Stop manipulating symlink targets

lib/snapshot/copy_op.go

@@ -73,12 +73,7 @@ func NewCopyOperation(
 
 // Execute performs the actual copying of files specified by the CopyOperation.
 func (c *CopyOperation) Execute() error {
-	var err error
 	for _, src := range c.srcs {
-		src, err = evalSymlinks(src, c.srcRoot)
-		if err != nil {
-			return fmt.Errorf("eval symlinks for %s: %s", src, err)
-		}
 		src = filepath.Join(c.srcRoot, src)
 		fi, err := os.Lstat(src)
 		if err != nil {

lib/snapshot/mem_fs.go

@@ -112,7 +112,7 @@ func (fs *MemFS) Checkpoint(newRoot string, sources []string) error {
 			return fmt.Errorf("trim src %s: %s", src, err)
 		}
 		dst := filepath.Join(newRoot, trimmedSrc)
-		sourceInfo, err := os.Stat(src)
+		sourceInfo, err := os.Lstat(src)
 		if err != nil {
 			return fmt.Errorf("stat %s: %s", src, err)
 		}
@@ -337,12 +337,11 @@ func (fs *MemFS) createLayerByScan() (*memLayer, error) {
 //   - files copied to dir2
 //   - contents of dirs copied to dir2
 func (fs *MemFS) addToLayer(l *memLayer, c *CopyOperation) error {
-	var err error
 	createDst := true
 
 	if len(c.srcs) == 1 {
 		src := filepath.Join(c.srcRoot, c.srcs[0])
-		if fi, err := os.Stat(src); err != nil {
+		if fi, err := os.Lstat(src); err != nil {
 			return fmt.Errorf("stat src %s: %s", src, err)
 		} else if !fi.IsDir() {
 			// Case 1, no need to ensure dst exists explicitly.
@@ -363,10 +362,6 @@ func (fs *MemFS) addToLayer(l *memLayer, c *CopyOperation) error {
 	}
 
 	for _, src := range c.srcs {
-		src, err = evalSymlinks(src, c.srcRoot)
-		if err != nil {
-			return fmt.Errorf("eval symlinks for %s: %s", src, err)
-		}
 		src = filepath.Join(c.srcRoot, src)
 		if err := walk(src, nil, func(currSrc string, fi os.FileInfo) error {
 			var currDst string
@@ -577,13 +572,6 @@ func (fs *MemFS) untarOneItem(path string, header *tar.Header, r *tar.Reader) er
 			if err != nil {
 				return fmt.Errorf("read link %s: %s", linkTarget, err)
 			}
-
-			if filepath.IsAbs(linkTarget) {
-				linkTarget, err = pathutils.TrimRoot(linkTarget, fs.tree.src)
-				if err != nil {
-					return fmt.Errorf("trim link %s: %s", linkTarget, err)
-				}
-			}
 		}
 		localHeader, err := tar.FileInfoHeader(localInfo, linkTarget)
 		if err != nil {

lib/snapshot/mem_fs_test.go

@@ -55,19 +55,22 @@ func TestUntarFromPath(t *testing.T) {
 	require.NoError(err)
 	err = ioutil.WriteFile(filepath.Join(src, "target.txt"), []byte("TARGET"), 0677) // 6
 	require.NoError(err)
-	err = os.Symlink(filepath.Join(src, "target.txt"), filepath.Join(src, "mydir")) // 7
+	err = os.Symlink("/target.txt", filepath.Join(src, "mydir")) // 7
 	require.NoError(err)
 
 	err = CreateTarFromDirectory(filepath.Join(tmpBase, "archive1.tar"), src)
 	require.NoError(err)
 
-	// Files already existing under the memfs root.
+	// Files already exist under the memfs root.
 	err = os.Mkdir(filepath.Join(tmpRoot, "test1"), os.ModePerm)
 	require.NoError(err)
 	err = ioutil.WriteFile(filepath.Join(tmpRoot, "test1", "test1.txt"), []byte("TEST1"), 0677)
 	require.NoError(err)
 	err = os.Mkdir(filepath.Join(tmpRoot, "mydir"), os.ModePerm)
 	require.NoError(err)
+	err = os.Symlink(filepath.Join("/test1", "test1.txt"),
+		filepath.Join(tmpRoot, "test1", "abs_symlink.txt"))
+	require.NoError(err)
 
 	clk := clock.NewMock()
 	fs, err := NewMemFS(clk, tmpRoot, pathutils.DefaultBlacklist)
@@ -95,7 +98,7 @@ func TestUntarFromPath(t *testing.T) {
 
 	require.Equal(7, fs.layers[len(fs.layers)-1].count())
 
-	// Whiteout files already existing in the memfs.
+	// Whiteout files already exist in the memfs.
 	err = os.Mkdir(filepath.Join(src2, ".wh.test.txt"), os.ModePerm)
 	require.NoError(err)
 	err = os.Mkdir(filepath.Join(src2, ".wh.test1"), os.ModePerm)

lib/snapshot/mem_layer.go

@@ -172,7 +172,7 @@ func (l *memLayer) createHeader(root, src, dst string, fi os.FileInfo) (*tar.Hea
 		} else if !ok {
 			return nil, fmt.Errorf("symlink in tar header but not on disk: %s", src)
 		} else {
-			if filepath.IsAbs(target) {
+			if filepath.IsAbs(target) && strings.HasPrefix(target, root) {
 				target, err = pathutils.TrimRoot(target, root)
 				if err != nil {
 					return nil, fmt.Errorf("trim symlink root: %s", err)

lib/snapshot/utils.go

@@ -148,8 +148,8 @@ func resolveSymlink(p string, fi os.FileInfo) (bool, string, error) {
 	return true, target, nil
 }
 
-// CreateTarFromDirectory creates a tar archive containing the contents of the given
-// directory. It also compresses the contents with given compression level.
+// CreateTarFromDirectory creates a tar archive containing the contents of the
+// given directory. It also compresses the content with given compression level.
 func CreateTarFromDirectory(target, dir string) error {
 	file, err := os.Create(target)
 	if err != nil {
@@ -178,7 +178,8 @@ func CreateTarFromDirectory(target, dir string) error {
 	})
 }
 
-// tarOneItem writes the header and (optionally) data corresponding to p to the tar writer.
+// tarOneItem writes the header and (optionally) data corresponding to p to the
+// tar writer.
 func tarOneItem(root, p string, fi os.FileInfo, tw *tar.Writer, inodes map[uint64]string) error {
 	var err error
 	link := fi.Name()
@@ -187,10 +188,6 @@ func tarOneItem(root, p string, fi os.FileInfo, tw *tar.Writer, inodes map[uint6
 		if err != nil {
 			return fmt.Errorf("read link: %s", err)
 		}
-		link, err = pathutils.TrimRoot(link, root)
-		if err != nil {
-			return fmt.Errorf("trim link: %s", err)
-		}
 	}
 	hdr, err := tar.FileInfoHeader(fi, link)
 	if err != nil {