1 /* gzlib.c -- zlib functions common to reading and writing gzip files
2 * Copyright (C) 2004-2024 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
8 #if defined(_WIN32) && !defined(__BORLANDC__)
9 # define LSEEK _lseeki64
11 #if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
12 # define LSEEK lseek64
20 /* Map the Windows error number in ERROR to a locale-dependent error message
21 string and return a pointer to it. Typically, the values for ERROR come
24 The string pointed to shall not be modified by the application, but may be
25 overwritten by a subsequent call to gz_strwinerror
27 The gz_strwinerror function does not change the current setting of
29 char ZLIB_INTERNAL *gz_strwinerror(DWORD error) {
30 static char buf[1024];
33 DWORD lasterr = GetLastError();
34 DWORD chars = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM
35 | FORMAT_MESSAGE_ALLOCATE_BUFFER,
38 0, /* Default language */
43 /* If there is an \r\n appended, zap it. */
45 && msgbuf[chars - 2] == '\r' && msgbuf[chars - 1] == '\n') {
50 if (chars > sizeof (buf) - 1) {
51 chars = sizeof (buf) - 1;
55 wcstombs(buf, msgbuf, chars + 1);
59 sprintf(buf, "unknown win32 error (%ld)", error);
62 SetLastError(lasterr);
68 /* Reset gzip file state */
69 local void gz_reset(gz_statep state) {
70 state->x.have = 0; /* no output data available */
71 if (state->mode == GZ_READ) { /* for reading ... */
72 state->eof = 0; /* not at end of file */
73 state->past = 0; /* have not read past end yet */
74 state->how = LOOK; /* look for gzip header */
76 else /* for writing ... */
77 state->reset = 0; /* no deflateReset pending */
78 state->seek = 0; /* no seek request pending */
79 gz_error(state, Z_OK, NULL); /* clear error */
80 state->x.pos = 0; /* no uncompressed data yet */
81 state->strm.avail_in = 0; /* no input data yet */
84 /* Open a gzip file either by name or file descriptor. */
85 local gzFile gz_open(const void *path, int fd, const char *mode) {
100 /* allocate gzFile structure to return */
101 state = (gz_statep)malloc(sizeof(gz_state));
104 state->size = 0; /* no buffers allocated yet */
105 state->want = GZBUFSIZE; /* requested buffer size */
106 state->msg = NULL; /* no error message yet */
109 state->mode = GZ_NONE;
110 state->level = Z_DEFAULT_COMPRESSION;
111 state->strategy = Z_DEFAULT_STRATEGY;
114 if (*mode >= '0' && *mode <= '9')
115 state->level = *mode - '0';
119 state->mode = GZ_READ;
121 #ifndef NO_GZCOMPRESS
123 state->mode = GZ_WRITE;
126 state->mode = GZ_APPEND;
129 case '+': /* can't read and write at the same time */
132 case 'b': /* ignore -- will request binary anyway */
145 state->strategy = Z_FILTERED;
148 state->strategy = Z_HUFFMAN_ONLY;
151 state->strategy = Z_RLE;
154 state->strategy = Z_FIXED;
159 default: /* could consider as an error, but just ignore */
165 /* must provide an "r", "w", or "a" */
166 if (state->mode == GZ_NONE) {
171 /* can't force transparent read */
172 if (state->mode == GZ_READ) {
177 state->direct = 1; /* for empty file */
180 /* save the path name for error messages */
183 len = wcstombs(NULL, path, 0);
184 if (len == (z_size_t)-1)
189 len = strlen((const char *)path);
190 state->path = (char *)malloc(len + 1);
191 if (state->path == NULL) {
198 wcstombs(state->path, path, len + 1);
203 #if !defined(NO_snprintf) && !defined(NO_vsnprintf)
204 (void)snprintf(state->path, len + 1, "%s", (const char *)path);
206 strcpy(state->path, path);
209 /* compute the flags for open() */
218 (cloexec ? O_CLOEXEC : 0) |
220 (state->mode == GZ_READ ?
222 (O_WRONLY | O_CREAT |
224 (exclusive ? O_EXCL : 0) |
226 (state->mode == GZ_WRITE ?
