David K. Bainbridge | e05cf0c | 2021-08-19 03:16:50 +0000 | [diff] [blame] | 1 | // Copyright 2018 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package impl |
| 6 | |
| 7 | import ( |
| 8 | "bytes" |
| 9 | "compress/gzip" |
| 10 | "io/ioutil" |
| 11 | "sync" |
| 12 | |
| 13 | "google.golang.org/protobuf/internal/filedesc" |
| 14 | "google.golang.org/protobuf/reflect/protoreflect" |
| 15 | "google.golang.org/protobuf/reflect/protoregistry" |
| 16 | ) |
| 17 | |
| 18 | // Every enum and message type generated by protoc-gen-go since commit 2fc053c5 |
| 19 | // on February 25th, 2016 has had a method to get the raw descriptor. |
| 20 | // Types that were not generated by protoc-gen-go or were generated prior |
| 21 | // to that version are not supported. |
| 22 | // |
| 23 | // The []byte returned is the encoded form of a FileDescriptorProto message |
| 24 | // compressed using GZIP. The []int is the path from the top-level file |
| 25 | // to the specific message or enum declaration. |
| 26 | type ( |
| 27 | enumV1 interface { |
| 28 | EnumDescriptor() ([]byte, []int) |
| 29 | } |
| 30 | messageV1 interface { |
| 31 | Descriptor() ([]byte, []int) |
| 32 | } |
| 33 | ) |
| 34 | |
| 35 | var legacyFileDescCache sync.Map // map[*byte]protoreflect.FileDescriptor |
| 36 | |
| 37 | // legacyLoadFileDesc unmarshals b as a compressed FileDescriptorProto message. |
| 38 | // |
| 39 | // This assumes that b is immutable and that b does not refer to part of a |
| 40 | // concatenated series of GZIP files (which would require shenanigans that |
| 41 | // rely on the concatenation properties of both protobufs and GZIP). |
| 42 | // File descriptors generated by protoc-gen-go do not rely on that property. |
| 43 | func legacyLoadFileDesc(b []byte) protoreflect.FileDescriptor { |
| 44 | // Fast-path: check whether we already have a cached file descriptor. |
| 45 | if fd, ok := legacyFileDescCache.Load(&b[0]); ok { |
| 46 | return fd.(protoreflect.FileDescriptor) |
| 47 | } |
| 48 | |
| 49 | // Slow-path: decompress and unmarshal the file descriptor proto. |
| 50 | zr, err := gzip.NewReader(bytes.NewReader(b)) |
| 51 | if err != nil { |
| 52 | panic(err) |
| 53 | } |
| 54 | b2, err := ioutil.ReadAll(zr) |
| 55 | if err != nil { |
| 56 | panic(err) |
| 57 | } |
| 58 | |
| 59 | fd := filedesc.Builder{ |
| 60 | RawDescriptor: b2, |
| 61 | FileRegistry: resolverOnly{protoregistry.GlobalFiles}, // do not register back to global registry |
| 62 | }.Build().File |
| 63 | if fd, ok := legacyFileDescCache.LoadOrStore(&b[0], fd); ok { |
| 64 | return fd.(protoreflect.FileDescriptor) |
| 65 | } |
| 66 | return fd |
| 67 | } |
| 68 | |
| 69 | type resolverOnly struct { |
| 70 | reg *protoregistry.Files |
| 71 | } |
| 72 | |
| 73 | func (r resolverOnly) FindFileByPath(path string) (protoreflect.FileDescriptor, error) { |
| 74 | return r.reg.FindFileByPath(path) |
| 75 | } |
| 76 | func (r resolverOnly) FindDescriptorByName(name protoreflect.FullName) (protoreflect.Descriptor, error) { |
| 77 | return r.reg.FindDescriptorByName(name) |
| 78 | } |
| 79 | func (resolverOnly) RegisterFile(protoreflect.FileDescriptor) error { |
| 80 | return nil |
| 81 | } |