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Make native multiplication overflow safe.

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This commit is contained in:
JoelKatz
2012-11-06 05:42:04 -08:00
parent 7eb1ce1b09
commit f9368b4209
1 changed files with 10 additions and 2 deletions
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12
src/Amount.cpp
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@@ -892,8 +892,16 @@ STAmount STAmount::multiply(const STAmount& v1, const STAmount& v2, const uint16
if (v1.isZero() || v2.isZero())
return STAmount(uCurrencyID, uIssuerID);
if (v1.mIsNative && v2.mIsNative) // FIXME: overflow
return STAmount(v1.getFName(), v1.getSNValue() * v2.getSNValue());
if (v1.mIsNative && v2.mIsNative)
{
uint64 minV = (v1.getSNValue() < v2.getSNValue()) ? v1.getSNValue() : v2.getSNValue();
uint64 maxV = (v1.getSNValue() < v2.getSNValue()) ? v2.getSNValue() : v1.getSNValue();
if (minV > 3000000000) // sqrt(cMaxNative)
throw std::runtime_error("Native value overflow");
if (((maxV >> 32) * minV) > 2095475792) // cMaxNative / 2^32
throw std::runtime_error("Native value overflow");
return STAmount(v1.getFName(), minV * maxV);
}
uint64 value1 = v1.mValue, value2 = v2.mValue;
int offset1 = v1.mOffset, offset2 = v2.mOffset;