1 /* inflate.c -- zlib decompression
2 * Copyright (C) 1995-2005 Mark Adler
3 * For conditions of distribution and use, see copyright notice in zlib.h
5 * Based on zlib 1.2.3 but modified for the Linux Kernel by
6 * Richard Purdie <richard@openedhand.com>
8 * Changes mainly for static instead of dynamic memory allocation
12 #include <linux/zutil.h>
18 int zlib_inflate_workspacesize(void)
20 return sizeof(struct inflate_workspace);
23 int zlib_inflateReset(z_streamp strm)
25 struct inflate_state *state;
27 if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
28 state = (struct inflate_state *)strm->state;
29 strm->total_in = strm->total_out = state->total = 0;
31 strm->adler = 1; /* to support ill-conceived Java test suite */
38 state->lencode = state->distcode = state->next = state->codes;
40 /* Initialise Window */
41 state->wsize = 1U << state->wbits;
49 int zlib_inflatePrime(z_streamp strm, int bits, int value)
51 struct inflate_state *state;
53 if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
54 state = (struct inflate_state *)strm->state;
55 if (bits > 16 || state->bits + bits > 32) return Z_STREAM_ERROR;
56 value &= (1L << bits) - 1;
57 state->hold += value << state->bits;
63 int zlib_inflateInit2(z_streamp strm, int windowBits)
65 struct inflate_state *state;
67 if (strm == NULL) return Z_STREAM_ERROR;
68 strm->msg = NULL; /* in case we return an error */
70 state = &WS(strm)->inflate_state;
71 strm->state = (struct internal_state *)state;
75 windowBits = -windowBits;
78 state->wrap = (windowBits >> 4) + 1;
80 if (windowBits < 8 || windowBits > 15) {
81 return Z_STREAM_ERROR;
83 state->wbits = (unsigned)windowBits;
84 state->window = &WS(strm)->working_window[0];
86 return zlib_inflateReset(strm);
90 Return state with length and distance decoding tables and index sizes set to
91 fixed code decoding. This returns fixed tables from inffixed.h.
93 static void zlib_fixedtables(struct inflate_state *state)
95 # include "inffixed.h"
96 state->lencode = lenfix;
98 state->distcode = distfix;
104 Update the window with the last wsize (normally 32K) bytes written before
105 returning. This is only called when a window is already in use, or when
106 output has been written during this inflate call, but the end of the deflate
107 stream has not been reached yet. It is also called to window dictionary data
108 when a dictionary is loaded.
110 Providing output buffers larger than 32K to inflate() should provide a speed
111 advantage, since only the last 32K of output is copied to the sliding window
112 upon return from inflate(), and since all distances after the first 32K of
113 output will fall in the output data, making match copies simpler and faster.
114 The advantage may be dependent on the size of the processor's data caches.
116 static void zlib_updatewindow(z_streamp strm, unsigned out)
118 struct inflate_state *state;
121 state = (struct inflate_state *)strm->state;
123 /* copy state->wsize or less output bytes into the circular window */
124 copy = out - strm->avail_out;
125 if (copy >= state->wsize) {
126 memcpy(state->window, strm->next_out - state->wsize, state->wsize);
128 state->whave = state->wsize;
131 dist = state->wsize - state->write;
132 if (dist > copy) dist = copy;
133 memcpy(state->window + state->write, strm->next_out - copy, dist);
136 memcpy(state->window, strm->next_out - copy, copy);
138 state->whave = state->wsize;
141 state->write += dist;
142 if (state->write == state->wsize) state->write = 0;
143 if (state->whave < state->wsize) state->whave += dist;
150 * At the end of a Deflate-compressed PPP packet, we expect to have seen
151 * a `stored' block type value but not the (zero) length bytes.
154 Returns true if inflate is currently at the end of a block generated by
155 Z_SYNC_FLUSH or Z_FULL_FLUSH. This function is used by one PPP
156 implementation to provide an additional safety check. PPP uses
157 Z_SYNC_FLUSH but removes the length bytes of the resulting empty stored
158 block. When decompressing, PPP checks that at the end of input packet,
159 inflate is waiting for these length bytes.
