From d5f5ecb658c7a6a0f04939061494c9d404d393ce Mon Sep 17 00:00:00 2001
From: Victor Vieux <victor@docker.com>
Date: Fri, 13 Dec 2013 15:01:54 -0800
Subject: [PATCH] improve GetenvJson

---
 engine/env.go |  7 ++-----
 engine/job.go |  4 ++--
 server.go     | 10 +++++-----
 3 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/engine/env.go b/engine/env.go
index 588cdeab2..81c76d5ad 100644
--- a/engine/env.go
+++ b/engine/env.go
@@ -77,15 +77,12 @@ func (env *Env) GetList(key string) []string {
 	return l
 }
 
-func (env *Env) GetJson(key string) interface{} {
+func (env *Env) GetJson(key string, iface interface{}) error {
 	sval := env.Get(key)
 	if sval == "" {
 		return nil
 	}
-	var m interface{}
-	//Discard error on purpose
-	json.Unmarshal([]byte(sval), &m)
-	return m
+	return json.Unmarshal([]byte(sval), iface)
 }
 
 func (env *Env) SetJson(key string, value interface{}) error {
diff --git a/engine/job.go b/engine/job.go
index c7b510d47..e960cffda 100644
--- a/engine/job.go
+++ b/engine/job.go
@@ -126,8 +126,8 @@ func (job *Job) GetenvList(key string) []string {
 	return job.env.GetList(key)
 }
 
-func (job *Job) GetenvJson(key string) interface{} {
-	return job.env.GetJson(key)
+func (job *Job) GetenvJson(key string, iface interface{}) error {
+	return job.env.GetJson(key, iface)
 }
 
 func (job *Job) SetenvJson(key string, value interface{}) error {
diff --git a/server.go b/server.go
index e7bb73d4e..ee1ca939e 100644
--- a/server.go
+++ b/server.go
@@ -785,13 +785,13 @@ func (srv *Server) ContainerCommit(job *engine.Job) engine.Status {
 		job.Errorf("No such container: %s", name)
 		return engine.StatusErr
 	}
-	var config *Config
-	iConfig, ok := job.GetenvJson("config").(Config)
-	if ok {
-		config = &iConfig
+	var config Config
+	if err := job.GetenvJson("config", &config); err != nil {
+		job.Error(err)
+		return engine.StatusErr
 	}
 
-	img, err := srv.runtime.Commit(container, job.Getenv("repo"), job.Getenv("tag"), job.Getenv("comment"), job.Getenv("author"), config)
+	img, err := srv.runtime.Commit(container, job.Getenv("repo"), job.Getenv("tag"), job.Getenv("comment"), job.Getenv("author"), &config)
 	if err != nil {
 		job.Error(err)
 		return engine.StatusErr