mirror of https://github.com/lua/lua
454 lines
13 KiB
C
454 lines
13 KiB
C
/*
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** $Id: ldo.c,v 1.210 2002/12/04 17:28:27 roberto Exp roberto $
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** Stack and Call structure of Lua
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** See Copyright Notice in lua.h
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*/
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#include <setjmp.h>
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#include <stdlib.h>
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#include <string.h>
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#define ldo_c
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#include "lua.h"
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#include "ldebug.h"
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#include "ldo.h"
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#include "lfunc.h"
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#include "lgc.h"
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#include "lmem.h"
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#include "lobject.h"
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#include "lopcodes.h"
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#include "lparser.h"
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#include "lstate.h"
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#include "lstring.h"
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#include "ltable.h"
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#include "ltm.h"
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#include "lundump.h"
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#include "lvm.h"
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#include "lzio.h"
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/*
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** {======================================================
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** Error-recovery functions (based on long jumps)
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** =======================================================
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*/
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/* chain list of long jump buffers */
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struct lua_longjmp {
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struct lua_longjmp *previous;
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jmp_buf b;
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volatile int status; /* error code */
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};
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static void seterrorobj (lua_State *L, int errcode, StkId oldtop) {
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switch (errcode) {
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case LUA_ERRMEM: {
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setsvalue2s(oldtop, luaS_new(L, MEMERRMSG));
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break;
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}
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case LUA_ERRERR: {
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setsvalue2s(oldtop, luaS_new(L, "error in error handling"));
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break;
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}
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case LUA_ERRSYNTAX:
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case LUA_ERRRUN: {
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setobjs2s(oldtop, L->top - 1); /* error message on current top */
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break;
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}
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}
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L->top = oldtop + 1;
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}
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void luaD_throw (lua_State *L, int errcode) {
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if (L->errorJmp) {
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L->errorJmp->status = errcode;
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longjmp(L->errorJmp->b, 1);
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}
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else {
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G(L)->panic(L);
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exit(EXIT_FAILURE);
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}
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}
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int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {
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struct lua_longjmp lj;
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lj.status = 0;
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lj.previous = L->errorJmp; /* chain new error handler */
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L->errorJmp = &lj;
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if (setjmp(lj.b) == 0)
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(*f)(L, ud);
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L->errorJmp = lj.previous; /* restore old error handler */
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return lj.status;
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}
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static void restore_stack_limit (lua_State *L) {
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L->stack_last = L->stack+L->stacksize-1;
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if (L->size_ci > LUA_MAXCALLS) { /* there was an overflow? */
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int inuse = (L->ci - L->base_ci);
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if (inuse + 1 < LUA_MAXCALLS) /* can `undo' overflow? */
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luaD_reallocCI(L, LUA_MAXCALLS);
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}
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}
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/* }====================================================== */
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static void correctstack (lua_State *L, TObject *oldstack) {
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CallInfo *ci;
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GCObject *up;
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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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gcotouv(up)->v = (gcotouv(up)->v - oldstack) + L->stack;
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for (ci = L->base_ci; ci <= L->ci; ci++) {
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ci->top = (ci->top - oldstack) + L->stack;
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ci->base = (ci->base - oldstack) + L->stack;
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}
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L->base = L->ci->base;
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}
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void luaD_reallocstack (lua_State *L, int newsize) {
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TObject *oldstack = L->stack;
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luaM_reallocvector(L, L->stack, L->stacksize, newsize, TObject);
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L->stacksize = newsize;
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L->stack_last = L->stack+newsize-1-EXTRA_STACK;
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correctstack(L, oldstack);
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}
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void luaD_reallocCI (lua_State *L, int newsize) {
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CallInfo *oldci = L->base_ci;