161 static int zlib_inflateSyncPacket(z_streamp strm)
163 struct inflate_state *state;
165 if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
166 state = (struct inflate_state *)strm->state;
168 if (state->mode == STORED && state->bits == 0) {
175 /* Macros for inflate(): */
177 /* check function to use adler32() for zlib or crc32() for gzip */
178 #define UPDATE(check, buf, len) zlib_adler32(check, buf, len)
180 /* Load registers with state in inflate() for speed */
183 put = strm->next_out; \
184 left = strm->avail_out; \
185 next = strm->next_in; \
186 have = strm->avail_in; \
187 hold = state->hold; \
188 bits = state->bits; \
191 /* Restore state from registers in inflate() */
194 strm->next_out = put; \
195 strm->avail_out = left; \
196 strm->next_in = next; \
197 strm->avail_in = have; \
198 state->hold = hold; \
199 state->bits = bits; \
202 /* Clear the input bit accumulator */
209 /* Get a byte of input into the bit accumulator, or return from inflate()
210 if there is no input available. */
213 if (have == 0) goto inf_leave; \
215 hold += (unsigned long)(*next++) << bits; \
219 /* Assure that there are at least n bits in the bit accumulator. If there is
220 not enough available input to do that, then return from inflate(). */
221 #define NEEDBITS(n) \
223 while (bits < (unsigned)(n)) \
227 /* Return the low n bits of the bit accumulator (n < 16) */
229 ((unsigned)hold & ((1U << (n)) - 1))
231 /* Remove n bits from the bit accumulator */
232 #define DROPBITS(n) \
235 bits -= (unsigned)(n); \
238 /* Remove zero to seven bits as needed to go to a byte boundary */
245 /* Reverse the bytes in a 32-bit value */
247 ((((q) >> 24) & 0xff) + (((q) >> 8) & 0xff00) + \
248 (((q) & 0xff00) << 8) + (((q) & 0xff) << 24))
251 inflate() uses a state machine to process as much input data and generate as
252 much output data as possible before returning. The state machine is
253 structured roughly as follows:
255 for (;;) switch (state) {
258 if (not enough input data or output space to make progress)
260 ... make progress ...
266 so when inflate() is called again, the same case is attempted again, and
267 if the appropriate resources are provided, the machine proceeds to the
268 next state. The NEEDBITS() macro is usually the way the state evaluates
269 whether it can proceed or should return. NEEDBITS() does the return if
270 the requested bits are not available. The typical use of the BITS macros
274 ... do something with BITS(n) ...
277 where NEEDBITS(n) either returns from inflate() if there isn't enough
278 input left to load n bits into the accumulator, or it continues. BITS(n)
279 gives the low n bits in the accumulator. When done, DROPBITS(n) drops
280 the low n bits off the accumulator. INITBITS() clears the accumulator
281 and sets the number of available bits to zero. BYTEBITS() discards just
282 enough bits to put the accumulator on a byte boundary. After BYTEBITS()
283 and a NEEDBITS(8), then BITS(8) would return the next byte in the stream.
285 NEEDBITS(n) uses PULLBYTE() to get an available byte of input, or to return
286 if there is no input available. The decoding of variable length codes uses
287 PULLBYTE() directly in order to pull just enough bytes to decode the next
290 Some states loop until they get enough input, making sure that enough
291 state information is maintained to continue the loop where it left off
292 if NEEDBITS() returns in the loop. For example, want, need, and keep
293 would all have to actually be part of the saved state in case NEEDBITS()
297 while (want < need) {
299 keep[want++] = BITS(n);
305 As shown above, if the next state is also the next case, then the break
308 A state may also return if there is not enough output space available to
309 complete that state. Those states are copying stored data, writing a
310 literal byte, and copying a matching string.
312 When returning, a "goto inf_leave" is used to update the total counters,
313 update the check value, and determine whether any progress has been made
314 during that inflate() call in order to return the proper return code.
315 Progress is defined as a change in either strm->avail_in or strm->avail_out.
316 When there is a window, goto inf_leave will update the window with the last
317 output written. If a goto inf_leave occurs in the middle of decompression
318 and there is no window currently, goto inf_leave will create one and copy
319 output to the window for the next call of inflate().
321 In this implementation, the flush parameter of inflate() only affects the
322 return code (per zlib.h). inflate() always writes as much as possible to
323 strm->next_out, given the space available and the provided input--the effect
324 documented in zlib.h of Z_SYNC_FLUSH. Furthermore, inflate() always defers
325 the allocation of and copying into a sliding window until necessary, which
326 provides the effect documented in zlib.h for Z_FINISH when the entire input
327 stream available. So the only thing the flush parameter actually does is:
328 when flush is set to Z_FINISH, inflate() cannot return Z_OK. Instead it
329 will return Z_BUF_ERROR if it has not reached the end of the stream.
