Replace use of locale dependent atoi(…) with locale-independent std::from_chars(…) (C++17)

test: Add test cases for LocaleIndependentAtoi

fuzz: Assert legacy atoi(s) == LocaleIndependentAtoi<int>(s)

fuzz: Assert legacy atoi64(s) == LocaleIndependentAtoi<int64_t>(s)

14 files changed, 142 insertions, 44 deletions

diff --git a/src/core_read.cpp b/src/core_read.cpp
index 6108961010..320811b9e9 100644
--- a/src/core_read.cpp
+++ b/src/core_read.cpp
@@ -69,7 +69,7 @@ CScript ParseScript(const std::string& s)
             (w->front() == '-' && w->size() > 1 && std::all_of(w->begin()+1, w->end(), ::IsDigit)))
         {
             // Number
-            int64_t n = atoi64(*w);
+            int64_t n = LocaleIndependentAtoi<int64_t>(*w);
 
             //limit the range of numbers ParseScript accepts in decimal
             //since numbers outside -0xFFFFFFFF...0xFFFFFFFF are illegal in scripts
diff --git a/src/node/blockstorage.cpp b/src/node/blockstorage.cpp
index 5ddcf95c84..104fe8bf01 100644
--- a/src/node/blockstorage.cpp
+++ b/src/node/blockstorage.cpp
@@ -85,7 +85,7 @@ void CleanupBlockRevFiles()
     // start removing block files.
     int nContigCounter = 0;
     for (const std::pair<const std::string, fs::path>& item : mapBlockFiles) {
-        if (atoi(item.first) == nContigCounter) {
+        if (LocaleIndependentAtoi<int>(item.first) == nContigCounter) {
             nContigCounter++;
             continue;
         }
diff --git a/src/qt/rpcconsole.cpp b/src/qt/rpcconsole.cpp
index 1c8ed22ada..3c0dc5aa40 100644
--- a/src/qt/rpcconsole.cpp
+++ b/src/qt/rpcconsole.cpp
@@ -250,7 +250,7 @@ bool RPCConsole::RPCParseCommandLine(interfaces::Node* node, std::string &strRes
                                     for(char argch: curarg)
                                         if (!IsDigit(argch))
                                             throw std::runtime_error("Invalid result query");
-                                    subelement = lastResult[atoi(curarg.c_str())];
+                                    subelement = lastResult[LocaleIndependentAtoi<int>(curarg)];
                                 }
                                 else if (lastResult.isObject())
                                     subelement = find_value(lastResult, curarg);
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index 066a60b71b..8cad51a710 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -702,7 +702,7 @@ static RPCHelpMan getblocktemplate()
             std::string lpstr = lpval.get_str();
 
             hashWatchedChain = ParseHashV(lpstr.substr(0, 64), "longpollid");
-            nTransactionsUpdatedLastLP = atoi64(lpstr.substr(64));
+            nTransactionsUpdatedLastLP = LocaleIndependentAtoi<int64_t>(lpstr.substr(64));
         }
         else
         {
diff --git a/src/test/fuzz/locale.cpp b/src/test/fuzz/locale.cpp
index 5b1acae57b..4ad8123554 100644
--- a/src/test/fuzz/locale.cpp
+++ b/src/test/fuzz/locale.cpp
@@ -50,8 +50,6 @@ FUZZ_TARGET(locale)
     const bool parseint32_without_locale = ParseInt32(random_string, &parseint32_out_without_locale);
     int64_t parseint64_out_without_locale;
     const bool parseint64_without_locale = ParseInt64(random_string, &parseint64_out_without_locale);
-    const int64_t atoi64_without_locale = atoi64(random_string);
-    const int atoi_without_locale = atoi(random_string);
     const int64_t random_int64 = fuzzed_data_provider.ConsumeIntegral<int64_t>();
     const std::string tostring_without_locale = ToString(random_int64);
     // The variable `random_int32` is no longer used, but the harness still needs to
@@ -77,10 +75,6 @@ FUZZ_TARGET(locale)
     if (parseint64_without_locale) {
         assert(parseint64_out_without_locale == parseint64_out_with_locale);
     }
-    const int64_t atoi64_with_locale = atoi64(random_string);
-    assert(atoi64_without_locale == atoi64_with_locale);
-    const int atoi_with_locale = atoi(random_string);
-    assert(atoi_without_locale == atoi_with_locale);
     const std::string tostring_with_locale = ToString(random_int64);
     assert(tostring_without_locale == tostring_with_locale);
     const std::string strprintf_int_with_locale = strprintf("%d", random_int64);
diff --git a/src/test/fuzz/parse_numbers.cpp b/src/test/fuzz/parse_numbers.cpp
index 69e58c3f63..6a302e1e06 100644
--- a/src/test/fuzz/parse_numbers.cpp
+++ b/src/test/fuzz/parse_numbers.cpp
@@ -25,13 +25,13 @@ FUZZ_TARGET(parse_numbers)
 
