Propagate path.Parser in GotSymlink

Right now we assume that symbolic links always contain UNIX style paths.
This is not necessarily true. On systems like Windows, targets may not
only contain backslashes. They could also be prefixed with drive
letters.

Fixes: #190

pkg/filesystem/path/component_walker.go

@@ -23,7 +23,7 @@ type GotSymlink struct {
 	Parent ScopeWalker
 
 	// The contents of the symbolic link.
-	Target string
+	Target Parser
 }
 
 // GotDirectoryOrSymlink is a union type of GotDirectory and GotSymlink.

pkg/filesystem/path/loop_detecting_scope_walker_test.go

@@ -22,7 +22,7 @@ func TestLoopDetectingScopeWalker(t *testing.T) {
 		componentWalker := mock.NewMockComponentWalker(ctrl)
 		scopeWalker.EXPECT().OnRelative().Return(componentWalker, nil).Times(41)
 		componentWalker.EXPECT().OnTerminal(path.MustNewComponent("foo")).
-			Return(&path.GotSymlink{Parent: scopeWalker, Target: "foo"}, nil).
+			Return(&path.GotSymlink{Parent: scopeWalker, Target: path.MustNewUNIXParser("foo")}, nil).
 			Times(41)
 
 		require.Equal(
@@ -38,7 +38,7 @@ func TestLoopDetectingScopeWalker(t *testing.T) {
 		scopeWalker1.EXPECT().OnAbsolute().Return(componentWalker1, nil)
 		scopeWalker2 := mock.NewMockScopeWalker(ctrl)
 		componentWalker1.EXPECT().OnTerminal(path.MustNewComponent("tmp")).
-			Return(&path.GotSymlink{Parent: scopeWalker2, Target: "private/tmp"}, nil)
+			Return(&path.GotSymlink{Parent: scopeWalker2, Target: path.MustNewUNIXParser("private/tmp")}, nil)
 		componentWalker2 := mock.NewMockComponentWalker(ctrl)
 		scopeWalker2.EXPECT().OnRelative().Return(componentWalker2, nil)
 		componentWalker3 := mock.NewMockComponentWalker(ctrl)

pkg/filesystem/path/resolve.go

@@ -47,16 +47,17 @@ func (rs *resolverState) resolve() error {
 		case GotDirectory:
 			rs.componentWalker = rv.Child
 		case GotSymlink:
-			target, err := NewUNIXParser(rv.Target)
-			if err != nil {
-				return err
-			}
-			if err := rs.push(rv.Parent, target); err != nil {
+			if err := rs.push(rv.Parent, rv.Target); err != nil {
 				return err
 			}
 		default:
 			panic("Missing result")
-		case nil: // Do nothing
+		case nil:
+			// Parsed a terminal component. This should only be permitted at the
+			// very end of the path resolution process.
+			if len(rs.stack) > 0 {
+				panic("Parser.ParseFirstComponent() did not respect mustBeDirectory")
+			}
 		}
 	}
 

