning
430 (one's complement) is now done inside crc32(). WARNING: this is
431 incompatible with previous versions; see zlib.h for the new usage.
433 Changes in 0.61 (12 April 95)
434 - workaround for a bug in TurboC. example and minigzip now work on MSDOS.
436 Changes in 0.6 (11 April 95)
438 - added gzdopen to reopen a file descriptor as gzFile
439 - added transparent reading of non-gziped files in gzread.
440 - fixed bug in gzread (don't read crc as data)
441 - fixed bug in destroy (gzio.c) (don't return Z_STREAM_END for gzclose).
442 - don't allocate big arrays in the stack (for MSDOS)
443 - fix some MSDOS compilation problems
446 - do real compression in deflate.c. Z_PARTIAL_FLUSH is supported but
447 not yet Z_FULL_FLUSH.
448 - support decompression but only in a single step (forced Z_FINISH)
449 - added opaque object for zalloc and zfree.
450 - added deflateReset and inflateReset
451 - added a variable zlib_version for consistency checking.
452 - renamed the 'filter' parameter of deflateInit2 as 'strategy'.
453 Added Z_FILTERED and Z_HUFFMAN_ONLY constants.
456 - avoid "zip" everywhere, use zlib instead of ziplib.
457 - suppress Z_BLOCK_FLUSH, interpret Z_PARTIAL_FLUSH as block flush
458 if compression method == 8.
459 - added adler32 and crc32
460 - renamed deflateOptions as deflateInit2, call one or the other but not both
461 - added the method parameter for deflateInit2.
463 - simplied considerably deflateInit and inflateInit by not supporting
464 user-provided history buffer. This is supported only in deflateInit2
468 - prefix all macro names with Z_
469 - use Z_FINISH instead of deflateEnd to finish compression.
470 - added Z_HUFFMAN_ONLY