zlib/gzio.c

   1 /* gzio.c -- IO on .gz files
   2  * Copyright (C) 1995-2005 Jean-loup Gailly.
   3  * For conditions of distribution and use, see copyright notice in zlib.h
   4  *
   5  * Compile this file with -DNO_GZCOMPRESS to avoid the compression code.
   6  */
   7
   8 /* @(#) $Id: gzio.c,v 1.1.1.2 2002/03/11 21:53:24 tromey Exp $ */
   9
  10 #include <stdio.h>
  11
  12 #include "zutil.h"
  13
  14 #ifdef NO_DEFLATE       /* for compatibility with old definition */
  15 #  define NO_GZCOMPRESS
  16 #endif
  17
  18 #ifndef NO_DUMMY_DECL
  19 struct internal_state {int dummy;}; /* for buggy compilers */
  20 #endif
  21
  22 #ifndef Z_BUFSIZE
  23 #  ifdef MAXSEG_64K
  24 #    define Z_BUFSIZE 4096 /* minimize memory usage for 16-bit DOS */
  25 #  else
  26 #    define Z_BUFSIZE 16384
  27 #  endif
  28 #endif
  29 #ifndef Z_PRINTF_BUFSIZE
  30 #  define Z_PRINTF_BUFSIZE 4096
  31 #endif
  32
  33 #ifdef __MVS__
  34 #  pragma map (fdopen , "\174\174FDOPEN")
  35    FILE *fdopen(int, const char *);
  36 #endif
  37
  38 #ifndef STDC
  39 extern voidp  malloc OF((uInt size));
  40 extern void   free   OF((voidpf ptr));
  41 #endif
  42
  43 #define ALLOC(size) malloc(size)
  44 #define TRYFREE(p) {if (p) free(p);}
  45
  46 static int const gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
  47
  48 /* gzip flag byte */
  49 #define ASCII_FLAG   0x01 /* bit 0 set: file probably ascii text */
  50 #define HEAD_CRC     0x02 /* bit 1 set: header CRC present */
  51 #define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */
  52 #define ORIG_NAME    0x08 /* bit 3 set: original file name present */
  53 #define COMMENT      0x10 /* bit 4 set: file comment present */
  54 #define RESERVED     0xE0 /* bits 5..7: reserved */
  55
  56 typedef struct gz_stream {
  57     z_stream stream;
  58     int      z_err;   /* error code for last stream operation */
  59     int      z_eof;   /* set if end of input file */
  60     FILE     *file;   /* .gz file */
  61     Byte     *inbuf;  /* input buffer */
  62     Byte     *outbuf; /* output buffer */
  63     uLong    crc;     /* crc32 of uncompressed data */
  64     char     *msg;    /* error message */
  65     char     *path;   /* path name for debugging only */
  66     int      transparent; /* 1 if input file is not a .gz file */
  67     char     mode;    /* 'w' or 'r' */
  68     z_off_t  start;   /* start of compressed data in file (header skipped) */
  69     z_off_t  in;      /* bytes into deflate or inflate */
  70     z_off_t  out;     /* bytes out of deflate or inflate */
  71     int      back;    /* one character push-back */
  72     int      last;    /* true if push-back is last character */
  73 } gz_stream;
  74
  75
  76 local gzFile gz_open      OF((const char *path, const char *mode, int  fd));
  77 local int do_flush        OF((gzFile file, int flush));
  78 local int    get_byte     OF((gz_stream *s));
  79 local void   check_header OF((gz_stream *s));
  80 local int    destroy      OF((gz_stream *s));
  81 local void   putLong      OF((FILE *file, uLong x));
  82 local uLong  getLong      OF((gz_stream *s));
  83
  84 /* ===========================================================================
  85      Opens a gzip (.gz) file for reading or writing. The mode parameter
  86    is as in fopen ("rb" or "wb"). The file is given either by file descriptor
  87    or path name (if fd == -1).
  88      gz_open returns NULL if the file could not be opened or if there was
  89    insufficient memory to allocate the (de)compression state; errno
  90    can be checked to distinguish the two cases (if errno is zero, the
  91    zlib error is Z_MEM_ERROR).
