GP-6654: Fix state.get/setVar(size=0)

Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/pcode/exec/trace/TraceEmulationIntegration.java

@@ -761,6 +761,9 @@ public enum TraceEmulationIntegration {
 				value)) {
 				return;
 			}
+			if (length == 0) {
+				return;
+			}
 			Address end = address.addWrap(length - 1);
 			if (address.compareTo(end) <= 0) {
 				written.add(address, end);

Ghidra/Debug/Framework-TraceModeling/src/test/java/ghidra/pcode/exec/trace/BytesTracePcodeEmulatorTest.java

@@ -32,6 +32,7 @@ import ghidra.pcode.emu.PcodeEmulator;
 import ghidra.pcode.emu.PcodeThread;
 import ghidra.pcode.exec.*;
 import ghidra.pcode.exec.PcodeExecutorStatePiece.Reason;
+import ghidra.pcode.exec.trace.TraceEmulationIntegration.TraceWriter;
 import ghidra.pcode.exec.trace.TraceEmulationIntegration.Writer;
 import ghidra.program.model.address.Address;
 import ghidra.program.model.address.AddressRangeImpl;
@@ -55,6 +56,74 @@ public class BytesTracePcodeEmulatorTest extends AbstractTracePcodeEmulatorTest
 		return new PcodeEmulator(platform.getLanguage(), writer.callbacks());
 	}
 
+	@Test
+	public void testSetVarSize0() throws Throwable {
+		try (ToyDBTraceBuilder tb = new ToyDBTraceBuilder("Test", "x86:LE:64:default")) {
+			initTrace(tb, """
+					RIP = 0x00400000;
+					""",
+				List.of());
+
+			Writer writer = createWriter(tb.host, 0);
+			PcodeEmulator emu = createEmulator(tb.host, writer);
+
+			emu.getSharedState().setVar(tb.addr(0x00400000), 0, false, tb.arr());
+			TraceWriter tw = (TraceWriter) writer;
+			assertEquals(tb.set(), tw.memWritten);
+		}
+	}
+
+	@Test
+	public void testGetVarSize0Uninit() throws Throwable {
+		try (ToyDBTraceBuilder tb = new ToyDBTraceBuilder("Test", "x86:LE:64:default")) {
+			initTrace(tb, """
+					RIP = 0x00400000;
+					""",
+				List.of());
+
+			Writer writer = createWriter(tb.host, 0);
+			PcodeEmulator emu = createEmulator(tb.host, writer);
+			PcodeExecutorState<byte[]> state = emu.getSharedState();
+			Address addr = tb.addr(0x00400000);
+
+			byte[] result = state.getVar(addr, 0, false, Reason.EXECUTE_READ);
+			assertArrayEquals(new byte[0], result);
+
+			assertNull(state.getNextEntryInternal(addr.getAddressSpace(), 0));
+		}
+	}
+
+	@Test
+	public void testGetVarSize0Init() throws Throwable {
+		try (ToyDBTraceBuilder tb = new ToyDBTraceBuilder("Test", "x86:LE:64:default")) {
+			// Put some known data in a place likely to show in erroneous "uninitialized" set
+			initTrace(tb, """
+					RIP = 0x00400000;
+					*:8 RIP = 0xdeadbeefcafeface;
+					""",
+				List.of());
+
+			Writer writer = createWriter(tb.host, 0);
+			PcodeEmulator emu = createEmulator(tb.host, writer);
+			PcodeExecutorState<byte[]> state = emu.getSharedState();
+			Address addr = tb.addr(0x00400000);
+			state.setVar(addr, 4, false, tb.arr(1, 2, 3, 4));
+
+			var entry = state.getNextEntryInternal(addr.getAddressSpace(), 0);
+			assertEquals(0x00400000L, entry.getKey().longValue());
+			assertArrayEquals(tb.arr(1, 2, 3, 4), entry.getValue());
+			assertNull(state.getNextEntryInternal(addr.getAddressSpace(), 0x00400004));
+
+			byte[] result = state.getVar(addr, 0, false, Reason.EXECUTE_READ);
+			assertArrayEquals(tb.arr(), result);
+
+			entry = state.getNextEntryInternal(addr.getAddressSpace(), 0);
+			assertEquals(0x00400000L, entry.getKey().longValue());
+			assertArrayEquals(tb.arr(1, 2, 3, 4), entry.getValue());
+			assertNull(state.getNextEntryInternal(addr.getAddressSpace(), 0x00400004));
+		}
+	}
+
 	/**
 	 * Test a single instruction
 	 * 

