1 // Go support for Protocol Buffers - Google's data interchange format 2 // 3 // Copyright 2011 The Go Authors. All rights reserved. 4 // https://github.com/golang/protobuf 5 // 6 // Redistribution and use in source and binary forms, with or without 7 // modification, are permitted provided that the following conditions are 8 // met: 9 // 10 // * Redistributions of source code must retain the above copyright 11 // notice, this list of conditions and the following disclaimer. 12 // * Redistributions in binary form must reproduce the above 13 // copyright notice, this list of conditions and the following disclaimer 14 // in the documentation and/or other materials provided with the 15 // distribution. 16 // * Neither the name of Google Inc. nor the names of its 17 // contributors may be used to endorse or promote products derived from 18 // this software without specific prior written permission. 19 // 20 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 23 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 24 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 25 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 26 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 30 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 32 // Protocol buffer deep copy and merge. 33 // TODO: RawMessage. 34 35 package proto 36 37 import ( 38 "fmt" 39 "log" 40 "reflect" 41 "strings" 42 ) 43 44 // Clone returns a deep copy of a protocol buffer. 45 func Clone(src Message) Message { 46 in := reflect.ValueOf(src) 47 if in.IsNil() { 48 return src 49 } 50 out := reflect.New(in.Type().Elem()) 51 dst := out.Interface().(Message) 52 Merge(dst, src) 53 return dst 54 } 55 56 // Merger is the interface representing objects that can merge messages of the same type. 57 type Merger interface { 58 // Merge merges src into this message. 59 // Required and optional fields that are set in src will be set to that value in dst. 60 // Elements of repeated fields will be appended. 61 // 62 // Merge may panic if called with a different argument type than the receiver. 63 Merge(src Message) 64 } 65 66 // generatedMerger is the custom merge method that generated protos will have. 67 // We must add this method since a generate Merge method will conflict with 68 // many existing protos that have a Merge data field already defined. 69 type generatedMerger interface { 70 XXX_Merge(src Message) 71 } 72 73 // Merge merges src into dst. 74 // Required and optional fields that are set in src will be set to that value in dst. 75 // Elements of repeated fields will be appended. 76 // Merge panics if src and dst are not the same type, or if dst is nil. 77 func Merge(dst, src Message) { 78 if m, ok := dst.(Merger); ok { 79 m.Merge(src) 80 return 81 } 82 83 in := reflect.ValueOf(src) 84 out := reflect.ValueOf(dst) 85 if out.IsNil() { 86 panic("proto: nil destination") 87 } 88 if in.Type() != out.Type() { 89 panic(fmt.Sprintf("proto.Merge(%T, %T) type mismatch", dst, src)) 90 } 91 if in.IsNil() { 92 return // Merge from nil src is a noop 93 } 94 if m, ok := dst.(generatedMerger); ok { 95 m.XXX_Merge(src) 96 return 97 } 98 mergeStruct(out.Elem(), in.Elem()) 99 } 100 101 func mergeStruct(out, in reflect.Value) { 102 sprop := GetProperties(in.Type()) 103 for i := 0; i < in.NumField(); i++ { 104 f := in.Type().Field(i) 105 if strings.HasPrefix(f.Name, "XXX_") { 106 continue 107 } 108 mergeAny(out.Field(i), in.Field(i), false, sprop.Prop[i]) 109 } 110 111 if emIn, err := extendable(in.Addr().Interface()); err == nil { 112 emOut, _ := extendable(out.Addr().Interface()) 113 mIn, muIn := emIn.extensionsRead() 114 if mIn != nil { 115 mOut := emOut.extensionsWrite() 116 muIn.Lock() 117 mergeExtension(mOut, mIn) 118 muIn.Unlock() 119 } 120 } 121 122 uf := in.FieldByName("XXX_unrecognized") 123 if !uf.IsValid() { 124 return 125 } 126 uin := uf.Bytes() 127 if len(uin) > 0 { 128 out.FieldByName("XXX_unrecognized").SetBytes(append([]byte(nil), uin...)) 129 } 130 } 131 132 // mergeAny performs a merge between two values of the same type. 133 // viaPtr indicates whether the values were indirected through a pointer (implying proto2). 