Mercurial > vba-clojure

     1 /* gzio.c -- IO on .gz files

     2  * Copyright (C) 1995-2002 Jean-loup Gailly.

     3  * For conditions of distribution and use, see copyright notice in zlib.h

     4  *

     5  * Compile this file with -DNO_DEFLATE to avoid the compression code.

     6  */

     7 

     8 /* memgzio.c - IO on .gz files in memory

     9  * Adapted from original gzio.c from zlib library by Forgotten

    10  */

    11 

    12 /* @(#) $Id: memgzio.c,v 1.5 2006/06/06 21:04:20 spacy51 Exp $ */

    13 

    14 #include <stdio.h>

    15 #include <stdarg.h>

    16 #include <stdlib.h>

    17 #include <string.h>

    18 #include <errno.h>

    19 

    20 #include "memgzio.h"

    21 

    22 #ifndef local

    23 #define local static

    24 #endif

    25 

    26 #ifndef DEF_MEM_LEVEL

    27 #  define DEF_MEM_LEVEL 8

    28 #endif

    29 

    30 #ifndef OS_CODE

    31 #define OS_CODE 3

    32 #endif

    33 

    34 #ifndef zmemcpy

    35 #define zmemcpy memcpy

    36 #endif

    37 

    38 /*struct internal_state {int dummy;};*/ /* for buggy compilers */

    39 

    40 #ifndef Z_BUFSIZE

    41 #  ifdef MAXSEG_64K

    42 #    define Z_BUFSIZE 4096 /* minimize memory usage for 16-bit DOS */

    43 #  else

    44 #    define Z_BUFSIZE 16384

    45 #  endif

    46 #endif

    47 #ifndef Z_PRINTF_BUFSIZE

    48 #  define Z_PRINTF_BUFSIZE 4096

    49 #endif

    50 

    51 #define ALLOC(size) malloc(size)

    52 #define TRYFREE(p) \

    53 	{if (p)                            \

    54 		 free(p);}

    55 

    56 static int gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */

    57 

    58 /* gzip flag byte */

    59 #define ASCII_FLAG   0x01 /* bit 0 set: file probably ascii text */

    60 #define HEAD_CRC     0x02 /* bit 1 set: header CRC present */

    61 #define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */

    62 #define ORIG_NAME    0x08 /* bit 3 set: original file name present */

    63 #define COMMENT      0x10 /* bit 4 set: file comment present */

    64 #define RESERVED     0xE0 /* bits 5..7: reserved */

    65 

    66 typedef struct _MemFile

    67 {

    68 	char *memory;

    69 	char *next;

    70 	int   available;

    71 	int   error;

    72 	char  mode;

    73 } MEMFILE;

    74 

    75 typedef struct mem_stream

    76 {

    77 	z_stream stream;

    78 	int      z_err;   /* error code for last stream operation */

    79 	int      z_eof;   /* set if end of input file */

    80 	MEMFILE *file;    /* memoru file */

    81 	Byte *   inbuf;   /* input buffer */

    82 	Byte *   outbuf;  /* output buffer */

    83 	uLong    crc;     /* crc32 of uncompressed data */

    84 	char *   msg;     /* error message */

    85 	int      transparent; /* 1 if input file is not a .gz file */

    86 	char     mode;    /* 'w' or 'r' */

    87 	long     startpos; /* start of compressed data in file (header skipped) */

    88 } mem_stream;

    89 

    90 local gzFile gz_open      OF((char *memory, const int available, const char *mode));

    91 local int do_flush        OF((gzFile file, int flush));

    92 local int get_byte     OF((mem_stream *s));

    93 local void check_header OF((mem_stream *s));

    94 local int destroy      OF((mem_stream *s));

    95 local void putLong      OF((MEMFILE *file, uLong x));

    96 local uLong getLong      OF((mem_stream *s));

    97 

    98 local MEMFILE *memOpen(char *memory, int available, char mode)

    99 {

   100 	MEMFILE *f;

   101 

   102 	if (available <= 8)

   103 		return NULL;