332 int zlib_inflate(z_streamp strm, int flush)
334 struct inflate_state *state;
335 const unsigned char *next; /* next input */
336 unsigned char *put; /* next output */
337 unsigned have, left; /* available input and output */
338 unsigned long hold; /* bit buffer */
339 unsigned bits; /* bits in bit buffer */
340 unsigned in, out; /* save starting available input and output */
341 unsigned copy; /* number of stored or match bytes to copy */
342 unsigned char *from; /* where to copy match bytes from */
343 code this; /* current decoding table entry */
344 code last; /* parent table entry */
345 unsigned len; /* length to copy for repeats, bits to drop */
346 int ret; /* return code */
347 static const unsigned short order[19] = /* permutation of code lengths */
348 {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
350 /* Do not check for strm->next_out == NULL here as ppc zImage
351 inflates to strm->next_out = 0 */
353 if (strm == NULL || strm->state == NULL ||
354 (strm->next_in == NULL && strm->avail_in != 0))
355 return Z_STREAM_ERROR;
357 state = (struct inflate_state *)strm->state;
359 if (state->mode == TYPE) state->mode = TYPEDO; /* skip check */
365 switch (state->mode) {
367 if (state->wrap == 0) {
368 state->mode = TYPEDO;
373 ((BITS(8) << 8) + (hold >> 8)) % 31) {
374 strm->msg = (char *)"incorrect header check";
378 if (BITS(4) != Z_DEFLATED) {
379 strm->msg = (char *)"unknown compression method";
385 if (len > state->wbits) {
386 strm->msg = (char *)"invalid window size";
390 state->dmax = 1U << len;
391 strm->adler = state->check = zlib_adler32(0L, NULL, 0);
392 state->mode = hold & 0x200 ? DICTID : TYPE;
397 strm->adler = state->check = REVERSE(hold);
401 if (state->havedict == 0) {
405 strm->adler = state->check = zlib_adler32(0L, NULL, 0);
408 if (flush == Z_BLOCK) goto inf_leave;
416 state->last = BITS(1);
419 case 0: /* stored block */
420 state->mode = STORED;
422 case 1: /* fixed block */
423 zlib_fixedtables(state);
424 state->mode = LEN; /* decode codes */
426 case 2: /* dynamic block */
430 strm->msg = (char *)"invalid block type";
436 BYTEBITS(); /* go to byte boundary */
438 if ((hold & 0xffff) != ((hold >> 16) ^ 0xffff)) {
439 strm->msg = (char *)"invalid stored block lengths";
443 state->length = (unsigned)hold & 0xffff;
447 copy = state->length;
449 if (copy > have) copy = have;
450 if (copy > left) copy = left;
451 if (copy == 0) goto inf_leave;
452 memcpy(put, next, copy);
457 state->length -= copy;
464 state->nlen = BITS(5) + 257;
466 state->ndist = BITS(5) + 1;
468 state->ncode = BITS(4) + 4;
470 #ifndef PKZIP_BUG_WORKAROUND
471 if (state->nlen > 286 || state->ndist > 30) {
472 strm->msg = (char *)"too many length or distance symbols";
478 state->mode = LENLENS;
480 while (state->have < state->ncode) {
482 state->lens[order[state->have++]] = (unsigned short)BITS(3);
485 while (state->have < 19)
486 state->lens[order[state->have++]] = 0;
487 state->next = state->codes;
488 state->lencode = (code const *)(state->next);
490 ret = zlib_inflate_table(CODES, state->lens, 19, &(state->next),
491 &(state->lenbits), state->work);
493 strm->msg = (char *)"invalid code lengths set";
498 state->mode = CODELENS;
500 while (state->have < state->nlen + state->ndist) {
502 this = state->lencode[BITS(state->lenbits)];
503 if ((unsigned)(this.bits) <= bits) break;
509 state->lens[state->have++] = this.val;
512 if (this.val == 16) {
