LogDog: Add prefix registration endpoint.

appengine/logdog/coordinator/auth.go

Index: appengine/logdog/coordinator/auth.go
diff --git a/appengine/logdog/coordinator/auth.go b/appengine/logdog/coordinator/auth.go
index 6f85e80928ed24d3e9b23430b938e45206d207f3..d9fc6dc622b3a44d579dbd12c29594a9b62bb95e 100644
--- a/appengine/logdog/coordinator/auth.go
+++ b/appengine/logdog/coordinator/auth.go
@@ -45,7 +45,7 @@ func IsServiceUser(c context.Context) error {
 // IsProjectReader tests whether the current user belongs to one of the
 // project's declared reader groups.
 //
-// If the user is not a member of any groups, a MembershipError will be
+// If the user is not a member of any of the groups, a MembershipError will be
 // returned.
 func IsProjectReader(c context.Context, project luciConfig.ProjectName) error {
 	pcfg, err := GetServices(c).ProjectConfig(c, project)
@@ -55,6 +55,19 @@ func IsProjectReader(c context.Context, project luciConfig.ProjectName) error {
 	return checkMember(c, pcfg.ReaderAuthGroups...)
 }
 
+// IsProjectWriter tests whether the current user belongs to one of the
+// project's declared writer groups.
+//
+// If the user is not a member of any of the groups, a MembershipError will be
+// returned.
+func IsProjectWriter(c context.Context, project luciConfig.ProjectName) error {
+	pcfg, err := GetServices(c).ProjectConfig(c, project)
+	if err != nil {
+		return err
+	}
+	return checkMember(c, pcfg.WriterAuthGroups...)
+}
+
 func checkMember(c context.Context, groups ...string) error {
 	// On dev-appserver, the superuser has implicit group membership to
 	// everything.