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Addition in math.random can overflow

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To avoid complains from some tools, the addition when computing
math.random(n,m), which is computed as n + random(0, m - n), should
use unsigned integers.
This commit is contained in:
Roberto Ierusalimschy
2025-03-25 11:43:03 -03:00
parent cad5a4fdbb
commit b0f3df16a4
1 changed files with 2 additions and 2 deletions
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4
lmathlib.c
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@@ -593,8 +593,8 @@ static int math_random (lua_State *L) {
/* random integer in the interval [low, up] */ /* random integer in the interval [low, up] */
luaL_argcheck(L, low <= up, 1, "interval is empty"); luaL_argcheck(L, low <= up, 1, "interval is empty");
/* project random integer into the interval [0, up - low] */ /* project random integer into the interval [0, up - low] */
p = project(I2UInt(rv), (lua_Unsigned)up - (lua_Unsigned)low, state); p = project(I2UInt(rv), l_castS2U(up) - l_castS2U(low), state);
lua_pushinteger(L, l_castU2S(p) + low); lua_pushinteger(L, l_castU2S(p + l_castS2U(low)));
return 1; return 1;
} }