/* ** $Id: ldo.c,v 2.80 2010/01/13 16:17:32 roberto Exp roberto $ ** Stack and Call structure of Lua ** See Copyright Notice in lua.h */ #include <setjmp.h> #include <stdlib.h> #include <string.h> #define ldo_c #define LUA_CORE #include "lua.h" #include "lapi.h" #include "ldebug.h" #include "ldo.h" #include "lfunc.h" #include "lgc.h" #include "lmem.h" #include "lobject.h" #include "lopcodes.h" #include "lparser.h" #include "lstate.h" #include "lstring.h" #include "ltable.h" #include "ltm.h" #include "lundump.h" #include "lvm.h" #include "lzio.h" /* ** {====================================================== ** Error-recovery functions ** ======================================================= */ /* ** LUAI_THROW/LUAI_TRY define how Lua does exception handling. By ** default, Lua handles errors with exceptions when compiling as ** C++ code, with _longjmp/_setjmp when asked to use them, and with ** longjmp/setjmp otherwise. */ #if !defined(LUAI_THROW) #if defined(__cplusplus) /* C++ exceptions */ #define LUAI_THROW(L,c) throw(c) #define LUAI_TRY(L,c,a) \ try { a } catch(...) { if ((c)->status == 0) (c)->status = -1; } #define luai_jmpbuf int /* dummy variable */ #elif defined(LUA_USE_ULONGJMP) /* in Unix, try _longjmp/_setjmp (more efficient) */ #define LUAI_THROW(L,c) _longjmp((c)->b, 1) #define LUAI_TRY(L,c,a) if (_setjmp((c)->b) == 0) { a } #define luai_jmpbuf jmp_buf #else /* default handling with long jumps */ #define LUAI_THROW(L,c) longjmp((c)->b, 1) #define LUAI_TRY(L,c,a) if (setjmp((c)->b) == 0) { a } #define luai_jmpbuf jmp_buf #endif #endif /* chain list of long jump buffers */ struct lua_longjmp { struct lua_longjmp *previous; luai_jmpbuf b; volatile int status; /* error code */ }; static void seterrorobj (lua_State *L, int errcode, StkId oldtop) { switch (errcode) { case LUA_ERRMEM: { setsvalue2s(L, oldtop, luaS_newliteral(L, MEMERRMSG)); break; } case LUA_ERRERR: { setsvalue2s(L, oldtop, luaS_newliteral(L, "error in error handling")); break; } default: { setobjs2s(L, oldtop, L->top - 1); /* error message on current top */ break; } } L->top = oldtop + 1; } void luaD_throw (lua_State *L, int errcode) { if (L->errorJmp) { /* thread has an error handler? */ L->errorJmp->status = errcode; /* set status */ LUAI_THROW(L, L->errorJmp); /* jump to it */ } else { /* thread has no error handler */ L->status = cast_byte(errcode); /* mark it as dead */ if (G(L)->mainthread->errorJmp) { /* main thread has a handler? */ setobjs2s(L, G(L)->mainthread->top++, L->top - 1); /* copy error obj. */ luaD_throw(G(L)->mainthread, errcode); /* re-throw in main thread */ } else { /* no handler at all; abort */ if (G(L)->panic) { /* panic function? */ lua_unlock(L); G(L)->panic(L); /* call it (last chance to jump out) */ } abort(); } } } int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) { unsigned short oldnCcalls = G(L)->nCcalls; struct lua_longjmp lj; lj.status = LUA_OK; lj.previous = L->errorJmp; /* chain new error handler */ L->errorJmp = &lj; LUAI_TRY(L, &lj, (*f)(L, ud); ); L->errorJmp = lj.previous; /* restore old error handler */ G(L)->nCcalls = oldnCcalls; return lj.status; } /* }====================================================== */ static void correctstack (lua_State *L, TValue *oldstack) { CallInfo *ci; GCObject *up; L->top = (L->top - oldstack) + L->stack; for (up = L->openupval; up != NULL; up = up->gch.next) gco2uv(up)->v = (gco2uv(up)->v - oldstack) + L->stack; for (ci = L->ci; ci != NULL; ci = ci->previous) { ci->top = (ci->top - oldstack) + L->stack; ci->func = (ci->func - oldstack) + L->stack; if (isLua(ci)) ci->u.l.base = (ci->u.l.base - oldstack) + L->stack; } } /* some space for error handling */ #define ERRORSTACKSIZE (LUAI_MAXSTACK + 200) void luaD_reallocstack (lua_State *L, int newsize) { TValue *oldstack = L->stack; int lim = L->stacksize; lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE); lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK); luaM_reallocvector(L, L->stack, L->stacksize, newsize, TValue); for (; lim < newsize; lim++) setnilvalue(L->stack + lim); /* erase new segment */ L->stacksize = newsize; L->stack_last = L->stack + newsize - EXTRA_STACK; correctstack(L, oldstack); } void luaD_growstack (lua_State *L, int n) { int size = L->stacksize; if (size > LUAI_MAXSTACK) /* error after extra size? */ luaD_throw(L, LUA_ERRERR); else { int needed = L->top - L->stack + n + EXTRA_STACK; int newsize = 2 * size; if (newsize > LUAI_MAXSTACK) newsize = LUAI_MAXSTACK; if (newsize < needed) newsize = needed; if (newsize > LUAI_MAXSTACK) { /* stack overflow? */ luaD_reallocstack(L, ERRORSTACKSIZE); luaG_runerror(L, "stack overflow"); } else luaD_reallocstack(L, newsize); } } static int stackinuse (lua_State *L) { CallInfo *ci; StkId lim = L->top; for (ci = L->ci; ci != NULL; ci = ci->previous) { lua_assert(ci->top <= L->stack_last); if (lim < ci->top) lim = ci->top; } return cast_int(lim - L->stack) + 1; /* part of stack in use */ } void luaD_shrinkstack (lua_State *L) { int inuse = stackinuse(L); int goodsize = inuse + (inuse / 8) + 2*EXTRA_STACK; if (goodsize > LUAI_MAXSTACK) goodsize = LUAI_MAXSTACK; if (inuse > LUAI_MAXSTACK || /* handling stack overflow? */ goodsize >= L->stacksize) /* would grow instead of shrink? */ condmovestack(L); /* don't change stack (change only for debugging) */ else luaD_reallocstack(L, goodsize); /* shrink it */ } void luaD_hook (lua_State *L, int event, int line) { lua_Hook hook = L->hook; if (hook && L->allowhook) { CallInfo *ci = L->ci; ptrdiff_t top = savestack(L, L->top); ptrdiff_t ci_top = savestack(L, ci->top); lua_Debug ar; ar.event = event; ar.currentline = line; ar.i_ci = ci; luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */ ci->top = L->top + LUA_MINSTACK; lua_assert(ci->top <= L->stack_last); L->allowhook = 0; /* cannot call hooks inside a hook */ ci->callstatus |= CIST_HOOKED; lua_unlock(L); (*hook)(L, &ar); lua_lock(L); lua_assert(!L->allowhook); L->allowhook = 1; ci->top = restorestack(L, ci_top); L->top = restorestack(L, top); ci->callstatus &= ~CIST_HOOKED; } } static void callhook (lua_State *L, CallInfo *ci) { int hook = LUA_HOOKCALL; ci->u.l.savedpc++; /* hooks assume 'pc' is already incremented */ if (isLua(ci->previous) && GET_OPCODE(*(ci->previous->u.l.savedpc - 1)) == OP_TAILCALL) { ci->callstatus |= CIST_TAIL; hook = LUA_HOOKTAILCALL; } luaD_hook(L, hook, -1); ci->u.l.savedpc--; /* correct 'pc' */ } static StkId adjust_varargs (lua_State *L, Proto *p, int actual) { int i; int nfixargs = p->numparams; StkId base, fixed; lua_assert(actual >= nfixargs); /* move fixed parameters to final position */ fixed = L->top - actual; /* first fixed argument */ base = L->top; /* final position of first argument */ for (i=0; i<nfixargs; i++) { setobjs2s(L, L->top++, fixed + i); setnilvalue(fixed + i); } return base; } static StkId tryfuncTM (lua_State *L, StkId func) { const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL); StkId p; ptrdiff_t funcr = savestack(L, func); if (!ttisfunction(tm)) luaG_typeerror(L, func, "call"); /* Open a hole inside the stack at `func' */ for (p = L->top; p > func; p--) setobjs2s(L, p, p-1); incr_top(L); func = restorestack(L, funcr); /* previous call may change stack */ setobj2s(L, func, tm); /* tag method is the new function to be called */ return func; } #define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L))) /* ** returns true if function has been executed (C function) */ int luaD_precall (lua_State *L, StkId func, int nresults) { LClosure *cl; ptrdiff_t funcr; if (!ttisfunction(func)) /* `func' is not a function? */ func = tryfuncTM(L, func); /* check the `function' tag method */ funcr = savestack(L, func); cl = &clvalue(func)->l; L->ci->nresults = nresults; if (!cl->isC) { /* Lua function? prepare its call */ CallInfo *ci; int nparams, nargs; StkId base; Proto *p = cl->p; luaD_checkstack(L, p->maxstacksize); func = restorestack(L, funcr); nargs = cast_int(L->top - func) - 1; /* number of real arguments */ nparams = p->numparams; /* number of expected parameters */ for (; nargs < nparams; nargs++) setnilvalue(L->top++); /* complete missing arguments */ if (!p->is_vararg) /* no varargs? */ base = func + 1; else /* vararg function */ base = adjust_varargs(L, p, nargs); ci = next_ci(L); /* now 'enter' new function */ ci->func = func; ci->u.l.base = base; ci->top = base + p->maxstacksize; lua_assert(ci->top <= L->stack_last); ci->u.l.savedpc = p->code; /* starting point */ ci->callstatus = CIST_LUA; L->top = ci->top; if (L->hookmask & LUA_MASKCALL) callhook(L, ci); return 0; } else { /* if is a C function, call it */ CallInfo *ci; int n; luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */ ci = next_ci(L); /* now 'enter' new function */ ci->func = restorestack(L, funcr); ci->top = L->top + LUA_MINSTACK; lua_assert(ci->top <= L->stack_last); ci->callstatus = 0; if (L->hookmask & LUA_MASKCALL) luaD_hook(L, LUA_HOOKCALL, -1); lua_unlock(L); n = (*curr_func(L)->c.f)(L); /* do the actual call */ lua_lock(L); api_checknelems(L, n); luaD_poscall(L, L->top - n); return 1; } } int luaD_poscall (lua_State *L, StkId firstResult) { StkId res; int wanted, i; CallInfo *ci = L->ci; if (L->hookmask & (LUA_MASKRET | LUA_MASKLINE)) { if (L->hookmask & LUA_MASKRET) { ptrdiff_t fr = savestack(L, firstResult); /* hook may change stack */ luaD_hook(L, LUA_HOOKRET, -1); firstResult = restorestack(L, fr); } L->oldpc = ci->previous->u.l.savedpc; /* 'oldpc' for caller function */ } res = ci->func; /* res == final position of 1st result */ L->ci = ci = ci->previous; /* back to caller */ wanted = ci->nresults; /* move results to correct place */ for (i = wanted; i != 0 && firstResult < L->top; i--) setobjs2s(L, res++, firstResult++); while (i-- > 0) setnilvalue(res++); L->top = res; return (wanted - LUA_MULTRET); /* 0 iff wanted == LUA_MULTRET */ } /* ** Call a function (C or Lua). The function to be called is at *func. ** The arguments are on the stack, right after the function. ** When returns, all the results are on the stack, starting at the original ** function position. */ void luaD_call (lua_State *L, StkId func, int nResults, int allowyield) { global_State *g = G(L); if (++g->nCcalls >= LUAI_MAXCCALLS) { if (g->nCcalls == LUAI_MAXCCALLS) luaG_runerror(L, "C stack overflow"); else if (g->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3))) luaD_throw(L, LUA_ERRERR); /* error while handing stack error */ } if (!allowyield) L->nny++; if (!luaD_precall(L, func, nResults)) /* is a Lua function? */ luaV_execute(L); /* call it */ if (!allowyield) L->nny--; g->nCcalls--; luaC_checkGC(L); } static void finishCcall (lua_State *L) { CallInfo *ci = L->ci; int n; lua_assert(ci->u.c.k != NULL); /* must have a continuation */ lua_assert(L->nny == 0); /* finish 'luaD_call' */ G(L)->nCcalls--; /* finish 'lua_callk' */ adjustresults(L, ci->nresults); /* call continuation function */ if (!