GP-1036 Improved RTTI handling of null pointer values. Changed IBO

pointers to return null for 0 value to retain backward compatibility.
Improved datatype drag onto root to preserve source category path.

Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/datamgr/util/DataTypeTreeCopyMoveTask.java

@@ -338,6 +338,12 @@ public class DataTypeTreeCopyMoveTask extends Task {
 		DataTypeManager nodeDtm = dataType.getDataTypeManager();
 		boolean sameManager = (dtm == nodeDtm);
 		DataType newDt = !sameManager ? dataType.clone(nodeDtm) : dataType.copy(nodeDtm);
+
+		if (!sameManager && toCategory.isRoot()) {
+			// preserve use of source category when copy to root
+			toCategory = dtm.createCategory(dataType.getCategoryPath());
+		}
+
 		if (sameManager && newDt.getCategoryPath().equals(toCategory.getCategoryPath())) {
 			renameAsCopy(toCategory, newDt);
 		}

Ghidra/Features/MicrosoftCodeAnalyzer/src/main/java/ghidra/app/cmd/data/TypeDescriptorModel.java

@@ -138,7 +138,7 @@ public class TypeDescriptorModel extends AbstractCreateDataTypeModel {
 
 		try {
 			Address spareDataAddress = getSpareDataAddress();
-			if (spareDataAddress != null && spareDataAddress.getOffset() != 0L &&
+			if (spareDataAddress != null && spareDataAddress.getOffset() != 0 &&
 				!loadedAndInitializedSet.contains(spareDataAddress)) {
 				throw new InvalidDataTypeException(getName() + " data type at " + getAddress() +
 					" doesn't point to a spare data address in a loaded and initialized memory block.");
@@ -360,8 +360,7 @@ public class TypeDescriptorModel extends AbstractCreateDataTypeModel {
 		Address vfTableAddress;
 		// component 0 is either vf table pointer or hash value.
 		vfTableAddress = EHDataTypeUtilities.getAddress(getDataType(), VF_TABLE_OR_HASH_ORDINAL, getMemBuffer());
-
-		return vfTableAddress.getOffset() != 0 ? vfTableAddress : null;
+		return (vfTableAddress != null && vfTableAddress.getOffset() != 0) ? vfTableAddress : null;
 	}
 
 	/**
@@ -393,7 +392,7 @@ public class TypeDescriptorModel extends AbstractCreateDataTypeModel {
 		// component 1 is the spare data.
 		Address spareAddress =
 			EHDataTypeUtilities.getAddress(getDataType(), SPARE_ORDINAL, getMemBuffer());
-		return spareAddress.getOffset() != 0 ? spareAddress : null;
+		return (spareAddress != null && spareAddress.getOffset() != 0) ? spareAddress : null;
 	}
 
 	/**

Ghidra/Features/MicrosoftCodeAnalyzer/src/main/java/ghidra/app/cmd/data/rtti/Rtti1Model.java

@@ -122,7 +122,7 @@ public class Rtti1Model extends AbstractCreateRttiDataModel {
 		// First component is either a direct reference or an image base offset.
 		Address rtti0Address = getReferencedAddress(program, startAddress);
 		if (rtti0Address == null) {
-			invalid(); // throws Exception
+			invalid("Invalid TypeDescriptor reference (pTypeDescriptor)."); // throws Exception
 		}
 		rtti0Model = new TypeDescriptorModel(program, rtti0Address, validationOptions);
 		if (validateReferredToData) {

Ghidra/Framework/Docking/src/main/java/ghidra/docking/settings/SettingsImpl.java

@@ -241,6 +241,9 @@ public class SettingsImpl implements Settings, Serializable {
 
 	@Override
 	public void clearAllSettings() {
+		if (map.isEmpty()) {
+			return;
+		}
 		if (checkSetting(null, null)) {
 			map.clear();
 			changed();

Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/data/PointerTypedefInspector.java

@@ -15,8 +15,8 @@
  */
 package ghidra.program.database.data;
 
-import ghidra.program.model.address.AddressFactory;
-import ghidra.program.model.address.AddressSpace;
+import ghidra.docking.settings.Settings;
+import ghidra.program.model.address.*;
 import ghidra.program.model.data.*;
 
 /**
@@ -60,12 +60,21 @@ public class PointerTypedefInspector {
 		if (!pointerTypeDef.isPointer()) {
 			return null;
 		}
+		Settings settings = pointerTypeDef.getDefaultSettings();
 		String spaceName =
-			AddressSpaceSettingsDefinition.DEF.getValue(pointerTypeDef.getDefaultSettings());
+			AddressSpaceSettingsDefinition.DEF.getValue(settings);
 		if (spaceName == null) {
 			return null;
 		}
-		return addrFactory.getAddressSpace(spaceName);
+		AddressSpace addressSpace = addrFactory.getAddressSpace(spaceName);
+		if (addressSpace instanceof SegmentedAddressSpace) {
+			// Other settings do not apply when SegmentedAddressSpace is used
+			// see PointerDataType.getAddressValue(MemBuffer, int, Settings)
+			return addressSpace;
+		}
+		// Address space setting ignored if Pointer Type has been specified
+		PointerType choice = PointerTypeSettingsDefinition.DEF.getType(settings);
+		return choice == PointerType.DEFAULT ? addressSpace : null;
 	}
 
 	/**

Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/data/DataTypeMnemonicSettingsDefinition.java

