Fixup Unix methods, minor refactor of CompareInfo

Author: GrabYourPitchforks

src/libraries/Common/src/Interop/Unix/System.Globalization.Native/Interop.Collation.cs

@@ -24,7 +24,7 @@ internal static partial class Globalization
         internal static extern unsafe int IndexOf(IntPtr sortHandle, char* target, int cwTargetLength, char* pSource, int cwSourceLength, CompareOptions options, int* matchLengthPtr);
 
         [DllImport(Libraries.GlobalizationNative, CharSet = CharSet.Unicode, EntryPoint = "GlobalizationNative_LastIndexOf")]
-        internal static extern unsafe int LastIndexOf(IntPtr sortHandle, char* target, int cwTargetLength, char* pSource, int cwSourceLength, CompareOptions options);
+        internal static extern unsafe int LastIndexOf(IntPtr sortHandle, char* target, int cwTargetLength, char* pSource, int cwSourceLength, CompareOptions options, int* matchLengthPtr);
 
         [DllImport(Libraries.GlobalizationNative, CharSet = CharSet.Unicode, EntryPoint = "GlobalizationNative_IndexOfOrdinalIgnoreCase")]
         internal static extern unsafe int IndexOfOrdinalIgnoreCase(string target, int cwTargetLength, char* pSource, int cwSourceLength, bool findLast);

src/libraries/Native/Unix/System.Globalization.Native/pal_collation.c

@@ -501,7 +501,8 @@ int32_t GlobalizationNative_LastIndexOf(
                         int32_t cwTargetLength,
                         const UChar* lpSource,
                         int32_t cwSourceLength,
-                        int32_t options)
+                        int32_t options,
+                        int32_t* pMatchedLength)
 {
     int32_t result = USEARCH_DONE;
     UErrorCode err = U_ZERO_ERROR;
@@ -514,6 +515,13 @@ int32_t GlobalizationNative_LastIndexOf(
         if (U_SUCCESS(err))
         {
             result = usearch_last(pSearch, &err);
+
+            // if the search was successful,
+            // we'll try to get the matched string length.
+            if (result != USEARCH_DONE && pMatchedLength != NULL)
+            {
+                *pMatchedLength = usearch_getMatchedLength(pSearch);
+            }
             usearch_close(pSearch);
         }
     }

src/libraries/Native/Unix/System.Globalization.Native/pal_collation.h

@@ -34,7 +34,8 @@ DLLEXPORT int32_t GlobalizationNative_LastIndexOf(SortHandle* pSortHandle,
                                                   int32_t cwTargetLength,
                                                   const UChar* lpSource,
                                                   int32_t cwSourceLength,
-                                                  int32_t options);
+                                                  int32_t options,
+                                                  int32_t* pMatchedLength);
 
 DLLEXPORT int32_t GlobalizationNative_IndexOfOrdinalIgnoreCase(const UChar* lpTarget,
                                                                int32_t cwTargetLength,