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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 #ifndef _WIN32
9 # include <unistd.h>
10 #endif
11
12 /* Local functions */
13 local int gz_load OF((gz_statep, unsigned char *, unsigned, unsigned *));
14 local int gz_avail OF((gz_statep));
15 local int gz_look OF((gz_statep));
16 local int gz_decomp OF((gz_statep));
17 local int gz_fetch OF((gz_statep));
18 local int gz_skip OF((gz_statep, z_off64_t));
19 local z_size_t gz_read OF((gz_statep, voidp, z_size_t));
20
21 /* Use read() to load a buffer -- return -1 on error, otherwise 0. Read from
22 state->fd, and update state->eof, state->err, and state->msg as appropriate.
23 This function needs to loop on read(), since read() is not guaranteed to
24 read the number of bytes requested, depending on the type of descriptor. */
25 local int gz_load(state, buf, len, have)
26 gz_statep state;
27 unsigned char *buf;
28 unsigned len;
29 unsigned *have;
30 {
31 int ret;
32 unsigned get, max = ((unsigned)-1 >> 2) + 1;
33
34 *have = 0;
35 do {
36 get = len - *have;
37 if (get > max)
38 get = max;
39 ret = read(state->fd, buf + *have, get);
40 if (ret <= 0)
41 break;
42 *have += (unsigned)ret;
43 } while (*have < len);
44 if (ret < 0) {
45 gz_error(state, Z_ERRNO, zstrerror());
46 return -1;
47 }
48 if (ret == 0)
49 state->eof = 1;
50 return 0;
51 }
52
53 /* Load up input buffer and set eof flag if last data loaded -- return -1 on
54 error, 0 otherwise. Note that the eof flag is set when the end of the input
55 file is reached, even though there may be unused data in the buffer. Once
56 that data has been used, no more attempts will be made to read the file.
57 If strm->avail_in != 0, then the current data is moved to the beginning of
58 the input buffer, and then the remainder of the buffer is loaded with the
59 available data from the input file. */
60 local int gz_avail(state)
61 gz_statep state;
62 {
63 unsigned got;
64 z_streamp strm = &(state->strm);
65
66 if (state->err != Z_OK && state->err != Z_BUF_ERROR)
67 return -1;
68 if (state->eof == 0) {
69 if (strm->avail_in) { /* copy what's there to the start */
70 unsigned char *p = state->in;
71 unsigned const char *q = strm->next_in;
72 unsigned n = strm->avail_in;
73 do {
74 *p++ = *q++;
75 } while (--n);
76 }
77 if (gz_load(state, state->in + strm->avail_in,
78 state->size - strm->avail_in, &got) == -1)
79 return -1;
80 strm->avail_in += got;
81 strm->next_in = state->in;
82 }
83 return 0;
84 }
85
86 /* Look for gzip header, set up for inflate or copy. state->x.have must be 0.
87 If this is the first time in, allocate required memory. state->how will be
88 left unchanged if there is no more input data available, will be set to COPY
89 if there is no gzip header and direct copying will be performed, or it will
90 be set to GZIP for decompression. If direct copying, then leftover input
91 data from the input buffer will be copied to the output buffer. In that
92 case, all further file reads will be directly to either the output buffer or
93 a user buffer. If decompressing, the inflate state will be initialized.