  92 */
  93 local gzFile gz_open (path, mode, fd)
  94     const char *path;
  95     const char *mode;
  96     int  fd;
  97 {
  98     int err;
  99     int level = Z_DEFAULT_COMPRESSION; /* compression level */
 100     int strategy = Z_DEFAULT_STRATEGY; /* compression strategy */
 101     char *p = (char*)mode;
 102     gz_stream *s;
 103     char fmode[80]; /* copy of mode, without the compression level */
 104     char *m = fmode;
 105
 106     if (!path || !mode) return Z_NULL;
 107
 108     s = (gz_stream *)ALLOC(sizeof(gz_stream));
 109     if (!s) return Z_NULL;
 110
 111     s->stream.zalloc = (alloc_func)0;
 112     s->stream.zfree = (free_func)0;
 113     s->stream.opaque = (voidpf)0;
 114     s->stream.next_in = s->inbuf = Z_NULL;
 115     s->stream.next_out = s->outbuf = Z_NULL;
 116     s->stream.avail_in = s->stream.avail_out = 0;
 117     s->file = NULL;
 118     s->z_err = Z_OK;
 119     s->z_eof = 0;
 120     s->in = 0;
 121     s->out = 0;
 122     s->back = EOF;
 123     s->crc = crc32(0L, Z_NULL, 0);
 124     s->msg = NULL;
 125     s->transparent = 0;
 126
 127     s->path = (char*)ALLOC(strlen(path)+1);
 128     if (s->path == NULL) {
 129         return destroy(s), (gzFile)Z_NULL;
 130     }
 131     strcpy(s->path, path); /* do this early for debugging */
 132
 133     s->mode = '\0';
 134     do {
 135         if (*p == 'r') s->mode = 'r';
 136         if (*p == 'w' || *p == 'a') s->mode = 'w';
 137         if (*p >= '0' && *p <= '9') {
 138             level = *p - '0';
 139         } else if (*p == 'f') {
 140           strategy = Z_FILTERED;
 141         } else if (*p == 'h') {
 142           strategy = Z_HUFFMAN_ONLY;
 143         } else if (*p == 'R') {
 144           strategy = Z_RLE;
 145         } else {
 146             *m++ = *p; /* copy the mode */
 147         }
 148     } while (*p++ && m != fmode + sizeof(fmode));
 149     if (s->mode == '\0') return destroy(s), (gzFile)Z_NULL;
 150
 151     if (s->mode == 'w') {
 152 #ifdef NO_GZCOMPRESS
 153         err = Z_STREAM_ERROR;
 154 #else
 155         err = deflateInit2(&(s->stream), level,
 156                            Z_DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL, strategy);
 157         /* windowBits is passed < 0 to suppress zlib header */
 158
 159         s->stream.next_out = s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
 160 #endif
 161         if (err != Z_OK || s->outbuf == Z_NULL) {
 162             return destroy(s), (gzFile)Z_NULL;
 163         }
 164     } else {
 165         s->stream.next_in  = s->inbuf = (Byte*)ALLOC(Z_BUFSIZE);
 166
 167         err = inflateInit2(&(s->stream), -MAX_WBITS);
 168         /* windowBits is passed < 0 to tell that there is no zlib header.
 169          * Note that in this case inflate *requires* an extra "dummy" byte
 170          * after the compressed stream in order to complete decompression and
 171          * return Z_STREAM_END. Here the gzip CRC32 ensures that 4 bytes are
 172          * present after the compressed stream.
 173          */
 174         if (err != Z_OK || s->inbuf == Z_NULL) {
 175             return destroy(s), (gzFile)Z_NULL;
 176         }
 177     }
 178     s->stream.avail_out = Z_BUFSIZE;
 179
 180     errno = 0;
 181     s->file = fd < 0 ? F_OPEN(path, fmode) : (FILE*)fdopen(fd, fmode);
 182
 183     if (s->file == NULL) {
 184         return destroy(s), (gzFile)Z_NULL;
 185     }
 186     if (s->mode == 'w') {
 187         /* Write a very simple .gz header:
 188          */
 189         fprintf(s->file, "%c%c%c%c%c%c%c%c%c%c", gz_magic[0], gz_magic[1],
 190              Z_DEFLATED, 0 /*flags*/, 0,0,0,0 /*time*/, 0 /*xflags*/, OS_CODE);
 191         s->start = 10L;
 192         /* We use 10L instead of ftell(s->file) to because ftell causes an
 193          * fflush on some systems. This version of the library doesn't use
 194          * start anyway in write mode, so this initialization is not
 195          * necessary.
 196          */
 197     } else {
 198         check_header(s); /* skip the .gz header */
 199         s->start = ftell(s->file) - s->stream.avail_in;
 200     }
 201
 202     return (gzFile)s;
 203 }
 204
 205 /* ===========================================================================
 206      Opens a gzip (.gz) file for reading or writing.
 207 */
 208 gzFile ZEXPORT gzopen (path, mode)
 209     const char *path;
 210     const char *mode;
 211 {
 212     return gz_open (path, mode, -1);
 213 }
 214
 215 /* ===========================================================================
 216      Associate a gzFile with the file descriptor fd. fd is not dup'ed here
 217    to mimic the behavio(u)r of fdopen.
