mirror of
https://github.com/protocolbuffers/protobuf-go.git
synced 2025-04-03 01:20:44 +00:00
987d570c08
We jump through many hoops to avoid generated protos depending on internal/legacy. Break the cycle in the other direction: Remove the dependency on descriptor.proto from internal/legacy by using a hand-written parser for the few descriptor fields we need. Still to do: Remove the descriptor.proto dependency from internal/encoding/tag. Change-Id: I5fd99a2170470ba8530eb2679b6dde899821bf3e Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/171457 Reviewed-by: Joe Tsai <thebrokentoaster@gmail.com>
73 lines
2.2 KiB
Go
73 lines
2.2 KiB
Go
// 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 legacy
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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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pref "github.com/golang/protobuf/v2/reflect/protoreflect"
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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 fileDescCache sync.Map // map[*byte]*descriptorpb.FileDescriptorProto
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// loadFileDesc 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 loadFileDesc(b []byte) *fileDescriptorProto {
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// Fast-path: check whether we already have a cached file descriptor.
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if fd, ok := fileDescCache.Load(&b[0]); ok {
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return fd.(*fileDescriptorProto)
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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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b, 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 := parseFileDescProto(b)
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if fd, ok := fileDescCache.LoadOrStore(&b[0], fd); ok {
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return fd.(*fileDescriptorProto)
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}
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return fd
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}
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// parentFileDescriptor returns the parent protoreflect.FileDescriptor for the
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// provide descriptor. It returns nil if there is no parent.
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func parentFileDescriptor(d pref.Descriptor) pref.FileDescriptor {
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for ok := true; ok; d, ok = d.Parent() {
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if fd, _ := d.(pref.FileDescriptor); fd != nil {
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return fd
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}
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}
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return nil
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}
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