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luaM_reallocvector(L, L->base_ci, L->size_ci, newsize, CallInfo);
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L->size_ci = cast(unsigned short, newsize);
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L->ci = (L->ci - oldci) + L->base_ci;
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L->end_ci = L->base_ci + L->size_ci;
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}
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void luaD_growstack (lua_State *L, int n) {
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if (n <= L->stacksize) /* double size is enough? */
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luaD_reallocstack(L, 2*L->stacksize);
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else
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luaD_reallocstack(L, L->stacksize + n + EXTRA_STACK);
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}
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static void luaD_growCI (lua_State *L) {
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if (L->size_ci > LUA_MAXCALLS) /* overflow while handling overflow? */
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luaD_throw(L, LUA_ERRERR);
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else {
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luaD_reallocCI(L, 2*L->size_ci);
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if (L->size_ci > LUA_MAXCALLS)
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luaG_runerror(L, "stack overflow");
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}
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}
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void luaD_callhook (lua_State *L, int event, int line) {
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lua_Hook hook = L->hook;
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if (hook && L->allowhook) {
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ptrdiff_t top = savestack(L, L->top);
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ptrdiff_t ci_top = savestack(L, L->ci->top);
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lua_Debug ar;
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ar.event = event;
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ar.currentline = line;
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ar.i_ci = L->ci - L->base_ci;
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luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
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L->ci->top = L->top + LUA_MINSTACK;
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L->allowhook = 0; /* cannot call hooks inside a hook */
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lua_unlock(L);
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(*hook)(L, &ar);
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lua_lock(L);
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lua_assert(!L->allowhook);
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L->allowhook = 1;
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L->ci->top = restorestack(L, ci_top);
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L->top = restorestack(L, top);
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}
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}
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static void adjust_varargs (lua_State *L, int nfixargs, StkId base) {
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int i;
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Table *htab;
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TObject nname;
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int actual = L->top - base; /* actual number of arguments */
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if (actual < nfixargs) {
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luaD_checkstack(L, nfixargs - actual);
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for (; actual < nfixargs; ++actual)
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setnilvalue(L->top++);
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}
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actual -= nfixargs; /* number of extra arguments */
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htab = luaH_new(L, 0, 0); /* create `arg' table */
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for (i=0; i<actual; i++) /* put extra arguments into `arg' table */
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setobj2n(luaH_setnum(L, htab, i+1), L->top - actual + i);
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/* store counter in field `n' */
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setsvalue(&nname, luaS_newliteral(L, "n"));
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setnvalue(luaH_set(L, htab, &nname), actual);
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L->top -= actual; /* remove extra elements from the stack */
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sethvalue(L->top, htab);
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incr_top(L);
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}
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static StkId tryfuncTM (lua_State *L, StkId func) {
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const TObject *tm = luaT_gettmbyobj(L, func, TM_CALL);
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StkId p;
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ptrdiff_t funcr = savestack(L, func);
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if (!ttisfunction(tm))
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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(p, p-1);
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incr_top(L);
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func = restorestack(L, funcr); /* previous call may change stack */
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setobj2s(func, tm); /* tag method is the new function to be called */
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return func;
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}
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StkId luaD_precall (lua_State *L, StkId func) {
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LClosure *cl;
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ptrdiff_t funcr = savestack(L, func);
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if (!ttisfunction(func)) /* `func' is not a function? */
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func = tryfuncTM(L, func); /* check the `function' tag method */
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if (L->ci + 1 == L->end_ci) luaD_growCI(L);
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else condhardstacktests(luaD_reallocCI(L, L->size_ci));
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cl = &clvalue(func)->l;
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if (!cl->isC) { /* Lua function? prepare its call */
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CallInfo *ci;
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Proto *p = cl->p;
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if (p->is_vararg) /* varargs? */
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adjust_varargs(L, p->numparams, func+1);
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luaD_checkstack(L, p->maxstacksize);
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ci = ++L->ci; /* now `enter' new function */
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L->base = L->ci->base = restorestack(L, funcr) + 1;
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ci->top = L->base + p->maxstacksize;
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ci->u.l.savedpc = p->code; /* starting point */
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ci->state = CI_SAVEDPC;
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while (L->top < ci->top)
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setnilvalue(L->top++);
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L->top = ci->top;