(ci->callstatus & CIST_STAT)) /* no call status? */ ci->u.c.status = LUA_YIELD; /* 'default' status */ lua_assert(ci->u.c.status != LUA_OK); ci->callstatus = (ci->callstatus & ~(CIST_YPCALL | CIST_STAT)) | CIST_YIELDED; lua_unlock(L); n = (*ci->u.c.k)(L); lua_lock(L); api_checknelems(L, n); /* finish 'luaD_precall' */ luaD_poscall(L, L->top - n); } static void unroll (lua_State *L, void *ud) { UNUSED(ud); for (;;) { if (L->ci == &L->base_ci) /* stack is empty? */ return; /* coroutine finished normally */ if (!isLua(L->ci)) /* C function? */ finishCcall(L); else { /* Lua function */ luaV_finishOp(L); /* finish interrupted instruction */ luaV_execute(L); /* execute down to higher C 'boundary' */ } } } /* ** check whether thread has a suspended protected call */ static CallInfo *findpcall (lua_State *L) { CallInfo *ci; for (ci = L->ci; ci != NULL; ci = ci->previous) { /* search for a pcall */ if (ci->callstatus & CIST_YPCALL) return ci; } return NULL; /* no pending pcall */ } static int recover (lua_State *L, int status) { StkId oldtop; CallInfo *ci = findpcall(L); if (ci == NULL) return 0; /* no recovery point */ /* "finish" luaD_pcall */ oldtop = restorestack(L, ci->u.c.extra); luaF_close(L, oldtop); seterrorobj(L, status, oldtop); L->ci = ci; L->allowhook = ci->u.c.old_allowhook; L->nny = 0; /* should be zero to be yieldable */ luaD_shrinkstack(L); L->errfunc = ci->u.c.old_errfunc; ci->callstatus |= CIST_STAT; /* call has error status */ ci->u.c.status = status; /* (here it is) */ return 1; /* continue running the coroutine */ } /* ** signal an error in the call to 'resume', not in the execution of the ** coroutine itself. (Such errors should not be handled by any coroutine ** error hanlder and should not kill the coroutine.) */ static void resume_error (lua_State *L, const char *msg, StkId firstArg) { L->top = firstArg; /* remove args from the stack */ setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */ incr_top(L); luaD_throw(L, -1); /* jump back to 'lua_resume' */ } /* ** do the work for 'lua_resume' in protected mode */ static void resume (lua_State *L, void *ud) { StkId firstArg = cast(StkId, ud); CallInfo *ci = L->ci; if (G(L)->nCcalls >= LUAI_MAXCCALLS) resume_error(L, "C stack overflow", firstArg); if (L->status == LUA_OK) { /* may be starting a coroutine */ if (ci != &L->base_ci) /* not in base level? */ resume_error(L, "cannot resume non-suspended coroutine", firstArg); /* coroutine is in base level; start running it */ if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */ luaV_execute(L); /* call it */ } else if (L->status != LUA_YIELD) resume_error(L, "cannot resume dead coroutine", firstArg); else { /* resuming from previous yield */ L->status = LUA_OK; if (isLua(ci)) /* yielded inside a hook? */ luaV_execute(L); /* just continue running Lua code */ else { /* 'common' yield */ ci->func = restorestack(L, ci->u.c.extra); if (ci->u.c.k != NULL) { /* does it have a continuation? */ int n; ci->u.c.status = LUA_YIELD; /* 'default' status */ ci->callstatus |= CIST_YIELDED; lua_unlock(L); n = (*ci->u.c.k)(L); /* call continuation */ lua_lock(L); api_checknelems(L, n); firstArg = L->top - n; /* yield results come from continuation */ } G(L)->nCcalls--; /* finish 'luaD_call' */ luaD_poscall(L, firstArg); /* finish 