in contrib/libz/infback.c [250:630]
int ZEXPORT inflateBack(strm, in, in_desc, out, out_desc)
z_streamp 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, left; /* available input and output */
unsigned long hold; /* bit buffer */
unsigned bits; /* bits in bit buffer */
unsigned copy; /* number of stored or match bytes to copy */
unsigned char FAR *from; /* where to copy match bytes from */
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};
/* 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;
state->mode = TYPE;
state->last = 0;
state->whave = 0;
next = strm->next_in;
have = next != Z_NULL ? strm->avail_in : 0;
hold = 0;
bits = 0;
put = state->window;
left = state->wsize;
/* Inflate until end of block marked as last */
for (;;)
switch (state->mode) {
case TYPE:
/* determine and dispatch block type */
if (state->last) {
BYTEBITS();
state->mode = DONE;
break;
}
NEEDBITS(3);
state->last = BITS(1);
DROPBITS(1);
switch (BITS(2)) {
case 0: /* stored block */
Tracev((stderr, "inflate: stored block%s\n",
state->last ? " (last)" : ""));
state->mode = STORED;
break;
case 1: /* fixed block */
fixedtables(state);
Tracev((stderr, "inflate: fixed codes block%s\n",
state->last ? " (last)" : ""));
state->mode = LEN; /* decode codes */
break;
case 2: /* dynamic block */
Tracev((stderr, "inflate: dynamic codes block%s\n",
state->last ? " (last)" : ""));
state->mode = TABLE;
break;
case 3:
strm->msg = (char *)"invalid block type";
state->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";
state->mode = BAD;
break;
}
state->length = (unsigned)hold & 0xffff;
Tracev((stderr, "inflate: stored length %u\n",
state->length));
INITBITS();
/* copy stored block from input to output */
while (state->length != 0) {
copy = state->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;
state->length -= copy;
}
Tracev((stderr, "inflate: stored end\n"));
state->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);
#ifndef PKZIP_BUG_WORKAROUND
if (state->nlen > 286 || state->ndist > 30) {
strm->msg = (char *)"too many length or distance symbols";
state->mode = BAD;
break;
}
#endif
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;
state->lencode = (code const FAR *)(state->next);
state->lenbits = 7;
ret = inflate_table(CODES, state->lens, 19, &(state->next),
&(state->lenbits), state->work);
if (ret) {
strm->msg = (char *)"invalid code lengths set";
state->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 = state->lencode[BITS(state->lenbits)];
if ((unsigned)(here.bits) <= bits) break;
PULLBYTE();
}
if (here.val < 16) {
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";
state->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";
state->mode = BAD;
break;
}
while (copy--)
state->lens[state->have++] = (unsigned short)len;
}
}
/* handle error breaks in while */
if (state->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";
state->mode = BAD;
break;
}
/* build code tables -- note: do not change the lenbits or distbits
values here (9 and 6) without reading the comments in inftrees.h
concerning the ENOUGH constants, which depend on those values */
state->next = state->codes;
state->lencode = (code const FAR *)(state->next);
state->lenbits = 9;
ret = inflate_table(LENS, state->lens, state->nlen, &(state->next),
&(state->lenbits), state->work);
if (ret) {
strm->msg = (char *)"invalid literal/lengths set";
state->mode = BAD;
break;
}
state->distcode = (code const FAR *)(state->next);
state->distbits = 6;
ret = inflate_table(DISTS, state->lens + state->nlen, state->ndist,
&(state->next), &(state->distbits), state->work);
if (ret) {
strm->msg = (char *)"invalid distances set";
state->mode = BAD;
break;
}
Tracev((stderr, "inflate: codes ok\n"));
state->mode = LEN;
/* fallthrough */
case LEN:
/* use inflate_fast() if we have enough input and output */
if (have >= 6 && left >= 258) {
RESTORE();
if (state->whave < state->wsize)
state->whave = state->wsize - left;
inflate_fast(strm, state->wsize);
LOAD();
break;
}
/* get a literal, length, or end-of-block code */
for (;;) {
here = state->lencode[BITS(state->lenbits)];
if ((unsigned)(here.bits) <= bits) break;
PULLBYTE();
}
if (here.op && (here.op & 0xf0) == 0) {
last = here;
for (;;) {
here = state->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);
state->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)(state->length);
left--;
state->mode = LEN;
break;
}
/* process end of block */
if (here.op & 32) {
Tracevv((stderr, "inflate: end of block\n"));
state->mode = TYPE;
break;
}
/* invalid code */
if (here.op & 64) {
strm->msg = (char *)"invalid literal/length code";
state->mode = BAD;
break;
}
/* length code -- get extra bits, if any */
state->extra = (unsigned)(here.op) & 15;
if (state->extra != 0) {
NEEDBITS(state->extra);
state->length += BITS(state->extra);
DROPBITS(state->extra);
}
Tracevv((stderr, "inflate: length %u\n", state->length));
/* get distance code */
for (;;) {
here = state->distcode[BITS(state->distbits)];
if ((unsigned)(here.bits) <= bits) break;
PULLBYTE();
}
if ((here.op & 0xf0) == 0) {
last = here;
for (;;) {
here = state->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";
state->mode = BAD;
break;
}
state->offset = (unsigned)here.val;
/* get distance extra bits, if any */
state->extra = (unsigned)(here.op) & 15;
if (state->extra != 0) {
NEEDBITS(state->extra);
state->offset += BITS(state->extra);
DROPBITS(state->extra);
}
if (state->offset > state->wsize - (state->whave < state->wsize ?
left : 0)) {
strm->msg = (char *)"invalid distance too far back";
state->mode = BAD;
break;
}
Tracevv((stderr, "inflate: distance %u\n", state->offset));
/* copy match from window to output */
do {
ROOM();
copy = state->wsize - state->offset;
if (copy < left) {
from = put + copy;
copy = left - copy;
}
else {
from = put - state->offset;
copy = left;
}
if (copy > state->length) copy = state->length;
state->length -= copy;
left -= copy;
do {
*put++ = *from++;
} while (--copy);
} while (state->length != 0);
break;
case DONE:
/* inflate stream terminated properly -- write leftover output */
ret = Z_STREAM_END;
if (left < state->wsize) {
if (out(out_desc, state->window, state->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;
}