346 lines
12 KiB
JavaScript
346 lines
12 KiB
JavaScript
'use strict';
|
|
|
|
// (C) 1995-2013 Jean-loup Gailly and Mark Adler
|
|
// (C) 2014-2017 Vitaly Puzrin and Andrey Tupitsin
|
|
//
|
|
// This software is provided 'as-is', without any express or implied
|
|
// warranty. In no event will the authors be held liable for any damages
|
|
// arising from the use of this software.
|
|
//
|
|
// Permission is granted to anyone to use this software for any purpose,
|
|
// including commercial applications, and to alter it and redistribute it
|
|
// freely, subject to the following restrictions:
|
|
//
|
|
// 1. The origin of this software must not be misrepresented; you must not
|
|
// claim that you wrote the original software. If you use this software
|
|
// in a product, an acknowledgment in the product documentation would be
|
|
// appreciated but is not required.
|
|
// 2. Altered source versions must be plainly marked as such, and must not be
|
|
// misrepresented as being the original software.
|
|
// 3. This notice may not be removed or altered from any source distribution.
|
|
|
|
// See state defs from inflate.js
|
|
var BAD = 30; /* got a data error -- remain here until reset */
|
|
var TYPE = 12; /* i: waiting for type bits, including last-flag bit */
|
|
|
|
/*
|
|
Decode literal, length, and distance codes and write out the resulting
|
|
literal and match bytes until either not enough input or output is
|
|
available, an end-of-block is encountered, or a data error is encountered.
|
|
When large enough input and output buffers are supplied to inflate(), for
|
|
example, a 16K input buffer and a 64K output buffer, more than 95% of the
|
|
inflate execution time is spent in this routine.
|
|
|
|
Entry assumptions:
|
|
|
|
state.mode === LEN
|
|
strm.avail_in >= 6
|
|
strm.avail_out >= 258
|
|
start >= strm.avail_out
|
|
state.bits < 8
|
|
|
|
On return, state.mode is one of:
|
|
|
|
LEN -- ran out of enough output space or enough available input
|
|
TYPE -- reached end of block code, inflate() to interpret next block
|
|
BAD -- error in block data
|
|
|
|
Notes:
|
|
|
|
- The maximum input bits used by a length/distance pair is 15 bits for the
|
|
length code, 5 bits for the length extra, 15 bits for the distance code,
|
|
and 13 bits for the distance extra. This totals 48 bits, or six bytes.
|
|
Therefore if strm.avail_in >= 6, then there is enough input to avoid
|
|
checking for available input while decoding.
|
|
|
|
- The maximum bytes that a single length/distance pair can output is 258
|
|
bytes, which is the maximum length that can be coded. inflate_fast()
|
|
requires strm.avail_out >= 258 for each loop to avoid checking for
|
|
output space.
|
|
*/
|
|
module.exports = function inflate_fast(strm, start) {
|
|
var state;
|
|
var _in; /* local strm.input */
|
|
var last; /* have enough input while in < last */
|
|
var _out; /* local strm.output */
|
|
var beg; /* inflate()'s initial strm.output */
|
|
var end; /* while out < end, enough space available */
|
|
//#ifdef INFLATE_STRICT
|
|
var dmax; /* maximum distance from zlib header */
|
|
//#endif
|
|
var wsize; /* window size or zero if not using window */
|
|
var whave; /* valid bytes in the window */
|
|
var wnext; /* window write index */
|
|
// Use `s_window` instead `window`, avoid conflict with instrumentation tools
|
|
var s_window; /* allocated sliding window, if wsize != 0 */
|
|
var hold; /* local strm.hold */
|
|
var bits; /* local strm.bits */
|
|
var lcode; /* local strm.lencode */