   104 

   105 	if (mode != 'w' && mode != 'r')

   106 		return NULL;

   107 

   108 	f = (MEMFILE *)malloc(sizeof(MEMFILE));

   109 

   110 	f->memory = memory;

   111 	f->mode   = mode;

   112 	f->error  = 0;

   113 

   114 	if (mode == 'w')

   115 	{

   116 		f->available         = available - 8;

   117 		f->next              = memory + 8;

   118 		memory[0]            = 'V';

   119 		memory[1]            = 'B';

   120 		memory[2]            = 'A';

   121 		memory[3]            = ' ';

   122 		*((int *)(memory+4)) = 0;

   123 	}

   124 	else

   125 	{

   126 		if (memory[0] != 'V' || memory[1] != 'B' || memory[2] != 'A' ||

   127 		    memory[3] != ' ')

   128 		{

   129 			free(f);

   130 			return NULL;

   131 		}

   132 		f->available = *((int *)(memory+4));

   133 		f->next      = memory+8;

   134 	}

   135 

   136 	return f;

   137 }

   138 

   139 local size_t memWrite(const void *buffer, size_t size, size_t count,

   140                       MEMFILE *file)

   141 {

   142 	size_t total = size*count;

   143 

   144 	if (file->mode != 'w')

   145 	{

   146 		file->error = 1;

   147 		return 0;

   148 	}

   149 

   150 	if (total > (size_t)file->available)

   151 	{

   152 		total = file->available;

   153 	}

   154 	memcpy(file->next, buffer, total);

   155 	file->available -= (int)total;

   156 	file->next      += total;

   157 	return total;

   158 }

   159 

   160 local size_t memRead(void *buffer, size_t size, size_t count,

   161                      MEMFILE *file)

   162 {

   163 	size_t total = size*count;

   164 

   165 	if (file->mode != 'r')

   166 	{

   167 		file->error = 1;

   168 		return 0;

   169 	}

   170 

   171 	if (file->available == 0)

   172 		return -1;

   173 

   174 	if (total > (size_t)file->available)

   175 	{

   176 		total = file->available;

   177 	}

   178 	memcpy(buffer, file->next, total);

   179 	file->available -= (int)total;

   180 	file->next      += total;

   181 	return total;

   182 }

   183 

   184 local int memPutc(int c, MEMFILE *file)

   185 {

   186 	if (file->mode != 'w')

   187 	{

   188 		file->error = 1;

   189 		return -1;

   190 	}

   191 

   192 	if (file->available >= 1)

   193 	{

   194 		*file->next++ = c;

   195 		file->available--;

   196 	}

   197 	else

   198 		return -1;

   199 

   200 	return c;

   201 }

   202 

   203 local long memTell(MEMFILE *f)

   204 {

   205 	return (long)(f->next - f->memory) - 8;

   206 }

   207 

   208 local int memError(MEMFILE *f)

   209 {

   210 	return f->error;

   211 }

   212 

   213 local int memClose(MEMFILE *f)

   214 {

   215 	if (f->mode == 'w')

   216 	{

   217 		*((int *)(f->memory+4)) = memTell(f);

   218 	}

   219 	free(f);

   220 	return 0;

   221 }

   222 

   223 local int memPrintf(MEMFILE *f, const char *format, ...)

   224 {

   225 	char    buffer[80];

   226 	va_list list;

   227 	int     len;

   228 

   229 	va_start(list, format);

   230 	len = vsprintf(buffer, format, list);

   231 	va_end(list);

   232 

   233 	return (int)memWrite(buffer, 1, len, f);

   234 }

   235 

   236 /* ===========================================================================

   237      Opens a gzip (.gz) file for reading or writing. The mode parameter

   238    is as in fopen ("rb" or "wb"). The file is given either by file descriptor

   239    or path name (if fd == -1).

   240      gz_open return NULL if the file could not be opened or if there was

   241    insufficient memory to allocate the (de)compression state; errno

   242    can be checked to distinguish the two cases (if errno is zero, the

   243    zlib error is Z_MEM_ERROR).

