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| -rw-r--r-- | src/script.h | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/src/script.h b/src/script.h index 657ac0b388..9bc06b2e07 100644 --- a/src/script.h +++ b/src/script.h @@ -25,6 +25,155 @@ class CTransaction; static const unsigned int MAX_SCRIPT_ELEMENT_SIZE = 520; // bytes static const unsigned int MAX_OP_RETURN_RELAY = 40; // bytes +class scriptnum_error : public std::runtime_error +{ +public: + explicit scriptnum_error(const std::string& str) : std::runtime_error(str) {} +}; + +class CScriptNum +{ +// Numeric opcodes (OP_1ADD, etc) are restricted to operating on 4-byte integers. +// The semantics are subtle, though: operands must be in the range [-2^31 +1...2^31 -1], +// but results may overflow (and are valid as long as they are not used in a subsequent +// numeric operation). CScriptNum enforces those semantics by storing results as +// an int64 and allowing out-of-range values to be returned as a vector of bytes but +// throwing an exception if arithmetic is done or the result is interpreted as an integer. +public: + + explicit CScriptNum(const int64_t& n) + { + m_value = n; + } + + explicit CScriptNum(const std::vector<unsigned char>& vch) + { + if (vch.size() > nMaxNumSize) + throw scriptnum_error("CScriptNum(const std::vector<unsigned char>&) : overflow"); + m_value = set_vch(vch); + } + + inline bool operator==(const int64_t& rhs) const { return m_value == rhs; } + inline bool operator!=(const int64_t& rhs) const { return m_value != rhs; } + inline bool operator<=(const int64_t& rhs) const { return m_value <= rhs; } + inline bool operator< (const int64_t& rhs) const { return m_value < rhs; } + inline bool operator>=(const int64_t& rhs) const { return m_value >= rhs; } + inline bool operator> (const int64_t& rhs) const { return m_value > rhs; } + + inline bool operator==(const CScriptNum& rhs) const { return operator==(rhs.m_value); } + inline bool operator!=(const CScriptNum& rhs) const { return operator!=(rhs.m_value); } + inline bool operator<=(const CScriptNum& rhs) const { return operator<=(rhs.m_value); } + inline bool operator< (const CScriptNum& rhs) const { return operator< (rhs.m_value); } + inline bool operator>=(const CScriptNum& rhs) const { return operator>=(rhs.m_value); } + inline bool operator> (const CScriptNum& rhs) const { return operator> (rhs.m_value); } + + inline CScriptNum operator+( const int64_t& rhs) const { return CScriptNum(m_value + rhs);} + inline CScriptNum operator-( const int64_t& rhs) const { return CScriptNum(m_value - rhs);} + inline CScriptNum operator+( const CScriptNum& rhs) const { return operator+(rhs.m_value); } + inline CScriptNum operator-( const CScriptNum& rhs) const { return operator-(rhs.m_value); } + + inline CScriptNum& operator+=( const CScriptNum& rhs) { return operator+=(rhs.m_value); } + inline CScriptNum& operator-=( const CScriptNum& rhs) { return operator-=(rhs.m_value); } + + inline CScriptNum operator-() const + { + assert(m_value != std::numeric_limits<int64_t>::min()); + return CScriptNum(-m_value); + } + + inline CScriptNum& operator=( const int64_t& rhs) + { + m_value = rhs; + return *this; + } + + inline CScriptNum& operator+=( const int64_t& rhs) + { + assert(rhs == 0 || (rhs > 0 && m_value <= std::numeric_limits<int64_t>::max() - rhs) || + (rhs < 0 && m_value >= std::numeric_limits<int64_t>::min() - rhs)); + m_value += rhs; + return *this; + } + + inline CScriptNum& operator-=( const int64_t& rhs) + { + assert(rhs == 0 || (rhs > 0 && m_value >= std::numeric_limits<int64_t>::min() + rhs) || + (rhs < 0 && m_value <= std::numeric_limits<int64_t>::max() + rhs)); + m_value -= rhs; + return *this; + } + + int getint() const + { + if (m_value > std::numeric_limits<int>::max()) + return std::numeric_limits<int>::max(); + else if (m_value < std::numeric_limits<int>::min()) + return std::numeric_limits<int>::min(); + return m_value; + } + + std::vector<unsigned char> getvch() const + { + return serialize(m_value); + } + + static std::vector<unsigned char> serialize(const int64_t& value) + { + if(value == 0) + return std::vector<unsigned char>(); + + std::vector<unsigned char> result; + const bool neg = value < 0; + uint64_t absvalue = neg ? -value : value; + + while(absvalue) + { + result.push_back(absvalue & 0xff); + absvalue >>= 8; + } + + +// - If the most significant byte is >= 0x80 and the value is positive, push a +// new zero-byte to make the significant byte < 0x80 again. + +// - If the most significant byte is >= 0x80 and the value is negative, push a +// new 0x80 byte that will be popped off when converting to an integral. + +// - If the most significant byte is < 0x80 and the value is negative, add +// 0x80 to it, since it will be subtracted and interpreted as a negative when +// converting to an integral. + + if (result.back() & 0x80) + result.push_back(neg ? 0x80 : 0); + else if (neg) + result.back() |= 0x80; + + return result; + } + + static const size_t nMaxNumSize = 4; + +private: + static int64_t set_vch(const std::vector<unsigned char>& vch) + { + if (vch.empty()) + return 0; + + int64_t result = 0; + for (size_t i = 0; i != vch.size(); ++i) + result |= static_cast<int64_t>(vch[i]) << 8*i; + + // If the input vector's most significant byte is 0x80, remove it from + // the result's msb and return a negative. + if (vch.back() & 0x80) + return -(result & ~(0x80 << (8 * (vch.size() - 1)))); + + return result; + } + + int64_t m_value; +}; + /** Signature hash types/flags */ enum { |