Commit a400b0e7 authored by Russ Cox's avatar Russ Cox

json: do not write to unexported fields

Fixes #977.
Fixes #451.

R=r, r2
CC=golang-dev
https://golang.org/cl/2246049
parent 00ffd59c
......@@ -82,6 +82,18 @@ func (e *UnmarshalTypeError) String() string {
return "json: cannot unmarshal " + e.Value + " into Go value of type " + e.Type.String()
}
// An UnmarshalFieldError describes a JSON object key that
// led to an unexported (and therefore unwritable) struct field.
type UnmarshalFieldError struct {
Key string
Type *reflect.StructType
Field reflect.StructField
}
func (e *UnmarshalFieldError) String() string {
return "json: cannot unmarshal object key " + strconv.Quote(e.Key) + " into unexported field " + e.Field.Name + " of type " + e.Type.String()
}
// An InvalidUnmarshalError describes an invalid argument passed to Unmarshal.
// (The argument to Unmarshal must be a non-nil pointer.)
type InvalidUnmarshalError struct {
......@@ -450,20 +462,32 @@ func (d *decodeState) object(v reflect.Value) {
if mv != nil {
subv = reflect.MakeZero(mv.Type().(*reflect.MapType).Elem())
} else {
var f reflect.StructField
var ok bool
// First try for field with that tag.
st := sv.Type().(*reflect.StructType)
for i := 0; i < sv.NumField(); i++ {
f := sv.Type().(*reflect.StructType).Field(i)
f = st.Field(i)
if f.Tag == key {
subv = sv.Field(i)
ok = true
break
}
}
if subv == nil {
if !ok {
// Second, exact match.
subv = sv.FieldByName(key)
if subv == nil {
// Third, case-insensitive match.
subv = sv.FieldByNameFunc(func(s string) bool { return matchName(key, s) })
f, ok = st.FieldByName(key)
}
if !ok {
// Third, case-insensitive match.
f, ok = st.FieldByNameFunc(func(s string) bool { return matchName(key, s) })
}
// Extract value; name must be exported.
if ok {
if f.PkgPath != "" {
d.saveError(&UnmarshalFieldError{key, st, f})
} else {
subv = sv.FieldByIndex(f.Index)
}
}
}
......
......@@ -17,6 +17,12 @@ type T struct {
Y int
}
type tx struct {
x int
}
var txType = reflect.Typeof((*tx)(nil)).(*reflect.PtrType).Elem().(*reflect.StructType)
type unmarshalTest struct {
in string
ptr interface{}
......@@ -36,6 +42,7 @@ var unmarshalTests = []unmarshalTest{
unmarshalTest{`"invalid: \uD834x\uDD1E"`, new(string), "invalid: \uFFFDx\uFFFD", nil},
unmarshalTest{"null", new(interface{}), nil, nil},
unmarshalTest{`{"X": [1,2,3], "Y": 4}`, new(T), T{Y: 4}, &UnmarshalTypeError{"array", reflect.Typeof("")}},
unmarshalTest{`{"x": 1}`, new(tx), tx{}, &UnmarshalFieldError{"x", txType, txType.Field(0)}},
// syntax errors
unmarshalTest{`{"X": "foo", "Y"}`, nil, nil, SyntaxError("invalid character '}' after object key")},
......
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