pkg/filesystem/path/resolve_test.go

@@ -108,7 +108,7 @@ func TestResolve(t *testing.T) {
 		scopeWalker1.EXPECT().OnRelative().Return(componentWalker1, nil)
 		scopeWalker2 := mock.NewMockScopeWalker(ctrl)
 		componentWalker1.EXPECT().OnTerminal(path.MustNewComponent("a")).
-			Return(&path.GotSymlink{Parent: scopeWalker2, Target: "b"}, nil)
+			Return(&path.GotSymlink{Parent: scopeWalker2, Target: path.MustNewUNIXParser("b")}, nil)
 		componentWalker2 := mock.NewMockComponentWalker(ctrl)
 		scopeWalker2.EXPECT().OnRelative().Return(componentWalker2, nil)
 		componentWalker2.EXPECT().OnTerminal(path.MustNewComponent("b"))
@@ -122,7 +122,7 @@ func TestResolve(t *testing.T) {
 		scopeWalker1.EXPECT().OnRelative().Return(componentWalker1, nil)
 		scopeWalker2 := mock.NewMockScopeWalker(ctrl)
 		componentWalker1.EXPECT().OnTerminal(path.MustNewComponent("a")).
-			Return(&path.GotSymlink{Parent: scopeWalker2, Target: "b/"}, nil)
+			Return(&path.GotSymlink{Parent: scopeWalker2, Target: path.MustNewUNIXParser("b/")}, nil)
 		componentWalker2 := mock.NewMockComponentWalker(ctrl)
 		scopeWalker2.EXPECT().OnRelative().Return(componentWalker2, nil)
 		componentWalker3 := mock.NewMockComponentWalker(ctrl)
@@ -138,7 +138,7 @@ func TestResolve(t *testing.T) {
 		scopeWalker1.EXPECT().OnRelative().Return(componentWalker1, nil)
 		scopeWalker2 := mock.NewMockScopeWalker(ctrl)
 		componentWalker1.EXPECT().OnDirectory(path.MustNewComponent("a")).
-			Return(path.GotSymlink{Parent: scopeWalker2, Target: "b"}, nil)
+			Return(path.GotSymlink{Parent: scopeWalker2, Target: path.MustNewUNIXParser("b")}, nil)
 		componentWalker2 := mock.NewMockComponentWalker(ctrl)
 		scopeWalker2.EXPECT().OnRelative().Return(componentWalker2, nil)
 		componentWalker3 := mock.NewMockComponentWalker(ctrl)
@@ -154,17 +154,17 @@ func TestResolve(t *testing.T) {
 		scopeWalker1.EXPECT().OnRelative().Return(componentWalker1, nil)
 		scopeWalker2 := mock.NewMockScopeWalker(ctrl)
 		componentWalker1.EXPECT().OnTerminal(path.MustNewComponent("a")).
-			Return(&path.GotSymlink{Parent: scopeWalker2, Target: "b/z"}, nil)
+			Return(&path.GotSymlink{Parent: scopeWalker2, Target: path.MustNewUNIXParser("b/z")}, nil)
 		componentWalker2 := mock.NewMockComponentWalker(ctrl)
 		scopeWalker2.EXPECT().OnRelative().Return(componentWalker2, nil)
 		scopeWalker3 := mock.NewMockScopeWalker(ctrl)
 		componentWalker2.EXPECT().OnDirectory(path.MustNewComponent("b")).
-			Return(path.GotSymlink{Parent: scopeWalker3, Target: "c/y"}, nil)
+			Return(path.GotSymlink{Parent: scopeWalker3, Target: path.MustNewUNIXParser("c/y")}, nil)
 		componentWalker3 := mock.NewMockComponentWalker(ctrl)
 		scopeWalker3.EXPECT().OnRelative().Return(componentWalker3, nil)
 		scopeWalker4 := mock.NewMockScopeWalker(ctrl)
 		componentWalker3.EXPECT().OnDirectory(path.MustNewComponent("c")).
-			Return(path.GotSymlink{Parent: scopeWalker4, Target: "x"}, nil)
+			Return(path.GotSymlink{Parent: scopeWalker4, Target: path.MustNewUNIXParser("x")}, nil)
 		componentWalker4 := mock.NewMockComponentWalker(ctrl)
 		scopeWalker4.EXPECT().OnRelative().Return(componentWalker4, nil)
 		componentWalker5 := mock.NewMockComponentWalker(ctrl)

pkg/filesystem/path/virtual_root_scope_walker_factory.go

@@ -22,7 +22,7 @@ type namelessVirtualRootNode struct {
 // that point into the root directory.
 type namedVirtualRootNode struct {
 	nameless namelessVirtualRootNode
-	target   string
+	target   Parser
 }
 
