Added FreeBSD support to Entitlement module

Author: sarog

libs/entitlement/src/main/java/org/elasticsearch/entitlement/runtime/policy/FileAccessTree.java

@@ -181,7 +181,7 @@ static char separatorChar() {
 
     private static final Logger logger = LogManager.getLogger(FileAccessTree.class);
     private static final String FILE_SEPARATOR = getDefaultFileSystem().getSeparator();
-    static final FileAccessTreeComparison DEFAULT_COMPARISON = Platform.LINUX.isCurrent()
+    static final FileAccessTreeComparison DEFAULT_COMPARISON = (Platform.LINUX.isCurrent() || Platform.FREEBSD.isCurrent())
         ? new CaseSensitiveComparison(separatorChar())
         : new CaseInsensitiveComparison(separatorChar());
 

libs/entitlement/src/main/java/org/elasticsearch/entitlement/runtime/policy/Platform.java

@@ -12,7 +12,8 @@
 public enum Platform {
     LINUX,
     MACOS,
-    WINDOWS;
+    WINDOWS,
+    FREEBSD;
 
     private static final Platform current = findCurrent();
 
@@ -24,6 +25,8 @@ private static Platform findCurrent() {
             return MACOS;
         } else if (os.startsWith("Windows")) {
             return WINDOWS;
+        } else if (os.startsWith("FreeBSD")) {
+            return FREEBSD;
         } else {
             throw new AssertionError("Unsupported platform [" + os + "]");
         }

libs/entitlement/src/main/java/org/elasticsearch/entitlement/runtime/policy/entitlements/FilesEntitlement.java

@@ -172,8 +172,10 @@ private static Platform parsePlatform(String platform) {
             return Platform.MACOS;
         } else if (platform.equals("windows")) {
             return Platform.WINDOWS;
+        } else if (platform.equals("freebsd")) {
+            return Platform.FREEBSD;
         } else {
-            throw new PolicyValidationException("invalid platform: " + platform + ", valid values: [linux, macos, windows]");
+            throw new PolicyValidationException("invalid platform: " + platform + ", valid values: [linux, macos, windows, freebsd]");
         }
     }