2
** $Id: ldo.c,v 2.108 2012/10/01 14:05:04 roberto Exp $
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** Stack and Call structure of Lua
4
** See Copyright Notice in lua.h
38
** {======================================================
39
** Error-recovery functions
40
** =======================================================
44
** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By
45
** default, Lua handles errors with exceptions when compiling as
46
** C++ code, with _longjmp/_setjmp when asked to use them, and with
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** longjmp/setjmp otherwise.
49
#if !defined(LUAI_THROW)
51
#if defined(__cplusplus) && !defined(LUA_USE_LONGJMP)
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#define LUAI_THROW(L,c) throw(c)
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#define LUAI_TRY(L,c,a) \
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try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; }
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#define luai_jmpbuf int /* dummy variable */
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#elif defined(LUA_USE_ULONGJMP)
59
/* in Unix, try _longjmp/_setjmp (more efficient) */
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#define LUAI_THROW(L,c) _longjmp((c)->b, 1)
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#define LUAI_TRY(L,c,a) if (_setjmp((c)->b) == 0) { a }
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#define luai_jmpbuf jmp_buf
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/* default handling with long jumps */
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#define LUAI_THROW(L,c) longjmp((c)->b, 1)
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#define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a }
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#define luai_jmpbuf jmp_buf
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/* chain list of long jump buffers */
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struct lua_longjmp *previous;
80
volatile int status; /* error code */
84
static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
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case LUA_ERRMEM: { /* memory error? */
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setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */
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setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling"));
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setobjs2s(L, oldtop, L->top - 1); /* error message on current top */
103
l_noret luaD_throw (lua_State *L, int errcode) {
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if (L->errorJmp) { /* thread has an error handler? */
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L->errorJmp->status = errcode; /* set status */
106
LUAI_THROW(L, L->errorJmp); /* jump to it */
108
else { /* thread has no error handler */
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L->status = cast_byte(errcode); /* mark it as dead */
110
if (G(L)->mainthread->errorJmp) { /* main thread has a handler? */
111
setobjs2s(L, G(L)->mainthread->top++, L->top - 1); /* copy error obj. */
112
luaD_throw(G(L)->mainthread, errcode); /* re-throw in main thread */
114
else { /* no handler at all; abort */
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if (G(L)->panic) { /* panic function? */
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G(L)->panic(L); /* call it (last chance to jump out) */
125
int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
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unsigned short oldnCcalls = L->nCcalls;
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struct lua_longjmp lj;
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lj.previous = L->errorJmp; /* chain new error handler */
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L->errorJmp = lj.previous; /* restore old error handler */
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L->nCcalls = oldnCcalls;
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/* }====================================================== */
142
static void correctstack (lua_State *L, TValue *oldstack) {
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L->top = (L->top - oldstack) + L->stack;
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for (up = L->openupval; up != NULL; up = up->gch.next)
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gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack;
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for (ci = L->ci; ci != NULL; ci = ci->previous) {
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ci->top = (ci->top - oldstack) + L->stack;
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ci->func = (ci->func - oldstack) + L->stack;
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ci->u.l.base = (ci->u.l.base - oldstack) + L->stack;
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/* some space for error handling */
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#define ERRORSTACKSIZE (LUAI_MAXSTACK + 200)
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void luaD_reallocstack (lua_State *L, int newsize) {
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TValue *oldstack = L->stack;
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int lim = L->stacksize;
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lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);
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lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);
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luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue);
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for (; lim < newsize; lim++)
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setnilvalue(L->stack + lim); /* erase new segment */
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L->stacksize = newsize;
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L->stack_last = L->stack + newsize - EXTRA_STACK;
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correctstack(L, oldstack);
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void luaD_growstack (lua_State *L, int n) {
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int size = L->stacksize;
177
if (size > LUAI_MAXSTACK) /* error after extra size? */
178
luaD_throw(L, LUA_ERRERR);
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int needed = cast_int(L->top - L->stack) + n + EXTRA_STACK;
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int newsize = 2 * size;
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if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK;
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if (newsize < needed) newsize = needed;
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if (newsize > LUAI_MAXSTACK) { /* stack overflow? */
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luaD_reallocstack(L, ERRORSTACKSIZE);
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luaG_runerror(L, "stack overflow");
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luaD_reallocstack(L, newsize);
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static int stackinuse (lua_State *L) {
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for (ci = L->ci; ci != NULL; ci = ci->previous) {
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lua_assert(ci->top <= L->stack_last);
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if (lim < ci->top) lim = ci->top;
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return cast_int(lim - L->stack) + 1; /* part of stack in use */
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void luaD_shrinkstack (lua_State *L) {
206
int inuse = stackinuse(L);
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int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK;
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if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK;
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if (inuse > LUAI_MAXSTACK || /* handling stack overflow? */
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goodsize >= L->stacksize) /* would grow instead of shrink? */
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condmovestack(L); /* don't change stack (change only for debugging) */
