mirror of
https://github.com/protocolbuffers/protobuf-go.git
synced 2025-02-23 06:41:09 +00:00
6dbffb765a
The legacy prefix made sense when this functionality was part of impl. Now that it is in its own package called legacy, the legacy prefix is silly. Change-Id: I9e6ddb6185ce1f701e02768b505e6a05f3986f77 Reviewed-on: https://go-review.googlesource.com/c/152543 Reviewed-by: Herbie Ong <herbie@google.com>
81 lines
2.6 KiB
Go
81 lines
2.6 KiB
Go
// 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"
|
|
|
|
// TODO: Avoid reliance on old API. However, there is currently a
|
|
// chicken and egg problem where we need the descriptor protos to implement
|
|
// the new API.
|
|
protoV1 "github.com/golang/protobuf/proto"
|
|
descriptorV1 "github.com/golang/protobuf/protoc-gen-go/descriptor"
|
|
pref "github.com/golang/protobuf/v2/reflect/protoreflect"
|
|
)
|
|
|
|
// 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]*descriptorV1.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) *descriptorV1.FileDescriptorProto {
|
|
// Fast-path: check whether we already have a cached file descriptor.
|
|
if v, ok := fileDescCache.Load(&b[0]); ok {
|
|
return v.(*descriptorV1.FileDescriptorProto)
|
|
}
|
|
|
|
// Slow-path: decompress and unmarshal the file descriptor proto.
|
|
m := new(descriptorV1.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 := protoV1.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
|
|
}
|