fixes #129

CHANGES.md

@@ -17,6 +17,8 @@ Bug Fixes
 * Fix crash in direct mode callbacks with certain type conversions - [@twall](https://github.com/twall).
 * More thoroughly propagate unexpected exceptions generated in jnidispatch - [@twall](https://github.com/twall).
 * Cleanup maven poms and publishing to central repo - [@bhamail](https://github.com/bhamail).
+* [#129](https://github.com/twall/jna/issues/129): Allow `Memory` field in structure - [@twall](https://github.com/twall).
+* Preserve `PointerType` fields on `Structure.read()` if unchanged - [@twall](https://github.com/twall).
 
 Release 3.4.2
 =============

src/com/sun/jna/Native.java

@@ -1025,7 +1025,7 @@ public static int getNativeSize(Class cls) {
             return POINTER_SIZE;
         }
         throw new IllegalArgumentException("Native size for type \"" + cls.getName() 
-        								   + "\" is unknown");
+                                           + "\" is unknown");
     }
 
     /** Indicate whether the given class is supported as a native argument

src/com/sun/jna/Pointer.java

@@ -452,6 +452,9 @@ else if (NativeMapped.class.isAssignableFrom(type)) {
             if (nm != null) {
                 Object value = getValue(offset, nm.nativeType(), null);
                 result = nm.fromNative(value, new FromNativeContext(type));
+                if (nm.equals(result)) {
+                    result = nm;
+                }
             }
             else {
                 NativeMappedConverter tc = NativeMappedConverter.getInstance(type);

src/com/sun/jna/PointerType.java

@@ -98,6 +98,6 @@ public boolean equals(Object o) {
     }
 
     public String toString() {
-        return pointer == null ? "NULL" : pointer.toString();
+        return pointer == null ? "NULL" : pointer.toString() + " (" + super.toString() + ")";
     }
 }

src/com/sun/jna/Structure.java

@@ -626,6 +626,9 @@ Object readField(StructField structField) {
         Object result = memory.getValue(offset, fieldType, currentValue);
         if (readConverter != null) {
             result = readConverter.fromNative(result, structField.context);
+            if (currentValue != null && currentValue.equals(result)) {
+                result = currentValue;
+            }
         }
 
         if (fieldType.equals(String.class)
@@ -1193,7 +1196,7 @@ protected int getNativeAlignment(Class type, Object value, boolean isFirstElemen
             || Float.class == type || Double.class == type) {
             alignment = size;
         }
-        else if (Pointer.class == type
+        else if ((Pointer.class.isAssignableFrom(type) && !Function.class.isAssignableFrom(type))
                  || (Platform.HAS_BUFFERS && Buffer.class.isAssignableFrom(type))
                  || Callback.class.isAssignableFrom(type)
                  || WString.class == type

test/com/sun/jna/StructureTest.java

@@ -553,6 +553,16 @@ protected List getFieldOrder() {
         }
     }
 
+    public void testMemoryField() {
+        class MemoryFieldStructure extends Structure {
+            public Memory m;
+            protected List getFieldOrder() {
+                return Arrays.asList(new String[] { "m" });
+            }
+        }
+        new MemoryFieldStructure().size();
+    }
+
     public void testDisallowFunctionPointerAsField() {
         class BadFieldStructure extends Structure {
             public Function cb;
@@ -785,9 +795,11 @@ protected List getFieldOrder() {
         }
         TestStructure s = new TestStructure();
         final Pointer p = s.p;
+        final TestPointer p2 = s.p2;
         s.write();
         s.read();
         assertSame("Should preserve Pointer references if peer unchanged", p, s.p);
+        assertSame("Should preserve PointerType references if peer unchanged", p2, s.p2);
     }
 
     public void testPreserveStringFields() {