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93 lines
3.3 KiB
93 lines
3.3 KiB
// Go support for Protocol Buffers - Google's data interchange format |
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// |
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// Copyright 2016 The Go Authors. All rights reserved. |
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// https://github.com/golang/protobuf |
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// |
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// Redistribution and use in source and binary forms, with or without |
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// modification, are permitted provided that the following conditions are |
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// met: |
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// |
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// * Redistributions of source code must retain the above copyright |
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// notice, this list of conditions and the following disclaimer. |
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// * Redistributions in binary form must reproduce the above |
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// copyright notice, this list of conditions and the following disclaimer |
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// in the documentation and/or other materials provided with the |
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// distribution. |
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// * Neither the name of Google Inc. nor the names of its |
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// contributors may be used to endorse or promote products derived from |
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// this software without specific prior written permission. |
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// |
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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// Package descriptor provides functions for obtaining protocol buffer |
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// descriptors for generated Go types. |
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// |
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// These functions cannot go in package proto because they depend on the |
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// generated protobuf descriptor messages, which themselves depend on proto. |
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package descriptor |
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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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protobuf "github.com/golang/protobuf/protoc-gen-go/descriptor" |
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) |
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// extractFile extracts a FileDescriptorProto from a gzip'd buffer. |
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func extractFile(gz []byte) (*protobuf.FileDescriptorProto, error) { |
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r, err := gzip.NewReader(bytes.NewReader(gz)) |
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if err != nil { |
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return nil, fmt.Errorf("failed to open gzip reader: %v", err) |
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} |
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defer r.Close() |
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b, err := ioutil.ReadAll(r) |
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if err != nil { |
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return nil, fmt.Errorf("failed to uncompress descriptor: %v", err) |
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} |
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fd := new(protobuf.FileDescriptorProto) |
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if err := proto.Unmarshal(b, fd); err != nil { |
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return nil, fmt.Errorf("malformed FileDescriptorProto: %v", err) |
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} |
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return fd, nil |
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} |
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// Message is a proto.Message with a method to return its descriptor. |
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// |
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// Message types generated by the protocol compiler always satisfy |
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// the Message interface. |
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type Message interface { |
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proto.Message |
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Descriptor() ([]byte, []int) |
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} |
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// ForMessage returns a FileDescriptorProto and a DescriptorProto from within it |
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// describing the given message. |
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func ForMessage(msg Message) (fd *protobuf.FileDescriptorProto, md *protobuf.DescriptorProto) { |
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gz, path := msg.Descriptor() |
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fd, err := extractFile(gz) |
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if err != nil { |
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panic(fmt.Sprintf("invalid FileDescriptorProto for %T: %v", msg, err)) |
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} |
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md = fd.MessageType[path[0]] |
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for _, i := range path[1:] { |
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md = md.NestedType[i] |
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} |
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return fd, md |
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}
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