Fix bugs in enumerate handler and s3's MaxEnumerateConfig.

Change-Id: Ib9cd52fe7d015a8c70416ec67ff6fd99a7a03d24

pkg/blobserver/handlers/enumerate.go

@@ -56,7 +56,7 @@ func handleEnumerateBlobs(conn http.ResponseWriter, req *http.Request, storage b
 	formValueAfter := req.FormValue("after")
 
 	maxEnumerate := defaultMaxEnumerate
-	if config, ok := storage.(blobserver.MaxEnumerateConfig); ok {
+	if config, ok := blobserver.Unwrap(storage).(blobserver.MaxEnumerateConfig); ok {
 		maxEnumerate = config.MaxEnumerate() - 1 // Since we'll add one below.
 	}
 

pkg/blobserver/interface.go

@@ -204,3 +204,14 @@ func MaybeWrapContext(sto Storage, req *http.Request) Storage {
 	}
 	return w.WrapContext(req)
 }
+
+// Unwrap returns the wrapped Storage interface, if wrapped, else returns sto.
+func Unwrap(sto interface{}) interface{} {
+	type get interface {
+		GetStorage() Storage
+	}
+	if g, ok := sto.(get); ok {
+		return Unwrap(g.GetStorage())
+	}
+	return sto
+}

pkg/blobserver/s3/enumerate.go

@@ -21,11 +21,14 @@ import (
 	"time"
 
 	"camlistore.org/pkg/blobref"
+	"camlistore.org/pkg/blobserver"
 )
 
 var _ = log.Printf
 
-func (sto *s3Storage) MaxEnumerate() uint { return 1000 }
+var _ blobserver.MaxEnumerateConfig = (*s3Storage)(nil)
+
+func (sto *s3Storage) MaxEnumerate() int { return 1000 }
 
 func (sto *s3Storage) EnumerateBlobs(dest chan<- blobref.SizedBlobRef, after string, limit int, wait time.Duration) error {
 	defer close(dest)

pkg/serverconfig/serverconfig.go

@@ -100,6 +100,12 @@ func (s *storageAndConfig) Config() *blobserver.Config {
 	return s.config
 }
 
+// GetStorage returns the unwrapped blobserver.Storage interface value for
+// callers to type-assert optional interface implementations on. (e.g. EnumeratorConfig)
+func (s *storageAndConfig) GetStorage() blobserver.Storage {
+	return s.Storage
+}
+
 func handleCamliUsingStorage(conn http.ResponseWriter, req *http.Request, action string, storage blobserver.StorageConfiger) {
 	handler := unsupportedHandler
 	switch req.Method {