fengari
Version:
A Lua VM written in JS ES6 targeting the browser
684 lines (622 loc) • 22.8 kB
JavaScript
"use strict";
const {
LUA_HOOKCOUNT,
LUA_HOOKLINE,
LUA_MASKCOUNT,
LUA_MASKLINE,
constant_types: {
LUA_TBOOLEAN,
LUA_TNIL,
LUA_TTABLE
},
thread_status: {
LUA_ERRRUN,
LUA_YIELD
},
from_userstring,
luastring_eq,
luastring_indexOf,
to_luastring
} = require('./defs.js');
const {
api_check,
lua_assert
} = require('./llimits.js');
const { LUA_IDSIZE } = require('./luaconf.js');
const lapi = require('./lapi.js');
const ldo = require('./ldo.js');
const lfunc = require('./lfunc.js');
const llex = require('./llex.js');
const lobject = require('./lobject.js');
const lopcodes = require('./lopcodes.js');
const lstate = require('./lstate.js');
const ltable = require('./ltable.js');
const ltm = require('./ltm.js');
const lvm = require('./lvm.js');
const currentpc = function(ci) {
lua_assert(ci.callstatus & lstate.CIST_LUA);
return ci.l_savedpc - 1;
};
const currentline = function(ci) {
return ci.func.value.p.lineinfo.length !== 0 ? ci.func.value.p.lineinfo[currentpc(ci)] : -1;
};
/*
** If function yielded, its 'func' can be in the 'extra' field. The
** next function restores 'func' to its correct value for debugging
** purposes. (It exchanges 'func' and 'extra'; so, when called again,
** after debugging, it also "re-restores" ** 'func' to its altered value.
*/
const swapextra = function(L) {
if (L.status === LUA_YIELD) {
let ci = L.ci; /* get function that yielded */
let temp = ci.funcOff; /* exchange its 'func' and 'extra' values */
ci.func = L.stack[ci.extra];
ci.funcOff = ci.extra;
ci.extra = temp;
}
};
const lua_sethook = function(L, func, mask, count) {
if (func === null || mask === 0) { /* turn off hooks? */
mask = 0;
func = null;
}
if (L.ci.callstatus & lstate.CIST_LUA)
L.oldpc = L.ci.l_savedpc;
L.hook = func;
L.basehookcount = count;
L.hookcount = L.basehookcount;
L.hookmask = mask;
};
const lua_gethook = function(L) {
return L.hook;
};
const lua_gethookmask = function(L) {
return L.hookmask;
};
const lua_gethookcount = function(L) {
return L.basehookcount;
};
const lua_getstack = function(L, level, ar) {
let ci;
let status;
if (level < 0) return 0; /* invalid (negative) level */
for (ci = L.ci; level > 0 && ci !== L.base_ci; ci = ci.previous)
level--;
if (level === 0 && ci !== L.base_ci) { /* level found? */
status = 1;
ar.i_ci = ci;
} else
status = 0; /* no such level */
return status;
};
const upvalname = function(p, uv) {
lua_assert(uv < p.upvalues.length);
let s = p.upvalues[uv].name;
if (s === null) return to_luastring("?", true);
return s.getstr();
};
const findvararg = function(ci, n) {
let nparams = ci.func.value.p.numparams;
if (n >= ci.l_base - ci.funcOff - nparams)
return null; /* no such vararg */
else {
return {
pos: ci.funcOff + nparams + n,
name: to_luastring("(*vararg)", true) /* generic name for any vararg */
};
}
};
const findlocal = function(L, ci, n) {
let base, name = null;
if (ci.callstatus & lstate.CIST_LUA) {
if (n < 0) /* access to vararg values? */
return findvararg(ci, -n);
else {
base = ci.l_base;