 218 */
 219 gzFile ZEXPORT gzdopen (fd, mode)
 220     int fd;
 221     const char *mode;
 222 {
 223     char name[46];      /* allow for up to 128-bit integers */
 224
 225     if (fd < 0) return (gzFile)Z_NULL;
 226     sprintf(name, "<fd:%d>", fd); /* for debugging */
 227
 228     return gz_open (name, mode, fd);
 229 }
 230
 231 /* ===========================================================================
 232  * Update the compression level and strategy
 233  */
 234 int ZEXPORT gzsetparams (file, level, strategy)
 235     gzFile file;
 236     int level;
 237     int strategy;
 238 {
 239     gz_stream *s = (gz_stream*)file;
 240
 241     if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
 242
 243     /* Make room to allow flushing */
 244     if (s->stream.avail_out == 0) {
 245
 246         s->stream.next_out = s->outbuf;
 247         if (fwrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE) {
 248             s->z_err = Z_ERRNO;
 249         }
 250         s->stream.avail_out = Z_BUFSIZE;
 251     }
 252
 253     return deflateParams (&(s->stream), level, strategy);
 254 }
 255
 256 /* ===========================================================================
 257      Read a byte from a gz_stream; update next_in and avail_in. Return EOF
 258    for end of file.
 259    IN assertion: the stream s has been sucessfully opened for reading.
 260 */
 261 local int get_byte(s)
 262     gz_stream *s;
 263 {
 264     if (s->z_eof) return EOF;
 265     if (s->stream.avail_in == 0) {
 266         errno = 0;
 267         s->stream.avail_in = (uInt)fread(s->inbuf, 1, Z_BUFSIZE, s->file);
 268         if (s->stream.avail_in == 0) {
 269             s->z_eof = 1;
 270             if (ferror(s->file)) s->z_err = Z_ERRNO;
 271             return EOF;
 272         }
 273         s->stream.next_in = s->inbuf;
 274     }
 275     s->stream.avail_in--;
 276     return *(s->stream.next_in)++;
 277 }
 278
 279 /* ===========================================================================
 280       Check the gzip header of a gz_stream opened for reading. Set the stream
 281     mode to transparent if the gzip magic header is not present; set s->err
 282     to Z_DATA_ERROR if the magic header is present but the rest of the header
 283     is incorrect.
 284     IN assertion: the stream s has already been created sucessfully;
 285        s->stream.avail_in is zero for the first time, but may be non-zero
 286        for concatenated .gz files.
 287 */
 288 local void check_header(s)
 289     gz_stream *s;
 290 {
 291     int method; /* method byte */
 292     int flags;  /* flags byte */
 293     uInt len;
 294     int c;
 295
 296     /* Assure two bytes in the buffer so we can peek ahead -- handle case
 297        where first byte of header is at the end of the buffer after the last
 298        gzip segment */
 299     len = s->stream.avail_in;
 300     if (len < 2) {
 301         if (len) s->inbuf[0] = s->stream.next_in[0];
 302         errno = 0;
 303         len = (uInt)fread(s->inbuf + len, 1, Z_BUFSIZE >> len, s->file);
 304         if (len == 0 && ferror(s->file)) s->z_err = Z_ERRNO;
 305         s->stream.avail_in += len;
 306         s->stream.next_in = s->inbuf;
 307         if (s->stream.avail_in < 2) {
 308             s->transparent = s->stream.avail_in;
 309             return;
 310         }
 311     }
 312
 313     /* Peek ahead to check the gzip magic header */
 314     if (s->stream.next_in[0] != gz_magic[0] ||
 315         s->stream.next_in[1] != gz_magic[1]) {
 316         s->transparent = 1;
 317         return;
 318     }
 319     s->stream.avail_in -= 2;
 320     s->stream.next_in += 2;
 321
 322     /* Check the rest of the gzip header */
 323     method = get_byte(s);
 324     flags = get_byte(s);
 325     if (method != Z_DEFLATED || (flags & RESERVED) != 0) {
 326         s->z_err = Z_DATA_ERROR;
 327         return;
 328     }
 329
 330     /* Discard time, xflags and OS code: */
 331     for (len = 0; len < 6; len++) (void)get_byte(s);
 332
 333     if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */
 334         len  =  (uInt)get_byte(s);
 335         len += ((uInt)get_byte(s))<<8;
 336         /* len is garbage if EOF but the loop below will quit anyway */
 337         while (len-- != 0 && get_byte(s) != EOF) ;
 338     }
 339     if ((flags & ORIG_NAME) != 0) { /* skip the original file name */
 340         while ((c = get_byte(s)) != 0 && c != EOF) ;
 341     }
 342     if ((flags & COMMENT) != 0) {   /* skip the .gz file comment */
 343         while ((c = get_byte(s)) != 0 && c != EOF) ;
 344     }
 345     if ((flags & HEAD_CRC) != 0) {  /* skip the header crc */
 346         for (len = 0; len < 2; len++) (void)get_byte(s);
 347     }
 348     s->z_err = s->z_eof ? Z_DATA_ERROR : Z_OK;
 349 }
 350
 351  /* ===========================================================================
 352  * Cleanup then free the given gz_stream. Return a zlib error code.
