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Diffstat (limited to 'vendor/google.golang.org/protobuf/proto/encode.go')
-rw-r--r-- | vendor/google.golang.org/protobuf/proto/encode.go | 343 |
1 files changed, 343 insertions, 0 deletions
diff --git a/vendor/google.golang.org/protobuf/proto/encode.go b/vendor/google.golang.org/protobuf/proto/encode.go new file mode 100644 index 00000000..456bfda4 --- /dev/null +++ b/vendor/google.golang.org/protobuf/proto/encode.go @@ -0,0 +1,343 @@ +// Copyright 2019 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 proto + +import ( + "sort" + + "google.golang.org/protobuf/encoding/protowire" + "google.golang.org/protobuf/internal/encoding/messageset" + "google.golang.org/protobuf/internal/fieldsort" + "google.golang.org/protobuf/internal/mapsort" + "google.golang.org/protobuf/internal/pragma" + "google.golang.org/protobuf/reflect/protoreflect" + "google.golang.org/protobuf/runtime/protoiface" +) + +// MarshalOptions configures the marshaler. +// +// Example usage: +// b, err := MarshalOptions{Deterministic: true}.Marshal(m) +type MarshalOptions struct { + pragma.NoUnkeyedLiterals + + // AllowPartial allows messages that have missing required fields to marshal + // without returning an error. If AllowPartial is false (the default), + // Marshal will return an error if there are any missing required fields. + AllowPartial bool + + // Deterministic controls whether the same message will always be + // serialized to the same bytes within the same binary. + // + // Setting this option guarantees that repeated serialization of + // the same message will return the same bytes, and that different + // processes of the same binary (which may be executing on different + // machines) will serialize equal messages to the same bytes. + // It has no effect on the resulting size of the encoded message compared + // to a non-deterministic marshal. + // + // Note that the deterministic serialization is NOT canonical across + // languages. It is not guaranteed to remain stable over time. It is + // unstable across different builds with schema changes due to unknown + // fields. Users who need canonical serialization (e.g., persistent + // storage in a canonical form, fingerprinting, etc.) must define + // their own canonicalization specification and implement their own + // serializer rather than relying on this API. + // + // If deterministic serialization is requested, map entries will be + // sorted by keys in lexographical order. This is an implementation + // detail and subject to change. + Deterministic bool + + // UseCachedSize indicates that the result of a previous Size call + // may be reused. + // + // Setting this option asserts that: + // + // 1. Size has previously been called on this message with identical + // options (except for UseCachedSize itself). + // + // 2. The message and all its submessages have not changed in any + // way since the Size call. + // + // If either of these invariants is violated, + // the results are undefined and may include panics or corrupted output. + // + // Implementations MAY take this option into account to provide + // better performance, but there is no guarantee that they will do so. + // There is absolutely no guarantee that Size followed by Marshal with + // UseCachedSize set will perform equivalently to Marshal alone. + UseCachedSize bool +} + +// Marshal returns the wire-format encoding of m. +func Marshal(m Message) ([]byte, error) { + // Treat nil message interface as an empty message; nothing to output. + if m == nil { + return nil, nil + } + + out, err := MarshalOptions{}.marshal(nil, m.ProtoReflect()) + if len(out.Buf) == 0 && err == nil { + out.Buf = emptyBytesForMessage(m) + } + return out.Buf, err +} + +// Marshal