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Merge pull request #390 from qwename/integer-overflow

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🔀 fix issue #380: Signed integer overflow check
This commit is contained in:
Niels Lohmann 2016-12-13 21:26:53 +01:00 • committed by GitHub
commit 4e2fb1a533
2 changed files with 12 additions and 12 deletions
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12
src/json.hpp
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@ -10619,19 +10619,19 @@ basic_json_parser_66:
// skip if definitely not an integer
if (type != value_t::number_float)
{
// multiply last value by ten and add the new digit
auto temp = value * 10 + *curptr - '0';
auto digit = static_cast<number_unsigned_t>(*curptr - '0');
// test for overflow
if (temp < value || temp > max)
// overflow if value * 10 + digit > max, move terms around
// to avoid overflow in intermediate values
if (value > (max - digit) / 10)
{
// overflow
type = value_t::number_float;
}
else
{
// no overflow - save it
value = temp;
// no overflow
value = value * 10 + digit;
}
}
}

12
src/json.hpp.re2c
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@ -9769,19 +9769,19 @@ class basic_json
// skip if definitely not an integer
if (type != value_t::number_float)
{
// multiply last value by ten and add the new digit
auto temp = value * 10 + *curptr - '0';
auto digit = static_cast<number_unsigned_t>(*curptr - '0');
// test for overflow
if (temp < value || temp > max)
// overflow if value * 10 + digit > max, move terms around
// to avoid overflow in intermediate values
if (value > (max - digit) / 10)
{
// overflow
type = value_t::number_float;
}
else
{
// no overflow - save it
value = temp;
// no overflow
value = value * 10 + digit;
}
}
}