name = lfunc.luaF_getlocalname(ci.func.value.p, n, currentpc(ci));
}
} else
base = ci.funcOff + 1;
if (name === null) { /* no 'standard' name? */
let limit = ci === L.ci ? L.top : ci.next.funcOff;
if (limit - base >= n && n > 0) /* is 'n' inside 'ci' stack? */
name = to_luastring("(*temporary)", true); /* generic name for any valid slot */
else
return null; /* no name */
}
return {
pos: base + (n - 1),
name: name
};
};
const lua_getlocal = function(L, ar, n) {
let name;
swapextra(L);
if (ar === null) { /* information about non-active function? */
if (!L.stack[L.top - 1].ttisLclosure()) /* not a Lua function? */
name = null;
else /* consider live variables at function start (parameters) */
name = lfunc.luaF_getlocalname(L.stack[L.top - 1].value.p, n, 0);
} else { /* active function; get information through 'ar' */
let local = findlocal(L, ar.i_ci, n);
if (local) {
name = local.name;
lobject.pushobj2s(L, L.stack[local.pos]);
api_check(L, L.top <= L.ci.top, "stack overflow");
} else {
name = null;
}
}
swapextra(L);
return name;
};
const lua_setlocal = function(L, ar, n) {
let name;
swapextra(L);
let local = findlocal(L, ar.i_ci, n);
if (local) {
name = local.name;
lobject.setobjs2s(L, local.pos, L.top - 1);
delete L.stack[--L.top]; /* pop value */
} else {
name = null;
}
swapextra(L);
return name;
};
const funcinfo = function(ar, cl) {
if (cl === null || cl instanceof lobject.CClosure) {
ar.source = to_luastring("=[JS]", true);
ar.linedefined = -1;
ar.lastlinedefined = -1;
ar.what = to_luastring("J", true);
} else {
let p = cl.p;
ar.source = p.source ? p.source.getstr() : to_luastring("=?", true);
ar.linedefined = p.linedefined;
ar.lastlinedefined = p.lastlinedefined;
ar.what = ar.linedefined === 0 ? to_luastring("main", true) : to_luastring("Lua", true);
}
ar.short_src = lobject.luaO_chunkid(ar.source, LUA_IDSIZE);
};
const collectvalidlines = function(L, f) {
if (f === null || f instanceof lobject.CClosure) {
L.stack[L.top] = new lobject.TValue(LUA_TNIL, null);
lapi.api_incr_top(L);
} else {
let lineinfo = f.p.lineinfo;
let t = ltable.luaH_new(L);
L.stack[L.top] = new lobject.TValue(LUA_TTABLE, t);
lapi.api_incr_top(L);
let v = new lobject.TValue(LUA_TBOOLEAN, true);
for (let i = 0; i < lineinfo.length; i++)
ltable.luaH_setint(t, lineinfo[i], v);
}
};
const getfuncname = function(L, ci) {
let r = {
name: null,
funcname: null
};
if (ci === null)
return null;
else if (ci.callstatus & lstate.CIST_FIN) { /* is this a finalizer? */
r.name = to_luastring("__gc", true);
r.funcname = to_luastring("metamethod", true); /* report it as such */
return r;
}
/* calling function is a known Lua function? */
else if (!(ci.callstatus & lstate.CIST_TAIL) && ci.previous.callstatus & lstate.CIST_LUA)
return funcnamefromcode(L, ci.previous);
else return null; /* no way to find a name */
};
const auxgetinfo = function(L, what, ar, f, ci) {
let status = 1;
for (; what.length > 0; what = what.subarray(1)) {
switch (what[0]) {
case 83 /* ('S').charCodeAt(0) */: {
funcinfo(ar, f);
break;
}
case 108 /* ('l').charCodeAt(0) */: {
