// Go support for Protocol Buffers - Google's data interchange format
//
// Copyright 2010 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
/*
* Types and routines for supporting protocol buffer extensions.
*/
import (
"errors"
"fmt"
"io"
"reflect"
"strconv"
"sync"
)
// ErrMissingExtension is the error returned by GetExtension if the named extension is not in the message.
var ErrMissingExtension = errors.New("proto: missing extension")
// ExtensionRange represents a range of message extensions for a protocol buffer.
// Used in code generated by the protocol compiler.
type ExtensionRange struct {
Start, End int32 // both inclusive
}
// extendableProto is an interface implemented by any protocol buffer generated by the current
// proto compiler that may be extended.
type extendableProto interface {
Message
ExtensionRangeArray() []ExtensionRange
extensionsWrite() map[int32]Extension
extensionsRead() (map[int32]Extension, sync.Locker)
}
// extendableProtoV1 is an interface implemented by a protocol buffer generated by the previous
// version of the proto compiler that may be extended.
type extendableProtoV1 interface {
Message
ExtensionRangeArray() []ExtensionRange
ExtensionMap() map[int32]Extension
}
// extensionAdapter is a wrapper around extendableProtoV1 that implements extendableProto.
type extensionAdapter struct {
extendableProtoV1
}
func (e extensionAdapter) extensionsWrite() map[int32]Extension {
return e.ExtensionMap()
}
func (e extensionAdapter) extensionsRead() (map[int32]Extension, sync.Locker) {
return e.ExtensionMap(), notLocker{}
}
// notLocker is a sync.Locker whose Lock and Unlock methods are nops.
type notLocker struct{}
func (n notLocker) Lock() {}
func (n notLocker) Unlock() {}
// extendable returns the extendableProto interface for the given generated proto message.
// If the proto message has the old extension format, it returns a wrapper that implements
// the extendableProto interface.
func extendable(p interface{}) (extendableProto, error) {
switch p := p.(type) {
case extendableProto:
if isNilPtr(p) {
return nil, fmt.Errorf("proto: nil %T is not extendable", p)
}
return p, nil
case extendableProtoV1:
if isNilPtr(p) {
return nil, fmt.Errorf("proto: nil %T is not extendable", p)
}
return extensionAdapter{p}, nil
}
// Don't allocate a specific error containing %T:
// this is the hot path for Clone and MarshalText.
return nil, errNotExtendable
}
var errNotExtendable = errors.New("proto: not an extendable proto.Message")
func isNilPtr(x interface{}) bool {
v := reflect.ValueOf(x)
return v.Kind() == reflect.Ptr && v.IsNil()
}
// XXX_InternalExtensions is an internal representation of proto extensions.
//
// Each generated message struct type embeds an anonymous XXX_InternalExtensions field,
// thus gaining the unexported 'extensions' method, which can be called only from the proto package.
//
// The methods of XXX_InternalExtensions are not concurrency safe in general,
// but calls to logically read-only methods such as has and get may be executed concurrently.
type XXX_InternalExtensions struct {
// The struct must be indirect so that if a user inadvertently copies a
// generated message and its embedded XXX_InternalExtensions, they
// avoid the mayhem of a copied mutex.
//
// The mutex serializes all logically read-only operations to p.extensionMap.
// It is up to the client to ensure that write operations to p.extensionMap are
// mutually exclusive with other accesses.
p *struct {
mu sync.Mutex
extensionMap map[int32]Extension
}
}
// extensionsWrite returns the extension map, creating it on first use.
func (e *XXX_InternalExtensions) extensionsWrite() map[int32]Extension {
if e.p == nil {
e.p = new(struct {
mu sync.Mutex
extensionMap map[int32]Extension
})
e.p.extensionMap = make(map[int32]Extension)
}
return e.p.extensionMap
}
// extensionsRead returns the extensions map for read-only use. It may be nil.
// The caller must hold the returned mutex's lock when accessing Elements within the map.
func (e *XXX_InternalExtensions) extensionsRead() (map[int32]Extension, sync.Locker) {
if e.p == nil {
return nil, nil
}
return e.p.extensionMap, &e.p.mu
}
// ExtensionDesc represents an extension specification.
