/*

** $Id: ldo.c $

** 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 {

};

void luaD_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;

}

case CLOSEPROTECT: {

setnilvalue(s2v(oldtop)); /* no error message */

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);

errcode = luaF_close(L, L->stack, errcode); /* close all upvalues */

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? */

luaD_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) */

}

abort();

}

}

}

int luaD_rawrunprotected (lua_State *L, Pfunc f, void *ud) {

global_State *g = G(L);

l_uint32 oldnCcalls = g->Cstacklimit - (L->nCcalls L->nci);

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 = g->Cstacklimit - oldnCcalls - L->nci;

return lj.status;

}

/* }====================================================== */

/*

** {==================================================================

** Stack reallocation

** ===================================================================

*/

static void correctstack (lua_State *L, StkId oldstack, StkId newstack) {

CallInfo *ci;

UpVal *up;

if (oldstack == newstack)

return; /* stack address did not change */

L->top = (L->top - oldstack) newstack;

for (up = L->openupval; up != NULL; up = up->u.open.next)

up->v = s2v((uplevel(up) - oldstack) newstack);

for (ci = L->ci; ci != NULL; ci = ci->previous) {

ci->top = (ci->top - oldstack) newstack;

ci->func = (ci->func - oldstack) newstack;

if (isLua(ci))

ci->u.l.trap = 1; /* signal to update 'trap' in 'luaV_execute' */

}

}

/* some space for error handling */

#define ERRORSTACKSIZE (LUAI_MAXSTACK 200)

int luaD_reallocstack (lua_State *L, int newsize, int raiseerror) {

int lim = L->stacksize;

StkId newstack = luaM_reallocvector(L, L->stack, lim, newsize, StackValue);

lua_assert(newsize <= LUAI_MAXSTACK || newsize == ERRORSTACKSIZE);

lua_assert(L->stack_last - L->stack == L->stacksize - EXTRA_STACK);

if (unlikely(newstack == NULL)) { /* reallocation failed? */

if (raiseerror)

luaM_error(L);

else return 0; /* do not raise an error */

}

for (; lim < newsize; lim )

setnilvalue(s2v(newstack lim)); /* erase new segment */

correctstack(L, L->stack, newstack);

L->stack = newstack;

L->stacksize = newsize;

L->stack_last = L->stack newsize - EXTRA_STACK;

return 1;

}

/*

** Try to grow the stack by at least 'n' elements. when 'raiseerror'

** is true, raises any error; otherwise, return 0 in case of errors.

*/

int luaD_growstack (lua_State *L, int n, int raiseerror) {

int size = L->stacksize;

int newsize = 2 * size; /* tentative new size */

if (unlikely(size > LUAI_MAXSTACK)) { /* need more space after extra size? */

if (raiseerror)

luaD_throw(L, LUA_ERRERR); /* error inside message handler */

else return 0;

}

else {

int needed = cast_int(L->top - L->stack) n EXTRA_STACK;

if (newsize > LUAI_MAXSTACK) /* cannot cross the limit */

newsize = LUAI_MAXSTACK;

if (newsize < needed) /* but must respect what was asked for */

newsize = needed;

if (unlikely(newsize > LUAI_MAXSTACK)) { /* stack overflow? */

/* add extra size to be able to handle the error message */

luaD_reallocstack(L, ERRORSTACKSIZE, raiseerror);

if (raiseerror)

luaG_runerror(L, "stack overflow");

else return 0;

}

} /* else no errors */

return luaD_reallocstack(L, newsize, raiseerror);

}

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 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, 0); /* ok if that fails */

else /* don't change stack */

condmovestack(L,{},{}); /* (change only for debugging) */

luaE_shrinkCI(L); /* shrink CI list */

}

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 trigger this

** function, can be changed asynchronously by signals.)

*/

void luaD_hook (lua_State *L, int event, int line,

int ftransfer, int ntransfer) {

lua_Hook hook = L->hook;

if (hook && L->allowhook) { /* make sure there is a hook */

int mask = CIST_HOOKED;

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;

if (ntransfer != 0) {

mask |= CIST_TRAN; /* 'ci' has transfer information */

ci->u2.transferinfo.ftransfer = ftransfer;

ci->u2.transferinfo.ntransfer = ntransfer;

