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
5 * Compile this file with -DNO_GZCOMPRESS to avoid the compression code.
14 #ifdef NO_DEFLATE /* for compatibility with old definition */
15 # define NO_GZCOMPRESS
19 struct internal_state {int dummy;}; /* for buggy compilers */
24 # define Z_BUFSIZE 4096 /* minimize memory usage for 16-bit DOS */
26 # define Z_BUFSIZE 16384
29 #ifndef Z_PRINTF_BUFSIZE
30 # define Z_PRINTF_BUFSIZE 4096
34 # pragma map (fdopen , "\174\174FDOPEN")
35 FILE *fdopen(int, const char *);
39 extern voidp malloc OF((uInt size));
40 extern void free OF((voidpf ptr));
43 #define ALLOC(size) malloc(size)
44 #define TRYFREE(p) {if (p) free(p);}
46 static int const gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
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 */
56 typedef struct gz_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 */
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));
81 int destroy OF((gz_stream *s));
82 local void putLong OF((FILE *file, uLong x));
83 local uLong getLong OF((gz_stream *s));
85 /* ===========================================================================
86 Opens a gzip (.gz) file for reading or writing. The mode parameter
87 is as in fopen ("rb" or "wb"). The file is given either by file descriptor
88 or path name (if fd == -1).
89 gz_open returns NULL if the file could not be opened or if there was
90 insufficient memory to allocate the (de)compression state; errno
91 can be checked to distinguish the two cases (if errno is zero, the
92 zlib error is Z_MEM_ERROR).
94 local gzFile gz_open (path, mode, fd)
100 int level = Z_DEFAULT_COMPRESSION; /* compression level */
101 int strategy = Z_DEFAULT_STRATEGY; /* compression strategy */
102 char *p = (char*)mode;
104 char fmode[80]; /* copy of mode, without the compression level */
107 if (!path || !mode) return Z_NULL;
109 s = (gz_stream *)ALLOC(sizeof(gz_stream));
110 if (!s) return Z_NULL;
112 s->stream.zalloc = (alloc_func)0;
113 s->stream.zfree = (free_func)0;
114 s->stream.opaque = (voidpf)0;
115 s->stream.next_in = s->inbuf = Z_NULL;
116 s->stream.next_out = s->outbuf = Z_NULL;
117 s->stream.avail_in = s->stream.avail_out = 0;
124 s->crc = crc32(0L, Z_NULL, 0);
128 s->path = (char*)ALLOC(strlen(path)+1);
129 if (s->path == NULL) {
130 return destroy(s), (gzFile)Z_NULL;
132 strcpy(s->path, path); /* do this early for debugging */
136 if (*p == 'r') s->mode = 'r';
137 if (*p == 'w' || *p == 'a') s->mode = 'w';
138 if (*p >= '0' && *p <= '9') {
140 } else if (*p == 'f') {
141 strategy = Z_FILTERED;
142 } else if (*p == 'h') {
143 strategy = Z_HUFFMAN_ONLY;
144 } else if (*p == 'R') {
147 *m++ = *p; /* copy the mode */
149 } while (*p++ && m != fmode + sizeof(fmode));
150 if (s->mode == '\0') return destroy(s), (gzFile)Z_NULL;
152 if (s->mode == 'w') {
154 err = Z_STREAM_ERROR;
156 err = deflateInit2(&(s->stream), level,
157 Z_DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL, strategy);
158 /* windowBits is passed < 0 to suppress zlib header */
160 s->stream.next_out = s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
162 if (err != Z_OK || s->outbuf == Z_NULL) {
163 return destroy(s), (gzFile)Z_NULL;
166 s->stream.next_in = s->inbuf = (Byte*)ALLOC(Z_BUFSIZE);
168 err = inflateInit2(&(s->stream), -MAX_WBITS);
169 /* windowBits is passed < 0 to tell that there is no zlib header.
170 * Note that in this case inflate *requires* an extra "dummy" byte
171 * after the compressed stream in order to complete decompression and
172 * return Z_STREAM_END. Here the gzip CRC32 ensures that 4 bytes are
173 * present after the compressed stream.