 // virtualRootNodeCreator is an implementation of ComponentWalker that
@@ -37,7 +37,7 @@ type virtualRootNodeCreator struct {
 func (cw *virtualRootNodeCreator) OnDirectory(name Component) (GotDirectoryOrSymlink, error) {
 	n, ok := cw.namelessNode.down[name]
 	if ok {
-		if n.nameless.isRoot || n.target != "" {
+		if n.nameless.isRoot || n.target != nil {
 			return nil, status.Error(codes.InvalidArgument, "Path resides at or below an already registered path")
 		}
 	} else {
@@ -129,7 +129,7 @@ func NewVirtualRootScopeWalkerFactory(rootPath string, aliases map[string]string
 
 	path, err := NewUNIXParser(rootPath)
 	if err != nil {
-		return nil, err
+		return nil, util.StatusWrapf(err, "Failed to parse root path %#v", rootPath)
 	}
 	if err := Resolve(path, rootPathWalker); err != nil {
 		return nil, util.StatusWrapf(err, "Failed to resolve root path %#v", rootPath)
@@ -139,11 +139,11 @@ func NewVirtualRootScopeWalkerFactory(rootPath string, aliases map[string]string
 	for alias, target := range aliases {
 		aliasPath, err := NewUNIXParser(alias)
 		if err != nil {
-			return nil, err
+			return nil, util.StatusWrapf(err, "Failed to parse alias path %#v", rootPath)
 		}
 		targetPath, err := NewUNIXParser(target)
 		if err != nil {
-			return nil, err
+			return nil, util.StatusWrapf(err, "Failed to parse target path %#v", targetPath)
 		}
 		// Resolve the location at which we want to create a fictive
 		// symlink that points into the virtual root directory.
@@ -165,7 +165,11 @@ func NewVirtualRootScopeWalkerFactory(rootPath string, aliases map[string]string
 		if err := Resolve(targetPath, targetPathWalker); err != nil {
 			return nil, util.StatusWrapf(err, "Failed to resolve alias target %#v", target)
 		}
-		aliasCreator.namedNode.target = targetPathBuilder.String()
+		parser, err := NewUNIXParser(targetPathBuilder.String())
+		if err != nil {
+			return nil, err
+		}
+		aliasCreator.namedNode.target = parser
 	}
 	return wf, nil
 }
@@ -242,7 +246,7 @@ func (cw *pendingVirtualRootComponentWalker) OnDirectory(name Component) (GotDir
 		// the full path.
 		return VoidComponentWalker.OnDirectory(name)
 	}
-	if n.target != "" {
+	if n.target != nil {
 		// Found an alias to the underlying root directory.
 		return GotSymlink{
 			Parent: cw.walker,

pkg/filesystem/path/virtual_root_scope_walker_factory_test.go

@@ -120,7 +120,7 @@ func TestVirtualRootScopeWalkerFactoryCreationSuccess(t *testing.T) {
 		componentWalker1.EXPECT().OnTerminal(path.MustNewComponent("a")).
 			Return(&path.GotSymlink{
 				Parent: scopeWalker2,
-				Target: "b",
+				Target: path.MustNewUNIXParser("b"),
 			}, nil)
 		componentWalker2 := mock.NewMockComponentWalker(ctrl)
 		scopeWalker2.EXPECT().OnRelative().Return(componentWalker2, nil)
@@ -139,7 +139,7 @@ func TestVirtualRootScopeWalkerFactoryCreationSuccess(t *testing.T) {
 		componentWalker1.EXPECT().OnTerminal(path.MustNewComponent("a")).
 			Return(&path.GotSymlink{
 				Parent: scopeWalker2,
-				Target: "/root/b",
+				Target: path.MustNewUNIXParser("/root/b"),
 			}, nil)
 		componentWalker2 := mock.NewMockComponentWalker(ctrl)
 		scopeWalker2.EXPECT().OnAbsolute().Return(componentWalker2, nil)
@@ -159,7 +159,7 @@ func TestVirtualRootScopeWalkerFactoryCreationSuccess(t *testing.T) {
 		componentWalker.EXPECT().OnTerminal(path.MustNewComponent("a")).
 			Return(&path.GotSymlink{
 				Parent: scopeWalker2,
-				Target: "/hello",
+				Target: path.MustNewUNIXParser("/hello"),
 			}, nil)
 
 		require.NoError(t, path.Resolve(path.MustNewUNIXParser("a"), factory.New(scopeWalker1)))