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// Go support for Protocol Buffers - Google's data interchange format
//
// Copyright 2017 The Go Authors. All rights reserved.
// https://github.com/golang/protobuf
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package proto
import (
"fmt"
"reflect"
"strings"
)
// DiscardUnknown recursively discards all unknown fields from this message
// and all embedded messages.
//
// When unmarshaling a message with unrecognized fields, the tags and values
// of such fields are preserved in the Message. This allows a later call to
// marshal to be able to produce a message that continues to have those
// unrecognized fields. To avoid this, DiscardUnknown is used to
// explicitly clear the unknown fields after unmarshaling.
//
// For proto2 messages, the unknown fields of message extensions are only
// discarded from messages that have been accessed via GetExtension.
func DiscardUnknown(m Message) {
discardLegacy(m)
}
func discardLegacy(m Message) {
v := reflect.ValueOf(m)
if v.Kind() != reflect.Ptr || v.IsNil() {
return
}
v = v.Elem()
if v.Kind() != reflect.Struct {
return
}
t := v.Type()
for i := 0; i < v.NumField(); i++ {
f := t.Field(i)
if strings.HasPrefix(f.Name, "XXX_") {
continue
}
vf := v.Field(i)
tf := f.Type
// Unwrap tf to get its most basic type.
var isPointer, isSlice bool
if tf.Kind() == reflect.Slice && tf.Elem().Kind() != reflect.Uint8 {
isSlice = true
tf = tf.Elem()
}
if tf.Kind() == reflect.Ptr {
isPointer = true
tf = tf.Elem()
}
if isPointer && isSlice && tf.Kind() != reflect.Struct {
panic(fmt.Sprintf("%T.%s cannot be a slice of pointers to primitive types", m, f.Name))
}
switch tf.Kind() {
case reflect.Struct:
switch {
case !isPointer:
panic(fmt.Sprintf("%T.%s cannot be a direct struct value", m, f.Name))
case isSlice: // E.g., []*pb.T
for j := 0; j < vf.Len(); j++ {
discardLegacy(vf.Index(j).Interface().(Message))
}
default: // E.g., *pb.T
discardLegacy(vf.Interface().(Message))
}
case reflect.Map:
switch {
case isPointer || isSlice:
panic(fmt.Sprintf("%T.%s cannot be a pointer to a map or a slice of map values", m, f.Name))
default: // E.g., map[K]V
tv := vf.Type().Elem()
if tv.Kind() == reflect.Ptr && tv.Implements(protoMessageType) { // Proto struct (e.g., *T)
for _, key := range vf.MapKeys() {
val := vf.MapIndex(key)
discardLegacy(val.Interface().(Message))
}
}
}
case reflect.Interface:
// Must be oneof field.
switch {
case isPointer || isSlice:
panic(fmt.Sprintf("%T.%s cannot be a pointer to a interface or a slice of interface values", m, f.Name))
default: // E.g., test_proto.isCommunique_Union interface
if !vf.IsNil() && f.Tag.Get("protobuf_oneof") != "" {
vf = vf.Elem() // E.g., *test_proto.Communique_Msg
if !vf.IsNil() {
vf = vf.Elem() // E.g., test_proto.Communique_Msg
vf = vf.Field(0) // E.g., Proto struct (e.g., *T) or primitive value
if vf.Kind() == reflect.Ptr {
discardLegacy(vf.Interface().(Message))
}
}
}
}
}
}
if vf := v.FieldByName("XXX_unrecognized"); vf.IsValid() {
if vf.Type() != reflect.TypeOf([]byte{}) {
panic("expected XXX_unrecognized to be of type []byte")
}
vf.Set(reflect.ValueOf([]byte(nil)))
}
// For proto2 messages, only discard unknown fields in message extensions
// that have been accessed via GetExtension.
if em, ok := extendable(m); ok {
// Ignore lock since discardLegacy is not concurrency safe.
emm, _ := em.extensionsRead()
for _, mx := range emm {
if m, ok := mx.value.(Message); ok {
discardLegacy(m)
}
}
}
}
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