1 /* gzread.c -- zlib functions for reading gzip files
2 * Copyright (C) 2004, 2005, 2010, 2011, 2012, 2013, 2016 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
4 */
5
6 #include "gzguts.h"
7
8 /* Local functions */
9 local int gz_load OF((gz_statep, unsigned char *, unsigned, unsigned *));
10 local int gz_avail OF((gz_statep));
11 local int gz_look OF((gz_statep));
12 local int gz_decomp OF((gz_statep));
13 local int gz_fetch OF((gz_statep));
14 local int gz_skip OF((gz_statep, z_off64_t));
15 local z_size_t gz_read OF((gz_statep, voidp, z_size_t));
16
17 /* Use read() to load a buffer -- return -1 on error, otherwise 0. Read from
18 state->fd, and update state->eof, state->err, and state->msg as appropriate.
19 This function needs to loop on read(), since read() is not guaranteed to
20 read the number of bytes requested, depending on the type of descriptor. */
21 local int gz_load(state, buf, len, have)
22 gz_statep state;
23 unsigned char *buf;
24 unsigned len;
25 unsigned *have;
26 {
27 int ret;
28 unsigned get, max = ((unsigned)-1 >> 2) + 1;
29
30 *have = 0;
31 do {
32 get = len - *have;
33 if (get > max)
34 get = max;
35 ret = read(state->fd, buf + *have, get);
36 if (ret <= 0)
37 break;
38 *have += (unsigned)ret;
39 } while (*have < len);
40 if (ret < 0) {
41 gz_error(state, Z_ERRNO, zstrerror());
42 return -1;
43 }
44 if (ret == 0)
45 state->eof = 1;
46 return 0;
47 }
48
49 /* Load up input buffer and set eof flag if last data loaded -- return -1 on
50 error, 0 otherwise. Note that the eof flag is set when the end of the input
51 file is reached, even though there may be unused data in the buffer. Once
52 that data has been used, no more attempts will be made to read the file.
53 If strm->avail_in != 0, then the current data is moved to the beginning of
54 the input buffer, and then the remainder of the buffer is loaded with the
55 available data from the input file. */
56 local int gz_avail(state)
57 gz_statep state;
58 {
59 unsigned got;
60 z_streamp strm = &(state->strm);
61
62 if (state->err != Z_OK && state->err != Z_BUF_ERROR)
63 return -1;
64 if (state->eof == 0) {
65 if (strm->avail_in) { /* copy what's there to the start */
66 unsigned char *p = state->in;
67 unsigned const char *q = strm->next_in;
68 unsigned n = strm->avail_in;
69 do {
70 *p++ = *q++;
71 } while (--n);
72 }
73 if (gz_load(state, state->in + strm->avail_in,
74 state->size - strm->avail_in, &got) == -1)
75 return -1;
76 strm->avail_in += got;
77 strm->next_in = state->in;
78 }
79 return 0;
80 }
81
82 /* Look for gzip header, set up for inflate or copy. state->x.have must be 0.
83 If this is the first time in, allocate required memory. state->how will be
84 left unchanged if there is no more input data available, will be set to COPY
85 if there is no gzip header and direct copying will be performed, or it will
86 be set to GZIP for decompression. If direct copying, then leftover input
87 data from the input buffer will be copied to the output buffer. In that
88 case, all further file reads will be directly to either the output buffer or
89 a user buffer. If decompressing, the inflate state will be initialized.
