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 */
9local int gz_load OF((gz_statep, unsigned char *, unsigned, unsigned *));
10local int gz_avail OF((gz_statep));
11local int gz_look OF((gz_statep));
12local int gz_decomp OF((gz_statep));
13local int gz_fetch OF((gz_statep));
14local int gz_skip OF((gz_statep, z_off64_t));
15local 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. */
21local 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. */
56local 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. */
91local 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. */
175local 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. */
229local 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. */
259local 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. */
294local 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 -- */
375int 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 -- */
411z_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# ifdef Z_CR_PREFIX_SET
447# define gzgetc Cr_z_gzgetc
448# endif
449#endif
450
451int 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
480int ZEXPORT gzgetc_(file)
481gzFile file;
482{
483 return gzgetc(file);
484}
485
486/* -- see zlib.h -- */
487int 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 -- */
547char * 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 -- */
611int 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 -- */
631int 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}
659