Ghidra/Framework/Emulation/src/main/java/ghidra/pcode/exec/AbstractPcodeExecutorState.java

@@ -16,6 +16,7 @@
 package ghidra.pcode.exec;
 
 import java.util.Map;
+import java.util.Map.Entry;
 import java.util.stream.Stream;
 
 import ghidra.pcode.exec.PcodeArithmetic.Purpose;
@@ -103,4 +104,9 @@ public abstract class AbstractPcodeExecutorState<A, T> implements PcodeExecutorS
 	public void clear() {
 		piece.clear();
 	}
+
+	@Override
+	public Entry<Long, T> getNextEntryInternal(AddressSpace space, long offset) {
+		return piece.getNextEntryInternal(space, offset);
+	}
 }

Ghidra/Framework/Emulation/src/main/java/ghidra/pcode/exec/BytesPcodeExecutorStatePiece.java

@@ -15,6 +15,12 @@
  */
 package ghidra.pcode.exec;
 
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import generic.ULongSpan;
+import generic.ULongSpan.ULongSpanSet;
 import ghidra.program.model.address.AddressSpace;
 import ghidra.program.model.lang.Language;
 
@@ -45,4 +51,24 @@ public class BytesPcodeExecutorStatePiece
 	protected BytesPcodeExecutorStateSpace newSpace(AddressSpace space) {
 		return new BytesPcodeExecutorStateSpace(language, space, this);
 	}
+
+	@Override
+	public Entry<Long, byte[]> getNextEntryInternal(AddressSpace space, long offset) {
+		BytesPcodeExecutorStateSpace s = getForSpace(space, false);
+		if (s == null) {
+			return null;
+		}
+		ULongSpanSet initialized = s.bytes.getInitialized(0, -1);
+		ULongSpan span = initialized.spanContaining(offset);
+		if (span == null) {
+			var it = initialized.intersecting(ULongSpan.span(offset, -1)).iterator();
+			if (!it.hasNext()) {
+				return null;
+			}
+			span = it.next();
+		}
+		byte[] data = new byte[(int) span.length()];
+		s.bytes.getData(span.min(), data);
+		return Map.entry(span.min(), data);
+	}
 }

Ghidra/Framework/Emulation/src/main/java/ghidra/pcode/exec/BytesPcodeExecutorStateSpace.java

@@ -180,6 +180,9 @@ public class BytesPcodeExecutorStateSpace {
 	 * @return the uninitialized offset ranges
 	 */
 	protected AddressSetView computeUninitialized(long offset, int size) {
+		if (size == 0) {
+			return new AddressSet();
+		}
 		long max = offset + size - 1;
 		if (Long.compareUnsigned(max, space.getMaxAddress().getOffset()) <= 0 &&
 			Long.compareUnsigned(offset, max) <= 0) {

Ghidra/Framework/Emulation/src/main/java/ghidra/pcode/exec/PcodeStateCallbacks.java

@@ -55,6 +55,9 @@ public interface PcodeStateCallbacks {
 	 * @return the address set
 	 */
 	static AddressSet rngSet(AddressSpace space, long offset, int length) {
+		if (length == 0) {
+			return new AddressSet();
+		}
 		Address min = space.getAddress(offset);
 		return new AddressSet(min, min.add(length - 1));
 	}