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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package legacy
import (
"bytes"
"compress/gzip"
"io/ioutil"
"sync"
"github.com/golang/protobuf/v2/proto"
pref "github.com/golang/protobuf/v2/reflect/protoreflect"
descriptorpb "github.com/golang/protobuf/v2/types/descriptor"
)
// Every enum and message type generated by protoc-gen-go since commit 2fc053c5
// on February 25th, 2016 has had a method to get the raw descriptor.
// Types that were not generated by protoc-gen-go or were generated prior
// to that version are not supported.
//
// The []byte returned is the encoded form of a FileDescriptorProto message
// compressed using GZIP. The []int is the path from the top-level file
// to the specific message or enum declaration.
type (
enumV1 interface {
EnumDescriptor() ([]byte, []int)
}
messageV1 interface {
Descriptor() ([]byte, []int)
}
)
var fileDescCache sync.Map // map[*byte]*descriptorpb.FileDescriptorProto
// loadFileDesc unmarshals b as a compressed FileDescriptorProto message.
//
// This assumes that b is immutable and that b does not refer to part of a
// concatenated series of GZIP files (which would require shenanigans that
// rely on the concatenation properties of both protobufs and GZIP).
// File descriptors generated by protoc-gen-go do not rely on that property.
func loadFileDesc(b []byte) *descriptorpb.FileDescriptorProto {
// Fast-path: check whether we already have a cached file descriptor.
if v, ok := fileDescCache.Load(&b[0]); ok {
return v.(*descriptorpb.FileDescriptorProto)
}
// Slow-path: decompress and unmarshal the file descriptor proto.
m := new(descriptorpb.FileDescriptorProto)
zr, err := gzip.NewReader(bytes.NewReader(b))
if err != nil {
panic(err)
}
b, err = ioutil.ReadAll(zr)
if err != nil {
panic(err)
}
// TODO: What about extensions?
// The protoV1 API does not eagerly unmarshal extensions.
if err := proto.Unmarshal(b, m); err != nil {
panic(err)
}
fileDescCache.Store(&b[0], m)
return m
}
// parentFileDescriptor returns the parent protoreflect.FileDescriptor for the
// provide descriptor. It returns nil if there is no parent.
func parentFileDescriptor(d pref.Descriptor) pref.FileDescriptor {
for ok := true; ok; d, ok = d.Parent() {
if fd, _ := d.(pref.FileDescriptor); fd != nil {
return fd
}
}
return nil
}