|
|
var dcode; /* local strm.distcode */
|
|
var lmask; /* mask for first level of length codes */
|
|
var dmask; /* mask for first level of distance codes */
|
|
var here; /* retrieved table entry */
|
|
var op; /* code bits, operation, extra bits, or */
|
|
/* window position, window bytes to copy */
|
|
var len; /* match length, unused bytes */
|
|
var dist; /* match distance */
|
|
var from; /* where to copy match from */
|
|
var from_source;
|
|
|
|
|
|
var input, output; // JS specific, because we have no pointers
|
|
|
|
/* copy state to local variables */
|
|
state = strm.state;
|
|
//here = state.here;
|
|
_in = strm.next_in;
|
|
input = strm.input;
|
|
last = _in + (strm.avail_in - 5);
|
|
_out = strm.next_out;
|
|
output = strm.output;
|
|
beg = _out - (start - strm.avail_out);
|
|
end = _out + (strm.avail_out - 257);
|
|
//#ifdef INFLATE_STRICT
|
|
dmax = state.dmax;
|
|
//#endif
|
|
wsize = state.wsize;
|
|
whave = state.whave;
|
|
wnext = state.wnext;
|
|
s_window = state.window;
|
|
hold = state.hold;
|
|
bits = state.bits;
|
|
lcode = state.lencode;
|
|
dcode = state.distcode;
|
|
lmask = (1 << state.lenbits) - 1;
|
|
dmask = (1 << state.distbits) - 1;
|
|
|
|
|
|
/* decode literals and length/distances until end-of-block or not enough
|
|
input data or output space */
|
|
|
|
top:
|
|
do {
|
|
if (bits < 15) {
|
|
hold += input[_in++] << bits;
|
|
bits += 8;
|
|
hold += input[_in++] << bits;
|
|
bits += 8;
|
|
}
|
|
|
|
here = lcode[hold & lmask];
|
|
|
|
dolen:
|
|
for (;;) { // Goto emulation
|
|
op = here >>> 24/*here.bits*/;
|
|
hold >>>= op;
|
|
bits -= op;
|
|
op = (here >>> 16) & 0xff/*here.op*/;
|
|
if (op === 0) { /* literal */
|
|
//Tracevv((stderr, here.val >= 0x20 && here.val < 0x7f ?
|
|
// "inflate: literal '%c'\n" :
|
|
// "inflate: literal 0x%02x\n", here.val));
|
|
output[_out++] = here & 0xffff/*here.val*/;
|
|
}
|
|
else if (op & 16) { /* length base */
|
|
len = here & 0xffff/*here.val*/;
|
|
op &= 15; /* number of extra bits */
|
|
if (op) {
|
|
if (bits < op) {
|
|
hold += input[_in++] << bits;
|
|
bits += 8;
|
|
}
|
|
len += hold & ((1 << op) - 1);
|
|
hold >>>= op;
|
|
bits -= op;
|
|
}
|
|
//Tracevv((stderr, "inflate: length %u\n", len));
|
|
if (bits < 15) {
|
|
hold += input[_in++] << bits;
|
|
bits += 8;
|
|
hold += input[_in++] << bits;
|
|
bits += 8;
|
|
}
|
|
here = dcode[hold & dmask];
|
|
|
|
dodist:
|
|
for (;;) { // goto emulation
|
|
op = here >>> 24/*here.bits*/;
|
|
hold >>>= op;
|
|
bits -= op;
|
|
op = (here >>> 16) & 0xff/*here.op*/;
|
|
|
|
if (op & 16) { /* distance base */
|
|
dist = here & 0xffff/*here.val*/;
|
|
op &= 15; /* number of extra bits */
|
|
if (bits < op) {
|
|
hold += input[_in++] << bits;
|
|
bits += 8;
|
|
if (bits < op) {
|
|
hold += input[_in++] << bits;
|
|
bits += 8;
|
|
}
|
|
}
|
|
dist += hold & ((1 << op) - 1);
|
|
//#ifdef INFLATE_STRICT
|
|
if (dist > dmax) {
|
|
strm.msg = 'invalid distance too far back';
|
|
state.mode = BAD;
|
|
break top;
|
|
}
|
|
//#endif
|
|
hold >>>= op;
|
|
bits -= op;
|
|
//Tracevv((stderr, "inflate: distance %u\n", dist));
|
|
op = _out - beg; /* max distance in output */
|
|
if (dist > op) { /* see if copy from window */
|
|
op = dist - op; /* distance back in window */
|
|
if (op > whave) {
|
|
if (state.sane) {
|
|
strm.msg = 'invalid distance too far back';
|
|
state.mode = BAD;
|
|
break top;
|
|
}
|
|
|
|
// (!) This block is disabled in zlib defaults,
|
|
// don't enable it for binary compatibility
|
|
//#ifdef INFLATE_ALLOW_INVALID_DISTANCE_TOOFAR_ARRR
