82 lines
2.5 KiB
Go
82 lines
2.5 KiB
Go
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// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package impl
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import (
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"bytes"
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"compress/gzip"
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"io/ioutil"
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"sync"
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"google.golang.org/protobuf/internal/filedesc"
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"google.golang.org/protobuf/reflect/protoreflect"
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"google.golang.org/protobuf/reflect/protoregistry"
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)
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// Every enum and message type generated by protoc-gen-go since commit 2fc053c5
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// on February 25th, 2016 has had a method to get the raw descriptor.
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// Types that were not generated by protoc-gen-go or were generated prior
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// to that version are not supported.
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//
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// The []byte returned is the encoded form of a FileDescriptorProto message
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// compressed using GZIP. The []int is the path from the top-level file
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// to the specific message or enum declaration.
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type (
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enumV1 interface {
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EnumDescriptor() ([]byte, []int)
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}
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messageV1 interface {
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Descriptor() ([]byte, []int)
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}
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)
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var legacyFileDescCache sync.Map // map[*byte]protoreflect.FileDescriptor
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// legacyLoadFileDesc unmarshals b as a compressed FileDescriptorProto message.
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//
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// This assumes that b is immutable and that b does not refer to part of a
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// concatenated series of GZIP files (which would require shenanigans that
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// rely on the concatenation properties of both protobufs and GZIP).
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// File descriptors generated by protoc-gen-go do not rely on that property.
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func legacyLoadFileDesc(b []byte) protoreflect.FileDescriptor {
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// Fast-path: check whether we already have a cached file descriptor.
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if fd, ok := legacyFileDescCache.Load(&b[0]); ok {
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return fd.(protoreflect.FileDescriptor)
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}
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// Slow-path: decompress and unmarshal the file descriptor proto.
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zr, err := gzip.NewReader(bytes.NewReader(b))
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if err != nil {
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panic(err)
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}
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b2, err := ioutil.ReadAll(zr)
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if err != nil {
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panic(err)
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}
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fd := filedesc.Builder{
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RawDescriptor: b2,
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FileRegistry: resolverOnly{protoregistry.GlobalFiles}, // do not register back to global registry
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}.Build().File
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if fd, ok := legacyFileDescCache.LoadOrStore(&b[0], fd); ok {
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return fd.(protoreflect.FileDescriptor)
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}
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return fd
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}
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type resolverOnly struct {
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reg *protoregistry.Files
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}
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func (r resolverOnly) FindFileByPath(path string) (protoreflect.FileDescriptor, error) {
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return r.reg.FindFileByPath(path)
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}
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func (r resolverOnly) FindDescriptorByName(name protoreflect.FullName) (protoreflect.Descriptor, error) {
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return r.reg.FindDescriptorByName(name)
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}
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func (resolverOnly) RegisterFile(protoreflect.FileDescriptor) error {
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return nil
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}
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