94 gz_look() will return 0 on success or -1 on failure. */
95 local int gz_look(state)
96 gz_statep state;
97 {
98 z_streamp strm = &(state->strm);
99
100 /* allocate read buffers and inflate memory */
101 if (state->size == 0) {
102 /* allocate buffers */
103 state->in = (unsigned char *)malloc(state->want);
104 state->out = (unsigned char *)malloc(state->want << 1);
105 if (state->in == NULL || state->out == NULL) {
106 free(state->out);
107 free(state->in);
108 gz_error(state, Z_MEM_ERROR, "out of memory");
109 return -1;
110 }
111 state->size = state->want;
112
113 /* allocate inflate memory */
114 state->strm.zalloc = Z_NULL;
115 state->strm.zfree = Z_NULL;
116 state->strm.opaque = Z_NULL;
117 state->strm.avail_in = 0;
118 state->strm.next_in = Z_NULL;
119 if (inflateInit2(&(state->strm), 15 + 16) != Z_OK) { /* gunzip */
120 free(state->out);
121 free(state->in);
122 state->size = 0;
123 gz_error(state, Z_MEM_ERROR, "out of memory");
124 return -1;
125 }
126 }
127
128 /* get at least the magic bytes in the input buffer */
129 if (strm->avail_in < 2) {
130 if (gz_avail(state) == -1)
131 return -1;
132 if (strm->avail_in == 0)
133 return 0;
134 }
135
136 /* look for gzip magic bytes -- if there, do gzip decoding (note: there is
137 a logical dilemma here when considering the case of a partially written
138 gzip file, to wit, if a single 31 byte is written, then we cannot tell
139 whether this is a single-byte file, or just a partially written gzip
140 file -- for here we assume that if a gzip file is being written, then
141 the header will be written in a single operation, so that reading a
142 single byte is sufficient indication that it is not a gzip file) */
143 if (strm->avail_in > 1 &&
144 strm->next_in[0] == 31 && strm->next_in[1] == 139) {
145 inflateReset(strm);
146 state->how = GZIP;
147 state->direct = 0;
148 return 0;
149 }
150
151 /* no gzip header -- if we were decoding gzip before, then this is trailing
152 garbage. Ignore the trailing garbage and finish. */
153 if (state->direct == 0) {
154 strm->avail_in = 0;
155 state->eof = 1;
156 state->x.have = 0;
157 return 0;
158 }
159
160 /* doing raw i/o, copy any leftover input to output -- this assumes that
161 the output buffer is larger than the input buffer, which also assures
162 space for gzungetc() */
163 state->x.next = state->out;
164 if (strm->avail_in) {
165 memcpy(state->x.next, strm->next_in, strm->avail_in);
166 state->x.have = strm->avail_in;
167 strm->avail_in = 0;
168 }
169 state->how = COPY;
170 state->direct = 1;
171 return 0;
172 }
173
174 /* Decompress from input to the provided next_out and avail_out in the state.
175 On return, state->x.have and state->x.next point to the just decompressed
176 data. If the gzip stream completes, state->how is reset to LOOK to look for
177 the next gzip stream or raw data, once state->x.have is depleted. Returns 0
178 on success, -1 on failure. */
179 local int gz_decomp(state)
180 gz_statep state;
181 {
182 int ret = Z_OK;
183 unsigned had;
184 z_streamp strm = &(state->strm);
185
186 /* fill output buffer up to end of deflate stream */
187 had = strm->avail_out;
188 do {
189 /* get more input for inflate() */
190 if (strm->avail_in == 0 && gz_avail(state) == -1)
191 return -1;
192 if (strm->avail_in == 0) {
193 gz_error(state, Z_BUF_ERROR, "unexpected end of file");
194 break;
195 }
196
197 /* decompress and handle errors */
198 ret = inflate(strm, Z_NO_FLUSH);
199 if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) {
200 gz_error(state, Z_STREAM_ERROR,
201 "internal error: inflate stream corrupt");
202 return -1;
203 }
204 if (ret == Z_MEM_ERROR) {
205 gz_error(state, Z_MEM_ERROR, "out of memory");
206 return -1;
207 }
208 if (ret == Z_DATA_ERROR) { /* deflate stream invalid */
209 gz_error(state, Z_DATA_ERROR,
210 strm->msg == NULL ? "compressed data error" : strm->msg);
211 return -1;
212 }
213 } while (strm->avail_out && ret != Z_STREAM_END);
214
215 /* update available output */
216 state->x.have = had - strm->avail_out;
217 state->x.next = strm->next_out - state->x.have;
218
219 /* if the gzip stream completed successfully, look for another */
220 if (ret == Z_STREAM_END)
221 state->how = LOOK;
222
223 /* good decompression */
224 return 0;
225 }
226
227 /* Fetch data and put it in the output buffer. Assumes state->x.have is 0.
