[RTL][NTDLL] Implement and export RtlCompareUnicodeStrings

dll/ntdll/def/ntdll.spec

@@ -682,7 +682,7 @@
 @ stdcall RtlCompareMemoryUlong(ptr long long)
 @ stdcall RtlCompareString(ptr ptr long)
 @ stdcall RtlCompareUnicodeString (ptr ptr long)
-@ stub -version=0x600+ RtlCompareUnicodeStrings
+@ stdcall -version=0x600+ RtlCompareUnicodeStrings(wstr long wstr long long)
 @ stub -version=0x600+ -arch=x86_64 RtlCompleteProcessCloning
 @ stdcall RtlCompressBuffer(long ptr long ptr long long ptr ptr)
 @ stdcall RtlComputeCrc32(long ptr long)

sdk/lib/rtl/unicode.c

@@ -2222,6 +2222,53 @@ RtlCompareUnicodeString(
     return ret;
 }
 
+/*
+ * @implemented
+ */
+_IRQL_requires_max_(PASSIVE_LEVEL)
+_Must_inspect_result_
+NTSYSAPI
+LONG
+NTAPI
+RtlCompareUnicodeStrings(
+    _In_reads_(String1Length) PCWCH String1,
+    _In_ SIZE_T String1Length,
+    _In_reads_(String2Length) PCWCH String2,
+    _In_ SIZE_T String2Length,
+    _In_ BOOLEAN CaseInSensitive)
+{
+    LONG Result = 0;
+    SIZE_T MinStringLength = min(String1Length, String2Length);
+    SIZE_T Index;
+
+    if (CaseInSensitive)
+    {
+        for (Index = 0; Index < MinStringLength; Index++)
+        {
+            WCHAR Char1 = RtlpUpcaseUnicodeChar(String1[Index]);
+            WCHAR Char2 = RtlpUpcaseUnicodeChar(String2[Index]);
+            Result = Char1 - Char2;
+            if (Result != 0)
+            {
+                return Result;
+            }
+        }
+    }
+    else
+    {
+        for (Index = 0; Index < MinStringLength; Index++)
+        {
+            Result = String1[Index] - String2[Index];
+            if (Result != 0)
+            {
+                return Result;
+            }
+        }
+    }
+
+    return String1Length - String2Length;
+}
+
 /*
  * @implemented
  */