   244  */

   245 local gzFile gz_open(memory, available, mode)

   246 char *memory;

   247 const int   available;

   248 const char *mode;

   249 {

   250 	int         err;

   251 	int         level    = Z_DEFAULT_COMPRESSION; /* compression level */

   252 	int         strategy = Z_DEFAULT_STRATEGY; /* compression strategy */

   253 	char *      p        = (char *)mode;

   254 	mem_stream *s;

   255 	char        fmode[80]; /* copy of mode, without the compression level */

   256 	char *      m = fmode;

   257 

   258 	s = (mem_stream *)ALLOC(sizeof(mem_stream));

   259 	if (!s)

   260 		return Z_NULL;

   261 

   262 	s->stream.zalloc   = (alloc_func)0;

   263 	s->stream.zfree    = (free_func)0;

   264 	s->stream.opaque   = (voidpf)0;

   265 	s->stream.next_in  = s->inbuf = Z_NULL;

   266 	s->stream.next_out = s->outbuf = Z_NULL;

   267 	s->stream.avail_in = s->stream.avail_out = 0;

   268 	s->z_err           = Z_OK;

   269 	s->z_eof           = 0;

   270 	s->crc             = crc32(0L, Z_NULL, 0);

   271 	s->msg             = NULL;

   272 	s->transparent     = 0;

   273 	s->file            = NULL;

   274 

   275 	s->mode = '\0';

   276 	do

   277 	{

   278 		if (*p == 'r')

   279 			s->mode = 'r';

   280 		if (*p == 'w' || *p == 'a')

   281 			s->mode = 'w';

   282 		if (*p >= '0' && *p <= '9')

   283 		{

   284 			level = *p - '0';

   285 		}

   286 		else if (*p == 'f')

   287 		{

   288 			strategy = Z_FILTERED;

   289 		}

   290 		else if (*p == 'h')

   291 		{

   292 			strategy = Z_HUFFMAN_ONLY;

   293 		}

   294 		else

   295 		{

   296 			*m++ = *p; /* copy the mode */

   297 		}

   298 	}

   299 	while (*p++ && m != fmode + sizeof(fmode));

   300 	if (s->mode == '\0')

   301 		return destroy(s), (gzFile)Z_NULL;

   302 

   303 	if (s->mode == 'w')

   304 	{

   305 #ifdef NO_DEFLATE

   306 		err = Z_STREAM_ERROR;

   307 #else

   308 		err = deflateInit2(&(s->stream), level,

   309 		                   Z_DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL, strategy);

   310 		/* windowBits is passed < 0 to suppress zlib header */

   311 

   312 		s->stream.next_out = s->outbuf = (Byte *)ALLOC(Z_BUFSIZE);

   313 #endif

   314 		if (err != Z_OK || s->outbuf == Z_NULL)

   315 		{

   316 			return destroy(s), (gzFile)Z_NULL;

   317 		}

   318 	}

   319 	else

   320 	{

   321 		s->stream.next_in = s->inbuf = (Byte *)ALLOC(Z_BUFSIZE);

   322 

   323 		err = inflateInit2(&(s->stream), -MAX_WBITS);

   324 		/* windowBits is passed < 0 to tell that there is no zlib header.

   325 		 * Note that in this case inflate *requires* an extra "dummy" byte

   326 		 * after the compressed stream in order to complete decompression and

   327 		 * return Z_STREAM_END. Here the gzip CRC32 ensures that 4 bytes are

   328 		 * present after the compressed stream.