returns the wire-format encoding of m. +func (o MarshalOptions) Marshal(m Message) ([]byte, error) { + // Treat nil message interface as an empty message; nothing to output. + if m == nil { + return nil, nil + } + + out, err := o.marshal(nil, m.ProtoReflect()) + if len(out.Buf) == 0 && err == nil { + out.Buf = emptyBytesForMessage(m) + } + return out.Buf, err +} + +// emptyBytesForMessage returns a nil buffer if and only if m is invalid, +// otherwise it returns a non-nil empty buffer. +// +// This is to assist the edge-case where user-code does the following: +// m1.OptionalBytes, _ = proto.Marshal(m2) +// where they expect the proto2 "optional_bytes" field to be populated +// if any only if m2 is a valid message. +func emptyBytesForMessage(m Message) []byte { + if m == nil || !m.ProtoReflect().IsValid() { + return nil + } + return emptyBuf[:] +} + +// MarshalAppend appends the wire-format encoding of m to b, +// returning the result. +func (o MarshalOptions) MarshalAppend(b []byte, m Message) ([]byte, error) { + // Treat nil message interface as an empty message; nothing to append. + if m == nil { + return b, nil + } + + out, err := o.marshal(b, m.ProtoReflect()) + return out.Buf, err +} + +// MarshalState returns the wire-format encoding of a message. +// +// This method permits fine-grained control over the marshaler. +// Most users should use Marshal instead. +func (o MarshalOptions) MarshalState(in protoiface.MarshalInput) (protoiface.MarshalOutput, error) { + return o.marshal(in.Buf, in.Message) +} + +func (o MarshalOptions) marshal(b []byte, m protoreflect.Message) (out protoiface.MarshalOutput, err error) { + allowPartial := o.AllowPartial + o.AllowPartial = true + if methods := protoMethods(m); methods != nil && methods.Marshal != nil && + !(o.Deterministic && methods.Flags&protoiface.SupportMarshalDeterministic == 0) { + in := protoiface.MarshalInput{ + Message: m, + Buf: b, + } + if o.Deterministic { + in.Flags |= protoiface.MarshalDeterministic + } + if o.UseCachedSize { + in.Flags |= protoiface.MarshalUseCachedSize + } + if methods.Size != nil { + sout := methods.Size(protoiface.SizeInput{ + Message: m, + Flags: in.Flags, + }) + if cap(b) < len(b)+sout.Size { + in.Buf = make([]byte, len(b), growcap(cap(b), len(b)+sout.Size)) + copy(in.Buf, b) + } + in.Flags |= protoiface.MarshalUseCachedSize + } + out, err = methods.Marshal(in) + } else { + out.Buf, err = o.marshalMessageSlow(b, m) + } + if err != nil { + return out, err + } + if allowPartial { + return out, nil + } + return out, checkInitialized(m) +} + +func (o MarshalOptions) marshalMessage(b []byte, m protoreflect.Message) ([]byte, error) { + out, err := o.marshal(b, m) + return out.Buf, err +} + +// growcap scales up the capacity of a slice. +// +// Given a slice with a current capacity of oldcap and a desired +// capacity of wantcap, growcap returns a new capacity >= wantcap. +// +// The algorithm is mostly identical to the one used by append as of Go 1.14. +func growcap(oldcap, wantcap int) (newcap int) { + if wantcap > oldcap*2 { + newcap = wantcap + } else if oldcap < 1024 { + // The Go 1.14 runtime takes this case when len(s) < 1024, + // not when cap(s) < 1024. The difference doesn't seem + // significant here. + newcap = oldcap * 2 + } else { + newcap = oldcap + for 0 < newcap && newcap < wantcap { + newcap += newcap / 4 + } + if newcap <= 0 { + newcap = wantcap + } + } + return newcap +} + +func (o MarshalOptions) marshalMessageSlow(b []byte, m protoreflect.Message) ([]byte, error) { + if messageset.IsMessageSet(m.Descriptor()) { + return marshalMessageSet(b, m, o) + } + // There are many choices for what order we visit fields in. The default one here + // is chosen for reasonable efficiency and simplicity given the protoreflect