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Diffstat (limited to 'src/lua/ldo.c')
| -rw-r--r-- | src/lua/ldo.c | 802 |
1 files changed, 802 insertions, 0 deletions
diff --git a/src/lua/ldo.c b/src/lua/ldo.c new file mode 100644 index 0000000..e3ff35f --- /dev/null +++ b/src/lua/ldo.c @@ -0,0 +1,802 @@ +/* +** $Id: ldo.c,v 2.157.1.1 2017/04/19 17:20:42 roberto Exp $ +** Stack and Call structure of Lua +** See Copyright Notice in lua.h +*/ + +#define ldo_c +#define LUA_CORE + +#include "lprefix.h" + + +#include "setjmp.h" +#include "stdlib.h" +#include "string.h" + +#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" + + + +#define errorstatus(s) ((s) > LUA_YIELD) + + +/* +** {====================================================== +** 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) && !defined(LUA_USE_LONGJMP) /* { */ + +/* 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_POSIX) /* }{ */ + +/* in POSIX, 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 /* }{ */ + +/* ISO C 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: { /* memory error? */ + setsvalue2s(L, oldtop, G(L)->memerrmsg); /* reuse preregistered msg. */ + 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; +} + + +l_noret 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 */ + global_State *g = G(L); + L->status = cast_byte(errcode); /* mark it as dead */ + if (g->mainthread->errorJmp) { /* main thread has a handler? */ + setobjs2s(L, g->mainthread->top++, L->top - 1); /* copy error obj. */ + luaD_throw(g->mainthread, errcode); /* re-throw in main thread */ + } + else { /* no handler at all; abort */ + if (g->panic) { /* panic function? */ + seterrorobj(L, errcode, L->top); /* assume EXTRA_STACK */ + if (L->ci->top < L->top) + L->ci->top = L->top; /* pushing msg. can break this invariant */ + lua_unlock(L); + g->panic(L); /* call panic function (last chance to jump out) */ + } + bees("fatal error"); + } + } +} + + +int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) { + unsigned short oldnCcalls = 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 */ + L->nCcalls = oldnCcalls; + return lj.status; +} + +/* }====================================================== */ + + +/* +** {================================================================== +** Stack reallocation +** =================================================================== +*/ +static void correctstack (lua_State *L, TValue *oldstack) { + CallInfo *ci; + UpVal *up; + L->top = (L->top - oldstack) + L->stack; + for (up = L->openupval; up != NULL; up = up->u.open.next) + up->v = (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 = cast_int(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) { + if (lim < ci->top) lim = ci->top; + } + lua_assert(lim <= L->stack_last); + 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; /* respect stack limit */ + if (L->stacksize > LUAI_MAXSTACK) /* had been handling stack overflow? */ + luaE_freeCI(L); /* free all CIs (list grew because of an error) */ + else + luaE_shrinkCI(L); /* shrink list */ + /* if thread is currently not handling a stack overflow and its + good size is smaller than current size, shrink its stack */ + if (inuse <= (LUAI_MAXSTACK - EXTRA_STACK) && + goodsize < L->stacksize) + luaD_reallocstack(L, goodsize); + else /* don't change stack */ + condmovestack(L,{},{}); /* (change only for debugging) */ +} + + +void luaD_inctop (lua_State *L) { + luaD_checkstack(L, 1); + L->top++; +} + +/* }================================================================== */ + + +/* +** Call a hook for the given event. Make sure there is a hook to be +** called. (Both 'L->hook' and 'L->hookmask', which triggers this +** function, can be changed asynchronously by signals.) +*/ +void luaD_hook (lua_State *L, int event, int line) { + lua_Hook hook = L->hook; + if (hook && L->allowhook) { /* make sure there is a hook */ + 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; + /* 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 < actual; i++) { + setobjs2s(L, L->top++, fixed + i); + setnilvalue(fixed + i); /* erase original copy (for GC) */ + } + for (; i < nfixargs; i++) + setnilvalue(L->top++); /* complete missing arguments */ + return base; +} + + +/* +** Check whether __call metafield of 'func' is a function. If so, put +** it in stack below original 'func' so that 'luaD_precall' can call +** it. Raise an error if __call metafield is not a function. +*/ +static void tryfuncTM (lua_State *L, StkId func) { + const TValue *tm = luaT_gettmbyobj(L, func, TM_CALL); + StkId p; + 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); + L->top++; /* slot ensured by caller */ + setobj2s(L, func, tm); /* tag method is the new function to be called */ +} + + +/* +** Given 'nres' results at 'firstResult', move 'wanted' of them to 'res'. +** Handle most typical cases (zero results for commands, one result for +** expressions, multiple results for tail calls/single parameters) +** separated. +*/ +static int moveresults (lua_State *L, const TValue *firstResult, StkId res, + int nres, int wanted) { + switch (wanted) { /* handle typical cases separately */ + case 0: break; /* nothing to move */ + case 1: { /* one result needed */ + if (nres == 0) /* no results? */ + firstResult = luaO_nilobject; /* adjust with nil */ + setobjs2s(L, res, firstResult); /* move it to proper place */ + break; + } + case LUA_MULTRET: { + int i; + for (i = 0; i < nres; i++) /* move all results to correct place */ + setobjs2s(L, res + i, firstResult + i); + L->top = res + nres; + return 0; /* wanted == LUA_MULTRET */ + } + default: { + int i; + if (wanted <= nres) { /* enough results? */ + for (i = 0; i < wanted; i++) /* move wanted results to correct place */ + setobjs2s(L, res + i, firstResult + i); + } + else { /* not enough results; use all of them plus nils */ + for (i = 0; i < nres; i++) /* move all results to correct place */ + setobjs2s(L, res + i, firstResult + i); + for (; i < wanted; i++) /* complete wanted number of results */ + setnilvalue(res + i); + } + break; + } + } + L->top = res + wanted; /* top points after the last result */ + return 1; +} + + +/* +** Finishes a function call: calls hook if necessary, removes CallInfo, +** moves current number of results to proper place; returns 0 iff call +** wanted multiple (variable number of) results. +*/ +int luaD_poscall (lua_State *L, CallInfo *ci, StkId firstResult, int nres) { + StkId res; + int wanted = ci->nresults; + 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->previous; /* back to caller */ + /* move results to proper place */ + return moveresults(L, firstResult, res, nres, wanted); +} + + + +#define next_ci(L) (L->ci = (L->ci->next ? L->ci->next : luaE_extendCI(L))) + + +/* macro to check stack size, preserving 'p' */ +#define checkstackp(L,n,p) \ + luaD_checkstackaux(L, n, \ + ptrdiff_t t__ = savestack(L, p); /* save 'p' */ \ + luaC_checkGC(L), /* stack grow uses memory */ \ + p = restorestack(L, t__)) /* 'pos' part: restore 'p' */ + + +/* +** Prepares a function call: checks the stack, creates a new CallInfo +** entry, fills in the relevant information, calls hook if needed. +** If function is a C function, does the call, too. (Otherwise, leave +** the execution ('luaV_execute') to the caller, to allow stackless +** calls.) Returns true iff function has been executed (C function). +*/ +int luaD_precall (lua_State *L, StkId func, int nresults) { + lua_CFunction f; + CallInfo *ci; + switch (ttype(func)) { + case LUA_TCCL: /* C closure */ + f = clCvalue(func)->f; + goto Cfunc; + case LUA_TLCF: /* light C function */ + f = fvalue(func); + Cfunc: { + int n; /* number of returns */ + checkstackp(L, LUA_MINSTACK, func); /* ensure minimum stack size */ + ci = next_ci(L); /* now 'enter' new function */ + ci->nresults = nresults; + ci->func = func; + 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 = (*f)(L); /* do the actual call */ + lua_lock(L); + api_checknelems(L, n); + luaD_poscall(L, ci, L->top - n, n); + return 1; + } + case LUA_TLCL: { /* Lua function: prepare its call */ + StkId base; + Proto *p = clLvalue(func)->p; + int n = cast_int(L->top - func) - 1; /* number of real arguments */ + int fsize = p->maxstacksize; /* frame size */ + checkstackp(L, fsize, func); + if (p->is_vararg) + base = adjust_varargs(L, p, n); + else { /* non vararg function */ + for (; n < p->numparams; n++) + setnilvalue(L->top++); /* complete missing arguments */ + base = func + 1; + } + ci = next_ci(L); /* now 'enter' new function */ + ci->nresults = nresults; + ci->func = func; + ci->u.l.base = base; + L->top = ci->top = base + fsize; + lua_assert(ci->top <= L->stack_last); + ci->u.l.savedpc = p->code; /* starting point */ + ci->callstatus = CIST_LUA; + if (L->hookmask & LUA_MASKCALL) + callhook(L, ci); + return 0; + } + default: { /* not a function */ + checkstackp(L, 1, func); /* ensure space for metamethod */ + tryfuncTM(L, func); /* try to