1 /* gzread.c -- zlib functions for reading 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 "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 = (unsigned)-1;
318 if (n > len)
319 n = (unsigned)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 = (unsigned)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 unsigned char buf[1];
451 gz_statep state;
452
453 /* get internal structure */
454 if (file == NULL)
455 return -1;
456 state = (gz_statep)file;
457
458 /* check that we're reading and that there's no (serious) error */
459 if (state->mode != GZ_READ ||
460 (state->err != Z_OK && state->err != Z_BUF_ERROR))
461 return -1;
462
463 /* try output buffer (no need to check for skip request) */
464 if (state->x.have) {
465 state->x.have--;
466 state->x.pos++;
467 return *(state->x.next)++;
468 }
469
470 /* nothing there -- try gz_read() */
471 return gz_read(state, buf, 1) < 1 ? -1 : buf[0];
472 }
473
474 int ZEXPORT gzgetc_(file)
475 gzFile file;
476 {
477 return gzgetc(file);
478 }
479
480 /* -- see zlib.h -- */
481 int ZEXPORT gzungetc(c, file)
482 int c;
483 gzFile file;
484 {
485 gz_statep state;
486
487 /* get internal structure */
488 if (file == NULL)
489 return -1;
490 state = (gz_statep)file;
491
492 /* check that we're reading and that there's no (serious) error */
493 if (state->mode != GZ_READ ||
494 (state->err != Z_OK && state->err != Z_BUF_ERROR))
495 return -1;
496
497 /* process a skip request */
498 if (state->seek) {
499 state->seek = 0;
500 if (gz_skip(state, state->skip) == -1)
501 return -1;
502 }
503
504 /* can't push EOF */
505 if (c < 0)
506 return -1;
507
508 /* if output buffer empty, put byte at end (allows more pushing) */
509 if (state->x.have == 0) {
510 state->x.have = 1;
511 state->x.next = state->out + (state->size << 1) - 1;
512 state->x.next[0] = (unsigned char)c;
513 state->x.pos--;
514 state->past = 0;
515 return c;
516 }
517
518 /* if no room, give up (must have already done a gzungetc()) */
519 if (state->x.have == (state->size << 1)) {
520 gz_error(state, Z_DATA_ERROR, "out of room to push characters");
521 return -1;
522 }
523
524 /* slide output data if needed and insert byte before existing data */
525 if (state->x.next == state->out) {
526 unsigned char *src = state->out + state->x.have;
527 unsigned char *dest = state->out + (state->size << 1);
528 while (src > state->out)
529 *--dest = *--src;
530 state->x.next = dest;
531 }
532 state->x.have++;
533 state->x.next--;
534 state->x.next[0] = (unsigned char)c;
535 state->x.pos--;
536 state->past = 0;
537 return c;
538 }
539
540 /* -- see zlib.h -- */
541 char * ZEXPORT gzgets(file, buf, len)
542 gzFile file;
543 char *buf;
544 int len;
545 {
546 unsigned left, n;
547 char *str;
548 unsigned char *eol;
549 gz_statep state;
550
551 /* check parameters and get internal structure */
552 if (file == NULL || buf == NULL || len < 1)
553 return NULL;
554 state = (gz_statep)file;
555
556 /* check that we're reading and that there's no (serious) error */
557 if (state->mode != GZ_READ ||
558 (state->err != Z_OK && state->err != Z_BUF_ERROR))
559 return NULL;
560
561 /* process a skip request */
562 if (state->seek) {
563 state->seek = 0;
564 if (gz_skip(state, state->skip) == -1)
565 return NULL;
566 }
567
568 /* copy output bytes up to new line or len - 1, whichever comes first --
569 append a terminating zero to the string (we don't check for a zero in
570 the contents, let the user worry about that) */
571 str = buf;
572 left = (unsigned)len - 1;
573 if (left) do {
574 /* assure that something is in the output buffer */
575 if (state->x.have == 0 && gz_fetch(state) == -1)
576 return NULL; /* error */
577 if (state->x.have == 0) { /* end of file */
578 state->past = 1; /* read past end */
579 break; /* return what we have */
580 }
581
582 /* look for end-of-line in current output buffer */
583 n = state->x.have > left ? left : state->x.have;
584 eol = (unsigned char *)memchr(state->x.next, '\n', n);
585 if (eol != NULL)
586 n = (unsigned)(eol - state->x.next) + 1;
587
588 /* copy through end-of-line, or remainder if not found */
589 memcpy(buf, state->x.next, n);
590 state->x.have -= n;
591 state->x.next += n;
592 state->x.pos += n;
593 left -= n;
594 buf += n;
595 } while (left && eol == NULL);
596
597 /* return terminated string, or if nothing, end of file */
598 if (buf == str)
599 return NULL;
600 buf[0] = 0;
601 return str;
602 }
603
604 /* -- see zlib.h -- */
605 int ZEXPORT gzdirect(file)
606 gzFile file;
607 {
608 gz_statep state;
609
610 /* get internal structure */
611 if (file == NULL)
612 return 0;
613 state = (gz_statep)file;
614
615 /* if the state is not known, but we can find out, then do so (this is
616 mainly for right after a gzopen() or gzdopen()) */
617 if (state->mode == GZ_READ && state->how == LOOK && state->x.have == 0)
618 (void)gz_look(state);
619
620 /* return 1 if transparent, 0 if processing a gzip stream */
621 return state->direct;
622 }
623
624 /* -- see zlib.h -- */
625 int ZEXPORT gzclose_r(file)
626 gzFile file;
627 {
628 int ret, err;
629 gz_statep state;
630
631 /* get internal structure */
632 if (file == NULL)
633 return Z_STREAM_ERROR;
634 state = (gz_statep)file;
635
636 /* check that we're reading */
637 if (state->mode != GZ_READ)
638 return Z_STREAM_ERROR;
639
640 /* free memory and close file */
641 if (state->size) {
642 inflateEnd(&(state->strm));
643 free(state->out);
644 free(state->in);
645 }
646 err = state->err == Z_BUF_ERROR ? Z_BUF_ERROR : Z_OK;
647 gz_error(state, Z_OK, NULL);
648 free(state->path);
649 ret = close(state->fd);
650 free(state);
651 return ret ? Z_ERRNO : err;
652 }