228 Data is either copied from the input file or decompressed from the input
229 file depending on state->how. If state->how is LOOK, then a gzip header is
230 looked for to determine whether to copy or decompress. Returns -1 on error,
231 otherwise 0. gz_fetch() will leave state->how as COPY or GZIP unless the
232 end of the input file has been reached and all data has been processed. */
233 local int gz_fetch(state)
234 gz_statep state;
235 {
236 z_streamp strm = &(state->strm);
237
238 do {
239 switch(state->how) {
240 case LOOK: /* -> LOOK, COPY (only if never GZIP), or GZIP */
241 if (gz_look(state) == -1)
242 return -1;
243 if (state->how == LOOK)
244 return 0;
245 break;
246 case COPY: /* -> COPY */
247 if (gz_load(state, state->out, state->size << 1, &(state->x.have))
248 == -1)
249 return -1;
250 state->x.next = state->out;
251 return 0;
252 case GZIP: /* -> GZIP or LOOK (if end of gzip stream) */
253 strm->avail_out = state->size << 1;
254 strm->next_out = state->out;
255 if (gz_decomp(state) == -1)
256 return -1;
257 }
258 } while (state->x.have == 0 && (!state->eof || strm->avail_in));
259 return 0;
260 }
261
262 /* Skip len uncompressed bytes of output. Return -1 on error, 0 on success. */
263 local int gz_skip(state, len)
264 gz_statep state;
265 z_off64_t len;
266 {
267 unsigned n;
268
269 /* skip over len bytes or reach end-of-file, whichever comes first */
270 while (len)
271 /* skip over whatever is in output buffer */
272 if (state->x.have) {
273 n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > len ?
274 (unsigned)len : state->x.have;
275 state->x.have -= n;
276 state->x.next += n;
277 state->x.pos += n;
278 len -= n;
279 }
280
281 /* output buffer empty -- return if we're at the end of the input */
282 else if (state->eof && state->strm.avail_in == 0)
283 break;
284
285 /* need more data to skip -- load up output buffer */
286 else {
287 /* get more output, looking for header if required */
288 if (gz_fetch(state) == -1)
289 return -1;
290 }
291 return 0;
292 }
293
294 /* Read len bytes into buf from file, or less than len up to the end of the
295 input. Return the number of bytes read. If zero is returned, either the
296 end of file was reached, or there was an error. state->err must be
297 consulted in that case to determine which. */
298 local z_size_t gz_read(state, buf, len)
299 gz_statep state;
300 voidp buf;
301 z_size_t len;
302 {
303 z_size_t got;
304 unsigned n;
305
306 /* if len is zero, avoid unnecessary operations */
307 if (len == 0)
308 return 0;
309
310 /* process a skip request */
311 if (state->seek) {
312 state->seek = 0;
313 if (gz_skip(state, state->skip) == -1)
314 return 0;
315 }
316
317 /* get len bytes to buf, or less than len if at the end */
318 got = 0;
319 do {
320 /* set n to the maximum amount of len that fits in an unsigned int */
321 n = -1;
322 if (n > len)
323 n = len;
324
325 /* first just try copying data from the output buffer */
326 if (state->x.have) {
327 if (state->x.have < n)
328 n = state->x.have;
329 memcpy(buf, state->x.next, n);
330 state->x.next += n;
331 state->x.have -= n;
332 }
333
334 /* output buffer empty -- return if we're at the end of the input */
335 else if (state->eof && state->strm.avail_in == 0) {
336 state->past = 1; /* tried to read past end */
337 break;
338 }
339
340 /* need output data -- for small len or new stream load up our output
341 buffer */
342 else if (state->how == LOOK || n < (state->size << 1)) {
343 /* get more output, looking for header if required */
344 if (gz_fetch(state) == -1)
345 return 0;
346 continue; /* no progress yet -- go back to copy above */
347 /* the copy above assures that we will leave with space in the
348 output buffer, allowing at least one gzungetc() to succeed */
349 }
350
351 /* large len -- read directly into user buffer */
352 else if (state->how == COPY) { /* read directly */
353 if (gz_load(state, (unsigned char *)buf, n, &n) == -1)
