GP-743 fix DWARF handling of empty compile units and older gcc dwarf info

Ghidra/Features/Base/src/main/java/ghidra/app/util/bin/format/dwarf4/DIEAggregate.java

@@ -15,9 +15,10 @@
  */
 package ghidra.app.util.bin.format.dwarf4;
 
-import java.io.IOException;
 import java.util.*;
 
+import java.io.IOException;
+
 import org.apache.commons.lang3.ArrayUtils;
 
 import ghidra.app.util.bin.BinaryReader;
@@ -884,6 +885,30 @@ public class DIEAggregate {
 		throw new IOException("Bad/unsupported DW_AT_high_pc attribute value or type");
 	}
 
+	/**
+	 * Returns true if the raw lowPc and highPc values are the same.
+	 * <p>
+	 * This indicates an empty range, in which case the caller may want to take
+	 * special steps to avoid issues with Ghidra ranges.
+	 * <p>
+	 * Only seen in extremely old gcc versions.  Typically the low & high
+	 * pc values are omitted if the CU is empty.
+	 * 
+	 * @return boolean true if the LowPC and HighPC values are present and equal
+	 */
+	public boolean isLowPCEqualHighPC() {
+		AttrInfo low = findAttribute(DWARFAttribute.DW_AT_low_pc);
+		AttrInfo high = findAttribute(DWARFAttribute.DW_AT_high_pc);
+		if (low != null && high != null && low.form == high.form &&
+			low.attr instanceof DWARFNumericAttribute &&
+			high.attr instanceof DWARFNumericAttribute) {
+			DWARFNumericAttribute lowVal = (DWARFNumericAttribute) low.attr;
+			DWARFNumericAttribute highVal = (DWARFNumericAttribute) high.attr;
+			return lowVal.getValue() == highVal.getValue();
+		}
+		return false;
+	}
+
 	/**
 	 * A simple class used by findAttribute() to return the found attribute, along with
 	 * the DIE it was found in, and the DWARFForm type of the raw attribute.

Ghidra/Features/Base/src/main/java/ghidra/app/util/bin/format/dwarf4/DWARFCompileUnit.java

@@ -49,11 +49,14 @@ public class DWARFCompileUnit {
 		String comp_dir = diea.getString(DWARFAttribute.DW_AT_comp_dir, null);
 
 		Number high_pc = null, low_pc = null, language = null, stmt_list = null;
+
 		if (diea.hasAttribute(DWARFAttribute.DW_AT_low_pc)) {
 			low_pc = diea.getLowPC(0);
 		}
 
-		if (diea.hasAttribute(DWARFAttribute.DW_AT_high_pc)) {
+		// if lowPC and highPC values are the same, don't read the high value
+		// because Ghidra can't express an empty range.
+		if (diea.hasAttribute(DWARFAttribute.DW_AT_high_pc) && !diea.isLowPCEqualHighPC()) {
 			high_pc = diea.getHighPC();
 		}
 

Ghidra/Features/Base/src/test.slow/java/ghidra/app/util/bin/format/dwarf4/next/DWARFStaticVarImporterTest.java

@@ -0,0 +1,54 @@
+/* ###
+ * IP: GHIDRA
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package ghidra.app.util.bin.format.dwarf4.next;
+
+import static ghidra.app.util.bin.format.dwarf4.encoding.DWARFAttribute.*;
+import static org.junit.Assert.*;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+import ghidra.app.util.bin.format.dwarf4.*;
+import ghidra.app.util.bin.format.dwarf4.encoding.DWARFTag;
+import ghidra.app.util.bin.format.dwarf4.expression.DWARFExpressionOpCodes;
+import ghidra.program.model.data.IntegerDataType;
+import ghidra.program.model.listing.CodeUnit;
+import ghidra.program.model.listing.Data;
+import ghidra.util.exception.CancelledException;
+
+public class DWARFStaticVarImporterTest extends DWARFTestBase {
+
+	@Test
+	public void testIntStaticVar() throws CancelledException, IOException, DWARFException {
+		DebugInfoEntry intDIE = addInt(cu);
+		new DIECreator(DWARFTag.DW_TAG_variable)
+				.addString(DW_AT_name, "static_var1")
+				.addRef(DW_AT_type, intDIE)
+				.addBlock(DW_AT_location, DWARFExpressionOpCodes.DW_OP_addr, 0x10, 0x4, 0, 0, 0, 0,
+					0, 0)
+				.create(cu);
+
+		importFunctions();
+
+		CodeUnit cu = program.getListing().getCodeUnitAt(addr(0x410));
+		assertNotNull(cu);
+		assertEquals("static_var1", cu.getLabel());
+		assertEquals(4, cu.getLength());
+		assertTrue(((Data) cu).getDataType() instanceof IntegerDataType);
+	}
+
+}

Ghidra/Features/Base/src/test/java/ghidra/app/util/bin/format/dwarf4/DIECreator.java

@@ -87,6 +87,16 @@ public class DIECreator {
 		return this;
 	}
 
+	public DIECreator addBlock(int attribute, int... intBytes) {
+		byte[] bytes = new byte[intBytes.length];
+		for (int i = 0; i < bytes.length; i++) {
+			bytes[i] = (byte) intBytes[i];
+		}
+		attributes.put(attribute,
+			new AttrInfo(attribute, DWARFForm.DW_FORM_block1, new DWARFBlobAttribute(bytes)));
+		return this;
+	}
+
 	DWARFAbbreviation createAbbreviation(MockDWARFCompilationUnit cu) {
 		DWARFAttributeSpecification[] attrSpecs =
 			new DWARFAttributeSpecification[attributes.size()];
@@ -121,13 +131,15 @@ public class DIECreator {
 			die.addChild(childDIE);
 		}
 
