Add OpenBSD support for ICU library loading

OpenBSD uses ABI versioning in SONAME rather than ICU version numbering.
Use unversioned dlopen calls and probe symbol versioning instead of
attempting to load versioned library names.

Author: am11

src/native/libs/System.Globalization.Native/pal_icushim.c

@@ -230,7 +230,35 @@ static int FindICULibs(char* symbolName, char* symbolVersion)
     return false;
 }
 
-#else // !TARGET_WINDOWS && !TARGET_OSX && !TARGET_ANDROID
+#elif defined(TARGET_OPENBSD)
+
+// OpenBSD uses ABI versioning in SONAME, not ICU version. Use unversioned dlopen.
+static int FindICULibs(char* symbolName, char* symbolVersion)
+{
+    libicuuc = dlopen("libicuuc.so", RTLD_LAZY);
+    if (libicuuc == NULL)
+        return false;
+
+    libicui18n = dlopen("libicui18n.so", RTLD_LAZY);
+    if (libicui18n == NULL)
+    {
+        dlclose(libicuuc);
+        libicuuc = NULL;
+        return false;
+    }
+
+    char symbolSuffix[SYMBOL_CUSTOM_SUFFIX_SIZE]="";
+    if (FindSymbolVersion(-1, -1, -1, symbolName, symbolVersion, MaxICUVersionStringLength, symbolSuffix))
+        return true;
+
+    dlclose(libicuuc);
+    dlclose(libicui18n);
+    libicuuc = NULL;
+    libicui18n = NULL;
+    return false;
+}
+
+#else // !TARGET_WINDOWS && !TARGET_OSX && !TARGET_ANDROID && !TARGET_OPENBSD
 
 // Version ranges to search for each of the three version components
 // The rationale for major version range is that we support versions higher or
@@ -442,6 +470,35 @@ static void InitializeUColClonePointers(char* symbolVersion)
     }
 }
 
+static void InitializeVariableMaxAndTopPointers(char* symbolVersion)
+{
+    if (ucol_setMaxVariable_ptr != NULL)
+    {
+        return;
+    }
+
+#if defined(TARGET_OSX) || defined(TARGET_ANDROID)
+    // OSX and Android always run against ICU version which has ucol_setMaxVariable.
+    // We shouldn't come here.
+    (void)symbolVersion;
+    assert(false);
+#elif defined(TARGET_WINDOWS)
+    char symbolName[SYMBOL_NAME_SIZE];
+    sprintf_s(symbolName, SYMBOL_NAME_SIZE, "ucol_setVariableTop%s", symbolVersion);
+    ucol_setVariableTop_ptr = (ucol_setVariableTop_func)GetProcAddress((HMODULE)libicui18n, symbolName);
+#else
+    char symbolName[SYMBOL_NAME_SIZE];
+    snprintf(symbolName, SYMBOL_NAME_SIZE, "ucol_setVariableTop%s", symbolVersion);
+    ucol_setVariableTop_ptr = (ucol_setVariableTop_func)dlsym(libicui18n, symbolName);
+#endif // defined(TARGET_OSX) || defined(TARGET_ANDROID)
+
+    if (ucol_setVariableTop_ptr == NULL)
+    {
+        fprintf(stderr, "Cannot get the symbols of ICU APIs ucol_setMaxVariable or ucol_setVariableTop.\n");
+        abort();
+    }
+}
+
 // GlobalizationNative_LoadICU
 // This method get called from the managed side during the globalization initialization.
 // This method shouldn't get called at all if we are running in globalization invariant mode
@@ -458,7 +515,7 @@ int32_t GlobalizationNative_LoadICU(void)
         return false;
     }
 
-#elif defined(TARGET_ANDROID)
+#elif defined(TARGET_ANDROID) || defined(TARGET_OPENBSD)
     if (!FindICULibs(symbolName, symbolVersion))
     {
         return false;
@@ -479,6 +536,7 @@ int32_t GlobalizationNative_LoadICU(void)
     FOR_ALL_ICU_FUNCTIONS
     ValidateICUDataCanLoad();
 
+    InitializeVariableMaxAndTopPointers(symbolVersion);
     InitializeUColClonePointers(symbolVersion);
 
     return true;
@@ -535,6 +593,7 @@ void GlobalizationNative_InitICUFunctions(void* icuuc, void* icuin, const char*
     FOR_ALL_ICU_FUNCTIONS
     ValidateICUDataCanLoad();
 
+    InitializeVariableMaxAndTopPointers(symbolVersion);
     InitializeUColClonePointers(symbolVersion);
 }