From da5cbc194a6fa337e0ae162da5c89605f8347232 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Tue, 25 Feb 2020 11:44:29 +0000
Subject: [PATCH] ftp: fix lockup on Close failures when using concurrency
 limit #3984

Before this change if rclone failed to close a file download for some
reason it would leak a concurrency token. When all the tokens were
leaked then rclone would lock up.

This fix returns the concurrency token regardless of the error status.
---
 backend/ftp/ftp.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/backend/ftp/ftp.go b/backend/ftp/ftp.go
index a818dd87b..f96e66a65 100644
--- a/backend/ftp/ftp.go
+++ b/backend/ftp/ftp.go
@@ -788,11 +788,13 @@ func (f *ftpReadCloser) Close() error {
 	case <-timer.C:
 		// if timer fired assume no error but connection dead
 		fs.Errorf(f.f, "Timeout when waiting for connection Close")
+		f.f.putFtpConnection(nil, nil)
 		return nil
 	}
 	// if errors while reading or closing, dump the connection
 	if err != nil || f.err != nil {
 		_ = f.c.Quit()
+		f.f.putFtpConnection(nil, nil)
 	} else {
 		f.f.putFtpConnection(&f.c, nil)
 	}