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luaD_reallocstack(L, goodsize); /* shrink it */
217
void luaD_hook (lua_State *L, int event, int line) {
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lua_Hook hook = L->hook;
219
if (hook && L->allowhook) {
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CallInfo *ci = L->ci;
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ptrdiff_t top = savestack(L, L->top);
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ptrdiff_t ci_top = savestack(L, ci->top);
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ar.currentline = line;
227
luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
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ci->top = L->top + LUA_MINSTACK;
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lua_assert(ci->top <= L->stack_last);
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L->allowhook = 0; /* cannot call hooks inside a hook */
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ci->callstatus |= CIST_HOOKED;
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lua_assert(!L->allowhook);
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ci->top = restorestack(L, ci_top);
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L->top = restorestack(L, top);
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ci->callstatus &= ~CIST_HOOKED;
244
static void callhook (lua_State *L, CallInfo *ci) {
245
int hook = LUA_HOOKCALL;
246
ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */
247
if (isLua(ci->previous) &&
248
GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) {
249
ci->callstatus |= CIST_TAIL;
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hook = LUA_HOOKTAILCALL;
252
luaD_hook(L, hook, -1);
253
ci->u.l.savedpc--; /* correct 'pc' */
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static StkId adjust_varargs (lua_State *L, Proto *p, int actual) {
259
int nfixargs = p->numparams;
261
lua_assert(actual >= nfixargs);
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/* move fixed parameters to final position */
263
fixed = L->top - actual; /* first fixed argument */
264
base = L->top; /* final position of first argument */
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for (i=0; i<nfixargs; i++) {
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setobjs2s(L, L->top++, fixed + i);
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setnilvalue(fixed + i);
273
static StkId tryfuncTM (lua_State *L, StkId func) {
274
const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL);
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ptrdiff_t funcr = savestack(L, func);
277
if (!ttisfunction(tm))
278
luaG_typeerror(L, func, "call");
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/* Open a hole inside the stack at `func' */
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for (p = L->top; p > func; p--) setobjs2s(L, p, p-1);
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func = restorestack(L, funcr); /* previous call may change stack */
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setobj2s(L, func, tm); /* tag method is the new function to be called */
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#define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L)))
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** returns true if function has been executed (C function)
295
int luaD_precall (lua_State *L, StkId func, int nresults) {
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int n; /* number of arguments (Lua) or returns (C) */
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ptrdiff_t funcr = savestack(L, func);
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switch (ttype(func)) {
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case LUA_TLCF: /* light C function */
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case LUA_TCCL: { /* C closure */
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f = clCvalue(func)->f;
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luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
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ci = next_ci(L); /* now 'enter' new function */
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ci->nresults = nresults;
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ci->func = restorestack(L, funcr);
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ci->top = L->top + LUA_MINSTACK;
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lua_assert(ci->top <= L->stack_last);
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luaC_checkGC(L); /* stack grow uses memory */
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if (L->hookmask & LUA_MASKCALL)
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luaD_hook(L, LUA_HOOKCALL, -1);
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n = (*f)(L); /* do the actual call */
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api_checknelems(L, n);
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luaD_poscall(L, L->top - n);
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case LUA_TLCL: { /* Lua function: prepare its call */
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Proto *p = clLvalue(func)->p;
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luaD_checkstack(L, p->maxstacksize);
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func = restorestack(L, funcr);
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n = cast_int(L->top - func) - 1; /* number of real arguments */
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for (; n < p->numparams; n++)
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setnilvalue(L->top++); /* complete missing arguments */
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base = (!p->is_vararg) ? func + 1 : adjust_varargs(L, p, n);
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ci = next_ci(L); /* now 'enter' new function */
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ci->nresults = nresults;
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ci->top = base + p->maxstacksize;
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lua_assert(ci->top <= L->stack_last);
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ci->u.l.savedpc = p->code; /* starting point */
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ci->callstatus = CIST_LUA;
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luaC_checkGC(L); /* stack grow uses memory */
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if (L->hookmask & LUA_MASKCALL)
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default: { /* not a function */
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func = tryfuncTM(L, func); /* retry with 'function' tag method */
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return luaD_precall(L, func, nresults); /* now it must be a function */
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int luaD_poscall (lua_State *L, StkId firstResult) {
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CallInfo *ci = L->ci;
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if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) {
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if (L->hookmask & LUA_MASKRET) {
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ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */
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luaD_hook(L, LUA_HOOKRET, -1);
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firstResult = restorestack(L, fr);
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L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */
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res = ci->func; /* res == final position of 1st result */
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wanted = ci->nresults;
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L->ci = ci = ci->previous; /* back to caller */
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/* move results to correct place */
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for (i = wanted; i != 0 && firstResult < L->top; i--)
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setobjs2s(L, res++, firstResult++);
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return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */
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** Call a function (C or Lua). The function to be called is at *func.