354 return 0;
355 }
356
357 /* large len -- decompress directly into user buffer */
358 else { /* state->how == GZIP */
359 state->strm.avail_out = n;
360 state->strm.next_out = (unsigned char *)buf;
361 if (gz_decomp(state) == -1)
362 return 0;
363 n = state->x.have;
364 state->x.have = 0;
365 }
366
367 /* update progress */
368 len -= n;
369 buf = (char *)buf + n;
370 got += n;
371 state->x.pos += n;
372 } while (len);
373
374 /* return number of bytes read into user buffer */
375 return got;
376 }
377
378 /* -- see zlib.h -- */
379 int ZEXPORT gzread(file, buf, len)
380 gzFile file;
381 voidp buf;
382 unsigned len;
383 {
384 gz_statep state;
385
386 /* get internal structure */
387 if (file == NULL)
388 return -1;
389 state = (gz_statep)file;
390
391 /* check that we're reading and that there's no (serious) error */
392 if (state->mode != GZ_READ ||
393 (state->err != Z_OK && state->err != Z_BUF_ERROR))
394 return -1;
395
396 /* since an int is returned, make sure len fits in one, otherwise return
397 with an error (this avoids a flaw in the interface) */
398 if ((int)len < 0) {
399 gz_error(state, Z_STREAM_ERROR, "request does not fit in an int");
400 return -1;
401 }
402
403 /* read len or fewer bytes to buf */
404 len = gz_read(state, buf, len);
405
406 /* check for an error */
407 if (len == 0 && state->err != Z_OK && state->err != Z_BUF_ERROR)
408 return -1;
409
410 /* return the number of bytes read (this is assured to fit in an int) */
411 return (int)len;
412 }
413
414 /* -- see zlib.h -- */
415 z_size_t ZEXPORT gzfread(buf, size, nitems, file)
416 voidp buf;
417 z_size_t size;
418 z_size_t nitems;
419 gzFile file;
420 {
421 z_size_t len;
422 gz_statep state;
423
424 /* get internal structure */
425 if (file == NULL)
426 return 0;
427 state = (gz_statep)file;
428
429 /* check that we're reading and that there's no (serious) error */
430 if (state->mode != GZ_READ ||
431 (state->err != Z_OK && state->err != Z_BUF_ERROR))
432 return 0;
433
434 /* compute bytes to read -- error on overflow */
435 len = nitems * size;
436 if (size && len / size != nitems) {
437 gz_error(state, Z_STREAM_ERROR, "request does not fit in a size_t");
438 return 0;
439 }
440
441 /* read len or fewer bytes to buf, return the number of full items read */
442 return len ? gz_read(state, buf, len) / size : 0;
443 }
444
445 /* -- see zlib.h -- */
446 #ifdef Z_PREFIX_SET
447 # undef z_gzgetc
448 #else
449 # undef gzgetc
450 #endif
451 int ZEXPORT gzgetc(file)
452 gzFile file;
453 {
454 int ret;
455 unsigned char buf[1];
456 gz_statep state;
457
458 /* get internal structure */
459 if (file == NULL)
460 return -1;
461 state = (gz_statep)file;
462
463 /* check that we're reading and that there's no (serious) error */
464 if (state->mode != GZ_READ ||
465 (state->err != Z_OK && state->err != Z_BUF_ERROR))
466 return -1;
467
468 /* try output buffer (no need to check for skip request) */
469 if (state->x.have) {
470 state->x.have--;
471 state->x.pos++;
472 return *(state->x.next)++;
473 }
474
475 /* nothing there -- try gz_read() */
476 ret = gz_read(state, buf, 1);
477 return ret < 1 ? -1 : buf[0];
478 }
479
480 int ZEXPORT gzgetc_(file)
481 gzFile file;
482 {
483 return gzgetc(file);
484 }
485
486 /* -- see zlib.h -- */
487 int ZEXPORT gzungetc(c, file)
488 int c;
489 gzFile file;
490 {
491 gz_statep state;
492
493 /* get internal structure */
494 if (file == NULL)
495 return -1;
496 state = (gz_statep)file;
497
498 /* check that we're reading and that there's no (serious) error */
499 if (state->mode != GZ_READ ||
500 (state->err != Z_OK && state->err != Z_BUF_ERROR))
501 return -1;
502
503 /* process a skip request */
504 if (state->seek) {
505 state->seek = 0;
506 if (gz_skip(state, state->skip) == -1)
507 return -1;
508 }
509
510 /* can't push EOF */
511 if (c < 0)
512 return -1;
513
514 /* if output buffer empty, put byte at end (allows more pushing) */