|
|
// if (len <= op - whave) {
|
|
// do {
|
|
// output[_out++] = 0;
|
|
// } while (--len);
|
|
// continue top;
|
|
// }
|
|
// len -= op - whave;
|
|
// do {
|
|
// output[_out++] = 0;
|
|
// } while (--op > whave);
|
|
// if (op === 0) {
|
|
// from = _out - dist;
|
|
// do {
|
|
// output[_out++] = output[from++];
|
|
// } while (--len);
|
|
// continue top;
|
|
// }
|
|
//#endif
|
|
}
|
|
from = 0; // window index
|
|
from_source = s_window;
|
|
if (wnext === 0) { /* very common case */
|
|
from += wsize - op;
|
|
if (op < len) { /* some from window */
|
|
len -= op;
|
|
do {
|
|
output[_out++] = s_window[from++];
|
|
} while (--op);
|
|
from = _out - dist; /* rest from output */
|
|
from_source = output;
|
|
}
|
|
}
|
|
else if (wnext < op) { /* wrap around window */
|
|
from += wsize + wnext - op;
|
|
op -= wnext;
|
|
if (op < len) { /* some from end of window */
|
|
len -= op;
|
|
do {
|
|
output[_out++] = s_window[from++];
|
|
} while (--op);
|
|
from = 0;
|
|
if (wnext < len) { /* some from start of window */
|
|
op = wnext;
|
|
len -= op;
|
|
do {
|
|
output[_out++] = s_window[from++];
|
|
} while (--op);
|
|
from = _out - dist; /* rest from output */
|
|
from_source = output;
|
|
}
|
|
}
|
|
}
|
|
else { /* contiguous in window */
|
|
from += wnext - op;
|
|
if (op < len) { /* some from window */
|
|
len -= op;
|
|
do {
|
|
output[_out++] = s_window[from++];
|
|
} while (--op);
|
|
from = _out - dist; /* rest from output */
|
|
from_source = output;
|
|
}
|
|
}
|
|
while (len > 2) {
|
|
output[_out++] = from_source[from++];
|
|
output[_out++] = from_source[from++];
|
|
output[_out++] = from_source[from++];
|
|
len -= 3;
|
|
}
|
|
if (len) {
|
|
output[_out++] = from_source[from++];
|
|
if (len > 1) {
|
|
output[_out++] = from_source[from++];
|
|
}
|
|
}
|
|
}
|
|
else {
|
|
from = _out - dist; /* copy direct from output */
|
|
do { /* minimum length is three */
|
|
output[_out++] = output[from++];
|
|
output[_out++] = output[from++];
|
|
output[_out++] = output[from++];
|
|
len -= 3;
|
|
} while (len > 2);
|
|
if (len) {
|
|
output[_out++] = output[from++];
|
|
if (len > 1) {
|
|
output[_out++] = output[from++];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
else if ((op & 64) === 0) { /* 2nd level distance code */
|
|
here = dcode[(here & 0xffff)/*here.val*/ + (hold & ((1 << op) - 1))];
|
|
continue dodist;
|
|
}
|
|
else {
|
|
strm.msg = 'invalid distance code';
|
|
state.mode = BAD;
|
|
break top;
|
|
}
|
|
|
|
break; // need to emulate goto via "continue"
|
|
}
|
|
}
|
|
else if ((op & 64) === 0) { /* 2nd level length code */
|
|
here = lcode[(here & 0xffff)/*here.val*/ + (hold & ((1 << op) - 1))];
|
|
continue dolen;
|
|
}
|
|
else if (op & 32) { /* end-of-block */
|
|
//Tracevv((stderr, "inflate: end of block\n"));
|
|
state.mode = TYPE;
|
|
break top;
|
|
}
|
|
else {
|
|
strm.msg = 'invalid literal/length code';
|
|
state.mode = BAD;
|
|
break top;
|
|
}
|
|
|
|
break; // need to emulate goto via "continue"
|
|
}
|
|
} while (_in < last && _out < end);
|
|
|
|
/* return unused bytes (on entry, bits < 8, so in won't go too far back) */
|
|
len = bits >> 3;
|
|
_in -= len;
|
|
bits -= len << 3;
|
|
hold &= (1 << bits) - 1;
|
|
|
|
/* update state and return */
|
|
strm.next_in = _in;
|
|
strm.next_out = _out;
|
|
strm.avail_in = (_in < last ? 5 + (last - _in) : 5 - (_in - last));
|
|
strm.avail_out = (_out < end ? 257 + (end - _out) : 257 - (_out - end));
|
|
state.hold = hold;
|
|
state.bits = bits;
|
|
return;
|
|
};
|