 353    Try freeing in the reverse order of allocations.
 354  */
 355 local int destroy (s)
 356     gz_stream *s;
 357 {
 358     int err = Z_OK;
 359
 360     if (!s) return Z_STREAM_ERROR;
 361
 362     TRYFREE(s->msg);
 363
 364     if (s->stream.state != NULL) {
 365         if (s->mode == 'w') {
 366 #ifdef NO_GZCOMPRESS
 367             err = Z_STREAM_ERROR;
 368 #else
 369             err = deflateEnd(&(s->stream));
 370 #endif
 371         } else if (s->mode == 'r') {
 372             err = inflateEnd(&(s->stream));
 373         }
 374     }
 375     if (s->file != NULL && fclose(s->file)) {
 376 #ifdef ESPIPE
 377         if (errno != ESPIPE) /* fclose is broken for pipes in HP/UX */
 378 #endif
 379             err = Z_ERRNO;
 380     }
 381     if (s->z_err < 0) err = s->z_err;
 382
 383     TRYFREE(s->inbuf);
 384     TRYFREE(s->outbuf);
 385     TRYFREE(s->path);
 386     TRYFREE(s);
 387     return err;
 388 }
 389
 390 /* ===========================================================================
 391      Reads the given number of uncompressed bytes from the compressed file.
 392    gzread returns the number of bytes actually read (0 for end of file).
 393 */
 394 int ZEXPORT gzread (file, buf, len)
 395     gzFile file;
 396     voidp buf;
 397     unsigned len;
 398 {
 399     gz_stream *s = (gz_stream*)file;
 400     Bytef *start = (Bytef*)buf; /* starting point for crc computation */
 401     Byte  *next_out; /* == stream.next_out but not forced far (for MSDOS) */
 402
 403     if (s == NULL || s->mode != 'r') return Z_STREAM_ERROR;
 404
 405     if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO) return -1;
 406     if (s->z_err == Z_STREAM_END) return 0;  /* EOF */
 407
 408     next_out = (Byte*)buf;
 409     s->stream.next_out = (Bytef*)buf;
 410     s->stream.avail_out = len;
 411
 412     if (s->stream.avail_out && s->back != EOF) {
 413         *next_out++ = s->back;
 414         s->stream.next_out++;
 415         s->stream.avail_out--;
 416         s->back = EOF;
 417         s->out++;
 418         start++;
 419         if (s->last) {
 420             s->z_err = Z_STREAM_END;
 421             return 1;
 422         }
 423     }
 424
 425     while (s->stream.avail_out != 0) {
 426
 427         if (s->transparent) {
 428             /* Copy first the lookahead bytes: */
 429             uInt n = s->stream.avail_in;
 430             if (n > s->stream.avail_out) n = s->stream.avail_out;
 431             if (n > 0) {
 432                 zmemcpy(s->stream.next_out, s->stream.next_in, n);
 433                 next_out += n;
 434                 s->stream.next_out = next_out;
 435                 s->stream.next_in   += n;
 436                 s->stream.avail_out -= n;
 437                 s->stream.avail_in  -= n;
 438             }
 439             if (s->stream.avail_out > 0) {
 440                 s->stream.avail_out -=
 441                     (uInt)fread(next_out, 1, s->stream.avail_out, s->file);
 442             }
 443             len -= s->stream.avail_out;
 444             s->in  += len;
 445             s->out += len;
 446             if (len == 0) s->z_eof = 1;
 447             return (int)len;
 448         }
 449         if (s->stream.avail_in == 0 && !s->z_eof) {
 450
 451             errno = 0;
 452             s->stream.avail_in = (uInt)fread(s->inbuf, 1, Z_BUFSIZE, s->file);
 453             if (s->stream.avail_in == 0) {
 454                 s->z_eof = 1;
 455                 if (ferror(s->file)) {
 456                     s->z_err = Z_ERRNO;
 457                     break;
 458                 }
 459             }
 460             s->stream.next_in = s->inbuf;
 461         }
 462         s->in += s->stream.avail_in;
 463         s->out += s->stream.avail_out;
 464         s->z_err = inflate(&(s->stream), Z_NO_FLUSH);
 465         s->in -= s->stream.avail_in;
 466         s->out -= s->stream.avail_out;
 467
 468         if (s->z_err == Z_STREAM_END) {
 469             /* Check CRC and original size */
 470             s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
 471             start = s->stream.next_out;
 472
 473             if (getLong(s) != s->crc) {
 474                 s->z_err = Z_DATA_ERROR;
 475             } else {
 476                 (void)getLong(s);
 477                 /* The uncompressed length returned by above getlong() may be
 478                  * different from s->out in case of concatenated .gz files.
