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Fix and cleanup safe spec; cryptonomex/graphene#10

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This commit is contained in:
Vikram Rajkumar 2015-07-13 14:28:44 -04:00
parent 2ef7583f90
commit 0391665471
3 changed files with 179 additions and 138 deletions
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4
include/fc/exception/exception.hpp
View file

@ -35,7 +35,8 @@ namespace fc
udt_error_code = 17,
aes_error_code = 18,
overflow_code = 19,
underflow_code = 20
underflow_code = 20,
divide_by_zero_code = 21
};
/**
@ -289,6 +290,7 @@ namespace fc
FC_DECLARE_EXCEPTION( aes_exception, aes_error_code, "AES error" );
FC_DECLARE_EXCEPTION( overflow_exception, overflow_code, "Integer Overflow" );
FC_DECLARE_EXCEPTION( underflow_exception, underflow_code, "Integer Underflow" );
FC_DECLARE_EXCEPTION( divide_by_zero_exception, divide_by_zero_code, "Integer Divide By Zero" );
std::string except_str();

192
include/fc/safe.hpp
View file

@ -13,126 +13,164 @@ namespace fc {
*
* It can only be used on built-in types. In particular,
* safe<uint128_t> is buggy and should not be used.
*
* Implemented using spec from:
* https://www.securecoding.cert.org/confluence/display/c/INT32-C.+Ensure+that+operations+on+signed+integers+do+not+result+in+overflow
*/
template<typename T>
struct safe
{
T value = 0;
template<typename O>
safe( O o ):value(o){}
safe(){}
safe( const safe& o ):value(o.value){}
static safe max()
{ return std::numeric_limits<T>::max(); }
static safe min()
{ return std::numeric_limits<T>::min(); }
safe& operator += ( const safe& b )
{
if( b.value > 0 && value > (std::numeric_limits<T>::max() - b.value) ) FC_CAPTURE_AND_THROW( overflow_exception, (*this)(b) );
if( b.value < 0 && value < (std::numeric_limits<T>::min() - b.value) ) FC_CAPTURE_AND_THROW( underflow_exception, (*this)(b) );
value += b.value;
return *this;
return std::numeric_limits<T>::min();
}
static safe max()
{
return std::numeric_limits<T>::max();
}
friend safe operator + ( const safe& a, const safe& b )
{
if( b.value > 0 && a.value > std::numeric_limits<T>::max() - b.value ) FC_CAPTURE_AND_THROW( overflow_exception, (a)(b) );
if( b.value < 0 && a.value < std::numeric_limits<T>::min() - b.value ) FC_CAPTURE_AND_THROW( underflow_exception, (a)(b) );
if( b.value > 0 && a.value > (std::numeric_limits<T>::max() - b.value) ) FC_CAPTURE_AND_THROW( overflow_exception, (a)(b) );
if( b.value < 0 && a.value < (std::numeric_limits<T>::min() - b.value) ) FC_CAPTURE_AND_THROW( underflow_exception, (a)(b) );
return safe( a.value + b.value );
}
safe& operator *= ( safe v ) { value *= v.value; return *this; }
safe& operator /= ( safe v ) { FC_ASSERT(v.value != 0); value /= v.value; return *this; }
safe& operator -= ( const safe& b ) { return *this += safe(-b.value); }
friend safe operator - ( const safe& a, const safe& b )
{
if( b.value > 0 && a.value < (std::numeric_limits<T>::min() + b.value) ) FC_CAPTURE_AND_THROW( underflow_exception, (a)(b) );
if( b.value < 0 && a.value > (std::numeric_limits<T>::max() + b.value) ) FC_CAPTURE_AND_THROW( overflow_exception, (a)(b) );
return safe( a.value - b.value );
}
friend safe operator * ( const safe& a, const safe& b )
{
if( a.value > 0 )
{
if( b.value > 0 )
{
if( a.value > (std::numeric_limits<T>::max() / b.value) ) FC_CAPTURE_AND_THROW( overflow_exception, (a)(b) );
}
else
{
if( b.value < (std::numeric_limits<T>::min() / a.value) ) FC_CAPTURE_AND_THROW( underflow_exception, (a)(b) );
}
}
else
{
if( b.value > 0 )
{
if( a.value < (std::numeric_limits<T>::min() / b.value) ) FC_CAPTURE_AND_THROW( underflow_exception, (a)(b) );
}
else
{
