128 lines
4.5 KiB
Go
128 lines
4.5 KiB
Go
// Package internal contains some code that should not be exported but needs to
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// be shared across more than one of the protoreflect sub-packages.
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package internal
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import (
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"bytes"
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"compress/gzip"
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"fmt"
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"io/ioutil"
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"github.com/golang/protobuf/proto"
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dpb "github.com/golang/protobuf/protoc-gen-go/descriptor"
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)
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// TODO: replace this alias configuration with desc.RegisterImportPath?
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// StdFileAliases are the standard protos included with protoc, but older versions of
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// their respective packages registered them using incorrect paths.
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var StdFileAliases = map[string]string{
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// Files for the github.com/golang/protobuf/ptypes package at one point were
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// registered using the path where the proto files are mirrored in GOPATH,
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// inside the golang/protobuf repo.
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// (Fixed as of https://github.com/golang/protobuf/pull/412)
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"google/protobuf/any.proto": "github.com/golang/protobuf/ptypes/any/any.proto",
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"google/protobuf/duration.proto": "github.com/golang/protobuf/ptypes/duration/duration.proto",
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"google/protobuf/empty.proto": "github.com/golang/protobuf/ptypes/empty/empty.proto",
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"google/protobuf/struct.proto": "github.com/golang/protobuf/ptypes/struct/struct.proto",
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"google/protobuf/timestamp.proto": "github.com/golang/protobuf/ptypes/timestamp/timestamp.proto",
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"google/protobuf/wrappers.proto": "github.com/golang/protobuf/ptypes/wrappers/wrappers.proto",
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// Files for the google.golang.org/genproto/protobuf package at one point
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// were registered with an anomalous "src/" prefix.
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// (Fixed as of https://github.com/google/go-genproto/pull/31)
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"google/protobuf/api.proto": "src/google/protobuf/api.proto",
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"google/protobuf/field_mask.proto": "src/google/protobuf/field_mask.proto",
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"google/protobuf/source_context.proto": "src/google/protobuf/source_context.proto",
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"google/protobuf/type.proto": "src/google/protobuf/type.proto",
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// Other standard files (descriptor.proto and compiler/plugin.proto) are
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// registered correctly, so we don't need rules for them here.
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}
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func init() {
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// We provide aliasing in both directions, to support files with the
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// proper import path linked against older versions of the generated
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// files AND files that used the aliased import path but linked against
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// newer versions of the generated files (which register with the
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// correct path).
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// Get all files defined above
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keys := make([]string, 0, len(StdFileAliases))
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for k := range StdFileAliases {
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keys = append(keys, k)
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}
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// And add inverse mappings
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for _, k := range keys {
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alias := StdFileAliases[k]
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StdFileAliases[alias] = k
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}
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}
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type ErrNoSuchFile string
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func (e ErrNoSuchFile) Error() string {
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return fmt.Sprintf("no such file: %q", string(e))
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}
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// LoadFileDescriptor loads a registered descriptor and decodes it. If the given
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// name cannot be loaded but is a known standard name, an alias will be tried,
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// so the standard files can be loaded even if linked against older "known bad"
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// versions of packages.
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func LoadFileDescriptor(file string) (*dpb.FileDescriptorProto, error) {
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fdb := proto.FileDescriptor(file)
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aliased := false
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if fdb == nil {
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var ok bool
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alias, ok := StdFileAliases[file]
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if ok {
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aliased = true
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if fdb = proto.FileDescriptor(alias); fdb == nil {
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return nil, ErrNoSuchFile(file)
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}
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} else {
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return nil, ErrNoSuchFile(file)
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}
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}
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fd, err := DecodeFileDescriptor(file, fdb)
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if err != nil {
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return nil, err
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}
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if aliased {
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// the file descriptor will have the alias used to load it, but
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// we need it to have the specified name in order to link it
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fd.Name = proto.String(file)
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}
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return fd, nil
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}
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// DecodeFileDescriptor decodes the bytes of a registered file descriptor.
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// Registered file descriptors are first "proto encoded" (e.g. binary format
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// for the descriptor protos) and then gzipped. So this function gunzips and
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// then unmarshals into a descriptor proto.
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func DecodeFileDescriptor(element string, fdb []byte) (*dpb.FileDescriptorProto, error) {
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raw, err := decompress(fdb)
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if err != nil {
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return nil, fmt.Errorf("failed to decompress %q descriptor: %v", element, err)
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}
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fd := dpb.FileDescriptorProto{}
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if err := proto.Unmarshal(raw, &fd); err != nil {
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return nil, fmt.Errorf("bad descriptor for %q: %v", element, err)
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}
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return &fd, nil
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}
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func decompress(b []byte) ([]byte, error) {
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r, err := gzip.NewReader(bytes.NewReader(b))
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if err != nil {
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return nil, fmt.Errorf("bad gzipped descriptor: %v", err)
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}
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out, err := ioutil.ReadAll(r)
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if err != nil {
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return nil, fmt.Errorf("bad gzipped descriptor: %v", err)
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}
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return out, nil
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}
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