-		cu.addMockEntry(die);
-
+		if (parent == null) {
+			parent = cu.getCompileUnitDIE();
+		}
 		if (parent != null) {
+			die.setParent(parent);
 			Assert.assertTrue(parent.getCompilationUnit() == cu);
 			parent.addChild(die);
-			die.setParent(parent);
 		}
+		cu.addMockEntry(die);
 
 		return die;
 	}

Ghidra/Features/Base/src/test/java/ghidra/app/util/bin/format/dwarf4/DWARFTestBase.java

@@ -32,6 +32,8 @@ import ghidra.app.util.bin.format.dwarf4.next.sectionprovider.NullSectionProvide
 import ghidra.program.database.ProgramBuilder;
 import ghidra.program.database.ProgramDB;
 import ghidra.program.database.data.DataTypeManagerDB;
+import ghidra.program.model.address.Address;
+import ghidra.program.model.address.AddressSpace;
 import ghidra.program.model.data.CategoryPath;
 import ghidra.program.model.data.DataTypeManager;
 import ghidra.test.AbstractGhidraHeadedIntegrationTest;
@@ -44,7 +46,10 @@ import ghidra.util.task.TaskMonitor;
  */
 public class DWARFTestBase extends AbstractGhidraHeadedIntegrationTest {
 
+	protected static final long BaseAddress = 0x400;
+
 	protected ProgramDB program;
+	protected AddressSpace space;
 	protected DataTypeManagerDB dataMgr;
 	protected DataTypeManager builtInDTM;
 	protected int transactionID;
@@ -62,10 +67,16 @@ public class DWARFTestBase extends AbstractGhidraHeadedIntegrationTest {
 	 */
 	@Before
 	public void setUp() throws Exception {
-		program = createDefaultProgram(testName.getMethodName(), ProgramBuilder._TOY, this);
+		program = createDefaultProgram(testName.getMethodName(), ProgramBuilder._X64, this);
+		space = program.getAddressFactory().getDefaultAddressSpace();
+
 		dataMgr = program.getDataTypeManager();
 		startTransaction();
 
+		program.getMemory()
+				.createInitializedBlock("test", addr(BaseAddress), 500, (byte) 0, TaskMonitor.DUMMY,
+					false);
+
 		AutoAnalysisManager mgr = AutoAnalysisManager.getAnalysisManager(program);
 		DataTypeManagerService dtms = mgr.getDataTypeManagerService();
 		builtInDTM = dtms.getBuiltInDataTypesManager();
@@ -113,6 +124,16 @@ public class DWARFTestBase extends AbstractGhidraHeadedIntegrationTest {
 		dwarfDTM.importAllDataTypes(monitor);
 	}
 
+	protected void importFunctions() throws CancelledException, IOException, DWARFException {
+		dwarfProg.checkPreconditions(monitor);
+		dwarfDTM.importAllDataTypes(monitor);
+		
+		DWARFImportSummary importSummary = new DWARFImportSummary();
+		DWARFFunctionImporter dfi =
+			new DWARFFunctionImporter(dwarfProg, dwarfDTM, importOptions, importSummary, monitor);
+		dfi.importFunctions();
+	}
+
 	protected DIEAggregate getAggregate(DebugInfoEntry die)
 			throws CancelledException, IOException, DWARFException {
 		dwarfProg.setCurrentCompilationUnit(die.getCompilationUnit(), monitor);
@@ -278,4 +299,7 @@ public class DWARFTestBase extends AbstractGhidraHeadedIntegrationTest {
 		return arrayType;
 	}
 
+	protected Address addr(long l) {
+		return space.getAddress(l);
+	}
 }

Ghidra/Features/Base/src/test/java/ghidra/app/util/bin/format/dwarf4/MockDWARFCompilationUnit.java

@@ -18,13 +18,14 @@ package ghidra.app.util.bin.format.dwarf4;
 import java.util.ArrayList;
 import java.util.List;
 
-import ghidra.app.util.bin.format.dwarf4.encoding.DWARFIdentifierCase;
+import ghidra.app.util.bin.format.dwarf4.encoding.*;
 import ghidra.app.util.bin.format.dwarf4.next.DWARFProgram;
 import ghidra.util.task.TaskMonitor;
 
 public class MockDWARFCompilationUnit extends DWARFCompilationUnit {
 
 	private List<DebugInfoEntry> mockEntries = new ArrayList<>();
+	private DebugInfoEntry compUnitDIE;
 
 	public MockDWARFCompilationUnit(DWARFProgram dwarfProgram, long startOffset, long endOffset,
 			long length, int format, short version, long abbreviationOffset, byte pointerSize,
@@ -35,6 +36,9 @@ public class MockDWARFCompilationUnit extends DWARFCompilationUnit {
 		setCompileUnit(
 			new DWARFCompileUnit("Mock Comp Unit", "Mock Comp Unit Producer", "Mock Comp Unit Dir",
 				0, 0, 0, 0, DWARFIdentifierCase.DW_ID_case_insensitive, false, null));
+		compUnitDIE = new DIECreator(DWARFTag.DW_TAG_compile_unit)
+				.addString(DWARFAttribute.DW_AT_name, "MockCompUnit" + compUnitNumber)
+				.create(this);
 	}
 
 	@Override
@@ -42,6 +46,10 @@ public class MockDWARFCompilationUnit extends DWARFCompilationUnit {
 		dies.addAll(mockEntries);
 	}
 
+	public DebugInfoEntry getCompileUnitDIE() {
+		return compUnitDIE;
+	}
+
 	public void addMockEntry(DebugInfoEntry die) {
 		mockEntries.add(die);
 	}