 479                  * Check for such files:
 480                  */
 481                 check_header(s);
 482                 if (s->z_err == Z_OK) {
 483                     inflateReset(&(s->stream));
 484                     s->crc = crc32(0L, Z_NULL, 0);
 485                 }
 486             }
 487         }
 488         if (s->z_err != Z_OK || s->z_eof) break;
 489     }
 490     s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
 491
 492     if (len == s->stream.avail_out &&
 493         (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO))
 494         return -1;
 495     return (int)(len - s->stream.avail_out);
 496 }
 497
 498
 499 /* ===========================================================================
 500       Reads one byte from the compressed file. gzgetc returns this byte
 501    or -1 in case of end of file or error.
 502 */
 503 int ZEXPORT gzgetc(file)
 504     gzFile file;
 505 {
 506     unsigned char c;
 507
 508     return gzread(file, &c, 1) == 1 ? c : -1;
 509 }
 510
 511
 512 /* ===========================================================================
 513       Push one byte back onto the stream.
 514 */
 515 int ZEXPORT gzungetc(c, file)
 516     int c;
 517     gzFile file;
 518 {
 519     gz_stream *s = (gz_stream*)file;
 520
 521     if (s == NULL || s->mode != 'r' || c == EOF || s->back != EOF) return EOF;
 522     s->back = c;
 523     s->out--;
 524     s->last = (s->z_err == Z_STREAM_END);
 525     if (s->last) s->z_err = Z_OK;
 526     s->z_eof = 0;
 527     return c;
 528 }
 529
 530
 531 /* ===========================================================================
 532       Reads bytes from the compressed file until len-1 characters are
 533    read, or a newline character is read and transferred to buf, or an
 534    end-of-file condition is encountered.  The string is then terminated
 535    with a null character.
 536       gzgets returns buf, or Z_NULL in case of error.
 537
 538       The current implementation is not optimized at all.
 539 */
 540 char * ZEXPORT gzgets(file, buf, len)
 541     gzFile file;
 542     char *buf;
 543     int len;
 544 {
 545     char *b = buf;
 546     if (buf == Z_NULL || len <= 0) return Z_NULL;
 547
 548     while (--len > 0 && gzread(file, buf, 1) == 1 && *buf++ != '\n') ;
 549     *buf = '\0';
 550     return b == buf && len > 0 ? Z_NULL : b;
 551 }
 552
 553
 554 #ifndef NO_GZCOMPRESS
 555 /* ===========================================================================
 556      Writes the given number of uncompressed bytes into the compressed file.
 557    gzwrite returns the number of bytes actually written (0 in case of error).
 558 */
 559 int ZEXPORT gzwrite (file, buf, len)
 560     gzFile file;
 561     voidpc buf;
 562     unsigned len;
 563 {
 564     gz_stream *s = (gz_stream*)file;
 565
 566     if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
 567
 568     s->stream.next_in = (Bytef*)buf;
 569     s->stream.avail_in = len;
 570
 571     while (s->stream.avail_in != 0) {
 572
 573         if (s->stream.avail_out == 0) {
 574
 575             s->stream.next_out = s->outbuf;
 576             if (fwrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE) {
 577                 s->z_err = Z_ERRNO;
 578                 break;
 579             }
 580             s->stream.avail_out = Z_BUFSIZE;
 581         }
 582         s->in += s->stream.avail_in;
 583         s->out += s->stream.avail_out;
 584         s->z_err = deflate(&(s->stream), Z_NO_FLUSH);
 585         s->in -= s->stream.avail_in;
 586         s->out -= s->stream.avail_out;
 587         if (s->z_err != Z_OK) break;
 588     }
 589     s->crc = crc32(s->crc, (const Bytef *)buf, len);
 590
 591     return (int)(len - s->stream.avail_in);
 592 }
 593
 594
 595 /* ===========================================================================
 596      Converts, formats, and writes the args to the compressed file under
 597    control of the format string, as in fprintf. gzprintf returns the number of
 598    uncompressed bytes actually written (0 in case of error).
 599 */
 600 #ifdef STDC
 601 #include <stdarg.h>
 602
 603 int ZEXPORTVA gzprintf (gzFile file, const char *format, /* args */ ...)
