1/* gzlib.c -- zlib functions common to reading and writing gzip files
2 * Copyright (C) 2004-2017 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */
5
6#include "zbuild.h"
7#include "gzguts.h"
8
9#if defined(WIN32) && !defined(__BORLANDC__)
10# define LSEEK _lseeki64
11#else
12#if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
13# define LSEEK lseek64
14#else
15# define LSEEK lseek
16#endif
17#endif
18
19/* Local functions */
20static void gz_reset(gz_state *);
21static gzFile gz_open(const void *, int, const char *);
22
23/* Reset gzip file state */
24static void gz_reset(gz_state *state) {
25 state->x.have = 0; /* no output data available */
26 if (state->mode == GZ_READ) { /* for reading ... */
27 state->eof = 0; /* not at end of file */
28 state->past = 0; /* have not read past end yet */
29 state->how = LOOK; /* look for gzip header */
30 }
31 else /* for writing ... */
32 state->reset = 0; /* no deflateReset pending */
33 state->seek = 0; /* no seek request pending */
34 gz_error(state, Z_OK, NULL); /* clear error */
35 state->x.pos = 0; /* no uncompressed data yet */
36 state->strm.avail_in = 0; /* no input data yet */
37}
38
39/* Open a gzip file either by name or file descriptor. */
40static gzFile gz_open(const void *path, int fd, const char *mode) {
41 gz_state *state;
42 size_t len;
43 int oflag;
44#ifdef O_CLOEXEC
45 int cloexec = 0;
46#endif
47#ifdef O_EXCL
48 int exclusive = 0;
49#endif
50
51 /* check input */
52 if (path == NULL)
53 return NULL;
54
55 /* allocate gzFile structure to return */
56 state = (gz_state *)malloc(sizeof(gz_state));
57 if (state == NULL)
58 return NULL;
59 state->size = 0; /* no buffers allocated yet */
60 state->want = GZBUFSIZE; /* requested buffer size */
61 state->msg = NULL; /* no error message yet */
62
63 /* interpret mode */
64 state->mode = GZ_NONE;
65 state->level = Z_DEFAULT_COMPRESSION;
66 state->strategy = Z_DEFAULT_STRATEGY;
67 state->direct = 0;
68 while (*mode) {
69 if (*mode >= '0' && *mode <= '9') {
70 state->level = *mode - '0';
71 } else {
72 switch (*mode) {
73 case 'r':
74 state->mode = GZ_READ;
75 break;
76#ifndef NO_GZCOMPRESS
77 case 'w':
78 state->mode = GZ_WRITE;
79 break;
80 case 'a':
81 state->mode = GZ_APPEND;
82 break;
83#endif
84 case '+': /* can't read and write at the same time */
85 free(state);
86 return NULL;
87 case 'b': /* ignore -- will request binary anyway */
88 break;
89#ifdef O_CLOEXEC
90 case 'e':
91 cloexec = 1;
92 break;
93#endif
94#ifdef O_EXCL
95 case 'x':
96 exclusive = 1;
97 break;
98#endif
99 case 'f':
100 state->strategy = Z_FILTERED;
101 break;
102 case 'h':
103 state->strategy = Z_HUFFMAN_ONLY;
104 break;
105 case 'R':
106 state->strategy = Z_RLE;
107 break;
108 case 'F':
109 state->strategy = Z_FIXED;
110 break;
111 case 'T':
112 state->direct = 1;
113 break;
114 default: /* could consider as an error, but just ignore */
115 {}
116 }
117 }
118 mode++;
119 }
120
121 /* must provide an "r", "w", or "a" */
122 if (state->mode == GZ_NONE) {
123 free(state);
124 return NULL;
125 }
126
127 /* can't force transparent read */
128 if (state->mode == GZ_READ) {
129 if (state->direct) {
130 free(state);
131 return NULL;
132 }
133 state->direct = 1; /* for empty file */
134 }
135
136 /* save the path name for error messages */
137#ifdef WIDECHAR
138 if (fd == -2) {
139 len = wcstombs(NULL, path, 0);
140 if (len == (size_t)-1)
141 len = 0;
142 } else
143#endif
144 len = strlen((const char *)path);
145 state->path = (char *)malloc(len + 1);
146 if (state->path == NULL) {
147 free(state);
148 return NULL;
149 }
150#ifdef WIDECHAR
151 if (fd == -2)
152 if (len) {
153 wcstombs(state->path, path, len + 1);
154 } else {
155 *(state->path) = 0;
156 }
157 else
158#endif
159 (void)snprintf(state->path, len + 1, "%s", (const char *)path);
160
161 /* compute the flags for open() */
162 oflag =
163#ifdef O_LARGEFILE
164 O_LARGEFILE |
165#endif
166#ifdef O_BINARY
167 O_BINARY |
168#endif
169#ifdef O_CLOEXEC
170 (cloexec ? O_CLOEXEC : 0) |
171#endif
172 (state->mode == GZ_READ ?