   329 		 */

   330 		if (err != Z_OK || s->inbuf == Z_NULL)

   331 		{

   332 			return destroy(s), (gzFile)Z_NULL;

   333 		}

   334 	}

   335 	s->stream.avail_out = Z_BUFSIZE;

   336 

   337 	errno   = 0;

   338 	s->file = memOpen(memory, available, s->mode);

   339 

   340 	if (s->file == NULL)

   341 	{

   342 		return destroy(s), (gzFile)Z_NULL;

   343 	}

   344 

   345 	if (s->mode == 'w')

   346 	{

   347 		/* Write a very simple .gz header:

   348 		 */

   349 		memPrintf(s->file, "%c%c%c%c%c%c%c%c%c%c", gz_magic[0], gz_magic[1],

   350 		          Z_DEFLATED, 0 /*flags*/, 0, 0, 0, 0 /*time*/, 0 /*xflags*/, OS_CODE);

   351 		s->startpos = 10L;

   352 		/* We use 10L instead of ftell(s->file) to because ftell causes an

   353 		 * fflush on some systems. This version of the library doesn't use

   354 		 * startpos anyway in write mode, so this initialization is not

   355 		 * necessary.

   356 		 */

   357 	}

   358 	else

   359 	{

   360 		check_header(s); /* skip the .gz header */

   361 		s->startpos = (memTell(s->file) - s->stream.avail_in);

   362 	}

   363 

   364 	return (gzFile)s;

   365 }

   366 

   367 /* ===========================================================================

   368      Opens a gzip (.gz) file for reading or writing.

   369  */

   370 gzFile ZEXPORT memgzopen(memory, available, mode)

   371 char *memory;

   372 int         available;

   373 const char *mode;

   374 {

   375 	return gz_open(memory, available, mode);

   376 }

   377 

   378 /* ===========================================================================

   379      Read a byte from a mem_stream; update next_in and avail_in. Return EOF

   380    for end of file.

   381    IN assertion: the stream s has been sucessfully opened for reading.

   382  */

   383 local int get_byte(s)

   384 mem_stream *s;

   385 {

   386 	if (s->z_eof)

   387 		return EOF;

   388 	if (s->stream.avail_in == 0)

   389 	{

   390 		errno = 0;

   391 		s->stream.avail_in = (uInt)memRead(s->inbuf, 1, Z_BUFSIZE, s->file);

   392 		if (s->stream.avail_in == 0)

   393 		{

   394 			s->z_eof = 1;

   395 			if (memError(s->file))

   396 				s->z_err = Z_ERRNO;

   397 			return EOF;

   398 		}

   399 		s->stream.next_in = s->inbuf;

   400 	}

   401 	s->stream.avail_in--;

   402 	return *(s->stream.next_in)++;

   403 }

   404 

   405 /* ===========================================================================

   406       Check the gzip header of a mem_stream opened for reading. Set the stream

   407     mode to transparent if the gzip magic header is not present; set s->err

   408     to Z_DATA_ERROR if the magic header is present but the rest of the header

   409     is incorrect.

   410     IN assertion: the stream s has already been created sucessfully;

   411        s->stream.avail_in is zero for the first time, but may be non-zero

   412        for concatenated .gz files.

   413  */

   414 local void check_header(s)

   415 mem_stream *s;

   416 {

   417 	int  method; /* method byte */

   418 	int  flags; /* flags byte */

   419 	uInt len;

   420 	int  c;

   421 

   422 	/* Check the gzip magic header */

   423 	for (len = 0; len < 2; len++)

   424 	{

   425 		c = get_byte(s);

   426 		if (c != gz_magic[len])

   427 		{

   428 			if (len != 0)

   429 				s->stream.avail_in++, s->stream.next_in--;

   430 			if (c != EOF)

   431 			{

   432 				s->stream.avail_in++, s->stream.next_in--;

   433 				s->transparent = 1;

   434 			}

   435 			s->z_err = s->stream.avail_in != 0 ? Z_OK : Z_STREAM_END;

   436 			return;

   437 		}

   438 	}

   439 	method = get_byte(s);

   440 	flags  = get_byte(s);

   441 	if (method != Z_DEFLATED || (flags & RESERVED) != 0)

   442 	{

   443 		s->z_err = Z_DATA_ERROR;

   444 		return;

   445 	}

   446 

   447 	/* Discard time, xflags and OS code: */

   448 	for (len = 0; len < 6; len++)

   449 		(void)get_byte(s);

   450 

   451 	if ((flags & EXTRA_FIELD) != 0)   /* skip the extra field */

   452 	{

   453 		len  =  (uInt)get_byte(s);

