From 4e300df7123a402aef472aaaac30907b18a10c27 Mon Sep 17 00:00:00 2001
From: Matthew Zipkin <pinheadmz@pm.me>
Date: Wed, 12 Mar 2025 13:31:47 -0400
Subject: [PATCH] string: add `base` argument for ToIntegral to operate on
 hexadecimal

---
 src/test/util_tests.cpp | 33 +++++++++++++++++++++++++++++++++
 src/util/strencodings.h |  7 ++++---
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index 13821db4b95..daa5b8b334d 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -835,6 +835,39 @@ BOOST_AUTO_TEST_CASE(test_LocaleIndependentAtoi)
     BOOST_CHECK_EQUAL(LocaleIndependentAtoi<uint8_t>("256"), 255U);
 }
 
+BOOST_AUTO_TEST_CASE(test_ToIntegralHex)
+{
+    std::optional<uint64_t> n;
+    // Valid values
+    n = ToIntegral<uint64_t>("1234", 16);
+    BOOST_CHECK_EQUAL(*n, 0x1234);
+    n = ToIntegral<uint64_t>("a", 16);
+    BOOST_CHECK_EQUAL(*n, 0xA);
+    n = ToIntegral<uint64_t>("0000000a", 16);
+    BOOST_CHECK_EQUAL(*n, 0xA);
+    n = ToIntegral<uint64_t>("100", 16);
+    BOOST_CHECK_EQUAL(*n, 0x100);
+    n = ToIntegral<uint64_t>("DEADbeef", 16);
+    BOOST_CHECK_EQUAL(*n, 0xDEADbeef);
+    n = ToIntegral<uint64_t>("FfFfFfFf", 16);
+    BOOST_CHECK_EQUAL(*n, 0xFfFfFfFf);
+    n = ToIntegral<uint64_t>("123456789", 16);
+    BOOST_CHECK_EQUAL(*n, 0x123456789ULL);
+    n = ToIntegral<uint64_t>("0", 16);
+    BOOST_CHECK_EQUAL(*n, 0);
+    n = ToIntegral<uint64_t>("FfFfFfFfFfFfFfFf", 16);
+    BOOST_CHECK_EQUAL(*n, 0xFfFfFfFfFfFfFfFfULL);
+    n = ToIntegral<int64_t>("-1", 16);
+    BOOST_CHECK_EQUAL(*n, -1);
+    // Invalid values
+    BOOST_CHECK(!ToIntegral<uint64_t>("", 16));
+    BOOST_CHECK(!ToIntegral<uint64_t>("-1", 16));
+    BOOST_CHECK(!ToIntegral<uint64_t>("10 00", 16));
+    BOOST_CHECK(!ToIntegral<uint64_t>("1 ", 16));
+    BOOST_CHECK(!ToIntegral<uint64_t>("0xAB", 16));
+    BOOST_CHECK(!ToIntegral<uint64_t>("FfFfFfFfFfFfFfFf0", 16));
+}
+
 BOOST_AUTO_TEST_CASE(test_FormatParagraph)
 {
     BOOST_CHECK_EQUAL(FormatParagraph("", 79, 0), "");
diff --git a/src/util/strencodings.h b/src/util/strencodings.h
index 01063858047..dc8493ff566 100644
--- a/src/util/strencodings.h
+++ b/src/util/strencodings.h
@@ -169,17 +169,18 @@ constexpr inline bool IsSpace(char c) noexcept {
 /**
  * Convert string to integral type T. Leading whitespace, a leading +, or any
  * trailing character fail the parsing. The required format expressed as regex
- * is `-?[0-9]+`. The minus sign is only permitted for signed integer types.
+ * is `-?[0-9]+` by default (or `-?[0-9a-fA-F]+` if base = 16).
+ * The minus sign is only permitted for signed integer types.
  *
  * @returns std::nullopt if the entire string could not be parsed, or if the
  *   parsed value is not in the range representable by the type T.
  */
 template <typename T>
-std::optional<T> ToIntegral(std::string_view str)
+std::optional<T> ToIntegral(std::string_view str, size_t base = 10)
 {
     static_assert(std::is_integral_v<T>);
     T result;
-    const auto [first_nonmatching, error_condition] = std::from_chars(str.data(), str.data() + str.size(), result);
+    const auto [first_nonmatching, error_condition] = std::from_chars(str.data(), str.data() + str.size(), result, base);
     if (first_nonmatching != str.data() + str.size() || error_condition != std::errc{}) {
         return std::nullopt;
     }