 604 {
 605     char buf[Z_PRINTF_BUFSIZE];
 606     va_list va;
 607     int len;
 608
 609     buf[sizeof(buf) - 1] = 0;
 610     va_start(va, format);
 611 #ifdef NO_vsnprintf
 612 #  ifdef HAS_vsprintf_void
 613     (void)vsprintf(buf, format, va);
 614     va_end(va);
 615     for (len = 0; len < sizeof(buf); len++)
 616         if (buf[len] == 0) break;
 617 #  else
 618     len = vsprintf(buf, format, va);
 619     va_end(va);
 620 #  endif
 621 #else
 622 #  ifdef HAS_vsnprintf_void
 623     (void)vsnprintf(buf, sizeof(buf), format, va);
 624     va_end(va);
 625     len = strlen(buf);
 626 #  else
 627     len = vsnprintf(buf, sizeof(buf), format, va);
 628     va_end(va);
 629 #  endif
 630 #endif
 631     if (len <= 0 || len >= (int)sizeof(buf) || buf[sizeof(buf) - 1] != 0)
 632         return 0;
 633     return gzwrite(file, buf, (unsigned)len);
 634 }
 635 #else /* not ANSI C */
 636
 637 int ZEXPORTVA gzprintf (file, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
 638                        a11, a12, a13, a14, a15, a16, a17, a18, a19, a20)
 639     gzFile file;
 640     const char *format;
 641     int a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
 642         a11, a12, a13, a14, a15, a16, a17, a18, a19, a20;
 643 {
 644     char buf[Z_PRINTF_BUFSIZE];
 645     int len;
 646
 647     buf[sizeof(buf) - 1] = 0;
 648 #ifdef NO_snprintf
 649 #  ifdef HAS_sprintf_void
 650     sprintf(buf, format, a1, a2, a3, a4, a5, a6, a7, a8,
 651             a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
 652     for (len = 0; len < sizeof(buf); len++)
 653         if (buf[len] == 0) break;
 654 #  else
 655     len = sprintf(buf, format, a1, a2, a3, a4, a5, a6, a7, a8,
 656                 a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
 657 #  endif
 658 #else
 659 #  ifdef HAS_snprintf_void
 660     snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
 661              a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
 662     len = strlen(buf);
 663 #  else
 664     len = snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
 665                  a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
 666 #  endif
 667 #endif
 668     if (len <= 0 || len >= sizeof(buf) || buf[sizeof(buf) - 1] != 0)
 669         return 0;
 670     return gzwrite(file, buf, len);
 671 }
 672 #endif
 673
 674 /* ===========================================================================
 675       Writes c, converted to an unsigned char, into the compressed file.
 676    gzputc returns the value that was written, or -1 in case of error.
 677 */
 678 int ZEXPORT gzputc(file, c)
 679     gzFile file;
 680     int c;
 681 {
 682     unsigned char cc = (unsigned char) c; /* required for big endian systems */
 683
 684     return gzwrite(file, &cc, 1) == 1 ? (int)cc : -1;
 685 }
 686
 687
 688 /* ===========================================================================
 689       Writes the given null-terminated string to the compressed file, excluding
 690    the terminating null character.
 691       gzputs returns the number of characters written, or -1 in case of error.
 692 */
 693 int ZEXPORT gzputs(file, s)
 694     gzFile file;
 695     const char *s;
 696 {
 697     return gzwrite(file, (char*)s, (unsigned)strlen(s));
 698 }
 699
 700
 701 /* ===========================================================================
 702      Flushes all pending output into the compressed file. The parameter
 703    flush is as in the deflate() function.
 704 */
 705 local int do_flush (file, flush)
 706     gzFile file;
 707     int flush;
 708 {
 709     uInt len;
 710     int done = 0;
 711     gz_stream *s = (gz_stream*)file;
 712
 713     if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
 714
 715     s->stream.avail_in = 0; /* should be zero already anyway */
 716
 717     for (;;) {
 718         len = Z_BUFSIZE - s->stream.avail_out;
 719
 720         if (len != 0) {
 721             if ((uInt)fwrite(s->outbuf, 1, len, s->file) != len) {
 722                 s->z_err = Z_ERRNO;
 723                 return Z_ERRNO;
 724             }
 725             s->stream.next_out = s->outbuf;
 726             s->stream.avail_out = Z_BUFSIZE;
 727         }
 728         if (done) break;
 729         s->out += s->stream.avail_out;
 730         s->z_err = deflate(&(s->stream), flush);
 731         s->out -= s->stream.avail_out;
 732
 733         /* Ignore the second of two consecutive flushes: */
 734         if (len == 0 && s->z_err == Z_BUF_ERROR) s->z_err = Z_OK;
 735
 736         /* deflate has finished flushing only when it hasn't used up
 737          * all the available space in the output buffer:
 738          */
 739         done = (s->stream.avail_out != 0 || s->z_err == Z_STREAM_END);
 740
 741         if (s->z_err != Z_OK && s->z_err != Z_STREAM_END) break;
 742     }
 743     return  s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
 744 }
 745
 746 int ZEXPORT gzflush (file, flush)
 747      gzFile file;
 748      int flush;
 749 {
 750     gz_stream *s = (gz_stream*)file;
 751     int err = do_flush (file, flush);
 752
 753     if (err) return err;
 754     fflush(s->file);
 755     return  s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
 756 }
 757 #endif /* NO_GZCOMPRESS */
 758
 759 /* ===========================================================================
 760       Sets the starting position for the next gzread or gzwrite on the given
 761    compressed file. The offset represents a number of bytes in the
 762       gzseek returns the resulting offset location as measured in bytes from
 763    the beginning of the uncompressed stream, or -1 in case of error.