90 gz_look() will return 0 on success or -1 on failure. */
91 local int gz_look(state)
92 gz_statep state;
93 {
94 z_streamp strm = &(state->strm);
95
96 /* allocate read buffers and inflate memory */
97 if (state->size == 0) {
98 /* allocate buffers */
99 state->in = (unsigned char *)malloc(state->want);
100 state->out = (unsigned char *)malloc(state->want << 1);
101 if (state->in == NULL || state->out == NULL) {
102 free(state->out);
103 free(state->in);
104 gz_error(state, Z_MEM_ERROR, "out of memory");
105 return -1;
106 }
107 state->size = state->want;
108
109 /* allocate inflate memory */
110 state->strm.zalloc = Z_NULL;
111 state->strm.zfree = Z_NULL;
112 state->strm.opaque = Z_NULL;
113 state->strm.avail_in = 0;
114 state->strm.next_in = Z_NULL;
115 if (inflateInit2(&(state->strm), 15 + 16) != Z_OK) { /* gunzip */
116 free(state->out);
117 free(state->in);
118 state->size = 0;
119 gz_error(state, Z_MEM_ERROR, "out of memory");
120 return -1;
121 }
122 }
123
124 /* get at least the magic bytes in the input buffer */
125 if (strm->avail_in < 2) {
126 if (gz_avail(state) == -1)
127 return -1;
128 if (strm->avail_in == 0)
129 return 0;
130 }
131
132 /* look for gzip magic bytes -- if there, do gzip decoding (note: there is
133 a logical dilemma here when considering the case of a partially written
134 gzip file, to wit, if a single 31 byte is written, then we cannot tell
135 whether this is a single-byte file, or just a partially written gzip
136 file -- for here we assume that if a gzip file is being written, then
137 the header will be written in a single operation, so that reading a
138 single byte is sufficient indication that it is not a gzip file) */
139 if (strm->avail_in > 1 &&
140 strm->next_in[0] == 31 && strm->next_in[1] == 139) {
141 inflateReset(strm);
142 state->how = GZIP;
143 state->direct = 0;
144 return 0;
145 }
146
147 /* no gzip header -- if we were decoding gzip before, then this is trailing
148 garbage. Ignore the trailing garbage and finish. */
149 if (state->direct == 0) {
150 strm->avail_in = 0;
151 state->eof = 1;
152 state->x.have = 0;
153 return 0;
154 }
155
156 /* doing raw i/o, copy any leftover input to output -- this assumes that
157 the output buffer is larger than the input buffer, which also assures
158 space for gzungetc() */
159 state->x.next = state->out;
160 if (strm->avail_in) {
161 memcpy(state->x.next, strm->next_in, strm->avail_in);
162 state->x.have = strm->avail_in;
163 strm->avail_in = 0;
164 }
165 state->how = COPY;
166 state->direct = 1;
167 return 0;
168 }
169
170 /* Decompress from input to the provided next_out and avail_out in the state.
171 On return, state->x.have and state->x.next point to the just decompressed
172 data. If the gzip stream completes, state->how is reset to LOOK to look for
173 the next gzip stream or raw data, once state->x.have is depleted. Returns 0
174 on success, -1 on failure. */
175 local int gz_decomp(state)
176 gz_statep state;
177 {
178 int ret = Z_OK;
179 unsigned had;
180 z_streamp strm = &(state->strm);
181
182 /* fill output buffer up to end of deflate stream */
183 had = strm->avail_out;
184 do {
185 /* get more input for inflate() */
186 if (strm->avail_in == 0 && gz_avail(state) == -1)
187 return -1;
188 if (strm->avail_in == 0) {
189 gz_error(state, Z_BUF_ERROR, "unexpected end of file");
190 break;
191 }
192
193 /* decompress and handle errors */
194 ret = inflate(strm, Z_NO_FLUSH);
195 if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) {
196 gz_error(state, Z_STREAM_ERROR,
197 "internal error: inflate stream corrupt");
198 return -1;
199 }
200 if (ret == Z_MEM_ERROR) {
201 gz_error(state, Z_MEM_ERROR, "out of memory");
202 return -1;
203 }
204 if (ret == Z_DATA_ERROR) { /* deflate stream invalid */
205 gz_error(state, Z_DATA_ERROR,
206 strm->msg == NULL ? "compressed data error" : strm->msg);
207 return -1;
208 }
209 } while (strm->avail_out && ret != Z_STREAM_END);
210
211 /* update available output */
212 state->x.have = had - strm->avail_out;
213 state->x.next = strm->next_out - state->x.have;
214
215 /* if the gzip stream completed successfully, look for another */
216 if (ret == Z_STREAM_END)
217 state->how = LOOK;
218
219 /* good decompression */
220 return 0;
221 }
222
223 /* Fetch data and put it in the output buffer. Assumes state->x.have is 0.
