gitea/vendor/google.golang.org/protobuf/internal/impl/legacy_file.go

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// 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 impl
import (
"bytes"
"compress/gzip"
"io/ioutil"
"sync"
"google.golang.org/protobuf/internal/filedesc"
"google.golang.org/protobuf/reflect/protoreflect"
"google.golang.org/protobuf/reflect/protoregistry"
)
// 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 legacyFileDescCache sync.Map // map[*byte]protoreflect.FileDescriptor
// legacyLoadFileDesc 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 legacyLoadFileDesc(b []byte) protoreflect.FileDescriptor {
// Fast-path: check whether we already have a cached file descriptor.
if fd, ok := legacyFileDescCache.Load(&b[0]); ok {
return fd.(protoreflect.FileDescriptor)
}
// Slow-path: decompress and unmarshal the file descriptor proto.
zr, err := gzip.NewReader(bytes.NewReader(b))
if err != nil {
panic(err)
}
b2, err := ioutil.ReadAll(zr)
if err != nil {
panic(err)
}
fd := filedesc.Builder{
RawDescriptor: b2,
FileRegistry: resolverOnly{protoregistry.GlobalFiles}, // do not register back to global registry
}.Build().File
if fd, ok := legacyFileDescCache.LoadOrStore(&b[0], fd); ok {
return fd.(protoreflect.FileDescriptor)
}
return fd
}
type resolverOnly struct {
reg *protoregistry.Files
}
func (r resolverOnly) FindFileByPath(path string) (protoreflect.FileDescriptor, error) {
return r.reg.FindFileByPath(path)
}
func (r resolverOnly) FindDescriptorByName(name protoreflect.FullName) (protoreflect.Descriptor, error) {
return r.reg.FindDescriptorByName(name)
}
func (resolverOnly) RegisterFile(protoreflect.FileDescriptor) error {
return nil
}