varint.go

Documentation: github.com/gogo/protobuf/io

     1  // Protocol Buffers for Go with Gadgets
     2  //
     3  // Copyright (c) 2013, The GoGo Authors. All rights reserved.
     4  // http://github.com/gogo/protobuf
     5  //
     6  // Redistribution and use in source and binary forms, with or without
     7  // modification, are permitted provided that the following conditions are
     8  // met:
     9  //
    10  //     * Redistributions of source code must retain the above copyright
    11  // notice, this list of conditions and the following disclaimer.
    12  //     * Redistributions in binary form must reproduce the above
    13  // copyright notice, this list of conditions and the following disclaimer
    14  // in the documentation and/or other materials provided with the
    15  // distribution.
    16  //
    17  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    18  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    19  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    20  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    21  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    22  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    23  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    24  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    25  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    26  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    27  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    28  
    29  package io
    30  
    31  import (
    32  	"bufio"
    33  	"encoding/binary"
    34  	"errors"
    35  	"github.com/gogo/protobuf/proto"
    36  	"io"
    37  )
    38  
    39  var (
    40  	errSmallBuffer = errors.New("Buffer Too Small")
    41  	errLargeValue  = errors.New("Value is Larger than 64 bits")
    42  )
    43  
    44  func NewDelimitedWriter(w io.Writer) WriteCloser {
    45  	return &varintWriter{w, make([]byte, binary.MaxVarintLen64), nil}
    46  }
    47  
    48  type varintWriter struct {
    49  	w      io.Writer
    50  	lenBuf []byte
    51  	buffer []byte
    52  }
    53  
    54  func (this *varintWriter) WriteMsg(msg proto.Message) (err error) {
    55  	var data []byte
    56  	if m, ok := msg.(marshaler); ok {
    57  		n, ok := getSize(m)
    58  		if ok {
    59  			if n+binary.MaxVarintLen64 >= len(this.buffer) {
    60  				this.buffer = make([]byte, n+binary.MaxVarintLen64)
    61  			}
    62  			lenOff := binary.PutUvarint(this.buffer, uint64(n))
    63  			_, err = m.MarshalTo(this.buffer[lenOff:])
    64  			if err != nil {
    65  				return err
    66  			}
    67  			_, err = this.w.Write(this.buffer[:lenOff+n])
    68  			return err
    69  		}
    70  	}
    71  
    72  	// fallback
    73  	data, err = proto.Marshal(msg)
    74  	if err != nil {
    75  		return err
    76  	}
    77  	length := uint64(len(data))
    78  	n := binary.PutUvarint(this.lenBuf, length)
    79  	_, err = this.w.Write(this.lenBuf[:n])
    80  	if err != nil {
    81  		return err
    82  	}
    83  	_, err = this.w.Write(data)
    84  	return err
    85  }
    86  
    87  func (this *varintWriter) Close() error {
    88  	if closer, ok := this.w.(io.Closer); ok {
    89  		return closer.Close()
    90  	}
    91  	return nil
    92  }
    93  
    94  func NewDelimitedReader(r io.Reader, maxSize int) ReadCloser {
    95  	var closer io.Closer
    96  	if c, ok := r.(io.Closer); ok {
    97  		closer = c
    98  	}
    99  	return &varintReader{bufio.NewReader(r), nil, maxSize, closer}
   100  }
   101  
   102  type varintReader struct {
   103  	r       *bufio.Reader
   104  	buf     []byte
   105  	maxSize int
   106  	closer  io.Closer
   107  }
   108  
   109  func (this *varintReader) ReadMsg(msg proto.Message) error {
   110  	length64, err := binary.ReadUvarint(this.r)
   111  	if err != nil {
   112  		return err
   113  	}
   114  	length := int(length64)
   115  	if length < 0 || length > this.maxSize {
   116  		return io.ErrShortBuffer
   117  	}
   118  	if len(this.buf) < length {
   119  		this.buf = make([]byte, length)
   120  	}
   121  	buf := this.buf[:length]
   122  	if _, err := io.ReadFull(this.r, buf); err != nil {
   123  		return err
   124  	}
   125  	return proto.Unmarshal(buf, msg)
   126  }
   127  
   128  func (this *varintReader) Close() error {
   129  	if this.closer != nil {
   130  		return this.closer.Close()
   131  	}
   132  	return nil
   133  }
   134
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