get '__call' metamethod */ + return luaD_precall(L, func, nresults); /* now it must be a function */ + } + } +} + + +/* +** Check appropriate error for stack overflow ("regular" overflow or +** overflow while handling stack overflow). If 'nCalls' is larger than +** LUAI_MAXCCALLS (which means it is handling a "regular" overflow) but +** smaller than 9/8 of LUAI_MAXCCALLS, does not report an error (to +** allow overflow handling to work) +*/ +static void stackerror (lua_State *L) { + if (L->nCcalls == LUAI_MAXCCALLS) + luaG_runerror(L, "C stack overflow"); + else if (L->nCcalls >= (LUAI_MAXCCALLS + (LUAI_MAXCCALLS>>3))) + luaD_throw(L, LUA_ERRERR); /* error while handing stack error */ +} + + +/* +** 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) { + if (++L->nCcalls >= LUAI_MAXCCALLS) + stackerror(L); + if (!luaD_precall(L, func, nResults)) /* is a Lua function? */ + luaV_execute(L); /* call it */ + L->nCcalls--; +} + + +/* +** Similar to 'luaD_call', but does not allow yields during the call +*/ +void luaD_callnoyield (lua_State *L, StkId func, int nResults) { + L->nny++; + luaD_call(L, func, nResults); + L->nny--; +} + + +/* +** Completes the execution of an interrupted C function, calling its +** continuation function. +*/ +static void finishCcall (lua_State *L, int status) { + CallInfo *ci = L->ci; + int n; + /* must have a continuation and must be able to call it */ + lua_assert(ci->u.c.k != NULL && L->nny == 0); + /* error status can only happen in a protected call */ + lua_assert((ci->callstatus & CIST_YPCALL) || status == LUA_YIELD); + if (ci->callstatus & CIST_YPCALL) { /* was inside a pcall? */ + ci->callstatus &= ~CIST_YPCALL; /* continuation is also inside it */ + L->errfunc = ci->u.c.old_errfunc; /* with the same error function */ + } + /* finish 'lua_callk'/'lua_pcall'; CIST_YPCALL and 'errfunc' already + handled */ + adjustresults(L, ci->nresults); + lua_unlock(L); + n = (*ci->u.c.k)(L, status, ci->u.c.ctx); /* call continuation function */ + lua_lock(L); + api_checknelems(L, n); + luaD_poscall(L, ci, L->top - n, n); /* finish 'luaD_precall' */ +} + + +/* +** Executes "full continuation" (everything in the stack) of a +** previously interrupted coroutine until the stack is empty (or another +** interruption long-jumps out of the loop). If the coroutine is +** recovering from an error, 'ud' points to the error status, which must +** be passed to the first continuation function (otherwise the default +** status is LUA_YIELD). +*/ +static void unroll (lua_State *L, void *ud) { + if (ud != NULL) /* error status? */ + finishCcall(L, *(int *)ud); /* finish 'lua_pcallk' callee */ + while (L->ci != &L->base_ci) { /* something in the stack */ + if (!isLua(L->ci)) /* C function? */ + finishCcall(L, LUA_YIELD); /* complete its execution */ + else { /* Lua function */ + luaV_finishOp(L); /* finish interrupted instruction */ + luaV_execute(L); /* execute down to higher C 'boundary' */ + } + } +} + + +/* +** Try to find a suspended protected call (a "recover point") for the +** given thread. +*/ +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 */ +} + + +/* +** Recovers from an error in a coroutine. Finds a recover point (if +** there is one) and completes the execution of the interrupted +** 'luaD_pcall'. If there is no recover point, returns zero. +*/ +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->extra); + luaF_close(L, oldtop); + seterrorobj(L, status, oldtop); + L->ci = ci; + L->allowhook = getoah(ci->callstatus); /* restore original 'allowhook' */ + L->nny = 0; /* should be zero to be yieldable */ + luaD_shrinkstack(L); + L->errfunc = ci->u.c.old_errfunc; + return 1; /* continue running the coroutine */ +} + + +/* +** Signal an error in the call to 'lua_resume', not in the execution +** of the coroutine itself. (Such errors should not be handled by any +** coroutine error handler and should not kill the coroutine.) +*/ +static int resume_error (lua_State *L, const char *msg, int narg) { + L->top -= narg; /* remove args from the stack */ + setsvalue2s(L, L->top, luaS_new(L, msg)); /* push error message */ + api_incr_top(L); + lua_unlock(L); + return LUA_ERRRUN; +} + + +/* +** Do the work for 'lua_resume' in protected mode. Most of the work +** depends on the status of the coroutine: initial state, suspended +** inside a hook, or regularly suspended (optionally with a continuation +** function), plus erroneous cases: non-suspended coroutine or dead +** coroutine. +*/ +static void resume (lua_State *L, void *ud) { + int n = *(cast(int*, ud)); /* number of arguments */ + StkId firstArg = L->top - n; /* first argument */ + CallInfo *ci = L->ci; + if (L->status == LUA_OK) { /* starting a coroutine? */ + if (!luaD_precall(L, firstArg - 1, LUA_MULTRET)) /* Lua function? */ + luaV_execute(L); /* call it */ + } + else { /* resuming from previous yield */ + lua_assert(L->status == LUA_YIELD); + L->status = LUA_OK; /* mark that it is running (again) */ + ci->func = restorestack(L, ci->extra); + if (isLua(ci)) /* yielded inside a hook? */ + luaV_execute(L); /* just continue running Lua code */ + else { /* 'common' yield */ + if (ci->u.c.k != NULL) { /* does it have a continuation function? */ + lua_unlock(L); + n = (*ci->u.c.k)(L, LUA_YIELD, ci->u.c.ctx); /* call continuation */ + lua_lock(L); + api_checknelems(L, n); + firstArg = L->top - n; /* yield results come from continuation */ + } + luaD_poscall(L, ci, firstArg, n); /* finish 'luaD_precall' */ + } + unroll(L, NULL); /* run continuation */ + } +} + + +LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs) { + int status; + unsigned short oldnny = L->nny; /* save "number of non-yieldable" calls */ + lua_lock(L); + if (L->status == LUA_OK) { /* may be starting a coroutine */ + if (L->ci != &L->base_ci) /* not in base level? */ + return resume_error(L, "cannot resume non-suspended coroutine", nargs); + } + else if (L->status != LUA_YIELD) + return resume_error(L, "cannot resume dead coroutine", nargs); + L->nCcalls = (from) ? from->nCcalls + 1 : 1; + if (L->nCcalls >= LUAI_MAXCCALLS) + return resume_error(L, "C stack overflow", nargs); + luai_userstateresume(L, nargs); + L->nny = 0; /* allow yields */ + api_checknelems(L, (L->status == LUA_OK) ? nargs + 1 : nargs); + status = luaD_rawrunprotected(L, resume, &nargs); + if (status == -1) /* error calling 'lua_resume'? */ + status = LUA_ERRRUN; + else { /* continue running after recoverable errors */ + while (errorstatus(status) && recover(L, status)) { + /* unroll continuation */ + status = luaD_rawrunprotected(L, unroll, &status); + } + if (errorstatus(status)) { /* unrecoverable error? */ + L->status = cast_byte(status); /* mark thread as 'dead' */ + seterrorobj(L, status, L->top); /* push error message */ + L->ci->top = L->top; + } + else lua_assert(status == L->status); /* normal end or yield */ + } + L->nny = oldnny; /* restore 'nny' */ + L->nCcalls--; + lua_assert(L->nCcalls == ((from) ? from->nCcalls : 0)); + lua_unlock(L); + return status; +} + + +LUA_API int lua_isyieldable (lua_State *L) { + return (L->nny == 0); +} + + +LUA_API int lua_yieldk (lua_State *L, int nresults, lua_KContext ctx, + lua_KFunction 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 a C-call boundary"); + else + luaG_runerror(L, "attempt to yield from outside a coroutine"); + } + L->status = LUA_YIELD; + ci->extra = savestack(L, ci->func); /* save current 'func' */ + 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->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; /* dynamic structure used by the scanner */ + Dyndata dyd; /* dynamic structures used by the parser */ + const char *mode; + const char *name; +}; + + +static void checkmode (lua_State *L, const char *mode, const char *x) { + if (mode && strchr(mode, x[0]) == NULL) { + luaO_pushfstring(L, + "attempt to load a %s chunk (mode is '%s')", x, mode); + luaD_throw(L, LUA_ERRSYNTAX); + } +} + + +static void f_parser (lua_State *L, void *ud) { + LClosure *cl; + struct SParser *p = cast(struct SParser *, ud); + int c = zgetc(p->z); /* read first character */ + if (c == LUA_SIGNATURE[0]) { + checkmode(L, p->mode, "binary"); + cl = luaU_undump(L, p->z, p->name); + } + else { + checkmode(L, p->mode, "text"); + cl = luaY_parser(L, p->z, &p->buff, &p->dyd, p->name, c); + } + lua_assert(cl->nupvalues == cl->p->sizeupvalues); + luaF_initupvals(L, cl); +} + + +int luaD_protectedparser (lua_State *L, ZIO *z, const char *name, + const char *mode) { + struct SParser p; + int status; + L->nny++; /* cannot yield during parsing */ + p.z = z; p.name = name; p.mode = mode; + p.dyd.actvar.arr = NULL; p.dyd.actvar.size = 0; + p.dyd.gt.arr = NULL; p.dyd.gt.size = 0; + p.dyd.label.arr = NULL; p.dyd.label.size = 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.dyd.actvar.arr, p.dyd.actvar.size); + luaM_freearray(L, p.dyd.gt.arr, p.dyd.gt.size); + luaM_freearray(L, p.dyd.label.arr, p.dyd.label.size); + L->nny--; + return status; +} + + |