     int32_t i32;
     (void)ParseInt32(random_string, &i32);
-    (void)atoi(random_string);
+    (void)LocaleIndependentAtoi<int>(random_string);
 
     uint32_t u32;
     (void)ParseUInt32(random_string, &u32);
 
     int64_t i64;
-    (void)atoi64(random_string);
+    (void)LocaleIndependentAtoi<int64_t>(random_string);
     (void)ParseFixedPoint(random_string, 3, &i64);
     (void)ParseInt64(random_string, &i64);
 
diff --git a/src/test/fuzz/string.cpp b/src/test/fuzz/string.cpp
index dc2bf7c860..ab646c68fc 100644
--- a/src/test/fuzz/string.cpp
+++ b/src/test/fuzz/string.cpp
@@ -122,6 +122,12 @@ bool LegacyParseUInt64(const std::string& str, uint64_t* out)
     return endp && *endp == 0 && !errno &&
            n <= std::numeric_limits<uint64_t>::max();
 }
+
+// For backwards compatibility checking.
+int64_t atoi64_legacy(const std::string& str)
+{
+    return strtoll(str.c_str(), nullptr, 10);
+}
 }; // namespace
 
 FUZZ_TARGET(string)
@@ -268,4 +274,22 @@ FUZZ_TARGET(string)
             assert(u8 == u8_legacy);
         }
     }
+
+    {
+        const int atoi_result = atoi(random_string_1.c_str());
+        const int locale_independent_atoi_result = LocaleIndependentAtoi<int>(random_string_1);
+        const int64_t atoi64_result = atoi64_legacy(random_string_1);
+        const bool out_of_range = atoi64_result < std::numeric_limits<int>::min() || atoi64_result > std::numeric_limits<int>::max();
+        if (out_of_range) {
+            assert(locale_independent_atoi_result == 0);
+        } else {
+            assert(atoi_result == locale_independent_atoi_result);
+        }
+    }
+
+    {
+        const int64_t atoi64_result = atoi64_legacy(random_string_1);
+        const int64_t locale_independent_atoi_result = LocaleIndependentAtoi<int64_t>(random_string_1);
+        assert(atoi64_result == locale_independent_atoi_result || locale_independent_atoi_result == 0);
+    }
 }
diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index a13700d733..5d1ad2ebf6 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -1549,6 +1549,77 @@ BOOST_AUTO_TEST_CASE(test_ToIntegral)
     BOOST_CHECK(!ToIntegral<uint8_t>("256"));
 }
 
