33 lines
767 B
Go
33 lines
767 B
Go
// Copyright (C) 2025 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package protoutil
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import (
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"errors"
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"google.golang.org/protobuf/proto"
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)
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var errBufferTooSmall = errors.New("buffer too small")
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func MarshalTo(buf []byte, pb proto.Message) (int, error) {
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if sz := proto.Size(pb); len(buf) < sz {
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return 0, errBufferTooSmall
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} else if sz == 0 {
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return 0, nil
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}
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opts := proto.MarshalOptions{}
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bs, err := opts.MarshalAppend(buf[:0], pb)
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if err != nil {
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return 0, err
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}
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if &buf[0] != &bs[0] {
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panic("can't happen: slice was reallocated")
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}
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return len(bs), nil
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}
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