fix: download folders through symlink roots

hotline/file_transfer.go

@@ -13,6 +13,7 @@ import (
 	"math"
 	"os"
 	"path"
+	"path/filepath"
 	"slices"
 	"strings"
 	"sync"
@@ -404,6 +405,15 @@ func DownloadFolderHandler(rwc io.ReadWriter, fullPath string, fileTransfer *Fil
 	// This notifies the server to send the next item header
 
 	basePathLen := len(fullPath)
+	walkRoot := fullPath + "/"
+	if target, err := fileStore.ReadLink(fullPath); err == nil {
+		if !filepath.IsAbs(target) {
+			target = filepath.Join(filepath.Dir(fullPath), target)
+		}
+		if targetInfo, err := fileStore.Stat(target); err == nil && targetInfo.IsDir() {
+			walkRoot = target
+		}
+	}
 
 	rLogger.Info("Start folder download", "path", fullPath)
 
@@ -413,25 +423,36 @@ func DownloadFolderHandler(rwc io.ReadWriter, fullPath string, fileTransfer *Fil
 	}
 
 	i := 0
-	err := fileStore.Walk(fullPath+"/", func(path string, info os.FileInfo, err error) error {
+	err := fileStore.Walk(walkRoot, func(walkPath string, info os.FileInfo, err error) error {
 		//s.Stats.DownloadCounter += 1
 		i += 1
 
 		if err != nil {
 			return err
 		}
+		displayPath := walkPath
+		if filepath.Clean(walkRoot) != filepath.Clean(fullPath+"/") {
+			relativePath, err := filepath.Rel(walkRoot, walkPath)
+			if err != nil {
+				return fmt.Errorf("map symlink download path: %w", err)
+			}
+			displayPath = fullPath + string(filepath.Separator)
+			if relativePath != "." {
+				displayPath = filepath.Join(fullPath, relativePath)
+			}
+		}
 
 		// skip dot files
 		if strings.HasPrefix(info.Name(), ".") {
 			return nil
 		}
 
-		hlFile, err := NewFile(fileStore, path, 0)
+		hlFile, err := NewFile(fileStore, walkPath, 0)
 		if err != nil {
 			return err
 		}
 
-		subPath := path[basePathLen+1:]
+		subPath := displayPath[basePathLen+1:]
 
 		if i == 1 {
 			return nil
@@ -496,14 +517,18 @@ func DownloadFolderHandler(rwc io.ReadWriter, fullPath string, fileTransfer *Fil
 			return fmt.Errorf("error sending flat file object: %w", err)
 		}
 
-		file, err := fileStore.Open(path)
+		file, err := fileStore.Open(walkPath)
 		if err != nil {
 			return fmt.Errorf("error opening file: %w", err)
 		}
 
 		if _, err = io.Copy(rwc, io.TeeReader(file, fileTransfer.bytesSentCounter)); err != nil {
+			_ = file.Close()
 			return fmt.Errorf("error sending file: %w", err)
 		}
+		if err := file.Close(); err != nil {
+			return fmt.Errorf("error closing file: %w", err)
+		}
 
 		if nextAction[1] != 2 && hlFile.Ffo.FlatFileHeader.ForkCount[1] == 3 {
 			err = binary.Write(rwc, binary.BigEndian, hlFile.rsrcForkHeader())
@@ -517,8 +542,12 @@ func DownloadFolderHandler(rwc io.ReadWriter, fullPath string, fileTransfer *Fil
 			}
 
 			if _, err = io.Copy(rwc, io.TeeReader(rFile, fileTransfer.bytesSentCounter)); err != nil {
+				_ = rFile.Close()
 				return fmt.Errorf("error sending resource fork: %w", err)
 			}
+			if err := rFile.Close(); err != nil {
+				return fmt.Errorf("error closing resource fork: %w", err)
+			}
 		}
 
 		// Read the client's Next Action request.  This is always 3, I think?

hotline/file_transfer_handlers_test.go

@@ -286,6 +286,19 @@ func runFolderDownloadClient(t *testing.T, conn net.Conn, nExpected int) []downl
 	return got
 }
 
+type symlinkRootFileStore struct {
+	*OSFileStore
+	linkName string
+	target   string
+}
+
+func (s *symlinkRootFileStore) ReadLink(name string) (string, error) {
+	if filepath.Clean(name) == filepath.Clean(s.linkName) {
+		return s.target, nil
+	}
+	return s.OSFileStore.ReadLink(name)
+}
+
 func TestDownloadFolderHandler(t *testing.T) {
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
 
@@ -333,6 +346,35 @@ func TestDownloadFolderHandler(t *testing.T) {
 		assert.Equal(t, []byte("bbbbb"), byName[filepath.Join("sub", "b.txt")].data)
 	})
 
+	t.Run("streams files from a symlinked root", func(t *testing.T) {
+		dir := t.TempDir()
+		fileStore := &symlinkRootFileStore{OSFileStore: &OSFileStore{}}
+
+		root := filepath.Join(dir, "share")
+		fileStore.linkName = root
+		target := filepath.Join(dir, "actual-share")
+		fileStore.target = filepath.Base(target) // Symlink targets are often relative to their parent.
+		require.NoError(t, os.Mkdir(root, 0755))
+		require.NoError(t, os.Mkdir(target, 0755))
+		require.NoError(t, os.WriteFile(filepath.Join(target, "a.txt"), []byte("from target"), 0644))
+
+		serverConn, clientConn := net.Pipe()
+		require.NoError(t, clientConn.SetDeadline(time.Now().Add(10*time.Second)))
+
+		ft := &FileTransfer{bytesSentCounter: &WriteCounter{}}
+		errCh := make(chan error, 1)
+		go func() {
+			errCh <- DownloadFolderHandler(serverConn, root, ft, fileStore, logger, true)
+			_ = serverConn.Close()
+		}()
+
+		got := runFolderDownloadClient(t, clientConn, 1)
+		require.NoError(t, <-errCh)
+		require.Len(t, got, 1)
+		assert.Equal(t, "a.txt", got[0].name)
+		assert.Equal(t, []byte("from target"), got[0].data)
+	})
+
 	t.Run("honors a resume request for a file", func(t *testing.T) {
 		dir := t.TempDir()
 		fileStore := &OSFileStore{}