gtsocial-umbx

Unnamed repository; edit this file 'description' to name the repository.
Log | Files | Refs | README | LICENSE

legacy_file.go (2570B)

      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 }