'luaD_precall' */ } unroll(L, NULL); } } LUA_API int lua_resume (lua_State *L, int nargs) { int status; lua_lock(L); luai_userstateresume(L, nargs); ++G(L)->nCcalls; /* count resume */ L->nny = 0; /* allow yields */ status = luaD_rawrunprotected(L, resume, L->top - nargs); if (status == -1) /* error calling 'lua_resume'? */ status = LUA_ERRRUN; else { /* yield or regular error */ while (status != LUA_OK && status != LUA_YIELD) { /* error? */ if (recover(L, status)) /* recover point? */ status = luaD_rawrunprotected(L, unroll, NULL); /* run continuation */ else { /* unrecoverable error */ L->status = cast_byte(status); /* mark thread as `dead' */ seterrorobj(L, status, L->top); L->ci->top = L->top; break; } } lua_assert(status == L->status); } L->nny = 1; /* do not allow yields */ --G(L)->nCcalls; lua_unlock(L); return status; } LUA_API int lua_yieldk (lua_State *L, int nresults, int ctx, lua_CFunction k) { CallInfo *ci = L->ci; luai_userstateyield(L, nresults); lua_lock(L); api_checknelems(L, nresults); if (L->nny > 0) { if (L != G(L)->mainthread) luaG_runerror(L, "attempt to yield across metamethod/C-call boundary"); else luaG_runerror(L, "attempt to yield from outside a coroutine"); } L->status = LUA_YIELD; if (isLua(ci)) { /* inside a hook? */ api_check(L, k == NULL, "hooks cannot continue after yielding"); } else { if ((ci->u.c.k = k) != NULL) /* is there a continuation? */ ci->u.c.ctx = ctx; /* save context */ ci->u.c.extra = savestack(L, ci->func); /* save current 'func' */ ci->func = L->top - nresults - 1; /* protect stack below results */ luaD_throw(L, LUA_YIELD); } lua_assert(ci->callstatus & CIST_HOOKED); /* must be inside a hook */ lua_unlock(L); return 0; /* return to 'luaD_hook' */ } int luaD_pcall (lua_State *L, Pfunc func, void *u, ptrdiff_t old_top, ptrdiff_t ef) { int status; CallInfo *old_ci = L->ci; lu_byte old_allowhooks = L->allowhook; unsigned short old_nny = L->nny; ptrdiff_t old_errfunc = L->errfunc; L->errfunc = ef; status = luaD_rawrunprotected(L, func, u); if (status != LUA_OK) { /* an error occurred? */ StkId oldtop = restorestack(L, old_top); luaF_close(L, oldtop); /* close possible pending closures */ seterrorobj(L, status, oldtop); L->ci = old_ci; L->allowhook = old_allowhooks; L->nny = old_nny; luaD_shrinkstack(L); } L->errfunc = old_errfunc; return status; } /* ** Execute a protected parser. */ struct SParser { /* data to `f_parser' */ ZIO *z; Mbuffer buff; /* buffer to be used by the scanner */ Varlist varl; /* list of local variables (to be used by the parser) */ const char *name; }; static void f_parser (lua_State *L, void *ud) { int i; Proto *tf; Closure *cl; struct SParser *p = cast(struct SParser *, ud); int c = luaZ_lookahead(p->z); tf = (c == LUA_SIGNATURE[0]) ? luaU_undump(L, p->z, &p->buff, p->name) : luaY_parser(L, p->z, &p->buff, &p->varl, p->name); setptvalue2s(L, L->top, tf); incr_top(L); cl = luaF_newLclosure(L, tf->sizeupvalues, G(L)->l_gt); cl->l.p = tf; setclvalue(L, L->top - 1, cl); for (i = 0; i < tf->sizeupvalues; i++) /* initialize upvalues */ cl->l.upvals[i] = luaF_newupval(L); } int luaD_protectedparser (lua_State *L, ZIO *z, const char *name) { struct SParser p; int status; L->nny++; /* cannot yield during parsing */ p.z = z; p.name = name; p.varl.actvar = NULL; p.varl.nactvar = p.varl.actvarsize = 0; luaZ_initbuffer(L, &p.buff); status = luaD_pcall(L, f_parser, &p, savestack(L, L->top), L->errfunc); luaZ_freebuffer(L, &p.buff); luaM_freearray(L, p.varl.actvar, p.varl.actvarsize); L->nny--; return status; }