// Used in generated code from the protocol compiler.
type ExtensionDesc struct {
ExtendedType Message // nil pointer to the type that is being extended
ExtensionType interface{} // nil pointer to the extension type
Field int32 // field number
Name string // fully-qualified name of extension, for text formatting
Tag string // protobuf tag style
Filename string // name of the file in which the extension is defined
}
func (ed *ExtensionDesc) repeated() bool {
t := reflect.TypeOf(ed.ExtensionType)
return t.Kind() == reflect.Slice && t.Elem().Kind() != reflect.Uint8
}
// Extension represents an extension in a message.
type Extension struct {
// When an extension is stored in a message using SetExtension
// only desc and value are set. When the message is marshaled
// enc will be set to the encoded form of the message.
//
// When a message is unmarshaled and contains extensions, each
// extension will have only enc set. When such an extension is
// accessed using GetExtension (or GetExtensions) desc and value
// will be set.
desc *ExtensionDesc
// value is a concrete value for the extension field. Let the type of
// desc.ExtensionType be the "API type" and the type of Extension.value
// be the "storage type". The API type and storage type are the same except:
// * For scalars (except []byte), the API type uses *T,
// while the storage type uses T.
// * For repeated fields, the API type uses []T, while the storage type
// uses *[]T.
//
// The reason for the divergence is so that the storage type more naturally
// matches what is expected of when retrieving the values through the
// protobuf reflection APIs.
//
// The value may only be populated if desc is also populated.
value interface{}
// enc is the raw bytes for the extension field.
enc []byte
}
// SetRawExtension is for testing only.
func SetRawExtension(base Message, id int32, b []byte) {
epb, err := extendable(base)
if err != nil {
return
}
extmap := epb.extensionsWrite()
extmap[id] = Extension{enc: b}
}
// isExtensionField returns true iff the given field number is in an extension range.
func isExtensionField(pb extendableProto, field int32) bool {
for _, er := range pb.ExtensionRangeArray() {
if er.Start <= field && field <= er.End {
return true
}
}
return false
}
// checkExtensionTypes checks that the given extension is valid for pb.
func checkExtensionTypes(pb extendableProto, extension *ExtensionDesc) error {
var pbi interface{} = pb
// Check the extended type.
if ea, ok := pbi.(extensionAdapter); ok {
pbi = ea.extendableProtoV1
}
if a, b := reflect.TypeOf(pbi), reflect.TypeOf(extension.ExtendedType); a != b {
return fmt.Errorf("proto: bad extended type; %v does not extend %v", b, a)
}
// Check the range.
if !isExtensionField(pb, extension.Field) {
return errors.New("proto: bad extension number; not in declared ranges")
}
return nil
}
// extPropKey is sufficient to uniquely identify an extension.
type extPropKey struct {
base reflect.Type
field int32
}
var extProp = struct {
sync.RWMutex
m map[extPropKey]*Properties
}{
m: make(map[extPropKey]*Properties),
}
func extensionProperties(ed *ExtensionDesc) *Properties {
key := extPropKey{base: reflect.TypeOf(ed.ExtendedType), field: ed.Field}
extProp.RLock()
if prop, ok := extProp.m[key]; ok {
extProp.RUnlock()
return prop
}
extProp.RUnlock()
extProp.Lock()
defer extProp.Unlock()
// Check again.
if prop, ok := extProp.m[key]; ok {
return prop
}
prop := new(Properties)
prop.Init(reflect.TypeOf(ed.ExtensionType), "unknown_name", ed.Tag, nil)
extProp.m[key] = prop
return prop
}
// HasExtension returns whether the given extension is present in pb.
func HasExtension(pb Message, extension *ExtensionDesc) bool {
// TODO: Check types, field numbers, etc.?
epb, err := extendable(pb)
if err != nil {
return false
}
extmap, mu := epb.extensionsRead()
if extmap == nil {
return false
}
mu.Lock()
_, ok := extmap[extension.Field]
mu.Unlock()
return ok
}
// ClearExtension removes the given extension from pb.
func ClearExtension(pb Message, extension *ExtensionDesc) {
epb, err := extendable(pb)
if err != nil {
return
}
// TODO: Check types, field numbers, etc.?
extmap := epb.extensionsWrite()
delete(extmap, extension.Field)
}
// GetExtension retrieves a proto2 extended field from pb.
//
// If the descriptor is type complete (i.e., ExtensionDesc.ExtensionType is non-nil),
// then GetExtension parses the encoded field and returns a Go value of the specified type.
// If the field is not present, then the default value is returned (if one is specified),
// otherwise ErrMissingExtension is reported.