224 Data is either copied from the input file or decompressed from the input
225 file depending on state->how. If state->how is LOOK, then a gzip header is
226 looked for to determine whether to copy or decompress. Returns -1 on error,
227 otherwise 0. gz_fetch() will leave state->how as COPY or GZIP unless the
228 end of the input file has been reached and all data has been processed. */
229 local int gz_fetch(state)
230 gz_statep state;
231 {
232 z_streamp strm = &(state->strm);
233
234 do {
235 switch(state->how) {
236 case LOOK: /* -> LOOK, COPY (only if never GZIP), or GZIP */
237 if (gz_look(state) == -1)
238 return -1;
239 if (state->how == LOOK)
240 return 0;
241 break;
242 case COPY: /* -> COPY */
243 if (gz_load(state, state->out, state->size << 1, &(state->x.have))
244 == -1)
245 return -1;
246 state->x.next = state->out;
247 return 0;
248 case GZIP: /* -> GZIP or LOOK (if end of gzip stream) */
249 strm->avail_out = state->size << 1;
250 strm->next_out = state->out;
251 if (gz_decomp(state) == -1)
252 return -1;
253 }
254 } while (state->x.have == 0 && (!state->eof || strm->avail_in));
255 return 0;
256 }
257
258 /* Skip len uncompressed bytes of output. Return -1 on error, 0 on success. */
259 local int gz_skip(state, len)
260 gz_statep state;
261 z_off64_t len;
262 {
263 unsigned n;
264
265 /* skip over len bytes or reach end-of-file, whichever comes first */
266 while (len)
267 /* skip over whatever is in output buffer */
268 if (state->x.have) {
269 n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > len ?
270 (unsigned)len : state->x.have;
271 state->x.have -= n;
272 state->x.next += n;
273 state->x.pos += n;
274 len -= n;
275 }
276
277 /* output buffer empty -- return if we're at the end of the input */
278 else if (state->eof && state->strm.avail_in == 0)
279 break;
280
281 /* need more data to skip -- load up output buffer */
282 else {
283 /* get more output, looking for header if required */
284 if (gz_fetch(state) == -1)
285 return -1;
286 }
287 return 0;
288 }
289
290 /* Read len bytes into buf from file, or less than len up to the end of the
291 input. Return the number of bytes read. If zero is returned, either the
292 end of file was reached, or there was an error. state->err must be
293 consulted in that case to determine which. */
294 local z_size_t gz_read(state, buf, len)
295 gz_statep state;
296 voidp buf;
297 z_size_t len;
298 {
299 z_size_t got;
300 unsigned n;
301
302 /* if len is zero, avoid unnecessary operations */
303 if (len == 0)
304 return 0;
305
306 /* process a skip request */
307 if (state->seek) {
308 state->seek = 0;
309 if (gz_skip(state, state->skip) == -1)
310 return 0;
311 }
312
313 /* get len bytes to buf, or less than len if at the end */
314 got = 0;
315 do {
316 /* set n to the maximum amount of len that fits in an unsigned int */
317 n = -1;
318 if (n > len)
319 n = len;
320
321 /* first just try copying data from the output buffer */
322 if (state->x.have) {
323 if (state->x.have < n)
324 n = state->x.have;
325 memcpy(buf, state->x.next, n);
326 state->x.next += n;
327 state->x.have -= n;
328 }
329
330 /* output buffer empty -- return if we're at the end of the input */
331 else if (state->eof && state->strm.avail_in == 0) {
332 state->past = 1; /* tried to read past end */
333 break;
334 }
335
336 /* need output data -- for small len or new stream load up our output
337 buffer */
338 else if (state->how == LOOK || n < (state->size << 1)) {
339 /* get more output, looking for header if required */
340 if (gz_fetch(state) == -1)
341 return 0;
342 continue; /* no progress yet -- go back to copy above */
343 /* the copy above assures that we will leave with space in the
344 output buffer, allowing at least one gzungetc() to succeed */
345 }
346
347 /* large len -- read directly into user buffer */
348 else if (state->how == COPY) { /* read directly */
349 if (gz_load(state, (unsigned char *)buf, n, &n) == -1)
