in zlib/contrib/infback9/infback9.c [212:594]
int ZEXPORT inflateBack9(z_stream FAR *strm, in_func in, void FAR *in_desc,
out_func out, void FAR *out_desc) {
struct inflate_state FAR *state;
z_const unsigned char FAR *next; /* next input */
unsigned char FAR *put; /* next output */
unsigned have; /* available input */
unsigned long left; /* available output */
inflate_mode mode; /* current inflate mode */
int lastblock; /* true if processing last block */
int wrap; /* true if the window has wrapped */
unsigned char FAR *window; /* allocated sliding window, if needed */
unsigned long hold; /* bit buffer */
unsigned bits; /* bits in bit buffer */
unsigned extra; /* extra bits needed */
unsigned long length; /* literal or length of data to copy */
unsigned long offset; /* distance back to copy string from */
unsigned long copy; /* number of stored or match bytes to copy */
unsigned char FAR *from; /* where to copy match bytes from */
code const FAR *lencode; /* starting table for length/literal codes */
code const FAR *distcode; /* starting table for distance codes */
unsigned lenbits; /* index bits for lencode */
unsigned distbits; /* index bits for distcode */
code here; /* current decoding table entry */
code last; /* parent table entry */
unsigned len; /* length to copy for repeats, bits to drop */
int ret; /* return code */
static const unsigned short order[19] = /* permutation of code lengths */
{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
#include "inffix9.h"
/* Check that the strm exists and that the state was initialized */
if (strm == Z_NULL || strm->state == Z_NULL)
return Z_STREAM_ERROR;
state = (struct inflate_state FAR *)strm->state;
/* Reset the state */
strm->msg = Z_NULL;
mode = TYPE;
lastblock = 0;
wrap = 0;
window = state->window;
next = strm->next_in;
have = next != Z_NULL ? strm->avail_in : 0;
hold = 0;
bits = 0;
put = window;
left = WSIZE;
lencode = Z_NULL;
distcode = Z_NULL;
/* Inflate until end of block marked as last */
for (;;)
switch (mode) {
case TYPE:
/* determine and dispatch block type */
if (lastblock) {
BYTEBITS();
mode = DONE;
break;
}
NEEDBITS(3);
lastblock = BITS(1);
DROPBITS(1);
switch (BITS(2)) {
case 0: /* stored block */
Tracev((stderr, "inflate: stored block%s\n",
lastblock ? " (last)" : ""));
mode = STORED;
break;
case 1: /* fixed block */
lencode = lenfix;
lenbits = 9;
distcode = distfix;
distbits = 5;
Tracev((stderr, "inflate: fixed codes block%s\n",
lastblock ? " (last)" : ""));
mode = LEN; /* decode codes */
break;
case 2: /* dynamic block */
Tracev((stderr, "inflate: dynamic codes block%s\n",
lastblock ? " (last)" : ""));
mode = TABLE;
break;
case 3:
strm->msg = (char *)"invalid block type";
mode = BAD;
}
DROPBITS(2);
break;
case STORED:
/* get and verify stored block length */
BYTEBITS(); /* go to byte boundary */
NEEDBITS(32);
if ((hold & 0xffff) != ((hold >> 16) ^ 0xffff)) {
strm->msg = (char *)"invalid stored block lengths";
mode = BAD;
break;
}
length = (unsigned)hold & 0xffff;
Tracev((stderr, "inflate: stored length %lu\n",
length));
INITBITS();
/* copy stored block from input to output */
while (length != 0) {
copy = length;
PULL();
ROOM();
if (copy > have) copy = have;
if (copy > left) copy = left;
zmemcpy(put, next, copy);
have -= copy;
next += copy;
left -= copy;
put += copy;
length -= copy;
}
Tracev((stderr, "inflate: stored end\n"));
mode = TYPE;
break;
case TABLE:
/* get dynamic table entries descriptor */
NEEDBITS(14);
state->nlen = BITS(5) + 257;
DROPBITS(5);
state->ndist = BITS(5) + 1;
DROPBITS(5);
state->ncode = BITS(4) + 4;
DROPBITS(4);
if (state->nlen > 286) {
strm->msg = (char *)"too many length symbols";
mode = BAD;
break;
}
Tracev((stderr, "inflate: table sizes ok\n"));
/* get code length code lengths (not a typo) */
state->have = 0;
while (state->have < state->ncode) {
NEEDBITS(3);
state->lens[order[state->have++]] = (unsigned short)BITS(3);
DROPBITS(3);
}
while (state->have < 19)
state->lens[order[state->have++]] = 0;
state->next = state->codes;
lencode = (code const FAR *)(state->next);
lenbits = 7;
ret = inflate_table9(CODES, state->lens, 19, &(state->next),
&(lenbits), state->work);
if (ret) {
strm->msg = (char *)"invalid code lengths set";
mode = BAD;
break;
}
Tracev((stderr, "inflate: code lengths ok\n"));
/* get length and distance code code lengths */
state->have = 0;
while (state->have < state->nlen + state->ndist) {
for (;;) {
here = lencode[BITS(lenbits)];
