### Eclipse Workspace Patch 1.0
#P org.eclipse.jdt.core.tests.model
Index: src/org/eclipse/jdt/core/tests/model/AttachSourceTests.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/model/AttachSourceTests.java,v
retrieving revision 1.53
diff -u -r1.53 AttachSourceTests.java
--- src/org/eclipse/jdt/core/tests/model/AttachSourceTests.java	18 Apr 2008 15:41:55 -0000	1.53
+++ src/org/eclipse/jdt/core/tests/model/AttachSourceTests.java	21 Apr 2008 08:47:38 -0000
@@ -410,6 +410,45 @@
 	}
 }
 /*
+ * Ensures that root paths are correctly detected when attaching an external source folder to an external library folder.
+ * (regression test for https://bugs.eclipse.org/bugs/show_bug.cgi?id=227813 )
+ */
+public void testExternalFolder4() throws Exception {
+	try {
+		String externalFolder = getExternalFolder();
+		String[] pathsAndContents = 
+			new String[] {
+				"p/X.java",
+				"package p;\n" +
+				"public class X {\n" +
+				"}"
+			};
+		org.eclipse.jdt.core.tests.util.Util.createSourceDir(pathsAndContents, externalFolder + "/src227813/root1/subroot");
+		pathsAndContents = 
+			new String[] {
+				"q/X.java",
+				"package q;\n" +
+				"public class X {\n" +
+				"}"
+			};
+		org.eclipse.jdt.core.tests.util.Util.createSourceDir(pathsAndContents, externalFolder + "/src227813/root2/subroot");
+		
+		String externalLib = externalFolder + "/lib";
+		IJavaProject javaProject = createJavaProject("P", new String[0], new String[] {externalLib}, "");
+		IPackageFragmentRoot root = javaProject.getPackageFragmentRoot(externalLib);
+		attachSource(root, externalFolder + "/src227813", "");
+		IType type = root.getPackageFragment("p").getClassFile("X.class").getType();
+		assertSourceEquals(
+			"Unexpected source",
+			"public class X {\n" + 
+			"}",
+			type.getSource());
+	} finally {
+		deleteExternalResource("src227813");
+		deleteProject("P");
+	}
+}
+/*
  * Ensures that one can attach an external ZIP archive containing sources to a library folder.
  */
 public void testZIPArchive1() throws CoreException {
#P org.eclipse.jdt.core
Index: model/org/eclipse/jdt/internal/core/SourceMapper.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/SourceMapper.java,v
retrieving revision 1.133
diff -u -r1.133 SourceMapper.java
--- model/org/eclipse/jdt/internal/core/SourceMapper.java	18 Apr 2008 15:41:46 -0000	1.133
+++ model/org/eclipse/jdt/internal/core/SourceMapper.java	21 Apr 2008 08:47:39 -0000
@@ -414,7 +414,8 @@
 
 		Object target = JavaModel.getTarget(this.sourcePath, true);
 		if (target instanceof IContainer) {
-			computeRootPath((IContainer)target, firstLevelPackageNames, containsADefaultPackage, tempRoots);
+			IContainer folder = (IContainer)target;
+			computeRootPath(folder, firstLevelPackageNames, containsADefaultPackage, tempRoots, folder.getFullPath().segmentCount()/*if external folder, this is the linked folder path*/);
 		} else {
 			JavaModelManager manager = JavaModelManager.getJavaModelManager();
 			ZipFile zip = null;
@@ -485,7 +486,7 @@
 		}
 	}
 	
-	private void computeRootPath(IContainer container, HashSet firstLevelPackageNames, boolean hasDefaultPackage, Set set) {
+	private void computeRootPath(IContainer container, HashSet firstLevelPackageNames, boolean hasDefaultPackage, Set set, int sourcePathSegmentCount) {
 		try {
 			IResource[] resources = container.members();
 			boolean hasSubDirectories = false;
@@ -495,11 +496,11 @@
 					hasSubDirectories = true;
 					if (firstLevelPackageNames.contains(resource.getName())) {
 						IPath fullPath = container.getFullPath();
-						IPath rootPathEntry = fullPath.removeFirstSegments(this.sourcePath.segmentCount()).setDevice(null);
+						IPath rootPathEntry = fullPath.removeFirstSegments(sourcePathSegmentCount).setDevice(null);
 						set.add(rootPathEntry);
 						break loop;
 					} else {
-						computeRootPath((IFolder) resource, firstLevelPackageNames, hasDefaultPackage, set);
+						computeRootPath((IFolder) resource, firstLevelPackageNames, hasDefaultPackage, set, sourcePathSegmentCount);
 					}
 				}
 				if (i == max - 1 && !hasSubDirectories && hasDefaultPackage) {
@@ -513,13 +514,14 @@
 					}
 					if (hasJavaSourceFile) {
 						IPath fullPath = container.getFullPath();
-						IPath rootPathEntry = fullPath.removeFirstSegments(this.sourcePath.segmentCount()).setDevice(null);
+						IPath rootPathEntry = fullPath.removeFirstSegments(sourcePathSegmentCount).setDevice(null);
 						set.add(rootPathEntry);
 					}
 				}
 			}
 		} catch (CoreException e) {
 			// ignore
+			e.printStackTrace();
 		}
 	}