ar.currentline = ci && ci.callstatus & lstate.CIST_LUA ? currentline(ci) : -1;
break;
}
case 117 /* ('u').charCodeAt(0) */: {
ar.nups = f === null ? 0 : f.nupvalues;
if (f === null || f instanceof lobject.CClosure) {
ar.isvararg = true;
ar.nparams = 0;
} else {
ar.isvararg = f.p.is_vararg;
ar.nparams = f.p.numparams;
}
break;
}
case 116 /* ('t').charCodeAt(0) */: {
ar.istailcall = ci ? ci.callstatus & lstate.CIST_TAIL : 0;
break;
}
case 110 /* ('n').charCodeAt(0) */: {
let r = getfuncname(L, ci);
if (r === null) {
ar.namewhat = to_luastring("", true);
ar.name = null;
} else {
ar.namewhat = r.funcname;
ar.name = r.name;
}
break;
}
case 76 /* ('L').charCodeAt(0) */:
case 102 /* ('f').charCodeAt(0) */: /* handled by lua_getinfo */
break;
default: status = 0; /* invalid option */
}
}
return status;
};
const lua_getinfo = function(L, what, ar) {
what = from_userstring(what);
let status, cl, ci, func;
swapextra(L);
if (what[0] === 62 /* ('>').charCodeAt(0) */) {
ci = null;
func = L.stack[L.top - 1];
api_check(L, func.ttisfunction(), "function expected");
what = what.subarray(1); /* skip the '>' */
L.top--; /* pop function */
} else {
ci = ar.i_ci;
func = ci.func;
lua_assert(ci.func.ttisfunction());
}
cl = func.ttisclosure() ? func.value : null;
status = auxgetinfo(L, what, ar, cl, ci);
if (luastring_indexOf(what, 102 /* ('f').charCodeAt(0) */) >= 0) {
lobject.pushobj2s(L, func);
api_check(L, L.top <= L.ci.top, "stack overflow");
}
swapextra(L);
if (luastring_indexOf(what, 76 /* ('L').charCodeAt(0) */) >= 0)
collectvalidlines(L, cl);
return status;
};
const kname = function(p, pc, c) {
let r = {
name: null,
funcname: null
};
if (lopcodes.ISK(c)) { /* is 'c' a constant? */
let kvalue = p.k[lopcodes.INDEXK(c)];
if (kvalue.ttisstring()) { /* literal constant? */
r.name = kvalue.svalue(); /* it is its own name */
return r;
}
/* else no reasonable name found */
} else { /* 'c' is a register */
let what = getobjname(p, pc, c); /* search for 'c' */
if (what && what.funcname[0] === 99 /* ('c').charCodeAt(0) */) { /* found a constant name? */
return what; /* 'name' already filled */
}
/* else no reasonable name found */
}
r.name = to_luastring("?", true);
return r; /* no reasonable name found */
};
const filterpc = function(pc, jmptarget) {
if (pc < jmptarget) /* is code conditional (inside a jump)? */
return -1; /* cannot know who sets that register */
else return pc; /* current position sets that register */
};
/*
** try to find last instruction before 'lastpc' that modified register 'reg'
*/
const findsetreg = function(p, lastpc, reg) {
let setreg = -1; /* keep last instruction that changed 'reg' */
let jmptarget = 0; /* any code before this address is conditional */
let OCi = lopcodes.OpCodesI;
for (let pc = 0; pc < lastpc; pc++) {
let i = p.code[pc];
let a = i.A;
switch (i.opcode) {
case OCi.OP_LOADNIL: {
let b = i.B;
if (a <= reg && reg <= a + b) /* set registers from 'a' to 'a+b' */
setreg = filterpc(pc, jmptarget);
break;
}
case OCi.OP_TFORCALL: {
if (reg >= a + 2) /* affect all regs above its base */
setreg = filterpc(pc, jmptarget);
break;
}
case OCi.OP_CALL:
