Retry errors which indicate the connection closed prematurely.

See discussion in #442

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
+}