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Detect overflow in functions to convert strings to numbers 

Otherwise these functions can strictly run into undefined behavior which
should be prevented.
This commit is contained in:
Martchus 2021-05-24 19:16:49 +02:00
parent d5e35e460c
commit 3afed30760
2 changed files with 35 additions and 32 deletions
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57
conversion/stringconversion.h
View File

@ -505,6 +505,27 @@ template <typename CharType> CharType charToDigit(CharType character, CharType b
throw ConversionException(std::move(errorMsg));
}
/// \cond
namespace Detail {
template <typename IntegralType, typename CharType, typename BaseType = IntegralType>
void raiseAndAdd(IntegralType &result, BaseType base, CharType character)
{
if (character == ' ') {
return;
}
#ifdef __GNUC__ // overflow detection only supported on GCC and Clang
if (__builtin_mul_overflow(result, base, &result)
|| __builtin_add_overflow(result, charToDigit(character, static_cast<CharType>(base)), &result)) {
throw ConversionException("Number exceeds limit.");
}
#else
result *= static_cast<IntegralType>(base);
result += static_cast<IntegralType>(charToDigit<CharType>(character, static_cast<CharType>(base)));
#endif
}
} // namespace Detail
/// \endcond
/*!
* \brief Converts the given \a string to an unsigned number assuming \a string uses the specified \a base.
* \tparam IntegralType The data type used to store the converted value.
@ -519,11 +540,7 @@ IntegralType stringToNumber(const StringType &string, BaseType base = 10)
{
IntegralType result = 0;
for (const auto &c : string) {
if (c == ' ') {
continue;
}
result *= static_cast<IntegralType>(base);
result += static_cast<IntegralType>(charToDigit<typename StringType::value_type>(c, static_cast<typename StringType::value_type>(base)));
Detail::raiseAndAdd(result, base, c);
}
return result;
}
@ -552,11 +569,7 @@ IntegralType stringToNumber(const StringType &string, BaseType base = 10)
}
IntegralType result = 0;
for (; i != end; ++i) {
if (*i == ' ') {
continue;
}
result *= static_cast<IntegralType>(base);
result += static_cast<IntegralType>(charToDigit<typename StringType::value_type>(*i, static_cast<typename StringType::value_type>(base)));
Detail::raiseAndAdd(result, base, *i);
}
return negative ? -result : result;
}
@ -601,11 +614,7 @@ IntegralType stringToNumber(const CharType *string, BaseType base = 10)
{
IntegralType result = 0;
for (; *string; ++string) {
if (*string == ' ') {
continue;
}
result *= static_cast<IntegralType>(base);
result += static_cast<IntegralType>(charToDigit<CharType>(*string, static_cast<CharType>(base)));
Detail::raiseAndAdd(result, base, *string);
}
return result;
}
@ -649,11 +658,7 @@ IntegralType bufferToNumber(const CharType *string, std::size_t size, BaseType b
{
IntegralType result = 0;
for (const CharType *end = string + size; string != end; ++string) {
if (*string == ' ') {
continue;
}
result *= static_cast<IntegralType>(base);
result += static_cast<IntegralType>(charToDigit<CharType>(*string, static_cast<CharType>(base)));
Detail::raiseAndAdd(result, base, *string);
}
return result;
}
@ -683,11 +688,7 @@ IntegralType stringToNumber(const CharType *string, IntegralType base = 10)
}
IntegralType result = 0;
for (; *string; ++string) {
if (*string == ' ') {
continue;
}
result *= static_cast<IntegralType>(base);
result += static_cast<IntegralType>(charToDigit<CharType>(*string, static_cast<CharType>(base)));
Detail::raiseAndAdd(result, base, *string);
}
return negative ? -result : result;
}
@ -718,11 +719,7 @@ IntegralType bufferToNumber(const CharType *string, std::size_t size, BaseType b
}
IntegralType result = 0;
for (; string != end; ++string) {
if (*string == ' ') {
continue;
}
result *= static_cast<IntegralType>(base);
result += static_cast<IntegralType>(charToDigit<CharType>(*string, static_cast<CharType>(base)));
Detail::raiseAndAdd(result, base, *string);
}
return negative ? -result : result;
}

10
tests/conversiontests.cpp
View File

@ -283,8 +283,14 @@ void ConversionTests::testStringConversions()
CPPUNIT_ASSERT_EQUAL(23u, stringToNumber<std::uint32_t>(" 023"s));
CPPUNIT_ASSERT_EQUAL(23u, bufferToNumber<std::uint32_t>(" 023", 5));
CPPUNIT_ASSERT_EQUAL(255u, stringToNumber<std::uint32_t>("fF", 16));
CPPUNIT_ASSERT_THROW(stringToNumber<std::uint32_t>("fF", 15), ConversionException);
CPPUNIT_ASSERT_THROW(stringToNumber<std::uint32_t>("(", 15), ConversionException);
CPPUNIT_ASSERT_THROW_MESSAGE("character out of range", stringToNumber<std::uint32_t>("fF", 15), ConversionException);
CPPUNIT_ASSERT_THROW_MESSAGE("invalid character", stringToNumber<std::uint32_t>("(", 15), ConversionException);
#ifdef __GNUC__ // overflow detection only supported on GCC and Clang
CPPUNIT_ASSERT_THROW_MESSAGE("overflow", stringToNumber<std::uint32_t>("100000000", 16), ConversionException);
CPPUNIT_ASSERT_THROW_MESSAGE("underflow", stringToNumber<std::int32_t>("-80000001", 16), ConversionException);
CPPUNIT_ASSERT_EQUAL_MESSAGE("positive limit", 0xFFFFFFFFu, stringToNumber<std::uint32_t>("FFFFFFFF", 16));
CPPUNIT_ASSERT_EQUAL_MESSAGE("negative limit", -2147483647, stringToNumber<std::int32_t>("-2147483647", 10));
#endif
// interpretIntegerAsString()
CPPUNIT_ASSERT_EQUAL("TEST"s, interpretIntegerAsString<std::uint32_t>(0x54455354));