forked from lix-project/lix
Fix SIGFPE from integer overflow during division
On some architectures (like x86_64 or i686, but not ARM for example) overflow during integer division causes a crash due to SIGFPE. Reproduces on a 64-bit system with: nix-instantiate --eval -E '(-9223372036854775807 - 1) / -1' The only way this can happen is when the smallest possible integer is divided by -1, so just special-case that.
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@ -1516,10 +1516,16 @@ static void prim_div(EvalState & state, const Pos & pos, Value * * args, Value &
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NixFloat f2 = state.forceFloat(*args[1], pos);
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if (f2 == 0) throw EvalError(format("division by zero, at %1%") % pos);
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if (args[0]->type == tFloat || args[1]->type == tFloat)
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if (args[0]->type == tFloat || args[1]->type == tFloat) {
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mkFloat(v, state.forceFloat(*args[0], pos) / state.forceFloat(*args[1], pos));
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else
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mkInt(v, state.forceInt(*args[0], pos) / state.forceInt(*args[1], pos));
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} else {
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NixInt i1 = state.forceInt(*args[0], pos);
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NixInt i2 = state.forceInt(*args[1], pos);
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/* Avoid division overflow as it might raise SIGFPE. */
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if (i1 == std::numeric_limits<NixInt>::min() && i2 == -1)
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throw EvalError(format("overflow in integer division, at %1%") % pos);
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mkInt(v, i1 / i2);
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}
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}
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