}

luaD_checkstack(L, LUA_MINSTACK); /* ensure minimum stack size */

if (L->top LUA_MINSTACK > ci->top)

ci->top = L->top LUA_MINSTACK;

L->allowhook = 0; /* cannot call hooks inside a hook */

ci->callstatus |= mask;

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 &= ~mask;

}

}

/*

** Executes a call hook for Lua functions. This function is called

** whenever 'hookmask' is not zero, so it checks whether call hooks are

** active.

*/

void luaD_hookcall (lua_State *L, CallInfo *ci) {

int hook = (ci->callstatus & CIST_TAIL) ? LUA_HOOKTAILCALL : LUA_HOOKCALL;

Proto *p;

if (!(L->hookmask & LUA_MASKCALL)) /* some other hook? */

return; /* don't call hook */

p = clLvalue(s2v(ci->func))->p;

L->top = ci->top; /* prepare top */

ci->u.l.savedpc ; /* hooks assume 'pc' is already incremented */

luaD_hook(L, hook, -1, 1, p->numparams);

ci->u.l.savedpc--; /* correct 'pc' */

}

static StkId rethook (lua_State *L, CallInfo *ci, StkId firstres, int nres) {

ptrdiff_t oldtop = savestack(L, L->top); /* hook may change top */

int delta = 0;

if (isLuacode(ci)) {

Proto *p = clLvalue(s2v(ci->func))->p;

if (p->is_vararg)

delta = ci->u.l.nextraargs p->numparams 1;

if (L->top < ci->top)

L->top = ci->top; /* correct top to run hook */

}

if (L->hookmask & LUA_MASKRET) { /* is return hook on? */

int ftransfer;

ci->func = delta; /* if vararg, back to virtual 'func' */

ftransfer = cast(unsigned short, firstres - ci->func);

luaD_hook(L, LUA_HOOKRET, -1, ftransfer, nres); /* call it */

ci->func -= delta;

}

if (isLua(ci->previous))

L->oldpc = ci->previous->u.l.savedpc; /* update 'oldpc' */

return restorestack(L, oldtop);

}

/*

** Check whether 'func' has a '__call' metafield. If so, put it in the

** stack, below original 'func', so that 'luaD_call' can call it. Raise

** an error if there is no '__call' metafield.

*/

void luaD_tryfuncTM (lua_State *L, StkId func) {

const TValue *tm = luaT_gettmbyobj(L, s2v(func), TM_CALL);

StkId p;

if (unlikely(ttisnil(tm)))

luaG_typeerror(L, s2v(func), "call"); /* nothing to call */

for (p = L->top; p > func; p--) /* open space for metamethod */

setobjs2s(L, p, p-1);

L->top ; /* stack space pre-allocated by the caller */

setobj2s(L, func, tm); /* metamethod 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 void moveresults (lua_State *L, StkId res, int nres, int wanted) {

StkId firstresult;

int i;

switch (wanted) { /* handle typical cases separately */

case 0: /* no values needed */

L->top = res;

return;

case 1: /* one value needed */

if (nres == 0) /* no results? */

setnilvalue(s2v(res)); /* adjust with nil */

else

setobjs2s(L, res, L->top - nres); /* move it to proper place */

L->top = res 1;

return;

case LUA_MULTRET:

wanted = nres; /* we want all results */

break;

default: /* multiple results (or to-be-closed variables) */

if (hastocloseCfunc(wanted)) { /* to-be-closed variables? */

ptrdiff_t savedres = savestack(L, res);

luaF_close(L, res, LUA_OK); /* may change the stack */

res = restorestack(L, savedres);

wanted = codeNresults(wanted); /* correct value */

if (wanted == LUA_MULTRET)

wanted = nres;

}

break;

}

firstresult = L->top - nres; /* index of first result */

/* move all results to correct place */

for (i = 0; i < nres && i < wanted; i )

setobjs2s(L, res i, firstresult i);

for (; i < wanted; i ) /* complete wanted number of results */

setnilvalue(s2v(res i));