 764       SEEK_END is not implemented, returns error.
 765       In this version of the library, gzseek can be extremely slow.
 766 */
 767 z_off_t ZEXPORT gzseek (file, offset, whence)
 768     gzFile file;
 769     z_off_t offset;
 770     int whence;
 771 {
 772     gz_stream *s = (gz_stream*)file;
 773
 774     if (s == NULL || whence == SEEK_END ||
 775         s->z_err == Z_ERRNO || s->z_err == Z_DATA_ERROR) {
 776         return -1L;
 777     }
 778
 779     if (s->mode == 'w') {
 780 #ifdef NO_GZCOMPRESS
 781         return -1L;
 782 #else
 783         if (whence == SEEK_SET) {
 784             offset -= s->in;
 785         }
 786         if (offset < 0) return -1L;
 787
 788         /* At this point, offset is the number of zero bytes to write. */
 789         if (s->inbuf == Z_NULL) {
 790             s->inbuf = (Byte*)ALLOC(Z_BUFSIZE); /* for seeking */
 791             if (s->inbuf == Z_NULL) return -1L;
 792             zmemzero(s->inbuf, Z_BUFSIZE);
 793         }
 794         while (offset > 0)  {
 795             uInt size = Z_BUFSIZE;
 796             if (offset < Z_BUFSIZE) size = (uInt)offset;
 797
 798             size = gzwrite(file, s->inbuf, size);
 799             if (size == 0) return -1L;
 800
 801             offset -= size;
 802         }
 803         return s->in;
 804 #endif
 805     }
 806     /* Rest of function is for reading only */
 807
 808     /* compute absolute position */
 809     if (whence == SEEK_CUR) {
 810         offset += s->out;
 811     }
 812     if (offset < 0) return -1L;
 813
 814     if (s->transparent) {
 815         /* map to fseek */
 816         s->back = EOF;
 817         s->stream.avail_in = 0;
 818         s->stream.next_in = s->inbuf;
 819         if (fseek(s->file, offset, SEEK_SET) < 0) return -1L;
 820
 821         s->in = s->out = offset;
 822         return offset;
 823     }
 824
 825     /* For a negative seek, rewind and use positive seek */
 826     if (offset >= s->out) {
 827         offset -= s->out;
 828     } else if (gzrewind(file) < 0) {
 829         return -1L;
 830     }
 831     /* offset is now the number of bytes to skip. */
 832
 833     if (offset != 0 && s->outbuf == Z_NULL) {
 834         s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
 835         if (s->outbuf == Z_NULL) return -1L;
 836     }
 837     if (offset && s->back != EOF) {
 838         s->back = EOF;
 839         s->out++;
 840         offset--;
 841         if (s->last) s->z_err = Z_STREAM_END;
 842     }
 843     while (offset > 0)  {
 844         int size = Z_BUFSIZE;
 845         if (offset < Z_BUFSIZE) size = (int)offset;
 846
 847         size = gzread(file, s->outbuf, (uInt)size);
 848         if (size <= 0) return -1L;
 849         offset -= size;
 850     }
 851     return s->out;
 852 }
 853
 854 /* ===========================================================================
 855      Rewinds input file.
 856 */
 857 int ZEXPORT gzrewind (file)
 858     gzFile file;
 859 {
 860     gz_stream *s = (gz_stream*)file;
 861
 862     if (s == NULL || s->mode != 'r') return -1;
 863
 864     s->z_err = Z_OK;
 865     s->z_eof = 0;
 866     s->back = EOF;
 867     s->stream.avail_in = 0;
 868     s->stream.next_in = s->inbuf;
 869     s->crc = crc32(0L, Z_NULL, 0);
 870     if (!s->transparent) (void)inflateReset(&s->stream);
 871     s->in = 0;
 872     s->out = 0;
 873     return fseek(s->file, s->start, SEEK_SET);
 874 }
 875
 876 /* ===========================================================================
 877      Returns the starting position for the next gzread or gzwrite on the
 878    given compressed file. This position represents a number of bytes in the
 879    uncompressed data stream.
 880 */
 881 z_off_t ZEXPORT gztell (file)
 882     gzFile file;
 883 {
 884     return gzseek(file, 0L, SEEK_CUR);
 885 }
 886
 887 /* ===========================================================================
 888      Returns 1 when EOF has previously been detected reading the given
 889    input stream, otherwise zero.
