From 24acda1afc24e668faf29340e76277edeb9db780 Mon Sep 17 00:00:00 2001
From: Jae Kwon <jae@tendermint.com>
Date: Sat, 11 Jul 2015 16:32:46 -0700
Subject: [PATCH] Distinguish between ReadJSON vs ReadJSONPtr.  The latter
 expects a non-nil pointer to write into.  The former creates new things
 intelligently

---
 binary/binary.go       | 30 +++++++++++++++++++++++++++++-
 node/node.go           |  2 +-
 rpc/server/handlers.go |  4 ++--
 state/genesis.go       |  2 +-
 4 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/binary/binary.go b/binary/binary.go
index 962eef98c..00b251163 100644
--- a/binary/binary.go
+++ b/binary/binary.go
@@ -16,6 +16,10 @@ var ErrBinaryReadSizeUnderflow = errors.New("Error: binary read size underflow")
 func ReadBinary(o interface{}, r io.Reader, n *int64, err *error) interface{} {
 	rv, rt := reflect.ValueOf(o), reflect.TypeOf(o)
 	if rv.Kind() == reflect.Ptr {
+		if rv.IsNil() {
+			rv = reflect.New(rt.Elem())
+			o = rv.Interface()
+		}
 		readReflectBinary(rv, rt, Options{}, r, n, err)
 		return o
 	} else {
@@ -51,10 +55,24 @@ func ReadJSON(o interface{}, bytes []byte, err *error) interface{} {
 	return ReadJSONObject(o, object, err)
 }
 
+func ReadJSONPtr(o interface{}, bytes []byte, err *error) interface{} {
+	var object interface{}
+	*err = json.Unmarshal(bytes, &object)
+	if *err != nil {
+		return o
+	}
+
+	return ReadJSONObjectPtr(o, object, err)
+}
+
 func ReadJSONObject(o interface{}, object interface{}, err *error) interface{} {
 	rv, rt := reflect.ValueOf(o), reflect.TypeOf(o)
 	if rv.Kind() == reflect.Ptr {
-		readReflectJSON(rv.Elem(), rt.Elem(), object, err)
+		if rv.IsNil() {
+			rv = reflect.New(rt.Elem())
+			o = rv.Interface()
+		}
+		readReflectJSON(rv, rt, object, err)
 		return o
 	} else {
 		ptrRv := reflect.New(rt)
@@ -63,6 +81,16 @@ func ReadJSONObject(o interface{}, object interface{}, err *error) interface{} {
 	}
 }
 
+func ReadJSONObjectPtr(o interface{}, object interface{}, err *error) interface{} {
+	rv, rt := reflect.ValueOf(o), reflect.TypeOf(o)
+	if rv.Kind() == reflect.Ptr {
+		readReflectJSON(rv.Elem(), rt.Elem(), object, err)
+		return o
+	} else {
+		panic("ReadJSON(Object)Ptr expects o to be a pointer")
+	}
+}
+
 func WriteJSON(o interface{}, w io.Writer, n *int64, err *error) {
 	rv := reflect.ValueOf(o)
 	rt := reflect.TypeOf(o)
diff --git a/node/node.go b/node/node.go
index 1075c1d7f..aa96606c9 100644
--- a/node/node.go
+++ b/node/node.go
@@ -69,7 +69,7 @@ func NewNode() *Node {
 	} else {
 		genDocBytes := stateDB.Get(sm.GenDocKey)
 		err := new(error)
-		binary.ReadJSON(&genDoc, genDocBytes, err)
+		binary.ReadJSONPtr(&genDoc, genDocBytes, err)
 		if *err != nil {
 			panic(Fmt("Unable to read gendoc from db: %v", err))
 		}
diff --git a/rpc/server/handlers.go b/rpc/server/handlers.go
index 77ecc5c92..be4733fd9 100644
--- a/rpc/server/handlers.go
+++ b/rpc/server/handlers.go
@@ -145,7 +145,7 @@ func jsonParamsToArgs(rpcFunc *RPCFunc, params []interface{}) ([]reflect.Value,
 func _jsonObjectToArg(ty reflect.Type, object interface{}) (reflect.Value, error) {
 	var err error
 	v := reflect.New(ty)
-	binary.ReadJSONObject(v.Interface(), object, &err)
+	binary.ReadJSONObjectPtr(v.Interface(), object, &err)
 	if err != nil {
 		return v, err
 	}
@@ -198,7 +198,7 @@ func httpParamsToArgs(rpcFunc *RPCFunc, r *http.Request) ([]reflect.Value, error
 func _jsonStringToArg(ty reflect.Type, arg string) (reflect.Value, error) {
 	var err error
 	v := reflect.New(ty)
-	binary.ReadJSON(v.Interface(), []byte(arg), &err)
+	binary.ReadJSONPtr(v.Interface(), []byte(arg), &err)
 	if err != nil {
 		return v, err
 	}
diff --git a/state/genesis.go b/state/genesis.go
index dfd333be4..c582cf5bb 100644
--- a/state/genesis.go
+++ b/state/genesis.go
@@ -58,7 +58,7 @@ type GenesisDoc struct {
 
 func GenesisDocFromJSON(jsonBlob []byte) (genState *GenesisDoc) {
 	var err error
-	binary.ReadJSON(&genState, jsonBlob, &err)
+	binary.ReadJSONPtr(&genState, jsonBlob, &err)
 	if err != nil {
 		log.Error(Fmt("Couldn't read GenesisDoc: %v", err))
 		os.Exit(1)