touch: fix issue where directory is created instead of file

Detected on ftp, sftp and Dropbox backends.

Fixes #5952

cmd/touch/touch.go

@@ -5,11 +5,13 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"log"
 	"time"
 
 	"github.com/rclone/rclone/cmd"
 	"github.com/rclone/rclone/fs"
 	"github.com/rclone/rclone/fs/config/flags"
+	"github.com/rclone/rclone/fs/fspath"
 	"github.com/rclone/rclone/fs/object"
 	"github.com/rclone/rclone/fs/operations"
 	"github.com/spf13/cobra"
@@ -63,13 +65,32 @@ then add the ` + "`--localtime`" + ` flag.
 `,
 	Run: func(command *cobra.Command, args []string) {
 		cmd.CheckArgs(1, 1, command, args)
-		f, fileName := cmd.NewFsFile(args[0])
+		f, remote := newFsDst(args)
 		cmd.Run(true, false, command, func() error {
-			return Touch(context.Background(), f, fileName)
+			return Touch(context.Background(), f, remote)
 		})
 	},
 }
 
+// newFsDst creates a new dst fs from the arguments.
+//
+// The returned fs will never point to a file. It will point to the
+// parent directory of specified path, and is returned together with
+// the basename of file or directory, except if argument is only a
+// remote name. Similar to cmd.NewFsDstFile, but without raising fatal
+// when name of file or directory is empty (e.g. "remote:" or "remote:path/").
+func newFsDst(args []string) (f fs.Fs, remote string) {
+	root, remote, err := fspath.Split(args[0])
+	if err != nil {
+		log.Fatalf("Parsing %q failed: %v", args[0], err)
+	}
+	if root == "" {
+		root = "."
+	}
+	f = cmd.NewFsDir([]string{root})
+	return f, remote
+}
+
 // parseTimeArgument parses a timestamp string according to specific layouts
 func parseTimeArgument(timeString string) (time.Time, error) {
 	layout := defaultLayout
@@ -107,47 +128,51 @@ func createEmptyObject(ctx context.Context, remote string, modTime time.Time, f
 }
 
 // Touch create new file or change file modification time.
-func Touch(ctx context.Context, f fs.Fs, fileName string) error {
+func Touch(ctx context.Context, f fs.Fs, remote string) error {
 	t, err := timeOfTouch()
 	if err != nil {
 		return err
 	}
 	fs.Debugf(nil, "Touch time %v", t)
-	file, err := f.NewObject(ctx, fileName)
+	file, err := f.NewObject(ctx, remote)
 	if err != nil {
 		if errors.Is(err, fs.ErrorObjectNotFound) {
-			// Touch single non-existent file
+			// Touching non-existant path, possibly creating it as new file
+			if remote == "" {
+				fs.Logf(f, "Not touching empty directory")
+				return nil
+			}
 			if notCreateNewFile {
 				fs.Logf(f, "Not touching non-existent file due to --no-create")
 				return nil
 			}
 			if recursive {
+				// For consistency, --recursive never creates new files.
 				fs.Logf(f, "Not touching non-existent file due to --recursive")
 				return nil
 			}
 			if operations.SkipDestructive(ctx, f, "touch (create)") {
 				return nil
 			}
-			fs.Debugf(f, "Touching (creating)")
-			if err = createEmptyObject(ctx, fileName, t, f); err != nil {
+			fs.Debugf(f, "Touching (creating) %q", remote)
+			if err = createEmptyObject(ctx, remote, t, f); err != nil {
 				return fmt.Errorf("failed to touch (create): %w", err)
 			}
 		}
 		if errors.Is(err, fs.ErrorIsDir) {
+			// Touching existing directory
 			if recursive {
-				// Touch existing directory, recursive
-				fs.Debugf(nil, "Touching files in directory recursively")
-				return operations.TouchDir(ctx, f, t, true)
+				fs.Debugf(f, "Touching recursively files in directory %q", remote)
+				return operations.TouchDir(ctx, f, remote, t, true)
 			}
-			// Touch existing directory without recursing
-			fs.Debugf(nil, "Touching files in directory non-recursively")
-			return operations.TouchDir(ctx, f, t, false)
+			fs.Debugf(f, "Touching non-recursively files in directory %q", remote)
+			return operations.TouchDir(ctx, f, remote, t, false)
 		}
 		return err
 	}
 	// Touch single existing file
-	if !operations.SkipDestructive(ctx, fileName, "touch") {
-		fs.Debugf(f, "Touching %q", fileName)
+	if !operations.SkipDestructive(ctx, remote, "touch") {
+		fs.Debugf(f, "Touching %q", remote)
 		err = file.SetModTime(ctx, t)
 		if err != nil {
 			return fmt.Errorf("failed to touch: %w", err)