if ((unsigned)(here.bits) <= bits) break;
PULLBYTE();
}
if (here.val < 16) {
NEEDBITS(here.bits);
DROPBITS(here.bits);
state->lens[state->have++] = here.val;
}
else {
if (here.val == 16) {
NEEDBITS(here.bits + 2);
DROPBITS(here.bits);
if (state->have == 0) {
strm->msg = (char *)"invalid bit length repeat";
mode = BAD;
break;
}
len = (unsigned)(state->lens[state->have - 1]);
copy = 3 + BITS(2);
DROPBITS(2);
}
else if (here.val == 17) {
NEEDBITS(here.bits + 3);
DROPBITS(here.bits);
len = 0;
copy = 3 + BITS(3);
DROPBITS(3);
}
else {
NEEDBITS(here.bits + 7);
DROPBITS(here.bits);
len = 0;
copy = 11 + BITS(7);
DROPBITS(7);
}
if (state->have + copy > state->nlen + state->ndist) {
strm->msg = (char *)"invalid bit length repeat";
mode = BAD;
break;
}
while (copy--)
state->lens[state->have++] = (unsigned short)len;
}
}
/* handle error breaks in while */
if (mode == BAD) break;
/* check for end-of-block code (better have one) */
if (state->lens[256] == 0) {
strm->msg = (char *)"invalid code -- missing end-of-block";
mode = BAD;
break;
}
/* build code tables -- note: do not change the lenbits or distbits
values here (9 and 6) without reading the comments in inftree9.h
concerning the ENOUGH constants, which depend on those values */
state->next = state->codes;
lencode = (code const FAR *)(state->next);
lenbits = 9;
ret = inflate_table9(LENS, state->lens, state->nlen,
&(state->next), &(lenbits), state->work);
if (ret) {
strm->msg = (char *)"invalid literal/lengths set";
mode = BAD;
break;
}
distcode = (code const FAR *)(state->next);
distbits = 6;
ret = inflate_table9(DISTS, state->lens + state->nlen,
state->ndist, &(state->next), &(distbits),
state->work);
if (ret) {
strm->msg = (char *)"invalid distances set";
mode = BAD;
break;
}
Tracev((stderr, "inflate: codes ok\n"));
mode = LEN;
case LEN:
/* get a literal, length, or end-of-block code */
for (;;) {
here = lencode[BITS(lenbits)];
if ((unsigned)(here.bits) <= bits) break;
PULLBYTE();
}
if (here.op && (here.op & 0xf0) == 0) {
last = here;
for (;;) {
here = lencode[last.val +
(BITS(last.bits + last.op) >> last.bits)];
if ((unsigned)(last.bits + here.bits) <= bits) break;
PULLBYTE();
}
DROPBITS(last.bits);
}
DROPBITS(here.bits);
length = (unsigned)here.val;
/* process literal */
if (here.op == 0) {
Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
"inflate: literal '%c'\n" :
"inflate: literal 0x%02x\n", here.val));
ROOM();
*put++ = (unsigned char)(length);
left--;
mode = LEN;
break;
}
/* process end of block */
if (here.op & 32) {
Tracevv((stderr, "inflate: end of block\n"));
mode = TYPE;
break;
}
/* invalid code */
if (here.op & 64) {
strm->msg = (char *)"invalid literal/length code";
mode = BAD;
break;
}
/* length code -- get extra bits, if any */
extra = (unsigned)(here.op) & 31;
if (extra != 0) {
NEEDBITS(extra);
length += BITS(extra);
DROPBITS(extra);
}
Tracevv((stderr, "inflate: length %lu\n", length));
/* get distance code */
for (;;) {
here = distcode[BITS(distbits)];
if ((unsigned)(here.bits) <= bits) break;
PULLBYTE();
}
if ((here.op & 0xf0) == 0) {
last = here;
for (;;) {
here = distcode[last.val +
(BITS(last.bits + last.op) >> last.bits)];
if ((unsigned)(last.bits + here.bits) <= bits) break;
PULLBYTE();
}
DROPBITS(last.bits);
}
DROPBITS(here.bits);
if (here.op & 64) {
strm->msg = (char *)"invalid distance code";
mode = BAD;
break;
}
offset = (unsigned)here.val;
/* get distance extra bits, if any */
extra = (unsigned)(here.op) & 15;
if (extra != 0) {
NEEDBITS(extra);
offset += BITS(extra);
DROPBITS(extra);
}
if (offset > WSIZE - (wrap ? 0: left)) {
strm->msg = (char *)"invalid distance too far back";
mode = BAD;
break;
}
Tracevv((stderr, "inflate: distance %lu\n", offset));
/* copy match from window to output */
do {
ROOM();
copy = WSIZE - offset;
if (copy < left) {
from = put + copy;
copy = left - copy;
}
else {
from = put - offset;
copy = left;
}
if (copy > length) copy = length;
length -= copy;
left -= copy;
do {
*put++ = *from++;
} while (--copy);
} while (length != 0);
break;
case DONE:
/* inflate stream terminated properly -- write leftover output */
ret = Z_STREAM_END;
if (left < WSIZE) {
if (out(out_desc, window, (unsigned)(WSIZE - left)))
ret = Z_BUF_ERROR;
}
goto inf_leave;
case BAD:
ret = Z_DATA_ERROR;
goto inf_leave;
default: /* can't happen, but makes compilers happy */
ret = Z_STREAM_ERROR;
goto inf_leave;
}
/* Return unused input */
inf_leave:
strm->next_in = next;
strm->avail_in = have;
return ret;
}