From 2de7f2021d1f4881ab1b19b63002e3c978634399 Mon Sep 17 00:00:00 2001
From: Jesse Buhagiar <jooster669@gmail.com>
Date: Sat, 1 Jan 2022 21:11:02 +1100
Subject: [PATCH] LibC: Support `X` modifier for `scanf`

This was currently crashing Half-Life because it was a considered an
"Unknown" specifier. We can use the same case statement as the regular
hex format conversion (lower case 'x'), as the backend
to convert the number already supports upper/lower case input, hence
we get it for free :^)
---
 Tests/LibC/TestScanf.cpp          | 3 +++
 Userland/Libraries/LibC/scanf.cpp | 1 +
 2 files changed, 4 insertions(+)

diff --git a/Tests/LibC/TestScanf.cpp b/Tests/LibC/TestScanf.cpp
index dee99b6611..4291276a4d 100644
--- a/Tests/LibC/TestScanf.cpp
+++ b/Tests/LibC/TestScanf.cpp
@@ -153,6 +153,9 @@ const TestSuite test_suites[] {
     { "%x", "0x519", 1, 1, { unsignedarg0 }, { to_value_t(0x519) } },
     { "%x", "0x51g", 1, 1, { unsignedarg0 }, { to_value_t(0x51u) } },
     { "%06x", "0xabcdef", 1, 1, { unsignedarg0 }, { to_value_t(0xabcdefu) } },
+    { "%X", "0xCAFEBABE", 1, 1, { unsignedarg0 }, { to_value_t(0xcafebabe) } },
+    { "%04X", "0x5E4E", 1, 1, { unsignedarg0 }, { to_value_t(0x5e4e) } },
+    { "%X", "0x51Eg", 1, 1, { unsignedarg0 }, { to_value_t(0x51e) } },
     { "\"%%%d#", "\"%42#", 1, 1, { intarg0 }, { to_value_t(42) } },
     { "  %d", "42", 1, 1, { intarg0 }, { to_value_t(42) } },
     { "%d", "  42", 1, 1, { intarg0 }, { to_value_t(42) } },
diff --git a/Userland/Libraries/LibC/scanf.cpp b/Userland/Libraries/LibC/scanf.cpp
index d66043aa10..f760922de3 100644
--- a/Userland/Libraries/LibC/scanf.cpp
+++ b/Userland/Libraries/LibC/scanf.cpp
@@ -488,6 +488,7 @@ extern "C" int vsscanf(const char* input, const char* format, va_list ap)
                 conversion_specifier = ConversionSpecifier::Unsigned;
                 break;
             case 'x':
+            case 'X':
                 format_lexer.consume();
                 conversion_specifier = ConversionSpecifier::Hex;
                 break;