if( a.value != 0 && b.value < (std::numeric_limits<T>::max() / a.value) ) FC_CAPTURE_AND_THROW( overflow_exception, (a)(b) );
}
}
return safe( a.value * b.value );
}
friend safe operator / ( const safe& a, const safe& b )
{
if( b.value == 0 ) FC_CAPTURE_AND_THROW( divide_by_zero_exception, (a)(b) );
if( a.value == std::numeric_limits<T>::min() && b.value == -1 ) FC_CAPTURE_AND_THROW( overflow_exception, (a)(b) );
return safe( a.value / b.value );
}
friend safe operator % ( const safe& a, const safe& b )
{
if( b.value == 0 ) FC_CAPTURE_AND_THROW( divide_by_zero_exception, (a)(b) );
if( a.value == std::numeric_limits<T>::min() && b.value == -1 ) FC_CAPTURE_AND_THROW( overflow_exception, (a)(b) );
return safe( a.value % b.value );
}
safe operator - ()const
{
if( value == std::numeric_limits<T>::min() )
FC_CAPTURE_AND_THROW( overflow_exception, (value) );
if( value == std::numeric_limits<T>::min() ) FC_CAPTURE_AND_THROW( overflow_exception, (*this) );
return safe( -value );
}
safe operator++(int) { safe bak = *this; *this += 1; return bak; }
safe& operator++() { return *this += 1; }
safe operator--(int) { safe bak = *this; *this -= 1; return bak; }
safe& operator--() { return *this -= 1; }
friend safe operator - ( const safe& a, const safe& b )
safe& operator += ( const safe& b )
{
safe tmp(a); tmp -= b; return tmp;
value = (*this + b).value;
return *this;
}
safe& operator -= ( const safe& b )
{
value = (*this - b).value;
return *this;
}
safe& operator *= ( const safe& b )
{
value = (*this * b).value;
return *this;
}
safe& operator /= ( const safe& b )
{
value = (*this / b).value;
return *this;
}
safe& operator %= ( const safe& b )
{
value = (*this % b).value;
return *this;
}
safe& operator++()
{
*this += 1;
return *this;
}
safe operator++( int )
{
safe bak = *this;
*this += 1;
return bak;
}
safe& operator--()
{
*this -= 1;
return *this;
}
safe operator--( int )
{
safe bak = *this;
*this -= 1;
return bak;
}
friend bool operator == ( const safe& a, const safe& b )
{
return a.value == b.value;
}
friend bool operator == ( const safe& a, const T& b )
{
return a.value == b;
}
friend bool operator == ( const T& a, const safe& b )
{
return a == b.value;
}
friend bool operator != ( const safe& a, const safe& b )
{
return a.value != b.value;
}
friend bool operator != ( const safe& a, const T& b )
{
return a.value != b;
}
friend bool operator != ( const T& a, const safe& b )
{
return a != b.value;
}
friend bool operator < ( const safe& a, const safe& b )
{
return a.value < b.value;
}
friend bool operator < ( const safe& a, const T& b )
{
return a.value < b;
}
friend bool operator < ( const T& a, const safe& b )
{
return a < b.value;
}
friend bool operator > ( const safe& a, const safe& b )
{
return a.value > b.value;
}
friend bool operator > ( const safe& a, const T& b )
friend bool operator != ( const safe& a, const safe& b )
{
return a.value > b;
}
friend bool operator > ( const T& a, const safe& b )
{
return a > b.value;
}
friend bool operator >= ( const safe& a, const safe& b )
{
return a.value >= b.value;
}
friend bool operator >= ( const safe& a, const T& b )
{
return a.value >= b;
}
friend bool operator >= ( const T& a, const safe& b )
{
return a >= b.value;
return !(a == b);
}
friend bool operator <= ( const safe& a, const safe& b )
{
return a.value <= b.value;
return !(a > b );
}
friend bool operator <= ( const safe& a, const T& b )
friend bool operator >= ( const safe& a, const safe& b )
{
return a.value <= b;
return !(a < b);
}
friend bool operator <= ( const T& a, const safe& b )
{
return a <= b.value;
}
T value = 0;
};
}

1
src/exception.cpp
View file

@ -25,6 +25,7 @@ namespace fc
(aes_exception)
(overflow_exception)
(underflow_exception)
(divide_by_zero_exception)
)
namespace detail