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return NULL;
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}
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else { /* if is a C function, call it */
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CallInfo *ci;
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int n;
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luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */
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ci = ++L->ci; /* now `enter' new function */
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L->base = L->ci->base = restorestack(L, funcr) + 1;
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ci->top = L->top + LUA_MINSTACK;
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ci->state = CI_C; /* a C function */
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if (L->hookmask & LUA_MASKCALL) {
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luaD_callhook(L, LUA_HOOKCALL, -1);
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ci = L->ci; /* previous call may reallocate `ci' */
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}
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lua_unlock(L);
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#ifdef LUA_COMPATUPVALUES
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lua_pushupvalues(L);
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#endif
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n = (*clvalue(L->base - 1)->c.f)(L); /* do the actual call */
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lua_lock(L);
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return L->top - n;
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}
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}
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void luaD_poscall (lua_State *L, int wanted, StkId firstResult) {
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StkId res;
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if (L->hookmask & LUA_MASKRET) {
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ptrdiff_t fr = savestack(L, firstResult); /* next call may change stack */
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luaD_callhook(L, LUA_HOOKRET, -1);
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firstResult = restorestack(L, fr);
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}
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res = L->base - 1; /* res == final position of 1st result */
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L->ci--;
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L->base = L->ci->base; /* restore base */
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/* move results to correct place */
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while (wanted != 0 && firstResult < L->top) {
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setobjs2s(res++, firstResult++);
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wanted--;
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}
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while (wanted-- > 0)
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setnilvalue(res++);
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L->top = res;
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luaC_checkGC(L);
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}
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/*
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** Call a function (C or Lua). The function to be called is at *func.
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** The arguments are on the stack, right after the function.
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** When returns, all the results are on the stack, starting at the original
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** function position.
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*/
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void luaD_call (lua_State *L, StkId func, int nResults) {
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StkId firstResult;
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if (++L->nCcalls >= LUA_MAXCCALLS) {
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if (L->nCcalls == LUA_MAXCCALLS)
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luaG_runerror(L, "stack overflow");
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else if (L->nCcalls >= (LUA_MAXCCALLS + (LUA_MAXCCALLS>>3)))
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luaD_throw(L, LUA_ERRERR); /* error while handing stack error */
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}
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firstResult = luaD_precall(L, func);
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if (firstResult == NULL) /* is a Lua function? */
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firstResult = luaV_execute(L); /* call it */
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luaD_poscall(L, nResults, firstResult);
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L->nCcalls--;
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}
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static void resume (lua_State *L, void *ud) {
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StkId firstResult;
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int nargs = *cast(int *, ud);
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CallInfo *ci = L->ci;
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if (ci == L->base_ci) { /* no activation record? */
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if (nargs >= L->top - L->base)
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luaG_runerror(L, "cannot resume dead coroutine");
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luaD_precall(L, L->top - (nargs + 1)); /* start coroutine */
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}
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else if (ci->state & CI_YIELD) { /* inside a yield? */
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if (ci->state & CI_C) { /* `common' yield? */
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/* finish interrupted execution of `OP_CALL' */
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int nresults;
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lua_assert((ci-1)->state & CI_SAVEDPC);
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lua_assert(GET_OPCODE(*((ci-1)->u.l.savedpc - 1)) == OP_CALL ||
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GET_OPCODE(*((ci-1)->u.l.savedpc - 1)) == OP_TAILCALL);
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nresults = GETARG_C(*((ci-1)->u.l.savedpc - 1)) - 1;
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luaD_poscall(L, nresults, L->top - nargs); /* complete it */
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if (nresults >= 0) L->top = L->ci->top;
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}
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else { /* yielded inside a hook: just continue its execution */
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ci->state &= ~CI_YIELD;
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}
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}
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else
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luaG_runerror(L, "cannot resume non-suspended coroutine");
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firstResult = luaV_execute(L);
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if (firstResult != NULL) /* return? */
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luaD_poscall(L, LUA_MULTRET, firstResult); /* finalize this coroutine */
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}
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LUA_API int lua_resume (lua_State *L, int nargs) {
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int status;
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lu_byte old_allowhooks;