175 if (err != Z_OK || s->inbuf == Z_NULL) {
176 return destroy(s), (gzFile)Z_NULL;
179 s->stream.avail_out = Z_BUFSIZE;
182 s->file = fd < 0 ? F_OPEN(path, fmode) : (FILE*)fdopen(fd, fmode);
184 if (s->file == NULL) {
185 return destroy(s), (gzFile)Z_NULL;
187 if (s->mode == 'w') {
188 /* Write a very simple .gz header:
190 fprintf(s->file, "%c%c%c%c%c%c%c%c%c%c", gz_magic[0], gz_magic[1],
191 Z_DEFLATED, 0 /*flags*/, 0,0,0,0 /*time*/, 0 /*xflags*/, OS_CODE);
193 /* We use 10L instead of ftell(s->file) to because ftell causes an
194 * fflush on some systems. This version of the library doesn't use
195 * start anyway in write mode, so this initialization is not
199 check_header(s); /* skip the .gz header */
200 s->start = ftell(s->file) - s->stream.avail_in;
206 /* ===========================================================================
207 Opens a gzip (.gz) file for reading or writing.
209 gzFile ZEXPORT gzopen (path, mode)
213 return gz_open (path, mode, -1);
216 /* ===========================================================================
217 Associate a gzFile with the file descriptor fd. fd is not dup'ed here
218 to mimic the behavio(u)r of fdopen.
220 gzFile ZEXPORT gzdopen (fd, mode)
224 char name[46]; /* allow for up to 128-bit integers */
226 if (fd < 0) return (gzFile)Z_NULL;
227 sprintf(name, "<fd:%d>", fd); /* for debugging */
229 return gz_open (name, mode, fd);
232 /* ===========================================================================
233 * Update the compression level and strategy
235 int ZEXPORT gzsetparams (file, level, strategy)
240 gz_stream *s = (gz_stream*)file;
242 if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
244 /* Make room to allow flushing */
245 if (s->stream.avail_out == 0) {
247 s->stream.next_out = s->outbuf;
248 if (fwrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE) {
251 s->stream.avail_out = Z_BUFSIZE;
254 return deflateParams (&(s->stream), level, strategy);
257 /* ===========================================================================
258 Read a byte from a gz_stream; update next_in and avail_in. Return EOF
260 IN assertion: the stream s has been sucessfully opened for reading.
262 local int get_byte(s)
265 if (s->z_eof) return EOF;
266 if (s->stream.avail_in == 0) {
268 s->stream.avail_in = (uInt)fread(s->inbuf, 1, Z_BUFSIZE, s->file);
269 if (s->stream.avail_in == 0) {
271 if (ferror(s->file)) s->z_err = Z_ERRNO;
274 s->stream.next_in = s->inbuf;
276 s->stream.avail_in--;
277 return *(s->stream.next_in)++;
280 /* ===========================================================================
281 Check the gzip header of a gz_stream opened for reading. Set the stream
282 mode to transparent if the gzip magic header is not present; set s->err
283 to Z_DATA_ERROR if the magic header is present but the rest of the header
285 IN assertion: the stream s has already been created sucessfully;
286 s->stream.avail_in is zero for the first time, but may be non-zero
287 for concatenated .gz files.
289 local void check_header(s)
292 int method; /* method byte */
293 int flags; /* flags byte */
297 /* Assure two bytes in the buffer so we can peek ahead -- handle case
298 where first byte of header is at the end of the buffer after the last
300 len = s->stream.avail_in;
302 if (len) s->inbuf[0] = s->stream.next_in[0];
304 len = (uInt)fread(s->inbuf + len, 1, Z_BUFSIZE >> len, s->file);
305 if (len == 0 && ferror(s->file)) s->z_err = Z_ERRNO;
306 s->stream.avail_in += len;
307 s->stream.next_in = s->inbuf;
308 if (s->stream.avail_in < 2) {
309 s->transparent = s->stream.avail_in;
314 /* Peek ahead to check the gzip magic header */
315 if (s->stream.next_in[0] != gz_magic[0] ||
316 s->stream.next_in[1] != gz_magic[1]) {
320 s->stream.avail_in -= 2;
321 s->stream.next_in += 2;
323 /* Check the rest of the gzip header */
324 method = get_byte(s);
326 if (method != Z_DEFLATED || (flags & RESERVED) != 0) {
327 s->z_err = Z_DATA_ERROR;
331 /* Discard time, xflags and OS code: */
332 for (len = 0; len < 6; len++) (void)get_byte(s);
334 if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */
335 len = (uInt)get_byte(s);
336 len += ((uInt)get_byte(s))<<8;
337 /* len is garbage if EOF but the loop below will quit anyway */
338 while (len-- != 0 && get_byte(s) != EOF) ;
340 if ((flags & ORIG_NAME) != 0) { /* skip the original file name */
341 while ((c = get_byte(s)) != 0 && c != EOF) ;
343 if ((flags & COMMENT) != 0) { /* skip the .gz file comment */
344 while ((c = get_byte(s)) != 0 && c != EOF) ;
346 if ((flags & HEAD_CRC) != 0) { /* skip the header crc */
347 for (len = 0; len < 2; len++) (void)get_byte(s);
349 s->z_err = s->z_eof ? Z_DATA_ERROR : Z_OK;
352 /* ===========================================================================
353 * Cleanup then free the given gz_stream. Return a zlib error code.
