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util: Restore GetIntArg saturating behavior

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The new locale-independent atoi64 method introduced in #20452 parses
large integer values higher than maximum representable value as 0
instead of the maximum value, which breaks backwards compatibility.
This commit restores compatibility and adds test coverage for this case
in terms of the related GetIntArg and strtoll functions.

Co-authored-by: Ryan Ofsky <ryan@ofsky.org>
This commit is contained in:
James O'Beirne
2021-12-22 12:11:13 -05:00
committed by Ryan Ofsky
parent c561f2f06e
commit b5c9bb5cb9
5 changed files with 66 additions and 25 deletions
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19
src/util/strencodings.h
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@@ -16,6 +16,7 @@
#include <charconv>
#include <cstdint>
#include <iterator>
#include <limits>
#include <optional>
#include <string>
#include <vector>
@@ -93,8 +94,12 @@ void SplitHostPort(std::string in, uint16_t& portOut, std::string& hostOut);
// New code should use ToIntegral or the ParseInt* functions
// which provide parse error feedback.
//
// The goal of LocaleIndependentAtoi is to replicate the exact defined behaviour
// of atoi and atoi64 as they behave under the "C" locale.
// The goal of LocaleIndependentAtoi is to replicate the defined behaviour of
// std::atoi as it behaves under the "C" locale, and remove some undefined
// behavior. If the parsed value is bigger than the integer type's maximum
// value, or smaller than the integer type's minimum value, std::atoi has
// undefined behavior, while this function returns the maximum or minimum
// values, respectively.
template <typename T>
T LocaleIndependentAtoi(const std::string& str)
{
@@ -109,7 +114,15 @@ T LocaleIndependentAtoi(const std::string& str)
s = s.substr(1);
}
auto [_, error_condition] = std::from_chars(s.data(), s.data() + s.size(), result);
if (error_condition != std::errc{}) {
if (error_condition == std::errc::result_out_of_range) {
if (s.length() >= 1 && s[0] == '-') {
// Saturate underflow, per strtoll's behavior.
return std::numeric_limits<T>::min();
} else {
// Saturate overflow, per strtoll's behavior.
return std::numeric_limits<T>::max();
}
} else if (error_condition != std::errc{}) {
return 0;
}
return result;