L->top = res wanted; /* top points after the last result */

}

/*

** Finishes a function call: calls hook if necessary, removes CallInfo,

** moves current number of results to proper place.

*/

void luaD_poscall (lua_State *L, CallInfo *ci, int nres) {

if (L->hookmask)

L->top = rethook(L, ci, L->top - nres, nres);

L->ci = ci->previous; /* back to caller */

/* move results to proper place */

moveresults(L, ci->func, nres, ci->nresults);

}

#define next_ci(L) (L->ci->next ? L->ci->next : luaE_extendCI(L))

/*

** Prepare a function for a tail call, building its call info on top

** of the current call info. 'narg1' is the number of arguments plus 1

** (so that it includes the function itself).

*/

void luaD_pretailcall (lua_State *L, CallInfo *ci, StkId func, int narg1) {

Proto *p = clLvalue(s2v(func))->p;

int fsize = p->maxstacksize; /* frame size */

int nfixparams = p->numparams;

int i;

for (i = 0; i < narg1; i ) /* move down function and arguments */

setobjs2s(L, ci->func i, func i);

checkstackGC(L, fsize);

func = ci->func; /* moved-down function */

for (; narg1 <= nfixparams; narg1 )

setnilvalue(s2v(func narg1)); /* complete missing arguments */

ci->top = func 1 fsize; /* top for new function */

lua_assert(ci->top <= L->stack_last);

ci->u.l.savedpc = p->code; /* starting point */

ci->callstatus |= CIST_TAIL;

L->top = func narg1; /* set top */

}

/*

** 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) {

lua_CFunction f;

retry:

switch (ttypetag(s2v(func))) {

case LUA_VCCL: /* C closure */

f = clCvalue(s2v(func))->f;

goto Cfunc;

case LUA_VLCF: /* light C function */

f = fvalue(s2v(func));

Cfunc: {

int n; /* number of returns */

CallInfo *ci = next_ci(L);

checkstackp(L, LUA_MINSTACK, func); /* ensure minimum stack size */

ci->nresults = nresults;

ci->callstatus = CIST_C;

ci->top = L->top LUA_MINSTACK;

ci->func = func;

L->ci = ci;

lua_assert(ci->top <= L->stack_last);

if (L->hookmask & LUA_MASKCALL) {

int narg = cast_int(L->top - func) - 1;

luaD_hook(L, LUA_HOOKCALL, -1, 1, narg);

}

lua_unlock(L);

n = (*f)(L); /* do the actual call */

lua_lock(L);

api_checknelems(L, n);

luaD_poscall(L, ci, n);

break;

}

case LUA_VLCL: { /* Lua function */

CallInfo *ci = next_ci(L);

Proto *p = clLvalue(s2v(func))->p;

int narg = cast_int(L->top - func) - 1; /* number of real arguments */

int nfixparams = p->numparams;

int fsize = p->maxstacksize; /* frame size */

checkstackp(L, fsize, func);

ci->nresults = nresults;

ci->u.l.savedpc = p->code; /* starting point */

ci->callstatus = 0;

ci->top = func 1 fsize;

ci->func = func;

L->ci = ci;

for (; narg < nfixparams; narg )

setnilvalue(s2v(L->top )); /* complete missing arguments */

lua_assert(ci->top <= L->stack_last);

luaV_execute(L, ci); /* run the function */

break;

}

default: { /* not a function */

checkstackp(L, 1, func); /* space for metamethod */

luaD_tryfuncTM(L, func); /* try to get '__call' metamethod */

goto retry; /* try again with metamethod */

}

}

}

/*

** Similar to 'luaD_call', but does not allow yields during the call.

** If there is a stack overflow, freeing all CI structures will

** force the subsequent call to invoke 'luaE_extendCI', which then

** will raise any errors.

*/

void luaD_callnoyield (lua_State *L, StkId func, int nResults) {

incXCcalls(L);

if (getCcalls(L) <= CSTACKERR) /* possible stack overflow? */

luaE_freeCI(L);

luaD_call(L, func, nResults);

decXCcalls(L);

}

/*

** 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 && yieldable(L));

/* 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, n); /* finish 'luaD_call' */