354 Try freeing in the reverse order of allocations.
362 if (!s) return Z_STREAM_ERROR;
366 if (s->stream.state != NULL) {
367 if (s->mode == 'w') {
369 err = Z_STREAM_ERROR;
371 err = deflateEnd(&(s->stream));
373 } else if (s->mode == 'r') {
374 err = inflateEnd(&(s->stream));
377 if (s->file != NULL && fclose(s->file)) {
379 if (errno != ESPIPE) /* fclose is broken for pipes in HP/UX */
383 if (s->z_err < 0) err = s->z_err;
392 /* ===========================================================================
393 Reads the given number of uncompressed bytes from the compressed file.
394 gzread returns the number of bytes actually read (0 for end of file).
396 int ZEXPORT gzread (file, buf, len)
401 gz_stream *s = (gz_stream*)file;
402 Bytef *start = (Bytef*)buf; /* starting point for crc computation */
403 Byte *next_out; /* == stream.next_out but not forced far (for MSDOS) */
405 if (s == NULL || s->mode != 'r') return Z_STREAM_ERROR;
407 if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO) return -1;
408 if (s->z_err == Z_STREAM_END) return 0; /* EOF */
410 next_out = (Byte*)buf;
411 s->stream.next_out = (Bytef*)buf;
412 s->stream.avail_out = len;
414 if (s->stream.avail_out && s->back != EOF) {
415 *next_out++ = s->back;
416 s->stream.next_out++;
417 s->stream.avail_out--;
422 s->z_err = Z_STREAM_END;
427 while (s->stream.avail_out != 0) {
429 if (s->transparent) {
430 /* Copy first the lookahead bytes: */
431 uInt n = s->stream.avail_in;
432 if (n > s->stream.avail_out) n = s->stream.avail_out;
434 zmemcpy(s->stream.next_out, s->stream.next_in, n);
436 s->stream.next_out = next_out;
437 s->stream.next_in += n;
438 s->stream.avail_out -= n;
439 s->stream.avail_in -= n;
441 if (s->stream.avail_out > 0) {
442 s->stream.avail_out -=
443 (uInt)fread(next_out, 1, s->stream.avail_out, s->file);
445 len -= s->stream.avail_out;
448 if (len == 0) s->z_eof = 1;
451 if (s->stream.avail_in == 0 && !s->z_eof) {
454 s->stream.avail_in = (uInt)fread(s->inbuf, 1, Z_BUFSIZE, s->file);
455 if (s->stream.avail_in == 0) {
457 if (ferror(s->file)) {
462 s->stream.next_in = s->inbuf;
464 s->in += s->stream.avail_in;
465 s->out += s->stream.avail_out;
466 s->z_err = inflate(&(s->stream), Z_NO_FLUSH);
467 s->in -= s->stream.avail_in;
468 s->out -= s->stream.avail_out;
470 if (s->z_err == Z_STREAM_END) {
471 /* Check CRC and original size */
472 s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
473 start = s->stream.next_out;
475 if (getLong(s) != s->crc) {
476 s->z_err = Z_DATA_ERROR;
479 /* The uncompressed length returned by above getlong() may be
480 * different from s->out in case of concatenated .gz files.
481 * Check for such files:
484 if (s->z_err == Z_OK) {
485 inflateReset(&(s->stream));
486 s->crc = crc32(0L, Z_NULL, 0);
490 if (s->z_err != Z_OK || s->z_eof) break;
492 s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
494 if (len == s->stream.avail_out &&
495 (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO))
497 return (int)(len - s->stream.avail_out);
501 /* ===========================================================================
502 Reads one byte from the compressed file. gzgetc returns this byte
503 or -1 in case of end of file or error.
