fix(OpenFlags): correct the O_DIRECT flag on aarch64

src/main/java/moe/cnkirito/kdio/DirectIOLib.java

@@ -244,11 +244,11 @@ public int pwrite(int fd, ByteBuffer buf, long offset) throws IOException {
      *
      */
     public int oDirectOpen(String pathname, boolean readOnly) throws IOException {
-        int flags = OpenFlags.O_DIRECT;
+        int flags = OpenFlags.INSTANCE.oDIRECT();
         if (readOnly) {
-            flags |= OpenFlags.O_RDONLY;
+            flags |= OpenFlags.INSTANCE.oRDONLY();
         } else {
-            flags |= OpenFlags.O_RDWR | OpenFlags.O_CREAT;
+            flags |= OpenFlags.INSTANCE.oWRONLY() | OpenFlags.INSTANCE.oCREAT();
         }
         int fd = open(pathname, flags, 00644);
         if (fd < 0) {
@@ -413,4 +413,3 @@ public static int lcm(long x, long y) {
     private static native String strerror(int errnum);
 
 }
-

src/main/java/moe/cnkirito/kdio/OpenFlags.java

@@ -18,14 +18,48 @@
 /**
  * Constants for {@link DirectIOLib#oDirectOpen(String, boolean)}.
  */
-public final class OpenFlags {
-    public static final int O_RDONLY = 00;
-    public static final int O_WRONLY = 01;
-    public static final int O_RDWR = 02;
-    public static final int O_CREAT = 0100;
-    public static final int O_TRUNC = 01000;
-    public static final int O_DIRECT = 040000;
-    public static final int O_SYNC = 04000000;
+public interface OpenFlags {
+    OpenFlags INSTANCE = instance();
 
-    private OpenFlags() {}
+    static OpenFlags instance() {
+        String arch = System.getProperty("os.arch");
+        switch (arch) {
+            case "aarch64":
+                return new Aarch64OpenFlags();
+            default:
+                return new DefaultOpenFlags();
+        }
+    }
+
+    default int oRDONLY() {
+        return 00;
+    }
+    default int oWRONLY() {
+        return 01;
+    }
+    default int oRDWR() {
+        return 02;
+    }
+    default int oCREAT() {
+        return 0100;
+    }
+    default int oTRUNC() {
+        return 01000;
+    }
+    default int oDIRECT() {
+        return 040000;
+    }
+    default int oSYNC() {
+        return 04010000;
+    }
+
+    class DefaultOpenFlags implements OpenFlags {
+    }
+
+    class Aarch64OpenFlags implements OpenFlags {
+        @Override
+        public int oDIRECT() {
+            return 0200000;
+        }
+    }
 }