513 NEEDBITS(this.bits + 2);
515 if (state->have == 0) {
516 strm->msg = (char *)"invalid bit length repeat";
520 len = state->lens[state->have - 1];
524 else if (this.val == 17) {
525 NEEDBITS(this.bits + 3);
532 NEEDBITS(this.bits + 7);
538 if (state->have + copy > state->nlen + state->ndist) {
539 strm->msg = (char *)"invalid bit length repeat";
544 state->lens[state->have++] = (unsigned short)len;
548 /* handle error breaks in while */
549 if (state->mode == BAD) break;
551 /* build code tables */
552 state->next = state->codes;
553 state->lencode = (code const *)(state->next);
555 ret = zlib_inflate_table(LENS, state->lens, state->nlen, &(state->next),
556 &(state->lenbits), state->work);
558 strm->msg = (char *)"invalid literal/lengths set";
562 state->distcode = (code const *)(state->next);
564 ret = zlib_inflate_table(DISTS, state->lens + state->nlen, state->ndist,
565 &(state->next), &(state->distbits), state->work);
567 strm->msg = (char *)"invalid distances set";
573 if (have >= 6 && left >= 258) {
575 inflate_fast(strm, out);
580 this = state->lencode[BITS(state->lenbits)];
581 if ((unsigned)(this.bits) <= bits) break;
584 if (this.op && (this.op & 0xf0) == 0) {
587 this = state->lencode[last.val +
588 (BITS(last.bits + last.op) >> last.bits)];
589 if ((unsigned)(last.bits + this.bits) <= bits) break;
595 state->length = (unsigned)this.val;
596 if ((int)(this.op) == 0) {
605 strm->msg = (char *)"invalid literal/length code";
609 state->extra = (unsigned)(this.op) & 15;
610 state->mode = LENEXT;
613 NEEDBITS(state->extra);
614 state->length += BITS(state->extra);
615 DROPBITS(state->extra);
620 this = state->distcode[BITS(state->distbits)];
621 if ((unsigned)(this.bits) <= bits) break;
624 if ((this.op & 0xf0) == 0) {
627 this = state->distcode[last.val +
628 (BITS(last.bits + last.op) >> last.bits)];
629 if ((unsigned)(last.bits + this.bits) <= bits) break;
636 strm->msg = (char *)"invalid distance code";
640 state->offset = (unsigned)this.val;
641 state->extra = (unsigned)(this.op) & 15;
642 state->mode = DISTEXT;
645 NEEDBITS(state->extra);
646 state->offset += BITS(state->extra);
647 DROPBITS(state->extra);
649 #ifdef INFLATE_STRICT
650 if (state->offset > state->dmax) {
651 strm->msg = (char *)"invalid distance too far back";
656 if (state->offset > state->whave + out - left) {
657 strm->msg = (char *)"invalid distance too far back";
663 if (left == 0) goto inf_leave;
665 if (state->offset > copy) { /* copy from window */
666 copy = state->offset - copy;
667 if (copy > state->write) {
668 copy -= state->write;
669 from = state->window + (state->wsize - copy);
672 from = state->window + (state->write - copy);
673 if (copy > state->length) copy = state->length;
675 else { /* copy from output */
676 from = put - state->offset;
677 copy = state->length;
679 if (copy > left) copy = left;
681 state->length -= copy;
685 if (state->length == 0) state->mode = LEN;
688 if (left == 0) goto inf_leave;
689 *put++ = (unsigned char)(state->length);
697 strm->total_out += out;
700 strm->adler = state->check =
701 UPDATE(state->check, put - out, out);
704 REVERSE(hold)) != state->check) {
705 strm->msg = (char *)"incorrect data check";
722 return Z_STREAM_ERROR;
726 Return from inflate(), updating the total counts and the check value.
727 If there was no progress during the inflate() call, return a buffer
728 error. Call zlib_updatewindow() to create and/or update the window state.