382
** The arguments are on the stack, right after the function.
383
** When returns, all the results are on the stack, starting at the original
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** function position.
386
void luaD_call (lua_State *L, StkId func, int nResults, int allowyield) {
387
if (++L->nCcalls >= LUAI_MAXCCALLS) {
388
if (L->nCcalls == LUAI_MAXCCALLS)
389
luaG_runerror(L, "C stack overflow");
390
else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3)))
391
luaD_throw(L, LUA_ERRERR); /* error while handing stack error */
393
if (!allowyield) L->nny++;
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if (!luaD_precall(L, func, nResults)) /* is a Lua function? */
395
luaV_execute(L); /* call it */
396
if (!allowyield) L->nny--;
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static void finishCcall (lua_State *L) {
402
CallInfo *ci = L->ci;
404
lua_assert(ci->u.c.k != NULL); /* must have a continuation */
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lua_assert(L->nny == 0);
406
if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */
407
ci->callstatus &= ~CIST_YPCALL; /* finish 'lua_pcall' */
408
L->errfunc = ci->u.c.old_errfunc;
410
/* finish 'lua_callk'/'lua_pcall' */
411
adjustresults(L, ci->nresults);
412
/* call continuation function */
413
if (!(ci->callstatus & CIST_STAT)) /* no call status? */
414
ci->u.c.status = LUA_YIELD; /* 'default' status */
415
lua_assert(ci->u.c.status != LUA_OK);
416
ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED;
420
api_checknelems(L, n);
421
/* finish 'luaD_precall' */
422
luaD_poscall(L, L->top - n);
426
static void unroll (lua_State *L, void *ud) {
429
if (L->ci == &L->base_ci) /* stack is empty? */
430
return; /* coroutine finished normally */
431
if (!isLua(L->ci)) /* C function? */
433
else { /* Lua function */
434
luaV_finishOp(L); /* finish interrupted instruction */
435
luaV_execute(L); /* execute down to higher C 'boundary' */
442
** check whether thread has a suspended protected call
444
static CallInfo *findpcall (lua_State *L) {
446
for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */
447
if (ci->callstatus & CIST_YPCALL)
450
return NULL; /* no pending pcall */
454
static int recover (lua_State *L, int status) {
456
CallInfo *ci = findpcall(L);
457
if (ci == NULL) return 0; /* no recovery point */
458
/* "finish" luaD_pcall */
459
oldtop = restorestack(L, ci->extra);
460
luaF_close(L, oldtop);
461
seterrorobj(L, status, oldtop);
463
L->allowhook = ci->u.c.old_allowhook;
464
L->nny = 0; /* should be zero to be yieldable */
466
L->errfunc = ci->u.c.old_errfunc;
