From 03778bd1d2c6ecea3b040fedad081f87e4f74317 Mon Sep 17 00:00:00 2001
From: Aaron Lehmann <aaron.lehmann@docker.com>
Date: Mon, 7 Dec 2015 17:28:10 -0800
Subject: [PATCH] Add missing bounds in ContinueOnError

ContinueOnError assumes that something of type errcode.Errors contains
at least one error. This is generally true, but might not be true if the
remote registry returns an empty error body or invalid JSON. Add the
bounds check, and in the case where it fails, allow fallbacks to v1.

Fixes #18481

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
---
 docs/registry.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/docs/registry.go b/docs/registry.go
index 6a0587a2..fc2959a5 100644
--- a/docs/registry.go
+++ b/docs/registry.go
@@ -213,6 +213,9 @@ func (e ErrNoSupport) Error() string {
 func ContinueOnError(err error) bool {
 	switch v := err.(type) {
 	case errcode.Errors:
+		if len(v) == 0 {
+			return true
+		}
 		return ContinueOnError(v[0])
 	case ErrNoSupport:
 		return ContinueOnError(v.Err)