Add null check for Disassembly view source

Disassembly view is expected to be populated with lines that are fetched from a given source file. There might be the case where instructions on what lines to append are wrong. This results in a null response that will propagate through the code leading to a NPE.

The current commit is proofing the code from NPE by:
- removing the source position of the lines that were not found within the given file
- null checking the source before becoming a key element in the code flow
- adding logging if expected lines are not found in the given file

Resolves: #287

dsf/org.eclipse.cdt.dsf.ui/META-INF/MANIFEST.MF

@@ -3,7 +3,7 @@ Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-Vendor: %providerName
 Bundle-SymbolicName: org.eclipse.cdt.dsf.ui;singleton:=true
-Bundle-Version: 2.7.0.qualifier
+Bundle-Version: 2.7.100.qualifier
 Bundle-Activator: org.eclipse.cdt.dsf.internal.ui.DsfUIPlugin
 Bundle-Localization: plugin
 Require-Bundle: org.eclipse.ui;bundle-version="3.5.0",

dsf/org.eclipse.cdt.dsf.ui/src/org/eclipse/cdt/dsf/debug/internal/ui/disassembly/DisassemblyPart.java

@@ -2778,7 +2778,12 @@ public abstract class DisassemblyPart extends WorkbenchPart
 				if (lineAddr == null) {
 					fi.fLine2Addr[lineNr] = pos.fAddressOffset;
 					String source = fi.getLines(lineNr, last);
+					// Remove source position if the lines were not found
+					if (source == null) {
+						fDocument.removeSourcePosition(pos);
+					} else {
 						fDocument.insertSource(pos, source, lineNr, true);
+					}
 				} else {
 					final int comparison = lineAddr.compareTo(pos.fAddressOffset);
 					if (comparison > 0) {
@@ -2805,10 +2810,20 @@ public abstract class DisassemblyPart extends WorkbenchPart
 						}
 						fi.fLine2Addr[lineNr] = pos.fAddressOffset;
 						String source = fi.getLines(lineNr, last);
+						// Remove source position if the lines were not found
+						if (source == null) {
+							fDocument.removeSourcePosition(pos);
+						} else {
 							fDocument.insertSource(pos, source, lineNr, true);
+						}
 					} else if (comparison == 0) {
 						String source = fi.getLines(lineNr, last);
+						// Remove source position if the lines were not found
+						if (source == null) {
+							fDocument.removeSourcePosition(pos);
+						} else {
 							fDocument.insertSource(pos, source, lineNr, true);
+						}
 					} else {
 						// new source position is after old position
 						try {
@@ -2823,12 +2838,22 @@ public abstract class DisassemblyPart extends WorkbenchPart
 									fDocument.removeSourcePosition(pos);
 								} else {
 									String source = fi.getLines(lineNr, last);
+									// Remove source position if the lines were not found
+									if (source == null) {
+										fDocument.removeSourcePosition(pos);
+									} else {
 										fDocument.insertSource(pos, source, lineNr, true);
 									}
+								}
 							} else {
 								String source = fi.getLines(lineNr, last);
+								// Remove source position if the lines were not found
+								if (source == null) {
+									fDocument.removeSourcePosition(pos);
+								} else {
 									fDocument.insertSource(pos, source, lineNr, true);
 								}
+							}
 						} catch (BadPositionCategoryException e) {
 							internalError(e);
 						}

dsf/org.eclipse.cdt.dsf.ui/src/org/eclipse/cdt/dsf/debug/internal/ui/disassembly/model/DisassemblyDocument.java

@@ -1229,6 +1229,8 @@ public class DisassemblyDocument extends REDDocument implements IDisassemblyDocu
 	public SourcePosition insertSource(SourcePosition pos, String source, int line, boolean endOfSource) {
 		//		System.out.println("insertSource at "+getAddressText(pos.fAddressOffset));
 		//		System.out.println(source);
+		// Check if source is not null, so it won't trigger NullPointerException later
+		if (source != null) {
 			String sourceLines = source;
 			if (!source.isEmpty() && sourceLines.charAt(source.length() - 1) != '\n') {
 				sourceLines += "\n"; //$NON-NLS-1$
@@ -1245,8 +1247,8 @@ public class DisassemblyDocument extends REDDocument implements IDisassemblyDocu
 					if (pos.length > 0) {
 						SourcePosition oldPos = getSourcePosition(pos.offset + pos.length);
 						if (oldPos == null || oldPos.fAddressOffset.compareTo(pos.fAddressOffset) != 0) {
-						pos = new SourcePosition(pos.offset + pos.length, 0, pos.fAddressOffset, pos.fFileInfo, line,
+							pos = new SourcePosition(pos.offset + pos.length, 0, pos.fAddressOffset, pos.fFileInfo,
-								pos.fLast, false);
+									line, pos.fLast, false);
 							addSourcePosition(pos);
 							addModelPosition(pos);
 							addInvalidSourcePositions(pos);
@@ -1259,6 +1261,8 @@ public class DisassemblyDocument extends REDDocument implements IDisassemblyDocu
 			} catch (BadLocationException e) {
 				internalError(e);
 			}
+		}
+
 		return pos;
 	}
 

dsf/org.eclipse.cdt.dsf.ui/src/org/eclipse/cdt/dsf/debug/internal/ui/disassembly/model/SourceFileInfo.java

@@ -25,6 +25,7 @@ import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IStorage;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IStatus;
+import org.eclipse.core.runtime.Status;
 import org.eclipse.core.runtime.content.IContentType;
 import org.eclipse.core.runtime.jobs.Job;
 import org.eclipse.jface.text.BadLocationException;
@@ -147,6 +148,10 @@ public class SourceFileInfo {
 			}
 			return fSource.get(startOffset, endOffset - startOffset);
 		} catch (BadLocationException e) {
+			// Log error to indicate what is the cause of the issue
+			String warningMessage = "Line(s) " + Integer.toString(first) + "-" + Integer.toString(last) //$NON-NLS-1$
+					+ " cannot be found in file: " + fFileKey + ".\nSkipping lines!"; //$NON-NLS-1$
+			DsfUIPlugin.log(Status.warning(warningMessage, e));
 			return null;
 		}
 	}