173 O_RDONLY :
174 (O_WRONLY | O_CREAT |
175#ifdef O_EXCL
176 (exclusive ? O_EXCL : 0) |
177#endif
178 (state->mode == GZ_WRITE ?
179 O_TRUNC :
180 O_APPEND)));
181
182 /* open the file with the appropriate flags (or just use fd) */
183 state->fd = fd > -1 ? fd : (
184#if defined(WIN32) || defined(__MINGW__)
185 fd == -2 ? _wopen(path, oflag, 0666) :
186#elif __CYGWIN__
187 fd == -2 ? open(state->path, oflag, 0666) :
188#endif
189 open((const char *)path, oflag, 0666));
190 if (state->fd == -1) {
191 free(state->path);
192 free(state);
193 return NULL;
194 }
195 if (state->mode == GZ_APPEND) {
196 LSEEK(state->fd, 0, SEEK_END); /* so gzoffset() is correct */
197 state->mode = GZ_WRITE; /* simplify later checks */
198 }
199
200 /* save the current position for rewinding (only if reading) */
201 if (state->mode == GZ_READ) {
202 state->start = LSEEK(state->fd, 0, SEEK_CUR);
203 if (state->start == -1) state->start = 0;
204 }
205
206 /* initialize stream */
207 gz_reset(state);
208
209 /* return stream */
210 return (gzFile)state;
211}
212
213/* -- see zlib.h -- */
214gzFile ZEXPORT PREFIX(gzopen)(const char *path, const char *mode) {
215 return gz_open(path, -1, mode);
216}
217
218/* -- see zlib.h -- */
219gzFile ZEXPORT PREFIX(gzopen64)(const char *path, const char *mode) {
220 return gz_open(path, -1, mode);
221}
222
223/* -- see zlib.h -- */
224gzFile ZEXPORT PREFIX(gzdopen)(int fd, const char *mode) {
225 char *path; /* identifier for error messages */
226 gzFile gz;
227
228 if (fd == -1 || (path = (char *)malloc(7 + 3 * sizeof(int))) == NULL)
229 return NULL;
230 (void)snprintf(path, 7 + 3 * sizeof(int), "<fd:%d>", fd); /* for debugging */
231 gz = gz_open(path, fd, mode);
232 free(path);
233 return gz;
234}
235
236/* -- see zlib.h -- */
237#ifdef WIDECHAR
238gzFile ZEXPORT PREFIX(gzopen_w)(const wchar_t *path, const char *mode) {
239 return gz_open(path, -2, mode);
240}
241#endif
242
243/* -- see zlib.h -- */
244int ZEXPORT PREFIX(gzbuffer)(gzFile file, unsigned size) {
245 gz_state *state;
246
247 /* get internal structure and check integrity */
248 if (file == NULL)
249 return -1;
250 state = (gz_state *)file;
251 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
252 return -1;
253
254 /* make sure we haven't already allocated memory */
255 if (state->size != 0)
256 return -1;
257
258 /* check and set requested size */
259 if ((size << 1) < size)
260 return -1; /* need to be able to double it */
261 if (size < 2)
262 size = 2; /* need two bytes to check magic header */
263 state->want = size;
264 return 0;
265}
266
267/* -- see zlib.h -- */
268int ZEXPORT PREFIX(gzrewind)(gzFile file) {
269 gz_state *state;
270
271 /* get internal structure */
272 if (file == NULL)
273 return -1;
274 state = (gz_state *)file;
275
276 /* check that we're reading and that there's no error */
277 if (state->mode != GZ_READ || (state->err != Z_OK && state->err != Z_BUF_ERROR))
278 return -1;
279
280 /* back up and start over */
281 if (LSEEK(state->fd, state->start, SEEK_SET) == -1)
282 return -1;
283 gz_reset(state);
284 return 0;
285}
286
287/* -- see zlib.h -- */
288z_off64_t ZEXPORT PREFIX(gzseek64)(gzFile file, z_off64_t offset, int whence) {
289 unsigned n;
290 z_off64_t ret;
291 gz_state *state;
292
293 /* get internal structure and check integrity */
294 if (file == NULL)