//
// If the descriptor is not type complete (i.e., ExtensionDesc.ExtensionType is nil),
// then GetExtension returns the raw encoded bytes of the field extension.
func GetExtension(pb Message, extension *ExtensionDesc) (interface{}, error) {
epb, err := extendable(pb)
if err != nil {
return nil, err
}
if extension.ExtendedType != nil {
// can only check type if this is a complete descriptor
if err := checkExtensionTypes(epb, extension); err != nil {
return nil, err
}
}
emap, mu := epb.extensionsRead()
if emap == nil {
return defaultExtensionValue(extension)
}
mu.Lock()
defer mu.Unlock()
e, ok := emap[extension.Field]
if !ok {
// defaultExtensionValue returns the default value or
// ErrMissingExtension if there is no default.
return defaultExtensionValue(extension)
}
if e.value != nil {
// Already decoded. Check the descriptor, though.
if e.desc != extension {
// This shouldn't happen. If it does, it means that
// GetExtension was called twice with two different
// descriptors with the same field number.
return nil, errors.New("proto: descriptor conflict")
}
return extensionAsLegacyType(e.value), nil
}
if extension.ExtensionType == nil {
// incomplete descriptor
return e.enc, nil
}
v, err := decodeExtension(e.enc, extension)
if err != nil {
return nil, err
}
// Remember the decoded version and drop the encoded version.
// That way it is safe to mutate what we return.
e.value = extensionAsStorageType(v)
e.desc = extension
e.enc = nil
emap[extension.Field] = e
return extensionAsLegacyType(e.value), nil
}
// defaultExtensionValue returns the default value for extension.
// If no default for an extension is defined ErrMissingExtension is returned.
func defaultExtensionValue(extension *ExtensionDesc) (interface{}, error) {
if extension.ExtensionType == nil {
// incomplete descriptor, so no default
return nil, ErrMissingExtension
}
t := reflect.TypeOf(extension.ExtensionType)
props := extensionProperties(extension)
sf, _, err := fieldDefault(t, props)
if err != nil {
return nil, err
}
if sf == nil || sf.value == nil {
// There is no default value.
return nil, ErrMissingExtension
}
if t.Kind() != reflect.Ptr {
// We do not need to return a Ptr, we can directly return sf.value.
return sf.value, nil
}
// We need to return an interface{} that is a pointer to sf.value.
value := reflect.New(t).Elem()
value.Set(reflect.New(value.Type().Elem()))
if sf.kind == reflect.Int32 {
// We may have an int32 or an enum, but the underlying data is int32.
// Since we can't set an int32 into a non int32 reflect.value directly
// set it as a int32.
value.Elem().SetInt(int64(sf.value.(int32)))
} else {
value.Elem().Set(reflect.ValueOf(sf.value))
}
return value.Interface(), nil
}
// decodeExtension decodes an extension encoded in b.
func decodeExtension(b []byte, extension *ExtensionDesc) (interface{}, error) {
t := reflect.TypeOf(extension.ExtensionType)
unmarshal := typeUnmarshaler(t, extension.Tag)
// t is a pointer to a struct, pointer to basic type or a slice.
// Allocate space to store the pointer/slice.
value := reflect.New(t).Elem()
var err error
for {
x, n := decodeVarint(b)
if n == 0 {
return nil, io.ErrUnexpectedEOF
}
b = b[n:]
wire := int(x) & 7
b, err = unmarshal(b, valToPointer(value.Addr()), wire)
if err != nil {
return nil, err
}
if len(b) == 0 {
break
}
}
return value.Interface(), nil
}
// GetExtensions returns a slice of the extensions present in pb that are also listed in es.
// The returned slice has the same length as es; missing extensions will appear as nil elements.
func GetExtensions(pb Message, es []*ExtensionDesc) (extensions []interface{}, err error) {
epb, err := extendable(pb)
if err != nil {
return nil, err
}
extensions = make([]interface{}, len(es))
for i, e := range es {
extensions[i], err = GetExtension(epb, e)
if err == ErrMissingExtension {
err = nil
}
if err != nil {
return
}
}
return
}
// ExtensionDescs returns a new slice containing pb's extension descriptors, in undefined order.