   454 		len += ((uInt)get_byte(s))<<8;

   455 		/* len is garbage if EOF but the loop below will quit anyway */

   456 		while (len-- != 0 && get_byte(s) != EOF)

   457 			;

   458 	}

   459 	if ((flags & ORIG_NAME) != 0)   /* skip the original file name */

   460 	{

   461 		while ((c = get_byte(s)) != 0 && c != EOF)

   462 			;

   463 	}

   464 	if ((flags & COMMENT) != 0)     /* skip the .gz file comment */

   465 	{

   466 		while ((c = get_byte(s)) != 0 && c != EOF)

   467 			;

   468 	}

   469 	if ((flags & HEAD_CRC) != 0)    /* skip the header crc */

   470 	{

   471 		for (len = 0; len < 2; len++)

   472 			(void)get_byte(s);

   473 	}

   474 	s->z_err = s->z_eof ? Z_DATA_ERROR : Z_OK;

   475 }

   476 

   477 /* ===========================================================================

   478  * Cleanup then free the given mem_stream. Return a zlib error code.

   479    Try freeing in the reverse order of allocations.

   480  */

   481 local int destroy(s)

   482 mem_stream *s;

   483 {

   484 	int err = Z_OK;

   485 

   486 	if (!s)

   487 		return Z_STREAM_ERROR;

   488 

   489 	TRYFREE(s->msg);

   490 

   491 	if (s->stream.state != NULL)

   492 	{

   493 		if (s->mode == 'w')

   494 		{

   495 #ifdef NO_DEFLATE

   496 			err = Z_STREAM_ERROR;

   497 #else

   498 			err = deflateEnd(&(s->stream));

   499 #endif

   500 		}

   501 		else if (s->mode == 'r')

   502 		{

   503 			err = inflateEnd(&(s->stream));

   504 		}

   505 	}

   506 	if (s->file != NULL && memClose(s->file))

   507 	{

   508 #ifdef ESPIPE

   509 		if (errno != ESPIPE) /* fclose is broken for pipes in HP/UX */

   510 #endif

   511 		err = Z_ERRNO;

   512 	}

   513 	if (s->z_err < 0)

   514 		err = s->z_err;

   515 

   516 	TRYFREE(s->inbuf);

   517 	TRYFREE(s->outbuf);

   518 	TRYFREE(s);

   519 	return err;

   520 }

   521 

   522 /* ===========================================================================

   523      Reads the given number of uncompressed bytes from the compressed file.

   524    gzread returns the number of bytes actually read (0 for end of file).

   525  */

   526 int ZEXPORT memgzread(file, buf, len)

   527 gzFile file;

   528 voidp    buf;

   529 unsigned len;

   530 {

   531 	mem_stream *s     = (mem_stream *)file;

   532 	Bytef *     start = (Bytef *)buf; /* starting point for crc computation */

   533 	Byte *      next_out; /* == stream.next_out but not forced far (for MSDOS) */

   534 

   535 	if (s == NULL || s->mode != 'r')

   536 		return Z_STREAM_ERROR;

   537 

   538 	if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO)

   539 		return -1;

   540 	if (s->z_err == Z_STREAM_END)

   541 		return 0;                            /* EOF */

   542 

   543 	next_out = (Byte *)buf;

   544 	s->stream.next_out  = (Bytef *)buf;

   545 	s->stream.avail_out = len;

   546 

   547 	while (s->stream.avail_out != 0)

   548 	{

   549 		if (s->transparent)

   550 		{

   551 			/* Copy first the lookahead bytes: */

   552 			uInt n = s->stream.avail_in;

   553 			if (n > s->stream.avail_out)

   554 				n = s->stream.avail_out;

   555 			if (n > 0)

   556 			{

   557 				zmemcpy(s->stream.next_out, s->stream.next_in, n);

   558 				next_out += n;

   559 				s->stream.next_out   = next_out;

   560 				s->stream.next_in   += n;

   561 				s->stream.avail_out -= n;

