From 3b91618d7d85822595fca15429e300ce32bc1a3b Mon Sep 17 00:00:00 2001
From: James Phillips <james@hashicorp.com>
Date: Wed, 24 Feb 2016 16:26:43 -0800
Subject: [PATCH] Changes to more idiomatic "ok" pattern for prefix getter.

---
 consul/acl.go                         |  6 +++---
 consul/prepared_query_endpoint.go     | 10 +++++-----
 consul/structs/prepared_query.go      |  9 +++++----
 consul/structs/prepared_query_test.go |  6 +++---
 4 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/consul/acl.go b/consul/acl.go
index 4fe4bb725..de305d04f 100644
--- a/consul/acl.go
+++ b/consul/acl.go
@@ -389,9 +389,9 @@ func (f *aclFilter) filterPreparedQueries(queries *structs.PreparedQueries) {
 	for _, query := range *queries {
 		// If no prefix ACL applies to this query then filter it, since
 		// we know at this point the user doesn't have a management
-		// token.
-		prefix := query.GetACLPrefix()
-		if prefix == nil || !f.acl.PreparedQueryRead(*prefix) {
+		// token, otherwise see what the policy says.
+		prefix, ok := query.GetACLPrefix()
+		if !ok || !f.acl.PreparedQueryRead(prefix) {
 			f.logger.Printf("[DEBUG] consul: dropping prepared query %q from result due to ACLs", query.ID)
 			continue
 		}
diff --git a/consul/prepared_query_endpoint.go b/consul/prepared_query_endpoint.go
index e17773e2c..7fc9ac86f 100644
--- a/consul/prepared_query_endpoint.go
+++ b/consul/prepared_query_endpoint.go
@@ -65,8 +65,8 @@ func (p *PreparedQuery) Apply(args *structs.PreparedQueryRequest, reply *string)
 	// If prefix ACLs apply to the incoming query, then do an ACL check. We
 	// need to make sure they have write access for whatever they are
 	// proposing.
-	if prefix := args.Query.GetACLPrefix(); prefix != nil {
-		if acl != nil && !acl.PreparedQueryWrite(*prefix) {
+	if prefix, ok := args.Query.GetACLPrefix(); ok {
+		if acl != nil && !acl.PreparedQueryWrite(prefix) {
 			p.srv.logger.Printf("[WARN] consul.prepared_query: Operation on prepared query '%s' denied due to ACLs", args.Query.ID)
 			return permissionDeniedErr
 		}
@@ -85,8 +85,8 @@ func (p *PreparedQuery) Apply(args *structs.PreparedQueryRequest, reply *string)
 			return fmt.Errorf("Cannot modify non-existent prepared query: '%s'", args.Query.ID)
 		}
 
-		if prefix := query.GetACLPrefix(); prefix != nil {
-			if acl != nil && !acl.PreparedQueryWrite(*prefix) {
+		if prefix, ok := query.GetACLPrefix(); ok {
+			if acl != nil && !acl.PreparedQueryWrite(prefix) {
 				p.srv.logger.Printf("[WARN] consul.prepared_query: Operation on prepared query '%s' denied due to ACLs", args.Query.ID)
 				return permissionDeniedErr
 			}
@@ -216,7 +216,7 @@ func (p *PreparedQuery) Get(args *structs.PreparedQuerySpecificRequest,
 			// always allowed to see it if they have the ID.
 			reply.Index = index
 			reply.Queries = structs.PreparedQueries{query}
-			if prefix := query.GetACLPrefix(); prefix == nil {
+			if _, ok := query.GetACLPrefix(); !ok {
 				return nil
 			}
 
diff --git a/consul/structs/prepared_query.go b/consul/structs/prepared_query.go
index 7d57e49a1..6058ca50f 100644
--- a/consul/structs/prepared_query.go
+++ b/consul/structs/prepared_query.go
@@ -73,13 +73,14 @@ type PreparedQuery struct {
 }
 
 // GetACLPrefix returns the prefix to look up the prepared_query ACL policy for
-// this query, or nil if such a policy doesn't apply.
-func (pq *PreparedQuery) GetACLPrefix() *string {
+// this query, and whether the prefix applies to this query. You always need to
+// check the ok value before using the prefix.
+func (pq *PreparedQuery) GetACLPrefix() (string, bool) {
 	if pq.Name != "" {
-		return &pq.Name
+		return pq.Name, true
 	}
 
-	return nil
+	return "", false
 }
 
 type PreparedQueries []*PreparedQuery
diff --git a/consul/structs/prepared_query_test.go b/consul/structs/prepared_query_test.go
index 4de25d2a3..b80fff897 100644
--- a/consul/structs/prepared_query_test.go
+++ b/consul/structs/prepared_query_test.go
@@ -6,12 +6,12 @@ import (
 
 func TestStructs_PreparedQuery_GetACLPrefix(t *testing.T) {
 	ephemeral := &PreparedQuery{}
-	if prefix := ephemeral.GetACLPrefix(); prefix != nil {
-		t.Fatalf("bad: %#v", prefix)
+	if prefix, ok := ephemeral.GetACLPrefix(); ok {
+		t.Fatalf("bad: %s", prefix)
 	}
 
 	named := &PreparedQuery{Name: "hello"}
-	if prefix := named.GetACLPrefix(); prefix == nil || *prefix != "hello" {
+	if prefix, ok := named.GetACLPrefix(); !ok || prefix != "hello" {
 		t.Fatalf("bad: %#v", prefix)
 	}
 }