295 return -1;
296 state = (gz_state *)file;
297 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
298 return -1;
299
300 /* check that there's no error */
301 if (state->err != Z_OK && state->err != Z_BUF_ERROR)
302 return -1;
303
304 /* can only seek from start or relative to current position */
305 if (whence != SEEK_SET && whence != SEEK_CUR)
306 return -1;
307
308 /* normalize offset to a SEEK_CUR specification */
309 if (whence == SEEK_SET)
310 offset -= state->x.pos;
311 else if (state->seek)
312 offset += state->skip;
313 state->seek = 0;
314
315 /* if within raw area while reading, just go there */
316 if (state->mode == GZ_READ && state->how == COPY && state->x.pos + offset >= 0) {
317 ret = LSEEK(state->fd, offset - (z_off64_t)state->x.have, SEEK_CUR);
318 if (ret == -1)
319 return -1;
320 state->x.have = 0;
321 state->eof = 0;
322 state->past = 0;
323 state->seek = 0;
324 gz_error(state, Z_OK, NULL);
325 state->strm.avail_in = 0;
326 state->x.pos += offset;
327 return state->x.pos;
328 }
329
330 /* calculate skip amount, rewinding if needed for back seek when reading */
331 if (offset < 0) {
332 if (state->mode != GZ_READ) /* writing -- can't go backwards */
333 return -1;
334 offset += state->x.pos;
335 if (offset < 0) /* before start of file! */
336 return -1;
337 if (PREFIX(gzrewind)(file) == -1) /* rewind, then skip to offset */
338 return -1;
339 }
340
341 /* if reading, skip what's in output buffer (one less gzgetc() check) */
342 if (state->mode == GZ_READ) {
343 n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > offset ? (unsigned)offset : state->x.have;
344 state->x.have -= n;
345 state->x.next += n;
346 state->x.pos += n;
347 offset -= n;
348 }
349
350 /* request skip (if not zero) */
351 if (offset) {
352 state->seek = 1;
353 state->skip = offset;
354 }
355 return state->x.pos + offset;
356}
357
358/* -- see zlib.h -- */
359z_off_t ZEXPORT PREFIX(gzseek)(gzFile file, z_off_t offset, int whence) {
360 z_off64_t ret;
361
362 ret = PREFIX(gzseek64)(file, (z_off64_t)offset, whence);
363 return ret == (z_off_t)ret ? (z_off_t)ret : -1;
364}
365
366/* -- see zlib.h -- */
367z_off64_t ZEXPORT PREFIX(gztell64)(gzFile file) {
368 gz_state *state;
369
370 /* get internal structure and check integrity */
371 if (file == NULL)
372 return -1;
373 state = (gz_state *)file;
374 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
375 return -1;
376
377 /* return position */
378 return state->x.pos + (state->seek ? state->skip : 0);
379}
380
381/* -- see zlib.h -- */
382z_off_t ZEXPORT PREFIX(gztell)(gzFile file) {
383 z_off64_t ret;
384
385 ret = PREFIX(gztell64)(file);
386 return ret == (z_off_t)ret ? (z_off_t)ret : -1;
387}
388
389/* -- see zlib.h -- */
390z_off64_t ZEXPORT PREFIX(gzoffset64)(gzFile file) {
391 z_off64_t offset;
392 gz_state *state;
393
394 /* get internal structure and check integrity */
395 if (file == NULL)
396 return -1;
397 state = (gz_state *)file;
398 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
399 return -1;
400
401 /* compute and return effective offset in file */
402 offset = LSEEK(state->fd, 0, SEEK_CUR);
403 if (offset == -1)
404 return -1;
405 if (state->mode == GZ_READ) /* reading */
406 offset -= state->strm.avail_in; /* don't count buffered input */
407 return offset;
408}
409
410/* -- see zlib.h -- */
