From 4846d9393d5dcd6993bbff9ec3f85ed813911e21 Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Tue, 15 Jan 2019 17:32:14 +0000
Subject: [PATCH] ftp: wait for 60 seconds for connection Close then declare it
 dead

This helps with indefinite hangs when transferring very large files on
some ftp server.

Fixes #2912
---
 backend/ftp/ftp.go | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/backend/ftp/ftp.go b/backend/ftp/ftp.go
index fafe6b702..fafe7bc53 100644
--- a/backend/ftp/ftp.go
+++ b/backend/ftp/ftp.go
@@ -646,7 +646,21 @@ func (f *ftpReadCloser) Read(p []byte) (n int, err error) {
 
 // Close the FTP reader and return the connection to the pool
 func (f *ftpReadCloser) Close() error {
-	err := f.rc.Close()
+	var err error
+	errchan := make(chan error, 1)
+	go func() {
+		errchan <- f.rc.Close()
+	}()
+	// Wait for Close for up to 60 seconds
+	timer := time.NewTimer(60 * time.Second)
+	select {
+	case err = <-errchan:
+		timer.Stop()
+	case <-timer.C:
+		// if timer fired assume no error but connection dead
+		fs.Errorf(f.f, "Timeout when waiting for connection Close")
+		return nil
+	}
 	// if errors while reading or closing, dump the connection
 	if err != nil || f.err != nil {
 		_ = f.c.Quit()