732 if (state->wsize || (state->mode < CHECK && out != strm->avail_out))
733 zlib_updatewindow(strm, out);
735 in -= strm->avail_in;
736 out -= strm->avail_out;
737 strm->total_in += in;
738 strm->total_out += out;
740 if (state->wrap && out)
741 strm->adler = state->check =
742 UPDATE(state->check, strm->next_out - out, out);
744 strm->data_type = state->bits + (state->last ? 64 : 0) +
745 (state->mode == TYPE ? 128 : 0);
747 if (flush == Z_PACKET_FLUSH && ret == Z_OK &&
748 strm->avail_out != 0 && strm->avail_in == 0)
749 return zlib_inflateSyncPacket(strm);
751 if (((in == 0 && out == 0) || flush == Z_FINISH) && ret == Z_OK)
757 int zlib_inflateEnd(z_streamp strm)
759 if (strm == NULL || strm->state == NULL)
760 return Z_STREAM_ERROR;
765 int zlib_inflateSetDictionary(z_streamp strm, const Byte *dictionary,
768 struct inflate_state *state;
772 if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
773 state = (struct inflate_state *)strm->state;
774 if (state->wrap != 0 && state->mode != DICT)
775 return Z_STREAM_ERROR;
777 /* check for correct dictionary id */
778 if (state->mode == DICT) {
779 id = zlib_adler32(0L, NULL, 0);
780 id = zlib_adler32(id, dictionary, dictLength);
781 if (id != state->check)
785 /* copy dictionary to window */
786 zlib_updatewindow(strm, strm->avail_out);
788 if (dictLength > state->wsize) {
789 memcpy(state->window, dictionary + dictLength - state->wsize,
791 state->whave = state->wsize;
794 memcpy(state->window + state->wsize - dictLength, dictionary,
796 state->whave = dictLength;
805 Search buf[0..len-1] for the pattern: 0, 0, 0xff, 0xff. Return when found
806 or when out of input. When called, *have is the number of pattern bytes
807 found in order so far, in 0..3. On return *have is updated to the new
808 state. If on return *have equals four, then the pattern was found and the
809 return value is how many bytes were read including the last byte of the
810 pattern. If *have is less than four, then the pattern has not been found
811 yet and the return value is len. In the latter case, zlib_syncsearch() can be
812 called again with more data and the *have state. *have is initialized to
813 zero for the first call.
815 static unsigned zlib_syncsearch(unsigned *have, unsigned char *buf,
823 while (next < len && got < 4) {
824 if ((int)(buf[next]) == (got < 2 ? 0 : 0xff))
838 int zlib_inflateSync(z_streamp strm)
840 unsigned len; /* number of bytes to look at or looked at */
841 unsigned long in, out; /* temporary to save total_in and total_out */
842 unsigned char buf[4]; /* to restore bit buffer to byte string */
843 struct inflate_state *state;
845 /* check parameters */
846 if (strm == NULL || strm->state == NULL) return Z_STREAM_ERROR;
847 state = (struct inflate_state *)strm->state;
848 if (strm->avail_in == 0 && state->bits < 8) return Z_BUF_ERROR;
850 /* if first time, start search in bit buffer */
851 if (state->mode != SYNC) {
853 state->hold <<= state->bits & 7;
854 state->bits -= state->bits & 7;
856 while (state->bits >= 8) {
857 buf[len++] = (unsigned char)(state->hold);
862 zlib_syncsearch(&(state->have), buf, len);
865 /* search available input */
866 len = zlib_syncsearch(&(state->have), strm->next_in, strm->avail_in);
867 strm->avail_in -= len;
868 strm->next_in += len;
869 strm->total_in += len;
871 /* return no joy or set up to restart inflate() on a new block */
872 if (state->have != 4) return Z_DATA_ERROR;
873 in = strm->total_in; out = strm->total_out;
874 zlib_inflateReset(strm);
875 strm->total_in = in; strm->total_out = out;
882 * This subroutine adds the data at next_in/avail_in to the output history
883 * without performing any output. The output buffer must be "caught up";
884 * i.e. no pending output but this should always be the case. The state must
885 * be waiting on the start of a block (i.e. mode == TYPE or HEAD). On exit,
886 * the output will also be caught up, and the checksum will have been updated
889 int zlib_inflateIncomp(z_stream *z)
891 struct inflate_state *state = (struct inflate_state *)z->state;
892 Byte *saved_no = z->next_out;
893 uInt saved_ao = z->avail_out;
895 if (state->mode != TYPE && state->mode != HEAD)
898 /* Setup some variables to allow misuse of updateWindow */
900 z->next_out = (unsigned char*)z->next_in + z->avail_in;
902 zlib_updatewindow(z, z->avail_in);
904 /* Restore saved variables */
905 z->avail_out = saved_ao;
906 z->next_out = saved_no;
908 z->adler = state->check =
909 UPDATE(state->check, z->next_in, z->avail_in);
911 z->total_out += z->avail_in;
912 z->total_in += z->avail_in;
913 z->next_in += z->avail_in;
914 state->total += z->avail_in;