+BOOST_AUTO_TEST_CASE(test_LocaleIndependentAtoi)
+{
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("1234"), 1'234);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("0"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("01234"), 1'234);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("-1234"), -1'234);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>(" 1"), 1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("1 "), 1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("1a"), 1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("1.1"), 1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("1.9"), 1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("+01.9"), 1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("-1"), -1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>(" -1"), -1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("-1 "), -1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>(" -1 "), -1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("+1"), 1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>(" +1"), 1);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>(" +1 "), 1);
+
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("+-1"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("-+1"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("++1"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("--1"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>(""), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("aap"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("0x1"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("-32482348723847471234"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("32482348723847471234"), 0);
+
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int64_t>("-9223372036854775809"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int64_t>("-9223372036854775808"), -9'223'372'036'854'775'807LL - 1LL);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int64_t>("9223372036854775807"), 9'223'372'036'854'775'807);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int64_t>("9223372036854775808"), 0);
+
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint64_t>("-1"), 0U);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint64_t>("0"), 0U);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint64_t>("18446744073709551615"), 18'446'744'073'709'551'615ULL);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint64_t>("18446744073709551616"), 0U);
+
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("-2147483649"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("-2147483648"), -2'147'483'648LL);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("2147483647"), 2'147'483'647);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int32_t>("2147483648"), 0);
+
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint32_t>("-1"), 0U);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint32_t>("0"), 0U);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint32_t>("4294967295"), 4'294'967'295U);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint32_t>("4294967296"), 0U);
+
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int16_t>("-32769"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int16_t>("-32768"), -32'768);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int16_t>("32767"), 32'767);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int16_t>("32768"), 0);
+
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint16_t>("-1"), 0U);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint16_t>("0"), 0U);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint16_t>("65535"), 65'535U);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint16_t>("65536"), 0U);
+
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int8_t>("-129"), 0);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int8_t>("-128"), -128);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int8_t>("127"), 127);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<int8_t>("128"), 0);
+
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint8_t>("-1"), 0U);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint8_t>("0"), 0U);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint8_t>("255"), 255U);
+    BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint8_t>("256"), 0U);
+}
+
 BOOST_AUTO_TEST_CASE(test_ParseInt64)
 {
     int64_t n;
diff --git a/src/torcontrol.cpp b/src/torcontrol.cpp
index bb296456ba..4bd19dcf45 100644
--- a/src/torcontrol.cpp
+++ b/src/torcontrol.cpp
@@ -83,7 +83,7 @@ void TorControlConnection::readcb(struct bufferevent *bev, void *ctx)
         if (s.size() < 4) // Short line
             continue;
         // <status>(-|+| )<data><CRLF>
-        self->message.code = atoi(s.substr(0,3));
+        self->message.code = LocaleIndependentAtoi<int>(s.substr(0,3));
         self->message.lines.push_back(s.substr(4));
         char ch = s[3]; // '-','+' or ' '
         if (ch == ' ') {
diff --git a/src/util/moneystr.cpp b/src/util/moneystr.cpp
index d3f4029607..95a919ad12 100644
--- a/src/util/moneystr.cpp
+++ b/src/util/moneystr.cpp
@@ -77,8 +77,7 @@ std::optional<CAmount> ParseMoney(const std::string& money_string)
         return std::nullopt;
     if (nUnits < 0 || nUnits > COIN)
         return std::nullopt;
-    int64_t nWhole = atoi64(strWhole);
-
+    int64_t nWhole = LocaleIndependentAtoi<int64_t>(strWhole);
     CAmount value = nWhole * COIN + nUnits;
 
     if (!MoneyRange(value)) {
diff --git a/src/util/strencodings.cpp b/src/util/strencodings.cpp
index 0aa80ea0ae..88fec6740a 100644
--- a/src/util/strencodings.cpp
+++ b/src/util/strencodings.cpp
@@ -403,20 +403,6 @@ std::string FormatParagraph(const std::string& in, size_t width, size_t indent)
     return out.str();
 }
 
-int64_t atoi64(const std::string& str)
-{
-#ifdef _MSC_VER
-    return _atoi64(str.c_str());
-#else
-    return strtoll(str.c_str(), nullptr, 10);
-#endif
-}
-
-int atoi(const std::string& str)
-{
-    return atoi(str.c_str());
-}
-
 /** Upper bound for mantissa.
  * 10^18-1 is the largest arbitrary decimal that will fit in a signed 64-bit integer.
  * Larger integers cannot consist of arbitrary combinations of 0-9:
diff --git a/src/util/strencodings.h b/src/util/strencodings.h
index 1217572c45..166352c42f 100644
--- a/src/util/strencodings.h
+++ b/src/util/strencodings.h
@@ -11,6 +11,7 @@
 