@@ -41,7 +41,9 @@ public class DataTypeMnemonicSettingsDefinition implements EnumSettingsDefinitio
 	/**
 	 * Returns the format based on the specified settings
 	 * @param settings the instance settings.
-	 * @return the format value (HEX, DECIMAL, BINARY, OCTAL, CHAR)
+	 * @return the mnemonic style (DEFAULT, ASSEMBLY, CSPEC).  
+	 * The ASSEMBLY style is returned if no setting has been made.
+	 * The DEFAULT style corresponds to the use of {@link DataType#getName()}.
 	 */
 	public int getMnemonicStyle(Settings settings) {
 		if (settings == null) {

Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/data/PointerDataType.java

@@ -368,6 +368,7 @@ public class PointerDataType extends BuiltIn implements Pointer {
 			Program program = mem.getProgram();
 			String spaceName = AddressSpaceSettingsDefinition.DEF.getValue(settings);
 			if (spaceName != null) {
+				// this space may be ignored if pointer type specified
 				targetSpace = program.getAddressFactory().getAddressSpace(spaceName);
 			}
 		}
@@ -377,12 +378,13 @@ public class PointerDataType extends BuiltIn implements Pointer {
 		}
 
 		if (targetSpace instanceof SegmentedAddressSpace) {
-			// ignore other settings
+			// ignore other settings with SegmentedAddressSpace use
 			return getAddressValue(buf, size, targetSpace);
 		}
 
 		Long offset = getStoredOffset(buf, size);
 		if (offset == null) {
+			// Insufficient bytes
 			return null;
 		}
 
@@ -403,7 +405,13 @@ public class PointerDataType extends BuiltIn implements Pointer {
 
 		try {
 			PointerType choice = PointerTypeSettingsDefinition.DEF.getType(settings);
+			// Address space setting ignored if Pointer Type has been specified
 			if (choice == PointerType.IMAGE_BASE_RELATIVE && mem != null) {
+				if (addrOffset == 0) {
+					// Done for consistency with old ImageBaseOffsetDataType.
+					// A 0 relative offset is considerd invalid (NaP)
+					return null;
+				}
 				// must ignore AddressSpaceSettingsDefinition
 				Address imageBase = mem.getProgram().getImageBase();
 				targetSpace = imageBase.getAddressSpace();
@@ -464,10 +472,16 @@ public class PointerDataType extends BuiltIn implements Pointer {
 			return null;
 		}
 
+		Long offset = getStoredOffset(buf, size);
+		if (offset == null) {
+			// Insufficient bytes
+			return null;
+		}
+
 		if (targetSpace instanceof SegmentedAddressSpace) {
 			try {
 				// NOTE: conversion assumes a little-endian space
-				return getSegmentedAddressValue(buf, size);
+				return getSegmentedAddressValue(buf, size, offset);
 			}
 			catch (AddressOutOfBoundsException e) {
 				// offset too large
@@ -482,14 +496,13 @@ public class PointerDataType extends BuiltIn implements Pointer {
 			return null;
 		}
 
-		Long offset = getStoredOffset(buf, size);
-		if (offset != null) {
-			try {
-				return targetSpace.getAddress(offset, true);
-			}
-			catch (AddressOutOfBoundsException e) {
-				// offset too large
-			}
+
+
+		try {
+			return targetSpace.getAddress(offset, true);
+		}
+		catch (AddressOutOfBoundsException e) {
+			// offset too large
 		}
 		return null;
 	}
@@ -503,27 +516,20 @@ public class PointerDataType extends BuiltIn implements Pointer {
 	 * @return address value returned as segmented Address object or null for
 	 *         unsupported pointer length or meory access error occurs.
 	 */
-	private static Address getSegmentedAddressValue(MemBuffer buf, int dataLen) {
+	private static Address getSegmentedAddressValue(MemBuffer buf, int dataLen, long storedOffset) {
 		SegmentedAddress a = (SegmentedAddress) buf.getAddress();
 		int segment = a.getSegment();
-		int offset = 0;
-		try {
-			switch (dataLen) {
-				case 2: // near pointer
-					offset = buf.getUnsignedShort(0);
-					break;
-				case 4: // far pointer
-					long value = buf.getUnsignedInt(0);
-					segment = (int) (value >> 16);
-					offset = (int) (value & 0xffff);
-					break;
-				default:
-					return null;
-			}
-
-		}
-		catch (MemoryAccessException e) {
-			return null;
+		int offset;
+		switch (dataLen) {
+			case 2: // near pointer
+				offset = (int) (storedOffset & 0xffff);
+				break;
+			case 4: // far pointer
+				segment = (int) ((storedOffset >> 16) & 0xffff);
+				offset = (int) (storedOffset & 0xffff);
+				break;
+			default:
+				return null;
 		}
 		SegmentedAddressSpace space = (SegmentedAddressSpace) a.getAddressSpace();
 		SegmentedAddress addr = space.getAddress(segment, offset);

Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/model/data/PointerTypeSettingsDefinition.java

@@ -43,7 +43,8 @@ public class PointerTypeSettingsDefinition
 	/**
 	 * Returns the format based on the specified settings
 	 * @param settings the instance settings or null for default value.
-	 * @return the format value (HEX, DECIMAL, BINARY, OCTAL, CHAR)
+	 * @return the {@link PointerType}.  {@link PointerType#DEFAULT} will be returned
+	 * if no setting has been made.
 	 */
 	public PointerType getType(Settings settings) {
 		if (settings == null) {