| // Copyright 2016 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 descriptor provides functions for obtaining protocol buffer |
| // descriptors for generated Go types. |
| // |
| // Deprecated: Do not use. The new v2 Message interface provides direct support |
| // for programmatically interacting with the descriptor information. |
| package descriptor |
| |
| import ( |
| "bytes" |
| "compress/gzip" |
| "fmt" |
| "io/ioutil" |
| |
| "github.com/golang/protobuf/proto" |
| descriptorpb "github.com/golang/protobuf/protoc-gen-go/descriptor" |
| ) |
| |
| // extractFile extracts a FileDescriptorProto from a gzip'd buffer. |
| func extractFile(gz []byte) (*descriptorpb.FileDescriptorProto, error) { |
| r, err := gzip.NewReader(bytes.NewReader(gz)) |
| if err != nil { |
| return nil, fmt.Errorf("failed to open gzip reader: %v", err) |
| } |
| defer r.Close() |
| |
| b, err := ioutil.ReadAll(r) |
| if err != nil { |
| return nil, fmt.Errorf("failed to uncompress descriptor: %v", err) |
| } |
| |
| fd := new(descriptorpb.FileDescriptorProto) |
| if err := proto.Unmarshal(b, fd); err != nil { |
| return nil, fmt.Errorf("malformed FileDescriptorProto: %v", err) |
| } |
| |
| return fd, nil |
| } |
| |
| // Message is a proto.Message with a method to return its descriptor. |
| // |
| // Message types generated by the protocol compiler always satisfy |
| // the Message interface. |
| type Message interface { |
| proto.Message |
| Descriptor() ([]byte, []int) |
| } |
| |
| // ForMessage returns a FileDescriptorProto and a DescriptorProto from within it |
| // describing the given message. |
| func ForMessage(msg Message) (fd *descriptorpb.FileDescriptorProto, md *descriptorpb.DescriptorProto) { |
| gz, path := msg.Descriptor() |
| fd, err := extractFile(gz) |
| if err != nil { |
| panic(fmt.Sprintf("invalid FileDescriptorProto for %T: %v", msg, err)) |
| } |
| |
| md = fd.MessageType[path[0]] |
| for _, i := range path[1:] { |
| md = md.NestedType[i] |
| } |
| return fd, md |
| } |