134 // prop is set if this is a struct field (it may be nil). 135 func mergeAny(out, in reflect.Value, viaPtr bool, prop *Properties) { 136 if in.Type() == protoMessageType { 137 if !in.IsNil() { 138 if out.IsNil() { 139 out.Set(reflect.ValueOf(Clone(in.Interface().(Message)))) 140 } else { 141 Merge(out.Interface().(Message), in.Interface().(Message)) 142 } 143 } 144 return 145 } 146 switch in.Kind() { 147 case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64, 148 reflect.String, reflect.Uint32, reflect.Uint64: 149 if !viaPtr && isProto3Zero(in) { 150 return 151 } 152 out.Set(in) 153 case reflect.Interface: 154 // Probably a oneof field; copy non-nil values. 155 if in.IsNil() { 156 return 157 } 158 // Allocate destination if it is not set, or set to a different type. 159 // Otherwise we will merge as normal. 160 if out.IsNil() || out.Elem().Type() != in.Elem().Type() { 161 out.Set(reflect.New(in.Elem().Elem().Type())) // interface -> *T -> T -> new(T) 162 } 163 mergeAny(out.Elem(), in.Elem(), false, nil) 164 case reflect.Map: 165 if in.Len() == 0 { 166 return 167 } 168 if out.IsNil() { 169 out.Set(reflect.MakeMap(in.Type())) 170 } 171 // For maps with value types of *T or []byte we need to deep copy each value. 172 elemKind := in.Type().Elem().Kind() 173 for _, key := range in.MapKeys() { 174 var val reflect.Value 175 switch elemKind { 176 case reflect.Ptr: 177 val = reflect.New(in.Type().Elem().Elem()) 178 mergeAny(val, in.MapIndex(key), false, nil) 179 case reflect.Slice: 180 val = in.MapIndex(key) 181 val = reflect.ValueOf(append([]byte{}, val.Bytes()...)) 182 default: 183 val = in.MapIndex(key) 184 } 185 out.SetMapIndex(key, val) 186 } 187 case reflect.Ptr: 188 if in.IsNil() { 189 return 190 } 191 if out.IsNil() { 192 out.Set(reflect.New(in.Elem().Type())) 193 } 194 mergeAny(out.Elem(), in.Elem(), true, nil) 195 case reflect.Slice: 196 if in.IsNil() { 197 return 198 } 199 if in.Type().Elem().Kind() == reflect.Uint8 { 200 // []byte is a scalar bytes field, not a repeated field. 201 202 // Edge case: if this is in a proto3 message, a zero length 203 // bytes field is considered the zero value, and should not 204 // be merged. 205 if prop != nil && prop.proto3 && in.Len() == 0 { 206 return 207 } 208 209 // Make a deep copy. 210 // Append to []byte{} instead of []byte(nil) so that we never end up 211 // with a nil result. 212 out.SetBytes(append([]byte{}, in.Bytes()...)) 213 return 214 } 215 n := in.Len() 216 if out.IsNil() { 217 out.Set(reflect.MakeSlice(in.Type(), 0, n)) 218 } 219 switch in.Type().Elem().Kind() { 220 case reflect.Bool, reflect.Float32, reflect.Float64, reflect.Int32, reflect.Int64, 221 reflect.String, reflect.Uint32, reflect.Uint64: 222 out.Set(reflect.AppendSlice(out, in)) 223 default: 224 for i := 0; i < n; i++ { 225 x := reflect.Indirect(reflect.New(in.Type().Elem())) 226 mergeAny(x, in.Index(i), false, nil) 227 out.Set(reflect.Append(out, x)) 228 } 229 } 230 case reflect.Struct: 231 mergeStruct(out, in) 232 default: 233 // unknown type, so not a protocol buffer 234 log.Printf("proto: don't know how to copy %v", in) 235 } 236 } 237 238 func mergeExtension(out, in map[int32]Extension) { 239 for extNum, eIn := range in { 240 eOut := Extension{desc: eIn.desc} 241 if eIn.value != nil { 242 v := reflect.New(reflect.TypeOf(eIn.value)).Elem() 243 mergeAny(v, reflect.ValueOf(eIn.value), false, nil) 244 eOut.value = v.Interface() 245 } 246 if eIn.enc != nil { 247 eOut.enc = make([]byte, len(eIn.enc)) 248 copy(eOut.enc, eIn.enc) 249 } 250 251 out[extNum] = eOut 252 } 253 } 254