 #include <attributes.h>
 #include <span.h>
+#include <util/string.h>
 
 #include <charconv>
 #include <cstdint>
@@ -68,8 +69,33 @@ std::string EncodeBase32(Span<const unsigned char> input, bool pad = true);
 std::string EncodeBase32(const std::string& str, bool pad = true);
 
 void SplitHostPort(std::string in, uint16_t& portOut, std::string& hostOut);
-int64_t atoi64(const std::string& str);
-int atoi(const std::string& str);
+
+// LocaleIndependentAtoi is provided for backwards compatibility reasons.
+//
+// New code should use the ParseInt64/ParseUInt64/ParseInt32/ParseUInt32 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.
+template <typename T>
+T LocaleIndependentAtoi(const std::string& str)
+{
+    static_assert(std::is_integral<T>::value);
+    T result;
+    // Emulate atoi(...) handling of white space and leading +/-.
+    std::string s = TrimString(str);
+    if (!s.empty() && s[0] == '+') {
+        if (s.length() >= 2 && s[1] == '-') {
+            return 0;
+        }
+        s = s.substr(1);
+    }
+    auto [_, error_condition] = std::from_chars(s.data(), s.data() + s.size(), result);
+    if (error_condition != std::errc{}) {
+        return 0;
+    }
+    return result;
+}
 
 /**
  * Tests if the given character is a decimal digit.
diff --git a/src/util/system.cpp b/src/util/system.cpp
index 4defeed4ce..79c08816fa 100644
--- a/src/util/system.cpp
+++ b/src/util/system.cpp
@@ -158,16 +158,14 @@ std::streampos GetFileSize(const char* path, std::streamsize max) {
 /**
  * Interpret a string argument as a boolean.
  *
- * The definition of atoi() requires that non-numeric string values like "foo",
- * return 0. This means that if a user unintentionally supplies a non-integer
- * argument here, the return value is always false. This means that -foo=false
- * does what the user probably expects, but -foo=true is well defined but does
- * not do what they probably expected.
+ * The definition of LocaleIndependentAtoi<int>() requires that non-numeric string values
+ * like "foo", return 0. This means that if a user unintentionally supplies a
+ * non-integer argument here, the return value is always false. This means that
+ * -foo=false does what the user probably expects, but -foo=true is well defined
+ * but does not do what they probably expected.
  *
- * The return value of atoi() is undefined when given input not representable as
- * an int. On most systems this means string value between "-2147483648" and
- * "2147483647" are well defined (this method will return true). Setting
- * -txindex=2147483648 on most systems, however, is probably undefined.
+ * The return value of LocaleIndependentAtoi<int>(...) is zero when given input not
+ * representable as an int.
  *
  * For a more extensive discussion of this topic (and a wide range of opinions
  * on the Right Way to change this code), see PR12713.
@@ -176,7 +174,7 @@ static bool InterpretBool(const std::string& strValue)
 {
     if (strValue.empty())
         return true;
-    return (atoi(strValue) != 0);
+    return (LocaleIndependentAtoi<int>(strValue) != 0);
 }
 
 static std::string SettingName(const std::string& arg)
@@ -594,7 +592,7 @@ std::string ArgsManager::GetArg(const std::string& strArg, const std::string& st
 int64_t ArgsManager::GetIntArg(const std::string& strArg, int64_t nDefault) const
 {
     const util::SettingsValue value = GetSetting(strArg);
-    return value.isNull() ? nDefault : value.isFalse() ? 0 : value.isTrue() ? 1 : value.isNum() ? value.get_int64() : atoi64(value.get_str());
+    return value.isNull() ? nDefault : value.isFalse() ? 0 : value.isTrue() ? 1 : value.isNum() ? value.get_int64() : LocaleIndependentAtoi<int64_t>(value.get_str());
 }
 
 bool ArgsManager::GetBoolArg(const std::string& strArg, bool fDefault) const
diff --git a/src/wallet/transaction.h b/src/wallet/transaction.h
index 0cd91b9ebe..223901586e 100644
--- a/src/wallet/transaction.h
+++ b/src/wallet/transaction.h
@@ -216,9 +216,9 @@ public:
         }
 
         const auto it_op = mapValue.find("n");
-        nOrderPos = (it_op != mapValue.end()) ? atoi64(it_op->second) : -1;
+        nOrderPos = (it_op != mapValue.end()) ? LocaleIndependentAtoi<int64_t>(it_op->second) : -1;
         const auto it_ts = mapValue.find("timesmart");
-        nTimeSmart = (it_ts != mapValue.end()) ? static_cast<unsigned int>(atoi64(it_ts->second)) : 0;
+        nTimeSmart = (it_ts != mapValue.end()) ? static_cast<unsigned int>(LocaleIndependentAtoi<int64_t>(it_ts->second)) : 0;
 
         mapValue.erase("fromaccount");
         mapValue.erase("spent");