case OCi.OP_TAILCALL: {
if (reg >= a) /* affect all registers above base */
setreg = filterpc(pc, jmptarget);
break;
}
case OCi.OP_JMP: {
let b = i.sBx;
let dest = pc + 1 + b;
/* jump is forward and do not skip 'lastpc'? */
if (pc < dest && dest <= lastpc) {
if (dest > jmptarget)
jmptarget = dest; /* update 'jmptarget' */
}
break;
}
default:
if (lopcodes.testAMode(i.opcode) && reg === a)
setreg = filterpc(pc, jmptarget);
break;
}
}
return setreg;
};
const getobjname = function(p, lastpc, reg) {
let r = {
name: lfunc.luaF_getlocalname(p, reg + 1, lastpc),
funcname: null
};
if (r.name) { /* is a local? */
r.funcname = to_luastring("local", true);
return r;
}
/* else try symbolic execution */
let pc = findsetreg(p, lastpc, reg);
let OCi = lopcodes.OpCodesI;
if (pc !== -1) { /* could find instruction? */
let i = p.code[pc];
switch (i.opcode) {
case OCi.OP_MOVE: {
let b = i.B; /* move from 'b' to 'a' */
if (b < i.A)
return getobjname(p, pc, b); /* get name for 'b' */
break;
}
case OCi.OP_GETTABUP:
case OCi.OP_GETTABLE: {
let k = i.C; /* key index */
let t = i.B; /* table index */
let vn = i.opcode === OCi.OP_GETTABLE ? lfunc.luaF_getlocalname(p, t + 1, pc) : upvalname(p, t);
r.name = kname(p, pc, k).name;
r.funcname = (vn && luastring_eq(vn, llex.LUA_ENV)) ? to_luastring("global", true) : to_luastring("field", true);
return r;
}
case OCi.OP_GETUPVAL: {
r.name = upvalname(p, i.B);
r.funcname = to_luastring("upvalue", true);
return r;
}
case OCi.OP_LOADK:
case OCi.OP_LOADKX: {
let b = i.opcode === OCi.OP_LOADK ? i.Bx : p.code[pc + 1].Ax;
if (p.k[b].ttisstring()) {
r.name = p.k[b].svalue();
r.funcname = to_luastring("constant", true);
return r;
}
break;
}
case OCi.OP_SELF: {
let k = i.C;
r.name = kname(p, pc, k).name;
r.funcname = to_luastring("method", true);
return r;
}
default: break;
}
}
return null;
};
/*
** Try to find a name for a function based on the code that called it.
** (Only works when function was called by a Lua function.)
** Returns what the name is (e.g., "for iterator", "method",
** "metamethod") and sets '*name' to point to the name.
*/
const funcnamefromcode = function(L, ci) {
let r = {
name: null,
funcname: null
};
let tm = 0; /* (initial value avoids warnings) */
let p = ci.func.value.p; /* calling function */
let pc = currentpc(ci); /* calling instruction index */
let i = p.code[pc]; /* calling instruction */
let OCi = lopcodes.OpCodesI;
if (ci.callstatus & lstate.CIST_HOOKED) {
r.name = to_luastring("?", true);
r.funcname = to_luastring("hook", true);
return r;
}
switch (i.opcode) {
case OCi.OP_CALL:
case OCi.OP_TAILCALL:
return getobjname(p, pc, i.A); /* get function name */
case OCi.OP_TFORCALL:
r.name = to_luastring("for iterator", true);
r.funcname = to_luastring("for iterator", true);
return r;
/* other instructions can do calls through metamethods */
case OCi.OP_SELF:
case OCi.OP_GETTABUP:
case OCi.OP_GETTABLE:
tm = ltm.TMS.TM_INDEX;
break;
case OCi.OP_SETTABUP:
case OCi.OP_SETTABLE:
tm = ltm.TMS.TM_NEWINDEX;
break;
case OCi.OP_ADD: tm = ltm.TMS.TM_ADD; break;
case OCi.OP_SUB: tm = ltm.TMS.TM_SUB; break;
