ftp: Improve performance to speed up --files-from and NewObject

This commit uses the MLST command (where available) to get the status
for single files rather than listing the parent directory and looking
for the file. This makes actions such as using `--files-from` much quicker.

* use getEntry to lookup remote files when supported
*  findItem now expects the full path directly

It makes the expected argument similar to the getInfo method, the
difference now is that one is returning a FileInfo whereas
the other is returning an ftp Entry.

Fixes #6225

Co-authored-by: Nick Craig-Wood <nick@craig-wood.com>

backend/ftp/ftp.go

@@ -657,8 +657,7 @@ func (f *Fs) dirFromStandardPath(dir string) string {
 // findItem finds a directory entry for the name in its parent directory
 func (f *Fs) findItem(ctx context.Context, remote string) (entry *ftp.Entry, err error) {
 	// defer fs.Trace(remote, "")("o=%v, err=%v", &o, &err)
-	fullPath := path.Join(f.root, remote)
+	if remote == "" || remote == "." || remote == "/" {
-	if fullPath == "" || fullPath == "." || fullPath == "/" {
 		// if root, assume exists and synthesize an entry
 		return &ftp.Entry{
 			Name: "",
@@ -666,13 +665,32 @@ func (f *Fs) findItem(ctx context.Context, remote string) (entry *ftp.Entry, err
 			Time: time.Now(),
 		}, nil
 	}
-	dir := path.Dir(fullPath)
-	base := path.Base(fullPath)
 
 	c, err := f.getFtpConnection(ctx)
 	if err != nil {
 		return nil, fmt.Errorf("findItem: %w", err)
 	}
+
+	// returns TRUE if MLST is supported which is required to call GetEntry
+	if c.IsTimePreciseInList() {
+		entry, err := c.GetEntry(f.opt.Enc.FromStandardPath(remote))
+		f.putFtpConnection(&c, err)
+		if err != nil {
+			err = translateErrorFile(err)
+			if err == fs.ErrorObjectNotFound {
+				return nil, nil
+			}
+			return nil, err
+		}
+		if entry != nil {
+			f.entryToStandard(entry)
+		}
+		return entry, nil
+	}
+
+	dir := path.Dir(remote)
+	base := path.Base(remote)
+
 	files, err := c.List(f.dirFromStandardPath(dir))
 	f.putFtpConnection(&c, err)
 	if err != nil {
@@ -691,7 +709,7 @@ func (f *Fs) findItem(ctx context.Context, remote string) (entry *ftp.Entry, err
 // it returns the error fs.ErrorObjectNotFound.
 func (f *Fs) NewObject(ctx context.Context, remote string) (o fs.Object, err error) {
 	// defer fs.Trace(remote, "")("o=%v, err=%v", &o, &err)
-	entry, err := f.findItem(ctx, remote)
+	entry, err := f.findItem(ctx, path.Join(f.root, remote))
 	if err != nil {
 		return nil, err
 	}
@@ -713,7 +731,7 @@ func (f *Fs) NewObject(ctx context.Context, remote string) (o fs.Object, err err
 
 // dirExists checks the directory pointed to by remote exists or not
 func (f *Fs) dirExists(ctx context.Context, remote string) (exists bool, err error) {
-	entry, err := f.findItem(ctx, remote)
+	entry, err := f.findItem(ctx, path.Join(f.root, remote))
 	if err != nil {
 		return false, fmt.Errorf("dirExists: %w", err)
 	}
@@ -857,32 +875,18 @@ func (f *Fs) PutStream(ctx context.Context, in io.Reader, src fs.ObjectInfo, opt
 // getInfo reads the FileInfo for a path
 func (f *Fs) getInfo(ctx context.Context, remote string) (fi *FileInfo, err error) {
 	// defer fs.Trace(remote, "")("fi=%v, err=%v", &fi, &err)
-	dir := path.Dir(remote)
+	file, err := f.findItem(ctx, remote)
-	base := path.Base(remote)
-
-	c, err := f.getFtpConnection(ctx)
 	if err != nil {
-		return nil, fmt.Errorf("getInfo: %w", err)
+		return nil, err
-	}
+	} else if file != nil {
-	files, err := c.List(f.dirFromStandardPath(dir))
+		info := &FileInfo{
-	f.putFtpConnection(&c, err)
+			Name:    remote,
-	if err != nil {
+			Size:    file.Size,
-		return nil, translateErrorFile(err)
+			ModTime: file.Time,
-	}
+			precise: f.fLstTime,
-
+			IsDir:   file.Type == ftp.EntryTypeFolder,
-	for i := range files {
-		file := files[i]
-		f.entryToStandard(file)
-		if file.Name == base {
-			info := &FileInfo{
-				Name:    remote,
-				Size:    file.Size,
-				ModTime: file.Time,
-				precise: f.fLstTime,
-				IsDir:   file.Type == ftp.EntryTypeFolder,
-			}
-			return info, nil
 		}
+		return info, nil
 	}
 	return nil, fs.ErrorObjectNotFound
 }