API. + // It is not deterministic, since Message.Range does not return fields in any + // defined order. + // + // When using deterministic serialization, we sort the known fields. + var err error + o.rangeFields(m, func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool { + b, err = o.marshalField(b, fd, v) + return err == nil + }) + if err != nil { + return b, err + } + b = append(b, m.GetUnknown()...) + return b, nil +} + +// rangeFields visits fields in a defined order when deterministic serialization is enabled. +func (o MarshalOptions) rangeFields(m protoreflect.Message, f func(protoreflect.FieldDescriptor, protoreflect.Value) bool) { + if !o.Deterministic { + m.Range(f) + return + } + var fds []protoreflect.FieldDescriptor + m.Range(func(fd protoreflect.FieldDescriptor, _ protoreflect.Value) bool { + fds = append(fds, fd) + return true + }) + sort.Slice(fds, func(a, b int) bool { + return fieldsort.Less(fds[a], fds[b]) + }) + for _, fd := range fds { + if !f(fd, m.Get(fd)) { + break + } + } +} + +func (o MarshalOptions) marshalField(b []byte, fd protoreflect.FieldDescriptor, value protoreflect.Value) ([]byte, error) { + switch { + case fd.IsList(): + return o.marshalList(b, fd, value.List()) + case fd.IsMap(): + return o.marshalMap(b, fd, value.Map()) + default: + b = protowire.AppendTag(b, fd.Number(), wireTypes[fd.Kind()]) + return o.marshalSingular(b, fd, value) + } +} + +func (o MarshalOptions) marshalList(b []byte, fd protoreflect.FieldDescriptor, list protoreflect.List) ([]byte, error) { + if fd.IsPacked() && list.Len() > 0 { + b = protowire.AppendTag(b, fd.Number(), protowire.BytesType) + b, pos := appendSpeculativeLength(b) + for i, llen := 0, list.Len(); i < llen; i++ { + var err error + b, err = o.marshalSingular(b, fd, list.Get(i)) + if err != nil { + return b, err + } + } + b = finishSpeculativeLength(b, pos) + return b, nil + } + + kind := fd.Kind() + for i, llen := 0, list.Len(); i < llen; i++ { + var err error + b = protowire.AppendTag(b, fd.Number(), wireTypes[kind]) + b, err = o.marshalSingular(b, fd, list.Get(i)) + if err != nil { + return b, err + } + } + return b, nil +} + +func (o MarshalOptions) marshalMap(b []byte, fd protoreflect.FieldDescriptor, mapv protoreflect.Map) ([]byte, error) { + keyf := fd.MapKey() + valf := fd.MapValue() + var err error + o.rangeMap(mapv, keyf.Kind(), func(key protoreflect.MapKey, value protoreflect.Value) bool { + b = protowire.AppendTag(b, fd.Number(), protowire.BytesType) + var pos int + b, pos = appendSpeculativeLength(b) + + b, err = o.marshalField(b, keyf, key.Value()) + if err != nil { + return false + } + b, err = o.marshalField(b, valf, value) + if err != nil { + return false + } + b = finishSpeculativeLength(b, pos) + return true + }) + return b, err +} + +func (o MarshalOptions) rangeMap(mapv protoreflect.Map, kind protoreflect.Kind, f func(protoreflect.MapKey, protoreflect.Value) bool) { + if !o.Deterministic { + mapv.Range(f) + return + } + mapsort.Range(mapv, kind, f) +} + +// When encoding length-prefixed fields, we speculatively set aside some number of bytes +// for the length, encode the data, and then encode the length (shifting the data if necessary +// to make room). +const speculativeLength = 1 + +func appendSpeculativeLength(b []byte) ([]byte, int) { + pos := len(b) + b = append(b, "\x00\x00\x00\x00"[:speculativeLength]...) + return b, pos +} + +func finishSpeculativeLength(b []byte, pos int) []byte { + mlen := len(b) - pos - speculativeLength + msiz := protowire.SizeVarint(uint64(mlen)) + if msiz != speculativeLength { + for i := 0; i < msiz-speculativeLength; i++ { + b = append(b, 0) + } + copy(b[pos+msiz:], b[pos+speculativeLength:]) + b = b[:pos+msiz+mlen] + } + protowire.AppendVarint(b[:pos], uint64(mlen)) + return b +} |