505 int ZEXPORT gzgetc(file)
510 return gzread(file, &c, 1) == 1 ? c : -1;
514 /* ===========================================================================
515 Push one byte back onto the stream.
517 int ZEXPORT gzungetc(c, file)
521 gz_stream *s = (gz_stream*)file;
523 if (s == NULL || s->mode != 'r' || c == EOF || s->back != EOF) return EOF;
526 s->last = (s->z_err == Z_STREAM_END);
527 if (s->last) s->z_err = Z_OK;
533 /* ===========================================================================
534 Reads bytes from the compressed file until len-1 characters are
535 read, or a newline character is read and transferred to buf, or an
536 end-of-file condition is encountered. The string is then terminated
537 with a null character.
538 gzgets returns buf, or Z_NULL in case of error.
540 The current implementation is not optimized at all.
542 char * ZEXPORT gzgets(file, buf, len)
548 if (buf == Z_NULL || len <= 0) return Z_NULL;
550 while (--len > 0 && gzread(file, buf, 1) == 1 && *buf++ != '\n') ;
552 return b == buf && len > 0 ? Z_NULL : b;
556 #ifndef NO_GZCOMPRESS
557 /* ===========================================================================
558 Writes the given number of uncompressed bytes into the compressed file.
559 gzwrite returns the number of bytes actually written (0 in case of error).
561 int ZEXPORT gzwrite (file, buf, len)
566 gz_stream *s = (gz_stream*)file;
568 if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
570 s->stream.next_in = (Bytef*)buf;
571 s->stream.avail_in = len;
573 while (s->stream.avail_in != 0) {
575 if (s->stream.avail_out == 0) {
577 s->stream.next_out = s->outbuf;
578 if (fwrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE) {
582 s->stream.avail_out = Z_BUFSIZE;
584 s->in += s->stream.avail_in;
585 s->out += s->stream.avail_out;
586 s->z_err = deflate(&(s->stream), Z_NO_FLUSH);
587 s->in -= s->stream.avail_in;
588 s->out -= s->stream.avail_out;
589 if (s->z_err != Z_OK) break;
591 s->crc = crc32(s->crc, (const Bytef *)buf, len);
593 return (int)(len - s->stream.avail_in);
597 /* ===========================================================================
598 Converts, formats, and writes the args to the compressed file under
599 control of the format string, as in fprintf. gzprintf returns the number of
600 uncompressed bytes actually written (0 in case of error).
605 int ZEXPORTVA gzprintf (gzFile file, const char *format, /* args */ ...)
607 char buf[Z_PRINTF_BUFSIZE];
611 buf[sizeof(buf) - 1] = 0;
612 va_start(va, format);
614 # ifdef HAS_vsprintf_void
615 (void)vsprintf(buf, format, va);
617 for (len = 0; len < sizeof(buf); len++)
618 if (buf[len] == 0) break;
620 len = vsprintf(buf, format, va);
624 # ifdef HAS_vsnprintf_void
625 (void)vsnprintf(buf, sizeof(buf), format, va);
629 len = vsnprintf(buf, sizeof(buf), format, va);
633 if (len <= 0 || len >= (int)sizeof(buf) || buf[sizeof(buf) - 1] != 0)
635 return gzwrite(file, buf, (unsigned)len);
637 #else /* not ANSI C */
639 int ZEXPORTVA gzprintf (file, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
640 a11, a12, a13, a14, a15, a16, a17, a18, a19, a20)
643 int a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
644 a11, a12, a13, a14, a15, a16, a17, a18, a19, a20;
646 char buf[Z_PRINTF_BUFSIZE];
649 buf[sizeof(buf) - 1] = 0;
651 # ifdef HAS_sprintf_void
652 sprintf(buf, format, a1, a2, a3, a4, a5, a6, a7, a8,
653 a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
654 for (len = 0; len < sizeof(buf); len++)
655 if (buf[len] == 0) break;
657 len = sprintf(buf, format, a1, a2, a3, a4, a5, a6, a7, a8,
658 a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
661 # ifdef HAS_snprintf_void
662 snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
663 a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
666 len = snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
667 a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
670 if (len <= 0 || len >= sizeof(buf) || buf[sizeof(buf) - 1] != 0)
672 return gzwrite(file, buf, len);
676 /* ===========================================================================
677 Writes c, converted to an unsigned char, into the compressed file.
678 gzputc returns the value that was written, or -1 in case of error.