   562 				s->stream.avail_in  -= n;

   563 			}

   564 			if (s->stream.avail_out > 0)

   565 			{

   566 				s->stream.avail_out -= (uInt)memRead(next_out, 1, s->stream.avail_out, s->file);

   567 			}

   568 			len -= s->stream.avail_out;

   569 			s->stream.total_in  += (uLong)len;

   570 			s->stream.total_out += (uLong)len;

   571 			if (len == 0)

   572 				s->z_eof = 1;

   573 			return (int)len;

   574 		}

   575 		if (s->stream.avail_in == 0 && !s->z_eof)

   576 		{

   577 			errno = 0;

   578 			s->stream.avail_in = (uInt)memRead(s->inbuf, 1, Z_BUFSIZE, s->file);

   579 			if (s->stream.avail_in == 0)

   580 			{

   581 				s->z_eof = 1;

   582 				if (memError(s->file))

   583 				{

   584 					s->z_err = Z_ERRNO;

   585 					break;

   586 				}

   587 			}

   588 			s->stream.next_in = s->inbuf;

   589 		}

   590 		s->z_err = inflate(&(s->stream), Z_NO_FLUSH);

   591 

   592 		if (s->z_err == Z_STREAM_END)

   593 		{

   594 			/* Check CRC and original size */

   595 			s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));

   596 			start  = s->stream.next_out;

   597 

   598 			if (getLong(s) != s->crc)

   599 			{

   600 				s->z_err = Z_DATA_ERROR;

   601 			}

   602 			else

   603 			{

   604 				(void)getLong(s);

   605 				/* The uncompressed length returned by above getlong() may

   606 				 * be different from s->stream.total_out) in case of

   607 				 * concatenated .gz files. Check for such files:

   608 				 */

   609 				check_header(s);

   610 				if (s->z_err == Z_OK)

   611 				{

   612 					uLong total_in  = s->stream.total_in;

   613 					uLong total_out = s->stream.total_out;

   614 

   615 					inflateReset(&(s->stream));

   616 					s->stream.total_in  = total_in;

   617 					s->stream.total_out = total_out;

   618 					s->crc = crc32(0L, Z_NULL, 0);

   619 				}

   620 			}

   621 		}

   622 		if (s->z_err != Z_OK || s->z_eof)

   623 			break;

   624 	}

   625 	s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));

   626 

   627 	return (int)(len - s->stream.avail_out);

   628 }

   629 

   630 #ifndef NO_DEFLATE

   631 /* ===========================================================================

   632      Writes the given number of uncompressed bytes into the compressed file.

   633    gzwrite returns the number of bytes actually written (0 in case of error).

   634  */

   635 int ZEXPORT memgzwrite(file, buf, len)

   636 gzFile file;

   637 const voidp buf;

   638 unsigned    len;

   639 {

   640 	mem_stream *s = (mem_stream *)file;

   641 

   642 	if (s == NULL || s->mode != 'w')

   643 		return Z_STREAM_ERROR;

   644 

   645 	s->stream.next_in  = (Bytef *)buf;

   646 	s->stream.avail_in = len;

   647 

   648 	while (s->stream.avail_in != 0)

   649 	{

   650 		if (s->stream.avail_out == 0)

   651 		{

   652 			s->stream.next_out = s->outbuf;

   653 			if (memWrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE)

   654 			{

   655 				s->z_err = Z_ERRNO;

   656 				break;

   657 			}

   658 			s->stream.avail_out = Z_BUFSIZE;

   659 		}

   660 		s->z_err = deflate(&(s->stream), Z_NO_FLUSH);

   661 		if (s->z_err != Z_OK)

   662 			break;

   663 	}

   664 	s->crc = crc32(s->crc, (const Bytef *)buf, len);

   665 

   666 	return (int)(len - s->stream.avail_in);

   667 }

   668 #endif

   669 /* ===========================================================================

   670      Flushes all pending output into the compressed file. The parameter

   671    flush is as in the deflate() function.