230 /* open the file with the appropriate flags (or just use fd) */
231 state->fd = fd > -1 ? fd : (
233 fd == -2 ? _wopen(path, oflag, 0666) :
235 open((const char *)path, oflag, 0666));
236 if (state->fd == -1) {
241 if (state->mode == GZ_APPEND) {
242 LSEEK(state->fd, 0, SEEK_END); /* so gzoffset() is correct */
243 state->mode = GZ_WRITE; /* simplify later checks */
246 /* save the current position for rewinding (only if reading) */
247 if (state->mode == GZ_READ) {
248 state->start = LSEEK(state->fd, 0, SEEK_CUR);
249 if (state->start == -1) state->start = 0;
252 /* initialize stream */
256 return (gzFile)state;
259 /* -- see zlib.h -- */
260 gzFile ZEXPORT gzopen(const char *path, const char *mode) {
261 return gz_open(path, -1, mode);
264 /* -- see zlib.h -- */
265 gzFile ZEXPORT gzopen64(const char *path, const char *mode) {
266 return gz_open(path, -1, mode);
269 /* -- see zlib.h -- */
270 gzFile ZEXPORT gzdopen(int fd, const char *mode) {
271 char *path; /* identifier for error messages */
274 if (fd == -1 || (path = (char *)malloc(7 + 3 * sizeof(int))) == NULL)
276 #if !defined(NO_snprintf) && !defined(NO_vsnprintf)
277 (void)snprintf(path, 7 + 3 * sizeof(int), "<fd:%d>", fd);
279 sprintf(path, "<fd:%d>", fd); /* for debugging */
281 gz = gz_open(path, fd, mode);
286 /* -- see zlib.h -- */
288 gzFile ZEXPORT gzopen_w(const wchar_t *path, const char *mode) {
289 return gz_open(path, -2, mode);
293 /* -- see zlib.h -- */
294 int ZEXPORT gzbuffer(gzFile file, unsigned size) {
297 /* get internal structure and check integrity */
300 state = (gz_statep)file;
301 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
304 /* make sure we haven't already allocated memory */
305 if (state->size != 0)
308 /* check and set requested size */
309 if ((size << 1) < size)
310 return -1; /* need to be able to double it */
312 size = 8; /* needed to behave well with flushing */
317 /* -- see zlib.h -- */
318 int ZEXPORT gzrewind(gzFile file) {
321 /* get internal structure */
324 state = (gz_statep)file;
326 /* check that we're reading and that there's no error */
327 if (state->mode != GZ_READ ||
328 (state->err != Z_OK && state->err != Z_BUF_ERROR))
331 /* back up and start over */
332 if (LSEEK(state->fd, state->start, SEEK_SET) == -1)
338 /* -- see zlib.h -- */
339 z_off64_t ZEXPORT gzseek64(gzFile file, z_off64_t offset, int whence) {
344 /* get internal structure and check integrity */
347 state = (gz_statep)file;
348 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
351 /* check that there's no error */
352 if (state->err != Z_OK && state->err != Z_BUF_ERROR)
355 /* can only seek from start or relative to current position */
356 if (whence != SEEK_SET && whence != SEEK_CUR)
359 /* normalize offset to a SEEK_CUR specification */
360 if (whence == SEEK_SET)
361 offset -= state->x.pos;
362 else if (state->seek)
363 offset += state->skip;
366 /* if within raw area while reading, just go there */
367 if (state->mode == GZ_READ && state->how == COPY &&
368 state->x.pos + offset >= 0) {
369 ret = LSEEK(state->fd, offset - (z_off64_t)state->x.have, SEEK_CUR);
376 gz_error(state, Z_OK, NULL);
377 state->strm.avail_in = 0;
378 state->x.pos += offset;
382 /* calculate skip amount, rewinding if needed for back seek when reading */
384 if (state->mode != GZ_READ) /* writing -- can't go backwards */
386 offset += state->x.pos;
387 if (offset < 0) /* before start of file! */
389 if (gzrewind(file) == -1) /* rewind, then skip to offset */
393 /* if reading, skip what's in output buffer (one less gzgetc() check) */
394 if (state->mode == GZ_READ) {
395 n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > offset ?