680 int ZEXPORT gzputc(file, c)
684 unsigned char cc = (unsigned char) c; /* required for big endian systems */
686 return gzwrite(file, &cc, 1) == 1 ? (int)cc : -1;
690 /* ===========================================================================
691 Writes the given null-terminated string to the compressed file, excluding
692 the terminating null character.
693 gzputs returns the number of characters written, or -1 in case of error.
695 int ZEXPORT gzputs(file, s)
699 return gzwrite(file, (char*)s, (unsigned)strlen(s));
703 /* ===========================================================================
704 Flushes all pending output into the compressed file. The parameter
705 flush is as in the deflate() function.
707 local int do_flush (file, flush)
713 gz_stream *s = (gz_stream*)file;
715 if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
717 s->stream.avail_in = 0; /* should be zero already anyway */
720 len = Z_BUFSIZE - s->stream.avail_out;
723 if ((uInt)fwrite(s->outbuf, 1, len, s->file) != len) {
727 s->stream.next_out = s->outbuf;
728 s->stream.avail_out = Z_BUFSIZE;
731 s->out += s->stream.avail_out;
732 s->z_err = deflate(&(s->stream), flush);
733 s->out -= s->stream.avail_out;
735 /* Ignore the second of two consecutive flushes: */
736 if (len == 0 && s->z_err == Z_BUF_ERROR) s->z_err = Z_OK;
738 /* deflate has finished flushing only when it hasn't used up
739 * all the available space in the output buffer:
741 done = (s->stream.avail_out != 0 || s->z_err == Z_STREAM_END);
743 if (s->z_err != Z_OK && s->z_err != Z_STREAM_END) break;
745 return s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
748 int ZEXPORT gzflush (file, flush)
752 gz_stream *s = (gz_stream*)file;
753 int err = do_flush (file, flush);
757 return s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
759 #endif /* NO_GZCOMPRESS */
761 /* ===========================================================================
762 Sets the starting position for the next gzread or gzwrite on the given
763 compressed file. The offset represents a number of bytes in the
764 gzseek returns the resulting offset location as measured in bytes from
765 the beginning of the uncompressed stream, or -1 in case of error.
766 SEEK_END is not implemented, returns error.
767 In this version of the library, gzseek can be extremely slow.
769 z_off_t ZEXPORT gzseek (file, offset, whence)
774 gz_stream *s = (gz_stream*)file;
776 if (s == NULL || whence == SEEK_END ||
777 s->z_err == Z_ERRNO || s->z_err == Z_DATA_ERROR) {
781 if (s->mode == 'w') {
785 if (whence == SEEK_SET) {
788 if (offset < 0) return -1L;
790 /* At this point, offset is the number of zero bytes to write. */
791 if (s->inbuf == Z_NULL) {
792 s->inbuf = (Byte*)ALLOC(Z_BUFSIZE); /* for seeking */
793 if (s->inbuf == Z_NULL) return -1L;
794 zmemzero(s->inbuf, Z_BUFSIZE);
797 uInt size = Z_BUFSIZE;
798 if (offset < Z_BUFSIZE) size = (uInt)offset;
800 size = gzwrite(file, s->inbuf, size);
801 if (size == 0) return -1L;
808 /* Rest of function is for reading only */
810 /* compute absolute position */
811 if (whence == SEEK_CUR) {
814 if (offset < 0) return -1L;
816 if (s->transparent) {
819 s->stream.avail_in = 0;
820 s->stream.next_in = s->inbuf;
821 if (fseek(s->file, offset, SEEK_SET) < 0) return -1L;
823 s->in = s->out = offset;
827 /* For a negative seek, rewind and use positive seek */
828 if (offset >= s->out) {
830 } else if (gzrewind(file) < 0) {
833 /* offset is now the number of bytes to skip. */
835 if (offset != 0 && s->outbuf == Z_NULL) {
836 s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
837 if (s->outbuf == Z_NULL) return -1L;
839 if (offset && s->back != EOF) {
843 if (s->last) s->z_err = Z_STREAM_END;
846 int size = Z_BUFSIZE;
847 if (offset < Z_BUFSIZE) size = (int)offset;
849 size = gzread(file, s->outbuf, (uInt)size);
850 if (size <= 0) return -1L;
856 /* ===========================================================================
859 int ZEXPORT gzrewind (file)
862 gz_stream *s = (gz_stream*)file;
864 if (s == NULL || s->mode != 'r') return -1;
869 s->stream.avail_in = 0;
870 s->stream.next_in = s->inbuf;
871 s->crc = crc32(0L, Z_NULL, 0);
872 if (!s->transparent) (void)inflateReset(&s->stream);
875 return fseek(s->file, s->start, SEEK_SET);
878 /* ===========================================================================
879 Returns the starting position for the next gzread or gzwrite on the
880 given compressed file. This position represents a number of bytes in the
881 uncompressed data stream.