   672  */

   673 local int do_flush(file, flush)

   674 gzFile file;

   675 int flush;

   676 {

   677 	uInt        len;

   678 	int         done = 0;

   679 	mem_stream *s    = (mem_stream *)file;

   680 

   681 	if (s == NULL || s->mode != 'w')

   682 		return Z_STREAM_ERROR;

   683 

   684 	s->stream.avail_in = 0; /* should be zero already anyway */

   685 

   686 	for (;;)

   687 	{

   688 		len = Z_BUFSIZE - s->stream.avail_out;

   689 

   690 		if (len != 0)

   691 		{

   692 			if ((uInt)memWrite(s->outbuf, 1, len, s->file) != len)

   693 			{

   694 				s->z_err = Z_ERRNO;

   695 				return Z_ERRNO;

   696 			}

   697 			s->stream.next_out  = s->outbuf;

   698 			s->stream.avail_out = Z_BUFSIZE;

   699 		}

   700 		if (done)

   701 			break;

   702 		s->z_err = deflate(&(s->stream), flush);

   703 

   704 		/* Ignore the second of two consecutive flushes: */

   705 		if (len == 0 && s->z_err == Z_BUF_ERROR)

   706 			s->z_err = Z_OK;

   707 

   708 		/* deflate has finished flushing only when it hasn't used up

   709 		 * all the available space in the output buffer:

   710 		 */

   711 		done = (s->stream.avail_out != 0 || s->z_err == Z_STREAM_END);

   712 

   713 		if (s->z_err != Z_OK && s->z_err != Z_STREAM_END)

   714 			break;

   715 	}

   716 	return s->z_err == Z_STREAM_END ? Z_OK : s->z_err;

   717 }

   718 

   719 /* ===========================================================================

   720    Outputs a long in LSB order to the given file

   721  */

   722 local void putLong(file, x)

   723 MEMFILE *file;

   724 uLong x;

   725 {

   726 	int n;

   727 	for (n = 0; n < 4; n++)

   728 	{

   729 		memPutc((int)(x & 0xff), file);

   730 		x >>= 8;

   731 	}

   732 }

   733 

   734 /* ===========================================================================

   735    Reads a long in LSB order from the given mem_stream. Sets z_err in case

   736    of error.

   737  */

   738 local uLong getLong(s)

   739 mem_stream *s;

   740 {

   741 	uLong x = (uLong)get_byte(s);

   742 	int   c;

   743 

   744 	x += ((uLong)get_byte(s))<<8;

   745 	x += ((uLong)get_byte(s))<<16;

   746 	c  = get_byte(s);

   747 	if (c == EOF)

   748 		s->z_err = Z_DATA_ERROR;

   749 	x += ((uLong)c)<<24;

   750 	return x;

   751 }

   752 

   753 /* ===========================================================================

   754      Flushes all pending output if necessary, closes the compressed file

   755    and deallocates all the (de)compression state.

   756  */

   757 int ZEXPORT memgzclose(file)

   758 gzFile file;

   759 {

   760 	int         err;

   761 	mem_stream *s = (mem_stream *)file;

   762 

   763 	if (s == NULL)

   764 		return Z_STREAM_ERROR;

   765 

   766 	if (s->mode == 'w')

   767 	{

   768 #ifdef NO_DEFLATE

   769 		return Z_STREAM_ERROR;

   770 #else

   771 		err = do_flush(file, Z_FINISH);

   772 		if (err != Z_OK)

   773 			return destroy((mem_stream *)file);

   774 

   775 		putLong(s->file, s->crc);

   776 		putLong(s->file, s->stream.total_in);

   777 #endif

   778 	}

   779 	return destroy((mem_stream *)file);

   780 }

   781 

   782 long ZEXPORT memtell(file)

   783 gzFile file;

   784 {

   785 	mem_stream *s = (mem_stream *)file;

   786 

   787 	if (s == NULL)

   788 		return Z_STREAM_ERROR;

   789 

   790 	return memTell(s->file);

   791 }
author	Robert McIntyre <rlm@mit.edu>
date	Sat, 03 Mar 2012 10:31:27 -0600
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