467
ci->callstatus |= CIST_STAT; /* call has error status */
468
ci->u.c.status = status; /* (here it is) */
469
return 1; /* continue running the coroutine */
474
** signal an error in the call to 'resume', not in the execution of the
475
** coroutine itself. (Such errors should not be handled by any coroutine
476
** error handler and should not kill the coroutine.)
478
static l_noret resume_error (lua_State *L, const char *msg, StkId firstArg) {
479
L->top = firstArg; /* remove args from the stack */
480
setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */
482
luaD_throw(L, -1); /* jump back to 'lua_resume' */
487
** do the work for 'lua_resume' in protected mode
489
static void resume (lua_State *L, void *ud) {
490
int nCcalls = L->nCcalls;
491
StkId firstArg = cast(StkId, ud);
492
CallInfo *ci = L->ci;
493
if (nCcalls >= LUAI_MAXCCALLS)
494
resume_error(L, "C stack overflow", firstArg);
495
if (L->status == LUA_OK) { /* may be starting a coroutine */
496
if (ci != &L->base_ci) /* not in base level? */
497
resume_error(L, "cannot resume non-suspended coroutine", firstArg);
498
/* coroutine is in base level; start running it */
499
if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */
500
luaV_execute(L); /* call it */
502
else if (L->status != LUA_YIELD)
503
resume_error(L, "cannot resume dead coroutine", firstArg);
504
else { /* resuming from previous yield */
506
ci->func = restorestack(L, ci->extra);
507
if (isLua(ci)) /* yielded inside a hook? */
508
luaV_execute(L); /* just continue running Lua code */
509
else { /* 'common' yield */
510
if (ci->u.c.k != NULL) { /* does it have a continuation? */
512
ci->u.c.status = LUA_YIELD; /* 'default' status */
513
ci->callstatus |= CIST_YIELDED;
515
n = (*ci->u.c.k)(L); /* call continuation */
517
api_checknelems(L, n);
518
firstArg = L->top - n; /* yield results come from continuation */
520
luaD_poscall(L, firstArg); /* finish 'luaD_precall' */
524
lua_assert(nCcalls == L->nCcalls);
528
LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) {
531
luai_userstateresume(L, nargs);
532
L->nCcalls = (from) ? from->nCcalls + 1 : 1;
533
L->nny = 0; /* allow yields */
534
api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs);
535
status = luaD_rawrunprotected(L, resume, L->top - nargs);
536
if (status == -1) /* error calling 'lua_resume'? */
538
else { /* yield or regular error */
539
while (status != LUA_OK && status != LUA_YIELD) { /* error? */
540
if (recover(L, status)) /* recover point? */
541
status = luaD_rawrunprotected(L, unroll, NULL); /* run continuation */
542
else { /* unrecoverable error */
543
L->status = cast_byte(status); /* mark thread as `dead' */
544
seterrorobj(L, status, L->top);
549
lua_assert(status == L->status);
551
L->nny = 1; /* do not allow yields */
553
lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0));
559
LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) {
560
CallInfo *ci = L->ci;
561
luai_userstateyield(L, nresults);
563
api_checknelems(L, nresults);
565
if (L != G(L)->mainthread)
566
luaG_runerror(L, "attempt to yield across a C-call boundary");
568
luaG_runerror(L, "attempt to yield from outside a coroutine");
570
L->status = LUA_YIELD;
571
ci->extra = savestack(L, ci->func); /* save current 'func' */
572
if (isLua(ci)) { /* inside a hook? */
573
api_check(L, k == NULL, "hooks cannot continue after yielding");
576
if ((ci->u.c.k = k) != NULL) /* is there a continuation? */
577
ci->u.c.ctx = ctx; /* save context */
578
ci->func = L->top - nresults - 1; /* protect stack below results */
579
luaD_throw(L, LUA_YIELD);
581
lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */
583
return 0; /* return to 'luaD_hook' */
587
int luaD_pcall (lua_State *L, Pfunc func, void *u,
588
ptrdiff_t old_top, ptrdiff_t ef) {
590
CallInfo *old_ci = L->ci;
591
lu_byte old_allowhooks = L->allowhook;
592
unsigned short old_nny = L->nny;
593
ptrdiff_t old_errfunc = L->errfunc;
595
status = luaD_rawrunprotected(L, func, u);
596
if (status != LUA_OK) { /* an error occurred? */
597
StkId oldtop = restorestack(L, old_top);
598
luaF_close(L, oldtop); /* close possible pending closures */
599
seterrorobj(L, status, oldtop);
601
L->allowhook = old_allowhooks;
605
L->errfunc = old_errfunc;
612
** Execute a protected parser.
614
struct SParser { /* data to `f_parser' */
616
Mbuffer buff; /* dynamic structure used by the scanner */
617
Dyndata dyd; /* dynamic structures used by the parser */
623
static void checkmode (lua_State *L, const char *mode, const char *x) {
624
if (mode && strchr(mode, x[0]) == NULL) {
626
"attempt to load a %s chunk (mode is " LUA_QS ")", x, mode);
627
luaD_throw(L, LUA_ERRSYNTAX);
632
static void f_parser (lua_State *L, void *ud) {
635
struct SParser *p = cast(struct SParser *, ud);
636
int c = zgetc(p->z); /* read first character */
637
if (c == LUA_SIGNATURE[0]) {
638
checkmode(L, p->mode, "binary");
639
cl = luaU_undump(L, p->z, &p->buff, p->name);
642
checkmode(L, p->mode, "text");
643
cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c);
645
lua_assert(cl->l.nupvalues == cl->l.p->sizeupvalues);
646
for (i = 0; i < cl->l.nupvalues; i++) { /* initialize upvalues */
647
UpVal *up = luaF_newupval(L);
648
cl->l.upvals[i] = up;
649
luaC_objbarrier(L, cl, up);
654
int luaD_protectedparser (lua_State *L, ZIO *z, const char *name,
658
L->nny++; /* cannot yield during parsing */
659
p.z = z; p.name = name; p.mode = mode;
660
p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0;
661
p.dyd.gt.arr = NULL; p.dyd.gt.size = 0;
662
p.dyd.label.arr = NULL; p.dyd.label.size = 0;
663
luaZ_initbuffer(L, &p.buff);
664
status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc);
665
luaZ_freebuffer(L, &p.buff);
666
luaM_freearray(L, p.dyd.actvar.arr, p.dyd.actvar.size);
667
luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size);
668
luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size);