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lua_lock(L);
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old_allowhooks = L->allowhook;
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lua_assert(L->errfunc == 0 && L->nCcalls == 0);
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status = luaD_rawrunprotected(L, resume, &nargs);
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if (status != 0) { /* error? */
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L->ci = L->base_ci; /* go back to initial level */
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L->base = L->ci->base;
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L->nCcalls = 0;
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luaF_close(L, L->base); /* close eventual pending closures */
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seterrorobj(L, status, L->base);
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L->allowhook = old_allowhooks;
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restore_stack_limit(L);
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}
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lua_unlock(L);
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return status;
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}
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LUA_API int lua_yield (lua_State *L, int nresults) {
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CallInfo *ci;
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lua_lock(L);
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ci = L->ci;
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if (L->nCcalls > 0)
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luaG_runerror(L, "attempt to yield across metamethod/C-call boundary");
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if (ci->state & CI_C) { /* usual yield */
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if ((ci-1)->state & CI_C)
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luaG_runerror(L, "cannot yield a C function");
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if (L->top - nresults > L->base) { /* is there garbage in the stack? */
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int i;
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for (i=0; i<nresults; i++) /* move down results */
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setobjs2s(L->base + i, L->top - nresults + i);
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L->top = L->base + nresults;
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}
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} /* else it's an yield inside a hook: nothing to do */
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ci->state |= CI_YIELD;
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lua_unlock(L);
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return -1;
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}
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int luaD_pcall (lua_State *L, Pfunc func, void *u,
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ptrdiff_t old_top, ptrdiff_t ef) {
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int status;
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unsigned short oldnCcalls = L->nCcalls;
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ptrdiff_t old_ci = saveci(L, L->ci);
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lu_byte old_allowhooks = L->allowhook;
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ptrdiff_t old_errfunc = L->errfunc;
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L->errfunc = ef;
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status = luaD_rawrunprotected(L, func, u);
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if (status != 0) { /* an error occurred? */
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StkId oldtop = restorestack(L, old_top);
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luaF_close(L, oldtop); /* close eventual pending closures */
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seterrorobj(L, status, oldtop);
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L->nCcalls = oldnCcalls;
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L->ci = restoreci(L, old_ci);
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L->base = L->ci->base;
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L->allowhook = old_allowhooks;
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restore_stack_limit(L);
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}
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L->errfunc = old_errfunc;
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return status;
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}
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/*
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** Execute a protected parser.
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*/
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struct SParser { /* data to `f_parser' */
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ZIO *z;
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Mbuffer buff; /* buffer to be used by the scanner */
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int bin;
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};
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static void f_parser (lua_State *L, void *ud) {
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struct SParser *p = cast(struct SParser *, ud);
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Proto *tf = p->bin ? luaU_undump(L, p->z, &p->buff) :
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luaY_parser(L, p->z, &p->buff);
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Closure *cl = luaF_newLclosure(L, 0, gt(L));
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cl->l.p = tf;
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setclvalue(L->top, cl);
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incr_top(L);
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}
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int luaD_protectedparser (lua_State *L, ZIO *z, int bin) {
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struct SParser p;
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lu_mem old_blocks;
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int status;
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ptrdiff_t oldtopr = savestack(L, L->top); /* save current top */
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p.z = z; p.bin = bin;
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luaZ_initbuffer(L, &p.buff);
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/* before parsing, give a (good) chance to GC */
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if (G(L)->nblocks + G(L)->nblocks/4 >= G(L)->GCthreshold)
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luaC_collectgarbage(L);
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old_blocks = G(L)->nblocks;
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status = luaD_rawrunprotected(L, f_parser, &p);
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luaZ_freebuffer(L, &p.buff);
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if (status == 0) {
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/* add new memory to threshold (as it probably will stay) */
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lua_assert(G(L)->nblocks >= old_blocks);
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G(L)->GCthreshold += (G(L)->nblocks - old_blocks);
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}
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else { /* error */
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StkId oldtop = restorestack(L, oldtopr);
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seterrorobj(L, status, oldtop);
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}
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return status;
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}
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