350 return 0;
351 }
352
353 /* large len -- decompress directly into user buffer */
354 else { /* state->how == GZIP */
355 state->strm.avail_out = n;
356 state->strm.next_out = (unsigned char *)buf;
357 if (gz_decomp(state) == -1)
358 return 0;
359 n = state->x.have;
360 state->x.have = 0;
361 }
362
363 /* update progress */
364 len -= n;
365 buf = (char *)buf + n;
366 got += n;
367 state->x.pos += n;
368 } while (len);
369
370 /* return number of bytes read into user buffer */
371 return got;
372 }
373
374 /* -- see zlib.h -- */
375 int ZEXPORT gzread(file, buf, len)
376 gzFile file;
377 voidp buf;
378 unsigned len;
379 {
380 gz_statep state;
381
382 /* get internal structure */
383 if (file == NULL)
384 return -1;
385 state = (gz_statep)file;
386
387 /* check that we're reading and that there's no (serious) error */
388 if (state->mode != GZ_READ ||
389 (state->err != Z_OK && state->err != Z_BUF_ERROR))
390 return -1;
391
392 /* since an int is returned, make sure len fits in one, otherwise return
393 with an error (this avoids a flaw in the interface) */
394 if ((int)len < 0) {
395 gz_error(state, Z_STREAM_ERROR, "request does not fit in an int");
396 return -1;
397 }
398
399 /* read len or fewer bytes to buf */
400 len = gz_read(state, buf, len);
401
402 /* check for an error */
403 if (len == 0 && state->err != Z_OK && state->err != Z_BUF_ERROR)
404 return -1;
405
406 /* return the number of bytes read (this is assured to fit in an int) */
407 return (int)len;
408 }
409
410 /* -- see zlib.h -- */
411 z_size_t ZEXPORT gzfread(buf, size, nitems, file)
412 voidp buf;
413 z_size_t size;
414 z_size_t nitems;
415 gzFile file;
416 {
417 z_size_t len;
418 gz_statep state;
419
420 /* get internal structure */
421 if (file == NULL)
422 return 0;
423 state = (gz_statep)file;
424
425 /* check that we're reading and that there's no (serious) error */
426 if (state->mode != GZ_READ ||
427 (state->err != Z_OK && state->err != Z_BUF_ERROR))
428 return 0;
429
430 /* compute bytes to read -- error on overflow */
431 len = nitems * size;
432 if (size && len / size != nitems) {
433 gz_error(state, Z_STREAM_ERROR, "request does not fit in a size_t");
434 return 0;
435 }
436
437 /* read len or fewer bytes to buf, return the number of full items read */
438 return len ? gz_read(state, buf, len) / size : 0;
439 }
440
441 /* -- see zlib.h -- */
442 #ifdef Z_PREFIX_SET
443 # undef z_gzgetc
444 #else
445 # undef gzgetc
446 #endif
447 int ZEXPORT gzgetc(file)
448 gzFile file;
449 {
450 int ret;
451 unsigned char buf[1];
452 gz_statep state;
453
454 /* get internal structure */
455 if (file == NULL)
456 return -1;
457 state = (gz_statep)file;
458
459 /* check that we're reading and that there's no (serious) error */
460 if (state->mode != GZ_READ ||
461 (state->err != Z_OK && state->err != Z_BUF_ERROR))
462 return -1;
463
464 /* try output buffer (no need to check for skip request) */
465 if (state->x.have) {
466 state->x.have--;
467 state->x.pos++;
468 return *(state->x.next)++;
469 }
470
471 /* nothing there -- try gz_read() */
472 ret = gz_read(state, buf, 1);
473 return ret < 1 ? -1 : buf[0];
474 }
475
476 int ZEXPORT gzgetc_(file)
477 gzFile file;
478 {
479 return gzgetc(file);
480 }
481
482 /* -- see zlib.h -- */
483 int ZEXPORT gzungetc(c, file)
484 int c;
485 gzFile file;
486 {
487 gz_statep state;
488
489 /* get internal structure */
490 if (file == NULL)
491 return -1;
492 state = (gz_statep)file;
493
494 /* check that we're reading and that there's no (serious) error */
495 if (state->mode != GZ_READ ||
496 (state->err != Z_OK && state->err != Z_BUF_ERROR))
497 return -1;
498
499 /* process a skip request */
500 if (state->seek) {
501 state->seek = 0;
502 if (gz_skip(state, state->skip) == -1)
503 return -1;
504 }
505
506 /* can't push EOF */
507 if (c < 0)
508 return -1;
509
510 /* if output buffer empty, put byte at end (allows more pushing) */
