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Improved overflow detection; removed debugging output statements.
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parent
6b78b5c2be
commit
4eafaab816
47
src/json.hpp
47
src/json.hpp
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@ -9223,14 +9223,6 @@ basic_json_parser_66:
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value = -0.0;
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}
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if(!ok) {
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std::cerr << "data:" << data
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<< " token:" << std::string(m_start, len)
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<< " value:" << value
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<< " len:" << len
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<< " parsed_len:" << (endptr - data) << std::endl;
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}
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return ok;
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}
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@ -9252,31 +9244,40 @@ basic_json_parser_66:
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++beg; // skip the leading sign
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}
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// using unsigned accumulator x because the signed
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// type can't hold absolute value of largest
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// negative value of this type, so overflow detection
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// becomes problematic.
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using unsigned_T = typename std::make_unsigned<T>::type;
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unsigned_T x = 0;
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bool valid = beg < end // must have some digits;
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and ( T(-1) < 0 // type must be signed
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or !is_negative); // if value is negative
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value = 0;
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while(beg < end and valid) {
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const uint8_t c = static_cast<uint8_t>(*beg - '0');
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const T upd_value = value * 10 + c;
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valid &= value <= std::numeric_limits<T>::max() / 10
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and value <= upd_value // did not overflow
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and c < 10; // char was digit
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value = upd_value;
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const unsigned_T upd_x = x * 10 + c;
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using lim_T = std::numeric_limits<T>;
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constexpr unsigned_T thr1 = lim_T::max() / 10;
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valid &= c < 10 // char was digit
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and x <= thr1 // multiplication did not overflow
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and x <= upd_x; // addition did not overflow.
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// note that x <= upd_x alone can't detect overflow since
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// we're not just adding a value of decltype(x) but
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// also multiplying by 10
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x = upd_x;
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++beg;
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}
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if(is_negative) {
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value = 0 - value;
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}
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value = static_cast<T>(is_negative ? 0 - x : x);
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if(!valid) {
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std::cerr << " token:" << std::string(m_start, m_end)
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<< std::endl;
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}
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return valid;
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// the final check to make sure the value did not roll over
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// into positives is for edge cases, e.g. -2^63
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return valid && (is_negative == (value < 0));
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}
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};
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@ -8372,14 +8372,6 @@ class basic_json
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value = -0.0;
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}
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if(!ok) {
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std::cerr << "data:" << data
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<< " token:" << std::string(m_start, len)
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<< " value:" << value
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<< " len:" << len
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<< " parsed_len:" << (endptr - data) << std::endl;
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}
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return ok;
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}
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@ -8401,31 +8393,40 @@ class basic_json
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++beg; // skip the leading sign
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}
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// using unsigned accumulator x because the signed
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// type can't hold absolute value of largest
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// negative value of this type, so overflow detection
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// becomes problematic.
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using unsigned_T = typename std::make_unsigned<T>::type;
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unsigned_T x = 0;
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bool valid = beg < end // must have some digits;
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and ( T(-1) < 0 // type must be signed
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or !is_negative); // if value is negative
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value = 0;
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while(beg < end and valid) {
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const uint8_t c = static_cast<uint8_t>(*beg - '0');
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const T upd_value = value * 10 + c;
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valid &= value <= std::numeric_limits<T>::max() / 10
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and value <= upd_value // did not overflow
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and c < 10; // char was digit
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value = upd_value;
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const unsigned_T upd_x = x * 10 + c;
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using lim_T = std::numeric_limits<T>;
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constexpr unsigned_T thr1 = lim_T::max() / 10;
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valid &= c < 10 // char was digit
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and x <= thr1 // multiplication did not overflow
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and x <= upd_x; // addition did not overflow.
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// note that x <= upd_x alone can't detect overflow since
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// we're not just adding a value of decltype(x) but
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// also multiplying by 10
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x = upd_x;
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++beg;
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}
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if(is_negative) {
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value = 0 - value;
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}
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value = static_cast<T>(is_negative ? 0 - x : x);
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if(!valid) {
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std::cerr << " token:" << std::string(m_start, m_end)
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<< std::endl;
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}
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return valid;
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// the final check to make sure the value did not roll over
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// into positives is for edge cases, e.g. -2^63
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return valid && (is_negative == (value < 0));
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}
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};
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