// For non-registered extensions, ExtensionDescs returns an incomplete descriptor containing
// just the Field field, which defines the extension's field number.
func ExtensionDescs(pb Message) ([]*ExtensionDesc, error) {
epb, err := extendable(pb)
if err != nil {
return nil, err
}
registeredExtensions := RegisteredExtensions(pb)
emap, mu := epb.extensionsRead()
if emap == nil {
return nil, nil
}
mu.Lock()
defer mu.Unlock()
extensions := make([]*ExtensionDesc, 0, len(emap))
for extid, e := range emap {
desc := e.desc
if desc == nil {
desc = registeredExtensions[extid]
if desc == nil {
desc = &ExtensionDesc{Field: extid}
}
}
extensions = append(extensions, desc)
}
return extensions, nil
}
// SetExtension sets the specified extension of pb to the specified value.
func SetExtension(pb Message, extension *ExtensionDesc, value interface{}) error {
epb, err := extendable(pb)
if err != nil {
return err
}
if err := checkExtensionTypes(epb, extension); err != nil {
return err
}
typ := reflect.TypeOf(extension.ExtensionType)
if typ != reflect.TypeOf(value) {
return fmt.Errorf("proto: bad extension value type. got: %T, want: %T", value, extension.ExtensionType)
}
// nil extension values need to be caught early, because the
// encoder can't distinguish an ErrNil due to a nil extension
// from an ErrNil due to a missing field. Extensions are
// always optional, so the encoder would just swallow the error
// and drop all the extensions from the encoded message.
if reflect.ValueOf(value).IsNil() {
return fmt.Errorf("proto: SetExtension called with nil value of type %T", value)
}
extmap := epb.extensionsWrite()
extmap[extension.Field] = Extension{desc: extension, value: extensionAsStorageType(value)}
return nil
}
// ClearAllExtensions clears all extensions from pb.
func ClearAllExtensions(pb Message) {
epb, err := extendable(pb)
if err != nil {
return
}
m := epb.extensionsWrite()
for k := range m {
delete(m, k)
}
}
// A global registry of extensions.
// The generated code will register the generated descriptors by calling RegisterExtension.
var extensionMaps = make(map[reflect.Type]map[int32]*ExtensionDesc)
// RegisterExtension is called from the generated code.
func RegisterExtension(desc *ExtensionDesc) {
st := reflect.TypeOf(desc.ExtendedType).Elem()
m := extensionMaps[st]
if m == nil {
m = make(map[int32]*ExtensionDesc)
extensionMaps[st] = m
}
if _, ok := m[desc.Field]; ok {
panic("proto: duplicate extension registered: " + st.String() + " " + strconv.Itoa(int(desc.Field)))
}
m[desc.Field] = desc
}
// RegisteredExtensions returns a map of the registered extensions of a
// protocol buffer struct, indexed by the extension number.
// The argument pb should be a nil pointer to the struct type.
func RegisteredExtensions(pb Message) map[int32]*ExtensionDesc {
return extensionMaps[reflect.TypeOf(pb).Elem()]
}
// extensionAsLegacyType converts an value in the storage type as the API type.
// See Extension.value.
func extensionAsLegacyType(v interface{}) interface{} {
switch rv := reflect.ValueOf(v); rv.Kind() {
case reflect.Bool, reflect.Int32, reflect.Int64, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64, reflect.String:
// Represent primitive types as a pointer to the value.
rv2 := reflect.New(rv.Type())
rv2.Elem().Set(rv)
v = rv2.Interface()
case reflect.Ptr:
// Represent slice types as the value itself.
switch rv.Type().Elem().Kind() {
case reflect.Slice:
if rv.IsNil() {
v = reflect.Zero(rv.Type().Elem()).Interface()
} else {
v = rv.Elem().Interface()
}
}
}
return v
}
// extensionAsStorageType converts an value in the API type as the storage type.
// See Extension.value.
func extensionAsStorageType(v interface{}) interface{} {
switch rv := reflect.ValueOf(v); rv.Kind() {
case reflect.Ptr:
// Represent slice types as the value itself.
switch rv.Type().Elem().Kind() {
case reflect.Bool, reflect.Int32, reflect.Int64, reflect.Uint32, reflect.Uint64, reflect.Float32, reflect.Float64, reflect.String:
if rv.IsNil() {
v = reflect.Zero(rv.Type().Elem()).Interface()
} else {
v = rv.Elem().Interface()
}
}
case reflect.Slice:
// Represent slice types as a pointer to the value.
if rv.Type().Elem().Kind() != reflect.Uint8 {
rv2 := reflect.New(rv.Type())
rv2.Elem().Set(rv)
v = rv2.Interface()
}
}
return v
}
