From 1752ee3c8b832fbca21b030c805260c7c2b882ce Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Fri, 29 Apr 2016 16:42:08 +0100
Subject: [PATCH] Retry errors which indicate the connection closed
 prematurely.

See discussion in #442
---
 amazonclouddrive/amazonclouddrive.go |  3 ---
 fs/closed_conn.go                    |  9 +++++++++
 fs/closed_conn_win.go                | 27 ++++++++++++++++++++++++++
 fs/error.go                          | 29 +++++++++++++++++++++++++++-
 4 files changed, 64 insertions(+), 4 deletions(-)
 create mode 100644 fs/closed_conn.go
 create mode 100644 fs/closed_conn_win.go

diff --git a/amazonclouddrive/amazonclouddrive.go b/amazonclouddrive/amazonclouddrive.go
index 40f852a34..80b2643bf 100644
--- a/amazonclouddrive/amazonclouddrive.go
+++ b/amazonclouddrive/amazonclouddrive.go
@@ -142,9 +142,6 @@ var retryErrorCodes = []int{
 // shouldRetry returns a boolean as to whether this resp and err
 // deserve to be retried.  It returns the err as a convenience
 func shouldRetry(resp *http.Response, err error) (bool, error) {
-	if err == io.EOF {
-		return true, err
-	}
 	return fs.ShouldRetry(err) || fs.ShouldRetryHTTP(resp, retryErrorCodes), err
 }
 
diff --git a/fs/closed_conn.go b/fs/closed_conn.go
new file mode 100644
index 000000000..dcf4974f9
--- /dev/null
+++ b/fs/closed_conn.go
@@ -0,0 +1,9 @@
+// +build !windows
+
+package fs
+
+// isClosedConnErrorPlatform reports whether err is an error from use
+// of a closed network connection using platform specific error codes.
+func isClosedConnErrorPlatform(err error) bool {
+	return false
+}
diff --git a/fs/closed_conn_win.go b/fs/closed_conn_win.go
new file mode 100644
index 000000000..6c843aace
--- /dev/null
+++ b/fs/closed_conn_win.go
@@ -0,0 +1,27 @@
+// +build windows
+
+package fs
+
+import (
+	"net"
+	"os"
+	"syscall"
+)
+
+// isClosedConnErrorPlatform reports whether err is an error from use
+// of a closed network connection using platform specific error codes.
+//
+// Code adapted from net/http
+func isClosedConnErrorPlatform(err error) bool {
+	if oe, ok := err.(*net.OpError); ok && oe.Op == "read" {
+		if se, ok := oe.Err.(*os.SyscallError); ok && se.Syscall == "wsarecv" {
+			if errno, ok := se.Err.(syscall.Errno); ok {
+				const WSAECONNABORTED syscall.Errno = 10053
+				if errno == syscall.WSAECONNRESET || errno == WSAECONNABORTED {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}
diff --git a/fs/error.go b/fs/error.go
index 820dd64b0..66d32af18 100644
--- a/fs/error.go
+++ b/fs/error.go
@@ -4,8 +4,10 @@ package fs
 
 import (
 	"fmt"
+	"io"
 	"net/http"
 	"net/url"
+	"strings"
 )
 
 // Retry is an optional interface for error as to whether the
@@ -56,14 +58,39 @@ func RetryError(err error) error {
 	return plainRetryError{err}
 }
 
+// isClosedConnError reports whether err is an error from use of a closed
+// network connection.
+//
+// Code adapted from net/http
+func isClosedConnError(err error) bool {
+	if err == nil {
+		return false
+	}
+
+	// Note that this error isn't exported so we have to do a
+	// string comparison :-(
+	str := err.Error()
+	if strings.Contains(str, "use of closed network connection") {
+		return true
+	}
+
+	return isClosedConnErrorPlatform(err)
+}
+
 // ShouldRetry looks at an error and tries to work out if retrying the
 // operation that caused it would be a good idea. It returns true if
-// the error implements Timeout() or Temporary() and it returns true.
+// the error implements Timeout() or Temporary() or if the error
+// indicates a premature closing of the connection.
 func ShouldRetry(err error) bool {
 	if err == nil {
 		return false
 	}
 
+	// Look for premature closing of connection
+	if err == io.EOF || err == io.ErrUnexpectedEOF || isClosedConnError(err) {
+		return true
+	}
+
 	// Unwrap url.Error
 	if urlErr, ok := err.(*url.Error); ok {
 		err = urlErr.Err