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'index2value' more robust

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'index2value' accepts pseudo-indices also when called from a Lua
function, through a hook.
This commit is contained in:
Roberto Ierusalimschy 2021-05-24 16:48:43 -03:00
parent 1e6918d553
commit fc6c74f100
1 changed files with 13 additions and 5 deletions
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18
lapi.c
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@ -53,6 +53,10 @@ const char lua_ident[] =
#define isupvalue(i) ((i) < LUA_REGISTRYINDEX)
/*
** Convert an acceptable index to a pointer to its respective value.
** Non-valid indices return the special nil value 'G(L)->nilvalue'.
*/
static TValue *index2value (lua_State *L, int idx) {
CallInfo *ci = L->ci;
if (idx > 0) {
@ -70,22 +74,26 @@ static TValue *index2value (lua_State *L, int idx) {
else { /* upvalues */
idx = LUA_REGISTRYINDEX - idx;
api_check(L, idx <= MAXUPVAL + 1, "upvalue index too large");
if (ttislcf(s2v(ci->func))) /* light C function? */
return &G(L)->nilvalue; /* it has no upvalues */
else {
if (ttisCclosure(s2v(ci->func))) { /* C closure? */
CClosure *func = clCvalue(s2v(ci->func));
return (idx <= func->nupvalues) ? &func->upvalue[idx-1]
: &G(L)->nilvalue;
}
else { /* light C function or Lua function (through a hook)?) */
api_check(L, ttislcf(s2v(ci->func)), "caller not a C function");
return &G(L)->nilvalue; /* no upvalues */
}
}
}
/*
** Convert a valid actual index (not a pseudo-index) to its address.
*/
static StkId index2stack (lua_State *L, int idx) {
CallInfo *ci = L->ci;
if (idx > 0) {
StkId o = ci->func + idx;
api_check(L, o < L->top, "unacceptable index");
api_check(L, o < L->top, "invalid index");
return o;
}
else { /* non-positive index */