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integer exponentiation with negative exponent is invalid

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This commit is contained in:
Roberto Ierusalimschy
2013-12-16 12:30:22 -02:00
parent 1a19893d6f
commit a8f8c7fd80
4 changed files with 32 additions and 30 deletions
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39
lvm.c
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@@ -1,5 +1,5 @@
/*
** $Id: lvm.c,v 2.179 2013/08/27 18:53:35 roberto Exp roberto $
** $Id: lvm.c,v 2.180 2013/08/29 13:49:57 roberto Exp roberto $
** Lua virtual machine
** See Copyright Notice in lua.h
*/
@@ -333,8 +333,7 @@ lua_Integer luaV_div (lua_State *L, lua_Integer x, lua_Integer y) {
if (cast_unsigned(y) + 1 <= 1U) { /* special cases: -1 or 0 */
if (y == 0)
luaG_runerror(L, "attempt to divide by zero");
else /* -1 */
return intop(-, 0, x); /* avoid overflow with 0x80000... */
return intop(-, 0, x); /* y==-1; avoid overflow with 0x80000...//-1 */
}
else {
lua_Integer d = x / y; /* perform division */
@@ -350,8 +349,7 @@ lua_Integer luaV_mod (lua_State *L, lua_Integer x, lua_Integer y) {
if (cast_unsigned(y) + 1 <= 1U) { /* special cases: -1 or 0 */
if (y == 0)
luaG_runerror(L, "attempt to perform 'n%%0'");
else /* -1 */
return 0; /* avoid overflow with 0x80000... */
return 0; /* y==-1; avoid overflow with 0x80000...%-1 */
}
else {
lua_Integer r = x % y;
@@ -363,16 +361,21 @@ lua_Integer luaV_mod (lua_State *L, lua_Integer x, lua_Integer y) {
}
lua_Integer luaV_pow (lua_Integer x, lua_Integer y) {
lua_Integer r = 1;
lua_assert(y >= 0);
if (y == 0) return r;
for (; y > 1; y >>= 1) {
if (y & 1) r = intop(*, r, x);
x = intop(*, x, x);
lua_Integer luaV_pow (lua_State *L, lua_Integer x, lua_Integer y) {
if (y <= 0) { /* special cases: 0 or negative exponent */
if (y < 0)
luaG_runerror(L, "integer exponentiation with negative exponent");
return 1; /* x^0 == 1 */
}
else {
lua_Integer r = 1;
for (; y > 1; y >>= 1) {
if (y & 1) r = intop(*, r, x);
x = intop(*, x, x);
}
r = intop(*, r, x);
return r;
}
r = intop(*, r, x);
return r;
}
@@ -685,11 +688,9 @@ void luaV_execute (lua_State *L) {
TValue *rb = RKB(i);
TValue *rc = RKC(i);
lua_Number nb; lua_Number nc;
lua_Integer ic;
if (ttisinteger(rb) && ttisinteger(rc) &&
(ic = ivalue(rc)) >= 0) {
lua_Integer ib = ivalue(rb);
setivalue(ra, luaV_pow(ib, ic));
if (ttisinteger(rb) && ttisinteger(rc)) {
lua_Integer ib = ivalue(rb); lua_Integer ic = ivalue(rc);
setivalue(ra, luaV_pow(L, ib, ic));
}
else if (tonumber(rb, &nb) && tonumber(rc, &nc)) {
setnvalue(ra, luai_numpow(L, nb, nc));