case OCi.OP_MUL: tm = ltm.TMS.TM_MUL; break;
case OCi.OP_MOD: tm = ltm.TMS.TM_MOD; break;
case OCi.OP_POW: tm = ltm.TMS.TM_POW; break;
case OCi.OP_DIV: tm = ltm.TMS.TM_DIV; break;
case OCi.OP_IDIV: tm = ltm.TMS.TM_IDIV; break;
case OCi.OP_BAND: tm = ltm.TMS.TM_BAND; break;
case OCi.OP_BOR: tm = ltm.TMS.TM_BOR; break;
case OCi.OP_BXOR: tm = ltm.TMS.TM_BXOR; break;
case OCi.OP_SHL: tm = ltm.TMS.TM_SHL; break;
case OCi.OP_SHR: tm = ltm.TMS.TM_SHR; break;
case OCi.OP_UNM: tm = ltm.TMS.TM_UNM; break;
case OCi.OP_BNOT: tm = ltm.TMS.TM_BNOT; break;
case OCi.OP_LEN: tm = ltm.TMS.TM_LEN; break;
case OCi.OP_CONCAT: tm = ltm.TMS.TM_CONCAT; break;
case OCi.OP_EQ: tm = ltm.TMS.TM_EQ; break;
case OCi.OP_LT: tm = ltm.TMS.TM_LT; break;
case OCi.OP_LE: tm = ltm.TMS.TM_LE; break;
default:
return null; /* cannot find a reasonable name */
}
r.name = L.l_G.tmname[tm].getstr();
r.funcname = to_luastring("metamethod", true);
return r;
};
const isinstack = function(L, ci, o) {
for (let i = ci.l_base; i < ci.top; i++) {
if (L.stack[i] === o)
return i;
}
return false;
};
/*
** Checks whether value 'o' came from an upvalue. (That can only happen
** with instructions OP_GETTABUP/OP_SETTABUP, which operate directly on
** upvalues.)
*/
const getupvalname = function(L, ci, o) {
let c = ci.func.value;
for (let i = 0; i < c.nupvalues; i++) {
if (c.upvals[i] === o) {
return {
name: upvalname(c.p, i),
funcname: to_luastring('upvalue', true)
};
}
}
return null;
};
const varinfo = function(L, o) {
let ci = L.ci;
let kind = null;
if (ci.callstatus & lstate.CIST_LUA) {
kind = getupvalname(L, ci, o); /* check whether 'o' is an upvalue */
let stkid = isinstack(L, ci, o);
if (!kind && stkid) /* no? try a register */
kind = getobjname(ci.func.value.p, currentpc(ci), stkid - ci.l_base);
}
return kind ? lobject.luaO_pushfstring(L, to_luastring(" (%s '%s')", true), kind.funcname, kind.name) : to_luastring("", true);
};
const luaG_typeerror = function(L, o, op) {
let t = ltm.luaT_objtypename(L, o);
luaG_runerror(L, to_luastring("attempt to %s a %s value%s", true), op, t, varinfo(L, o));
};
const luaG_concaterror = function(L, p1, p2) {
if (p1.ttisstring() || lvm.cvt2str(p1)) p1 = p2;
luaG_typeerror(L, p1, to_luastring('concatenate', true));
};
/*
** Error when both values are convertible to numbers, but not to integers
*/
const luaG_opinterror = function(L, p1, p2, msg) {
if (lvm.tonumber(p1) === false)
p2 = p1;
luaG_typeerror(L, p2, msg);
};
const luaG_ordererror = function(L, p1, p2) {
let t1 = ltm.luaT_objtypename(L, p1);
let t2 = ltm.luaT_objtypename(L, p2);
if (luastring_eq(t1, t2))
luaG_runerror(L, to_luastring("attempt to compare two %s values", true), t1);
else
luaG_runerror(L, to_luastring("attempt to compare %s with %s", true), t1, t2);
};
/* add src:line information to 'msg' */
const luaG_addinfo = function(L, msg, src, line) {
let buff;
if (src)
buff = lobject.luaO_chunkid(src.getstr(), LUA_IDSIZE);
else
buff = to_luastring("?", true);
return lobject.luaO_pushfstring(L, to_luastring("%s:%d: %s", true), buff, line, msg);
};
const luaG_runerror = function(L, fmt, ...argp) {
