Matt Jeanneret | cab955f | 2019-04-10 15:45:57 -0400 | [diff] [blame] | 1 | // Go support for Protocol Buffers - Google's data interchange format |
| 2 | // |
| 3 | // Copyright 2016 The Go Authors. All rights reserved. |
| 4 | // https://github.com/golang/protobuf |
| 5 | // |
| 6 | // Redistribution and use in source and binary forms, with or without |
| 7 | // modification, are permitted provided that the following conditions are |
| 8 | // met: |
| 9 | // |
| 10 | // * Redistributions of source code must retain the above copyright |
| 11 | // notice, this list of conditions and the following disclaimer. |
| 12 | // * Redistributions in binary form must reproduce the above |
| 13 | // copyright notice, this list of conditions and the following disclaimer |
| 14 | // in the documentation and/or other materials provided with the |
| 15 | // distribution. |
| 16 | // * Neither the name of Google Inc. nor the names of its |
| 17 | // contributors may be used to endorse or promote products derived from |
| 18 | // this software without specific prior written permission. |
| 19 | // |
| 20 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 21 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 22 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 23 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 24 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 25 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 26 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 27 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 28 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 29 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 30 | // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 31 | |
| 32 | // Package descriptor provides functions for obtaining protocol buffer |
| 33 | // descriptors for generated Go types. |
| 34 | // |
| 35 | // These functions cannot go in package proto because they depend on the |
| 36 | // generated protobuf descriptor messages, which themselves depend on proto. |
| 37 | package descriptor |
| 38 | |
| 39 | import ( |
| 40 | "bytes" |
| 41 | "compress/gzip" |
| 42 | "fmt" |
| 43 | "io/ioutil" |
| 44 | |
| 45 | "github.com/golang/protobuf/proto" |
| 46 | protobuf "github.com/golang/protobuf/protoc-gen-go/descriptor" |
| 47 | ) |
| 48 | |
| 49 | // extractFile extracts a FileDescriptorProto from a gzip'd buffer. |
| 50 | func extractFile(gz []byte) (*protobuf.FileDescriptorProto, error) { |
| 51 | r, err := gzip.NewReader(bytes.NewReader(gz)) |
| 52 | if err != nil { |
| 53 | return nil, fmt.Errorf("failed to open gzip reader: %v", err) |
| 54 | } |
| 55 | defer r.Close() |
| 56 | |
| 57 | b, err := ioutil.ReadAll(r) |
| 58 | if err != nil { |
| 59 | return nil, fmt.Errorf("failed to uncompress descriptor: %v", err) |
| 60 | } |
| 61 | |
| 62 | fd := new(protobuf.FileDescriptorProto) |
| 63 | if err := proto.Unmarshal(b, fd); err != nil { |
| 64 | return nil, fmt.Errorf("malformed FileDescriptorProto: %v", err) |
| 65 | } |
| 66 | |
| 67 | return fd, nil |
| 68 | } |
| 69 | |
| 70 | // Message is a proto.Message with a method to return its descriptor. |
| 71 | // |
| 72 | // Message types generated by the protocol compiler always satisfy |
| 73 | // the Message interface. |
| 74 | type Message interface { |
| 75 | proto.Message |
| 76 | Descriptor() ([]byte, []int) |
| 77 | } |
| 78 | |
| 79 | // ForMessage returns a FileDescriptorProto and a DescriptorProto from within it |
| 80 | // describing the given message. |
| 81 | func ForMessage(msg Message) (fd *protobuf.FileDescriptorProto, md *protobuf.DescriptorProto) { |
| 82 | gz, path := msg.Descriptor() |
| 83 | fd, err := extractFile(gz) |
| 84 | if err != nil { |
| 85 | panic(fmt.Sprintf("invalid FileDescriptorProto for %T: %v", msg, err)) |
| 86 | } |
| 87 | |
| 88 | md = fd.MessageType[path[0]] |
| 89 | for _, i := range path[1:] { |
| 90 | md = md.NestedType[i] |
| 91 | } |
| 92 | return fd, md |
| 93 | } |