/usr/share/gocode/src/github.com/golang/protobuf/proto/extensions.go is in golang-goprotobuf-dev 0.0~git20150526-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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//
// 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"
"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 that may be extended.
type extendableProto interface {
Message
ExtensionRangeArray() []ExtensionRange
ExtensionMap() map[int32]Extension
}
var extendableProtoType = reflect.TypeOf((*extendableProto)(nil)).Elem()
// 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
}
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 interface{}
enc []byte
}
// SetRawExtension is for testing only.
func SetRawExtension(base extendableProto, id int32, b []byte) {
base.ExtensionMap()[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 {
// Check the extended type.
if a, b := reflect.TypeOf(pb), reflect.TypeOf(extension.ExtendedType); a != b {
return errors.New("proto: bad extended type; " + b.String() + " does not extend " + a.String())
}
// 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
}
// encodeExtensionMap encodes any unmarshaled (unencoded) extensions in m.
func encodeExtensionMap(m map[int32]Extension) error {
for k, e := range m {
if e.value == nil || e.desc == nil {
// Extension is only in its encoded form.
continue
}
// We don't skip extensions that have an encoded form set,
// because the extension value may have been mutated after
// the last time this function was called.
et := reflect.TypeOf(e.desc.ExtensionType)
props := extensionProperties(e.desc)
p := NewBuffer(nil)
// If e.value has type T, the encoder expects a *struct{ X T }.
// Pass a *T with a zero field and hope it all works out.
x := reflect.New(et)
x.Elem().Set(reflect.ValueOf(e.value))
if err := props.enc(p, props, toStructPointer(x)); err != nil {
return err
}
e.enc = p.buf
m[k] = e
}
return nil
}
func sizeExtensionMap(m map[int32]Extension) (n int) {
for _, e := range m {
if e.value == nil || e.desc == nil {
// Extension is only in its encoded form.
n += len(e.enc)
continue
}
// We don't skip extensions that have an encoded form set,
// because the extension value may have been mutated after
// the last time this function was called.
et := reflect.TypeOf(e.desc.ExtensionType)
props := extensionProperties(e.desc)
// If e.value has type T, the encoder expects a *struct{ X T }.
// Pass a *T with a zero field and hope it all works out.
x := reflect.New(et)
x.Elem().Set(reflect.ValueOf(e.value))
n += props.size(props, toStructPointer(x))
}
return
}
// HasExtension returns whether the given extension is present in pb.
func HasExtension(pb extendableProto, extension *ExtensionDesc) bool {
// TODO: Check types, field numbers, etc.?
_, ok := pb.ExtensionMap()[extension.Field]
return ok
}
// ClearExtension removes the given extension from pb.
func ClearExtension(pb extendableProto, extension *ExtensionDesc) {
// TODO: Check types, field numbers, etc.?
delete(pb.ExtensionMap(), extension.Field)
}
// GetExtension parses and returns the given extension of pb.
// If the extension is not present and has no default value it returns ErrMissingExtension.
func GetExtension(pb extendableProto, extension *ExtensionDesc) (interface{}, error) {
if err := checkExtensionTypes(pb, extension); err != nil {
return nil, err
}
emap := pb.ExtensionMap()
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 e.value, 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 = v
e.desc = extension
e.enc = nil
emap[extension.Field] = e
return 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) {
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) {
o := NewBuffer(b)
t := reflect.TypeOf(extension.ExtensionType)
rep := extension.repeated()
props := extensionProperties(extension)
// t is a pointer to a struct, pointer to basic type or a slice.
// Allocate a "field" to store the pointer/slice itself; the
// pointer/slice will be stored here. We pass
// the address of this field to props.dec.
// This passes a zero field and a *t and lets props.dec
// interpret it as a *struct{ x t }.
value := reflect.New(t).Elem()
for {
// Discard wire type and field number varint. It isn't needed.
if _, err := o.DecodeVarint(); err != nil {
return nil, err
}
if err := props.dec(o, props, toStructPointer(value.Addr())); err != nil {
return nil, err
}
if !rep || o.index >= len(o.buf) {
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, ok := pb.(extendableProto)
if !ok {
err = errors.New("proto: not an extendable proto")
return
}
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
}
// SetExtension sets the specified extension of pb to the specified value.
func SetExtension(pb extendableProto, extension *ExtensionDesc, value interface{}) error {
if err := checkExtensionTypes(pb, extension); err != nil {
return err
}
typ := reflect.TypeOf(extension.ExtensionType)
if typ != reflect.TypeOf(value) {
return errors.New("proto: bad extension value type")
}
// 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)
}
pb.ExtensionMap()[extension.Field] = Extension{desc: extension, value: value}
return nil
}
// 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()]
}
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