883 z_off_t ZEXPORT gztell (file)
886 return gzseek(file, 0L, SEEK_CUR);
889 /* ===========================================================================
890 Returns 1 when EOF has previously been detected reading the given
891 input stream, otherwise zero.
893 int ZEXPORT gzeof (file)
896 gz_stream *s = (gz_stream*)file;
898 /* With concatenated compressed files that can have embedded
899 * crc trailers, z_eof is no longer the only/best indicator of EOF
900 * on a gz_stream. Handle end-of-stream error explicitly here.
902 if (s == NULL || s->mode != 'r') return 0;
903 if (s->z_eof) return 1;
904 return s->z_err == Z_STREAM_END;
907 /* ===========================================================================
908 Returns 1 if reading and doing so transparently, otherwise zero.
910 int ZEXPORT gzdirect (file)
913 gz_stream *s = (gz_stream*)file;
915 if (s == NULL || s->mode != 'r') return 0;
916 return s->transparent;
919 /* ===========================================================================
920 Outputs a long in LSB order to the given file
922 local void putLong (file, x)
927 for (n = 0; n < 4; n++) {
928 fputc((int)(x & 0xff), file);
933 /* ===========================================================================
934 Reads a long in LSB order from the given gz_stream. Sets z_err in case
937 local uLong getLong (s)
940 uLong x = (uLong)get_byte(s);
943 x += ((uLong)get_byte(s))<<8;
944 x += ((uLong)get_byte(s))<<16;
946 if (c == EOF) s->z_err = Z_DATA_ERROR;
951 /* ===========================================================================
952 Flushes all pending output if necessary, closes the compressed file
953 and deallocates all the (de)compression state.
955 int ZEXPORT gzclose (file)
958 gz_stream *s = (gz_stream*)file;
960 if (s == NULL) return Z_STREAM_ERROR;
962 if (s->mode == 'w') {
964 return Z_STREAM_ERROR;
966 if (do_flush (file, Z_FINISH) != Z_OK)
967 return destroy((gz_stream*)file);
969 putLong (s->file, s->crc);
970 putLong (s->file, (uLong)(s->in & 0xffffffff));
973 return destroy((gz_stream*)file);
977 # define zstrerror(errnum) strerror(errnum)
979 # define zstrerror(errnum) ""
982 /* ===========================================================================
983 Returns the error message for the last error which occurred on the
984 given compressed file. errnum is set to zlib error number. If an
985 error occurred in the file system and not in the compression library,
986 errnum is set to Z_ERRNO and the application may consult errno
987 to get the exact error code.
989 const char * ZEXPORT gzerror (file, errnum)
994 gz_stream *s = (gz_stream*)file;
997 *errnum = Z_STREAM_ERROR;
998 return (const char*)ERR_MSG(Z_STREAM_ERROR);
1001 if (*errnum == Z_OK) return (const char*)"";
1003 m = (char*)(*errnum == Z_ERRNO ? zstrerror(errno) : s->stream.msg);
1005 if (m == NULL || *m == '\0') m = (char*)ERR_MSG(s->z_err);
1008 s->msg = (char*)ALLOC(strlen(s->path) + strlen(m) + 3);
1009 if (s->msg == Z_NULL) return (const char*)ERR_MSG(Z_MEM_ERROR);
1010 strcpy(s->msg, s->path);
1011 strcat(s->msg, ": ");
1013 return (const char*)s->msg;
1016 /* ===========================================================================
1017 Clear the error and end-of-file flags, and do the same for the real file.
1019 void ZEXPORT gzclearerr (file)
1022 gz_stream *s = (gz_stream*)file;
1024 if (s == NULL) return;
1025 if (s->z_err != Z_STREAM_END) s->z_err = Z_OK;