411z_off_t ZEXPORT PREFIX(gzoffset)(gzFile file) {
412 z_off64_t ret;
413
414 ret = PREFIX(gzoffset64)(file);
415 return ret == (z_off_t)ret ? (z_off_t)ret : -1;
416}
417
418/* -- see zlib.h -- */
419int ZEXPORT PREFIX(gzeof)(gzFile file) {
420 gz_state *state;
421
422 /* get internal structure and check integrity */
423 if (file == NULL)
424 return 0;
425 state = (gz_state *)file;
426 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
427 return 0;
428
429 /* return end-of-file state */
430 return state->mode == GZ_READ ? state->past : 0;
431}
432
433/* -- see zlib.h -- */
434const char * ZEXPORT PREFIX(gzerror)(gzFile file, int *errnum) {
435 gz_state *state;
436
437 /* get internal structure and check integrity */
438 if (file == NULL)
439 return NULL;
440 state = (gz_state *)file;
441 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
442 return NULL;
443
444 /* return error information */
445 if (errnum != NULL)
446 *errnum = state->err;
447 return state->err == Z_MEM_ERROR ? "out of memory" : (state->msg == NULL ? "" : state->msg);
448}
449
450/* -- see zlib.h -- */
451void ZEXPORT PREFIX(gzclearerr)(gzFile file) {
452 gz_state *state;
453
454 /* get internal structure and check integrity */
455 if (file == NULL)
456 return;
457 state = (gz_state *)file;
458 if (state->mode != GZ_READ && state->mode != GZ_WRITE)
459 return;
460
461 /* clear error and end-of-file */
462 if (state->mode == GZ_READ) {
463 state->eof = 0;
464 state->past = 0;
465 }
466 gz_error(state, Z_OK, NULL);
467}
468
469/* Create an error message in allocated memory and set state->err and
470 state->msg accordingly. Free any previous error message already there. Do
471 not try to free or allocate space if the error is Z_MEM_ERROR (out of
472 memory). Simply save the error message as a static string. If there is an
473 allocation failure constructing the error message, then convert the error to
474 out of memory. */
475void ZLIB_INTERNAL gz_error(gz_state *state, int err, const char *msg) {
476 /* free previously allocated message and clear */
477 if (state->msg != NULL) {
478 if (state->err != Z_MEM_ERROR)
479 free(state->msg);
480 state->msg = NULL;
481 }
482
483 /* if fatal, set state->x.have to 0 so that the gzgetc() macro fails */
484 if (err != Z_OK && err != Z_BUF_ERROR)
485 state->x.have = 0;
486
487 /* set error code, and if no message, then done */
488 state->err = err;
489 if (msg == NULL)
490 return;
491
492 /* for an out of memory error, return literal string when requested */
493 if (err == Z_MEM_ERROR)
494 return;
495
496 /* construct error message with path */
497 if ((state->msg = (char *)malloc(strlen(state->path) + strlen(msg) + 3)) == NULL) {
498 state->err = Z_MEM_ERROR;
499 return;
500 }
501 (void)snprintf(state->msg, strlen(state->path) + strlen(msg) + 3, "%s%s%s", state->path, ": ", msg);
502}
503
504#ifndef INT_MAX
505/* portably return maximum value for an int (when limits.h presumed not
506 available) -- we need to do this to cover cases where 2's complement not
507 used, since C standard permits 1's complement and sign-bit representations,
508 otherwise we could just use ((unsigned)-1) >> 1 */
509unsigned ZLIB_INTERNAL gz_intmax() {
510 unsigned p, q;
511
512 p = 1;
513 do {
514 q = p;
515 p <<= 1;
516 p++;
517 } while (p > q);
518 return q >> 1;
519}
520#endif
521