511 if (state->x.have == 0) {
512 state->x.have = 1;
513 state->x.next = state->out + (state->size << 1) - 1;
514 state->x.next[0] = (unsigned char)c;
515 state->x.pos--;
516 state->past = 0;
517 return c;
518 }
519
520 /* if no room, give up (must have already done a gzungetc()) */
521 if (state->x.have == (state->size << 1)) {
522 gz_error(state, Z_DATA_ERROR, "out of room to push characters");
523 return -1;
524 }
525
526 /* slide output data if needed and insert byte before existing data */
527 if (state->x.next == state->out) {
528 unsigned char *src = state->out + state->x.have;
529 unsigned char *dest = state->out + (state->size << 1);
530 while (src > state->out)
531 *--dest = *--src;
532 state->x.next = dest;
533 }
534 state->x.have++;
535 state->x.next--;
536 state->x.next[0] = (unsigned char)c;
537 state->x.pos--;
538 state->past = 0;
539 return c;
540 }
541
542 /* -- see zlib.h -- */
543 char * ZEXPORT gzgets(file, buf, len)
544 gzFile file;
545 char *buf;
546 int len;
547 {
548 unsigned left, n;
549 char *str;
550 unsigned char *eol;
551 gz_statep state;
552
553 /* check parameters and get internal structure */
554 if (file == NULL || buf == NULL || len < 1)
555 return NULL;
556 state = (gz_statep)file;
557
558 /* check that we're reading and that there's no (serious) error */
559 if (state->mode != GZ_READ ||
560 (state->err != Z_OK && state->err != Z_BUF_ERROR))
561 return NULL;
562
563 /* process a skip request */
564 if (state->seek) {
565 state->seek = 0;
566 if (gz_skip(state, state->skip) == -1)
567 return NULL;
568 }
569
570 /* copy output bytes up to new line or len - 1, whichever comes first --
571 append a terminating zero to the string (we don't check for a zero in
572 the contents, let the user worry about that) */
573 str = buf;
574 left = (unsigned)len - 1;
575 if (left) do {
576 /* assure that something is in the output buffer */
577 if (state->x.have == 0 && gz_fetch(state) == -1)
578 return NULL; /* error */
579 if (state->x.have == 0) { /* end of file */
580 state->past = 1; /* read past end */
581 break; /* return what we have */
582 }
583
584 /* look for end-of-line in current output buffer */
585 n = state->x.have > left ? left : state->x.have;
586 eol = (unsigned char *)memchr(state->x.next, '\n', n);
587 if (eol != NULL)
588 n = (unsigned)(eol - state->x.next) + 1;
589
590 /* copy through end-of-line, or remainder if not found */
591 memcpy(buf, state->x.next, n);
592 state->x.have -= n;
593 state->x.next += n;
594 state->x.pos += n;
595 left -= n;
596 buf += n;
597 } while (left && eol == NULL);
598
599 /* return terminated string, or if nothing, end of file */
600 if (buf == str)
601 return NULL;
602 buf[0] = 0;
603 return str;
604 }
605
606 /* -- see zlib.h -- */
607 int ZEXPORT gzdirect(file)
608 gzFile file;
609 {
610 gz_statep state;
611
612 /* get internal structure */
613 if (file == NULL)
614 return 0;
615 state = (gz_statep)file;
616
617 /* if the state is not known, but we can find out, then do so (this is
618 mainly for right after a gzopen() or gzdopen()) */
619 if (state->mode == GZ_READ && state->how == LOOK && state->x.have == 0)
620 (void)gz_look(state);
621
622 /* return 1 if transparent, 0 if processing a gzip stream */
623 return state->direct;
624 }
625
626 /* -- see zlib.h -- */
627 int ZEXPORT gzclose_r(file)
628 gzFile file;
629 {
630 int ret, err;
631 gz_statep state;
632
633 /* get internal structure */
634 if (file == NULL)
635 return Z_STREAM_ERROR;
636 state = (gz_statep)file;
637
638 /* check that we're reading */
639 if (state->mode != GZ_READ)
640 return Z_STREAM_ERROR;
641
642 /* free memory and close file */
643 if (state->size) {
644 inflateEnd(&(state->strm));
645 free(state->out);
646 free(state->in);
647 }
648 err = state->err == Z_BUF_ERROR ? Z_BUF_ERROR : Z_OK;
649 gz_error(state, Z_OK, NULL);
650 free(state->path);
651 ret = close(state->fd);
652 free(state);
653 return ret ? Z_ERRNO : err;
654 }