 890 */
 891 int ZEXPORT gzeof (file)
 892     gzFile file;
 893 {
 894     gz_stream *s = (gz_stream*)file;
 895
 896     /* With concatenated compressed files that can have embedded
 897      * crc trailers, z_eof is no longer the only/best indicator of EOF
 898      * on a gz_stream. Handle end-of-stream error explicitly here.
 899      */
 900     if (s == NULL || s->mode != 'r') return 0;
 901     if (s->z_eof) return 1;
 902     return s->z_err == Z_STREAM_END;
 903 }
 904
 905 /* ===========================================================================
 906      Returns 1 if reading and doing so transparently, otherwise zero.
 907 */
 908 int ZEXPORT gzdirect (file)
 909     gzFile file;
 910 {
 911     gz_stream *s = (gz_stream*)file;
 912
 913     if (s == NULL || s->mode != 'r') return 0;
 914     return s->transparent;
 915 }
 916
 917 /* ===========================================================================
 918    Outputs a long in LSB order to the given file
 919 */
 920 local void putLong (file, x)
 921     FILE *file;
 922     uLong x;
 923 {
 924     int n;
 925     for (n = 0; n < 4; n++) {
 926         fputc((int)(x & 0xff), file);
 927         x >>= 8;
 928     }
 929 }
 930
 931 /* ===========================================================================
 932    Reads a long in LSB order from the given gz_stream. Sets z_err in case
 933    of error.
 934 */
 935 local uLong getLong (s)
 936     gz_stream *s;
 937 {
 938     uLong x = (uLong)get_byte(s);
 939     int c;
 940
 941     x += ((uLong)get_byte(s))<<8;
 942     x += ((uLong)get_byte(s))<<16;
 943     c = get_byte(s);
 944     if (c == EOF) s->z_err = Z_DATA_ERROR;
 945     x += ((uLong)c)<<24;
 946     return x;
 947 }
 948
 949 /* ===========================================================================
 950      Flushes all pending output if necessary, closes the compressed file
 951    and deallocates all the (de)compression state.
 952 */
 953 int ZEXPORT gzclose (file)
 954     gzFile file;
 955 {
 956     gz_stream *s = (gz_stream*)file;
 957
 958     if (s == NULL) return Z_STREAM_ERROR;
 959
 960     if (s->mode == 'w') {
 961 #ifdef NO_GZCOMPRESS
 962         return Z_STREAM_ERROR;
 963 #else
 964         if (do_flush (file, Z_FINISH) != Z_OK)
 965             return destroy((gz_stream*)file);
 966
 967         putLong (s->file, s->crc);
 968         putLong (s->file, (uLong)(s->in & 0xffffffff));
 969 #endif
 970     }
 971     return destroy((gz_stream*)file);
 972 }
 973
 974 #ifdef STDC
 975 #  define zstrerror(errnum) strerror(errnum)
 976 #else
 977 #  define zstrerror(errnum) ""
 978 #endif
 979
 980 /* ===========================================================================
 981      Returns the error message for the last error which occurred on the
 982    given compressed file. errnum is set to zlib error number. If an
 983    error occurred in the file system and not in the compression library,
 984    errnum is set to Z_ERRNO and the application may consult errno
 985    to get the exact error code.
 986 */
 987 const char * ZEXPORT gzerror (file, errnum)
 988     gzFile file;
 989     int *errnum;
 990 {
 991     char *m;
 992     gz_stream *s = (gz_stream*)file;
 993
 994     if (s == NULL) {
 995         *errnum = Z_STREAM_ERROR;
 996         return (const char*)ERR_MSG(Z_STREAM_ERROR);
 997     }
 998     *errnum = s->z_err;
 999     if (*errnum == Z_OK) return (const char*)"";
1000
1001     m = (char*)(*errnum == Z_ERRNO ? zstrerror(errno) : s->stream.msg);
1002
1003     if (m == NULL || *m == '\0') m = (char*)ERR_MSG(s->z_err);
1004
1005     TRYFREE(s->msg);
1006     s->msg = (char*)ALLOC(strlen(s->path) + strlen(m) + 3);
1007     if (s->msg == Z_NULL) return (const char*)ERR_MSG(Z_MEM_ERROR);
1008     strcpy(s->msg, s->path);
1009     strcat(s->msg, ": ");
1010     strcat(s->msg, m);
1011     return (const char*)s->msg;
1012 }
1013
1014 /* ===========================================================================
1015      Clear the error and end-of-file flags, and do the same for the real file.
1016 */
1017 void ZEXPORT gzclearerr (file)
1018     gzFile file;
1019 {
1020     gz_stream *s = (gz_stream*)file;
1021
1022     if (s == NULL) return;
1023     if (s->z_err != Z_STREAM_END) s->z_err = Z_OK;
1024     s->z_eof = 0;
1025     clearerr(s->file);
1026 }