let ci = L.ci;
let msg = lobject.luaO_pushvfstring(L, fmt, argp);
if (ci.callstatus & lstate.CIST_LUA) /* if Lua function, add source:line information */
luaG_addinfo(L, msg, ci.func.value.p.source, currentline(ci));
luaG_errormsg(L);
};
const luaG_errormsg = function(L) {
if (L.errfunc !== 0) { /* is there an error handling function? */
let errfunc = L.errfunc;
lobject.pushobj2s(L, L.stack[L.top - 1]); /* move argument */
lobject.setobjs2s(L, L.top - 2, errfunc); /* push function */
ldo.luaD_callnoyield(L, L.top - 2, 1);
}
ldo.luaD_throw(L, LUA_ERRRUN);
};
/*
** Error when both values are convertible to numbers, but not to integers
*/
const luaG_tointerror = function(L, p1, p2) {
let temp = lvm.tointeger(p1);
if (temp === false)
p2 = p1;
luaG_runerror(L, to_luastring("number%s has no integer representation", true), varinfo(L, p2));
};
const luaG_traceexec = function(L) {
let ci = L.ci;
let mask = L.hookmask;
let counthook = (--L.hookcount === 0 && (mask & LUA_MASKCOUNT));
if (counthook)
L.hookcount = L.basehookcount; /* reset count */
else if (!(mask & LUA_MASKLINE))
return; /* no line hook and count != 0; nothing to be done */
if (ci.callstatus & lstate.CIST_HOOKYIELD) { /* called hook last time? */
ci.callstatus &= ~lstate.CIST_HOOKYIELD; /* erase mark */
return; /* do not call hook again (VM yielded, so it did not move) */
}
if (counthook)
ldo.luaD_hook(L, LUA_HOOKCOUNT, -1); /* call count hook */
if (mask & LUA_MASKLINE) {
let p = ci.func.value.p;
let npc = ci.l_savedpc - 1; // pcRel(ci.u.l.savedpc, p);
let newline = p.lineinfo.length !== 0 ? p.lineinfo[npc] : -1;
if (npc === 0 || /* call linehook when enter a new function, */
ci.l_savedpc <= L.oldpc || /* when jump back (loop), or when */
newline !== (p.lineinfo.length !== 0 ? p.lineinfo[L.oldpc - 1] : -1)) /* enter a new line */
ldo.luaD_hook(L, LUA_HOOKLINE, newline); /* call line hook */
}
L.oldpc = ci.l_savedpc;
if (L.status === LUA_YIELD) { /* did hook yield? */
if (counthook)
L.hookcount = 1; /* undo decrement to zero */
ci.l_savedpc--; /* undo increment (resume will increment it again) */
ci.callstatus |= lstate.CIST_HOOKYIELD; /* mark that it yielded */
ci.funcOff = L.top - 1; /* protect stack below results */
ci.func = L.stack[ci.funcOff];
ldo.luaD_throw(L, LUA_YIELD);
}
};
module.exports.luaG_addinfo = luaG_addinfo;
module.exports.luaG_concaterror = luaG_concaterror;
module.exports.luaG_errormsg = luaG_errormsg;
module.exports.luaG_opinterror = luaG_opinterror;
module.exports.luaG_ordererror = luaG_ordererror;
module.exports.luaG_runerror = luaG_runerror;
module.exports.luaG_tointerror = luaG_tointerror;
module.exports.luaG_traceexec = luaG_traceexec;
module.exports.luaG_typeerror = luaG_typeerror;
module.exports.lua_gethook = lua_gethook;
module.exports.lua_gethookcount = lua_gethookcount;
module.exports.lua_gethookmask = lua_gethookmask;
module.exports.lua_getinfo = lua_getinfo;
module.exports.lua_getlocal = lua_getlocal;
module.exports.lua_getstack = lua_getstack;
module.exports.lua_sethook = lua_sethook;
module.exports.lua_setlocal = lua_setlocal;