515 if (state->x.have == 0) {
516 state->x.have = 1;
517 state->x.next = state->out + (state->size << 1) - 1;
518 state->x.next[0] = (unsigned char)c;
519 state->x.pos--;
520 state->past = 0;
521 return c;
522 }
523
524 /* if no room, give up (must have already done a gzungetc()) */
525 if (state->x.have == (state->size << 1)) {
526 gz_error(state, Z_DATA_ERROR, "out of room to push characters");
527 return -1;
528 }
529
530 /* slide output data if needed and insert byte before existing data */
531 if (state->x.next == state->out) {
532 unsigned char *src = state->out + state->x.have;
533 unsigned char *dest = state->out + (state->size << 1);
534 while (src > state->out)
535 *--dest = *--src;
536 state->x.next = dest;
537 }
538 state->x.have++;
539 state->x.next--;
540 state->x.next[0] = (unsigned char)c;
541 state->x.pos--;
542 state->past = 0;
543 return c;
544 }
545
546 /* -- see zlib.h -- */
547 char * ZEXPORT gzgets(file, buf, len)
548 gzFile file;
549 char *buf;
550 int len;
551 {
552 unsigned left, n;
553 char *str;
554 unsigned char *eol;
555 gz_statep state;
556
557 /* check parameters and get internal structure */
558 if (file == NULL || buf == NULL || len < 1)
559 return NULL;
560 state = (gz_statep)file;
561
562 /* check that we're reading and that there's no (serious) error */
563 if (state->mode != GZ_READ ||
564 (state->err != Z_OK && state->err != Z_BUF_ERROR))
565 return NULL;
566
567 /* process a skip request */
568 if (state->seek) {
569 state->seek = 0;
570 if (gz_skip(state, state->skip) == -1)
571 return NULL;
572 }
573
574 /* copy output bytes up to new line or len - 1, whichever comes first --
575 append a terminating zero to the string (we don't check for a zero in
576 the contents, let the user worry about that) */
577 str = buf;
578 left = (unsigned)len - 1;
579 if (left) do {
580 /* assure that something is in the output buffer */
581 if (state->x.have == 0 && gz_fetch(state) == -1)
582 return NULL; /* error */
583 if (state->x.have == 0) { /* end of file */
584 state->past = 1; /* read past end */
585 break; /* return what we have */
586 }
587
588 /* look for end-of-line in current output buffer */
589 n = state->x.have > left ? left : state->x.have;
590 eol = (unsigned char *)memchr(state->x.next, '\n', n);
591 if (eol != NULL)
592 n = (unsigned)(eol - state->x.next) + 1;
593
594 /* copy through end-of-line, or remainder if not found */
595 memcpy(buf, state->x.next, n);
596 state->x.have -= n;
597 state->x.next += n;
598 state->x.pos += n;
599 left -= n;
600 buf += n;
601 } while (left && eol == NULL);
602
603 /* return terminated string, or if nothing, end of file */
604 if (buf == str)
605 return NULL;
606 buf[0] = 0;
607 return str;
608 }
609
610 /* -- see zlib.h -- */
611 int ZEXPORT gzdirect(file)
612 gzFile file;
613 {
614 gz_statep state;
615
616 /* get internal structure */
617 if (file == NULL)
618 return 0;
619 state = (gz_statep)file;
620
621 /* if the state is not known, but we can find out, then do so (this is
622 mainly for right after a gzopen() or gzdopen()) */
623 if (state->mode == GZ_READ && state->how == LOOK && state->x.have == 0)
624 (void)gz_look(state);
625
626 /* return 1 if transparent, 0 if processing a gzip stream */
627 return state->direct;
628 }
629
630 /* -- see zlib.h -- */
631 int ZEXPORT gzclose_r(file)
632 gzFile file;
633 {
634 int ret, err;
635 gz_statep state;
636
637 /* get internal structure */
638 if (file == NULL)
639 return Z_STREAM_ERROR;
640 state = (gz_statep)file;
641
642 /* check that we're reading */
643 if (state->mode != GZ_READ)
644 return Z_STREAM_ERROR;
645
646 /* free memory and close file */
647 if (state->size) {
648 inflateEnd(&(state->strm));
649 free(state->out);
650 free(state->in);
651 }
652 err = state->err == Z_BUF_ERROR ? Z_BUF_ERROR : Z_OK;
653 gz_error(state, Z_OK, NULL);
654 free(state->path);
655 ret = close(state->fd);
656 free(state);
657 return ret ? Z_ERRNO : err;
658 }