eliminated panic when serving requests from empty registry v0.4.11

when generating an etag from a query that returns no results,
indexing into the byte slice caused that thread to panic.

now checking for a nil byte slice or a small byte slice in
handlers.go:46:getEtag()

on nil byte slice, return empty string for etag. on small
byte slice, don't truncate it, but return the whole thing.

1 files changed, 6 insertions, 0 deletions

diff --git a/svc/handlers.go b/svc/handlers.go
index ee58622..7ce4b77 100644
--- a/svc/handlers.go
+++ b/svc/handlers.go
@@ -45,6 +45,12 @@ func getEtagFromTime(modtime time.Time) string {
 // responses.
 func getEtag(data []byte) string {
 	bytes := fnv.New32().Sum(data)
+	if bytes == nil {
+		return ""
+	}
+	if len(bytes) < 16 {
+		return fmt.Sprintf("%x", bytes)
+	}
 	return fmt.Sprintf("%x", bytes[:16])
 }