}

/*

** 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) {

CallInfo *ci;

if (ud != NULL) /* error status? */

finishCcall(L, *(int *)ud); /* finish 'lua_pcallk' callee */

while ((ci = L->ci) != &L->base_ci) { /* something in the stack */

if (!isLua(ci)) /* C function? */

finishCcall(L, LUA_YIELD); /* complete its execution */

else { /* Lua function */

luaV_finishOp(L); /* finish interrupted instruction */

luaV_execute(L, ci); /* 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->u2.funcidx);

luaF_close(L, oldtop, status); /* may change the stack */

oldtop = restorestack(L, ci->u2.funcidx);

luaD_seterrorobj(L, status, oldtop);

L->ci = ci;

L->allowhook = getoah(ci->callstatus); /* restore original 'allowhook' */

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? */

luaD_call(L, firstArg - 1, LUA_MULTRET);

}

else { /* resuming from previous yield */

lua_assert(L->status == LUA_YIELD);

L->status = LUA_OK; /* mark that it is running (again) */

if (isLua(ci)) /* yielded inside a hook? */

luaV_execute(L, ci); /* 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);

}

luaD_poscall(L, ci, n); /* finish 'luaD_call' */

}

unroll(L, NULL); /* run continuation */

}

}

LUA_API int lua_resume (lua_State *L, lua_State *from, int nargs,

int *nresults) {

int status;

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->top - (L->ci->func 1) == nargs) /* no function? */

return resume_error(L, "cannot resume dead coroutine", nargs);

}

else if (L->status != LUA_YIELD) /* ended with errors? */

return resume_error(L, "cannot resume dead coroutine", nargs);

if (from == NULL)

L->nCcalls = CSTACKTHREAD;

else /* correct 'nCcalls' for this thread */

L->nCcalls = getCcalls(from) from->nci - L->nci - CSTACKCF;

if (L->nCcalls <= CSTACKERR)

return resume_error(L, "C stack overflow", nargs);

luai_userstateresume(L, nargs);

api_checknelems(L, (L->status == LUA_OK) ? nargs 1 : nargs);

status = luaD_rawrunprotected(L, resume, &nargs);

/* continue running after recoverable errors */

while (errorstatus(status) && recover(L, status)) {

/* unroll continuation */

status = luaD_rawrunprotected(L, unroll, &status);

}

if (likely(!errorstatus(status)))

lua_assert(status == L->status); /* normal end or yield */

else { /* unrecoverable error */

L->status = cast_byte(status); /* mark thread as 'dead' */

luaD_seterrorobj(L, status, L->top); /* push error message */

L->ci->top = L->top;

}

*nresults = (status == LUA_YIELD) ? L->ci->u2.nyield

: cast_int(L->top - (L->ci->func 1));

lua_unlock(L);

return status;

}

LUA_API int lua_isyieldable (lua_State *L) {

return yieldable(L);

}

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 (unlikely(!yieldable(L))) {

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;

if (isLua(ci)) { /* inside a hook? */

lua_assert(!isLuacode(ci));

api_check(L, k == NULL, "hooks cannot continue after yielding");

ci->u2.nyield = 0; /* no results */

}

else {

if ((ci->u.c.k = k) != NULL) /* is there a continuation? */

ci->u.c.ctx = ctx; /* save context */

ci->u2.nyield = nresults; /* save number of 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' */

}

/*

** Call the C function 'func' in protected mode, restoring basic

** thread information ('allowhook', etc.) and in particular

** its stack level in case of errors.

*/

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;

ptrdiff_t old_errfunc = L->errfunc;

L->errfunc = ef;

status = luaD_rawrunprotected(L, func, u);

if (unlikely(status != LUA_OK)) { /* an error occurred? */

StkId oldtop = restorestack(L, old_top);

L->ci = old_ci;

L->allowhook = old_allowhooks;

status = luaF_close(L, oldtop, status);

oldtop = restorestack(L, old_top); /* previous call may change stack */

luaD_seterrorobj(L, status, oldtop);

luaD_shrinkstack(L);

}

L->errfunc = old_errfunc;

return status;

}

/*

** Execute a protected parser.

*/

struct SParser { /* data to 'f_parser' */

};

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;

incnny(L); /* 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);

decnny(L);

return status;

}