396 (unsigned)offset : state->x.have;
403 /* request skip (if not zero) */
406 state->skip = offset;
408 return state->x.pos + offset;
411 /* -- see zlib.h -- */
412 z_off_t ZEXPORT gzseek(gzFile file, z_off_t offset, int whence) {
415 ret = gzseek64(file, (z_off64_t)offset, whence);
416 return ret == (z_off_t)ret ? (z_off_t)ret : -1;
419 /* -- see zlib.h -- */
420 z_off64_t ZEXPORT gztell64(gzFile file) {
423 /* get internal structure and check integrity */
426 state = (gz_statep)file;
427 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
430 /* return position */
431 return state->x.pos + (state->seek ? state->skip : 0);
434 /* -- see zlib.h -- */
435 z_off_t ZEXPORT gztell(gzFile file) {
438 ret = gztell64(file);
439 return ret == (z_off_t)ret ? (z_off_t)ret : -1;
442 /* -- see zlib.h -- */
443 z_off64_t ZEXPORT gzoffset64(gzFile file) {
447 /* get internal structure and check integrity */
450 state = (gz_statep)file;
451 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
454 /* compute and return effective offset in file */
455 offset = LSEEK(state->fd, 0, SEEK_CUR);
458 if (state->mode == GZ_READ) /* reading */
459 offset -= state->strm.avail_in; /* don't count buffered input */
463 /* -- see zlib.h -- */
464 z_off_t ZEXPORT gzoffset(gzFile file) {
467 ret = gzoffset64(file);
468 return ret == (z_off_t)ret ? (z_off_t)ret : -1;
471 /* -- see zlib.h -- */
472 int ZEXPORT gzeof(gzFile file) {
475 /* get internal structure and check integrity */
478 state = (gz_statep)file;
479 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
482 /* return end-of-file state */
483 return state->mode == GZ_READ ? state->past : 0;
486 /* -- see zlib.h -- */
487 const char * ZEXPORT gzerror(gzFile file, int *errnum) {
490 /* get internal structure and check integrity */
493 state = (gz_statep)file;
494 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
497 /* return error information */
499 *errnum = state->err;
500 return state->err == Z_MEM_ERROR ? "out of memory" :
501 (state->msg == NULL ? "" : state->msg);
504 /* -- see zlib.h -- */
505 void ZEXPORT gzclearerr(gzFile file) {
508 /* get internal structure and check integrity */
511 state = (gz_statep)file;
512 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
515 /* clear error and end-of-file */
516 if (state->mode == GZ_READ) {
520 gz_error(state, Z_OK, NULL);
523 /* Create an error message in allocated memory and set state->err and
524 state->msg accordingly. Free any previous error message already there. Do
525 not try to free or allocate space if the error is Z_MEM_ERROR (out of
526 memory). Simply save the error message as a static string. If there is an
527 allocation failure constructing the error message, then convert the error to
529 void ZLIB_INTERNAL gz_error(gz_statep state, int err, const char *msg) {
530 /* free previously allocated message and clear */
531 if (state->msg != NULL) {
532 if (state->err != Z_MEM_ERROR)
537 /* if fatal, set state->x.have to 0 so that the gzgetc() macro fails */
538 if (err != Z_OK && err != Z_BUF_ERROR)
541 /* set error code, and if no message, then done */
546 /* for an out of memory error, return literal string when requested */
547 if (err == Z_MEM_ERROR)
550 /* construct error message with path */
551 if ((state->msg = (char *)malloc(strlen(state->path) + strlen(msg) + 3)) ==
553 state->err = Z_MEM_ERROR;
556 #if !defined(NO_snprintf) && !defined(NO_vsnprintf)
557 (void)snprintf(state->msg, strlen(state->path) + strlen(msg) + 3,
558 "%s%s%s", state->path, ": ", msg);
560 strcpy(state->msg, state->path);
561 strcat(state->msg, ": ");
562 strcat(state->msg, msg);
566 /* portably return maximum value for an int (when limits.h presumed not
567 available) -- we need to do this to cover cases where 2's complement not
568 used, since C standard permits 1's complement and sign-bit representations,
569 otherwise we could just use ((unsigned)-1) >> 1 */
570 unsigned ZLIB_INTERNAL gz_intmax(void) {