87 lines
1.9 KiB
Go
87 lines
1.9 KiB
Go
package util
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import (
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"bytes"
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"encoding/binary"
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"io"
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)
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//BinReader is a convenient wrapper around a io.Reader and err object
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// Used to simplify error handling when reading into a struct with many fields
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type BinReader struct {
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r io.Reader
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Err error
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}
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// NewBinReaderFromIO makes a BinReader from io.Reader.
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func NewBinReaderFromIO(ior io.Reader) *BinReader {
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return &BinReader{r: ior}
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}
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// NewBinReaderFromBuf makes a BinReader from byte buffer.
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func NewBinReaderFromBuf(b []byte) *BinReader {
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r := bytes.NewReader(b)
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return NewBinReaderFromIO(r)
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}
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// ReadLE reads from the underlying io.Reader
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// into the interface v in little-endian format
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func (r *BinReader) ReadLE(v interface{}) {
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if r.Err != nil {
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return
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}
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r.Err = binary.Read(r.r, binary.LittleEndian, v)
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}
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// ReadBE reads from the underlying io.Reader
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// into the interface v in big-endian format
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func (r *BinReader) ReadBE(v interface{}) {
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if r.Err != nil {
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return
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}
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r.Err = binary.Read(r.r, binary.BigEndian, v)
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}
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// ReadVarUint reads a variable-length-encoded integer from the
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// underlying reader
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func (r *BinReader) ReadVarUint() uint64 {
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if r.Err != nil {
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return 0
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}
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var b uint8
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r.Err = binary.Read(r.r, binary.LittleEndian, &b)
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if b == 0xfd {
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var v uint16
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r.Err = binary.Read(r.r, binary.LittleEndian, &v)
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return uint64(v)
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}
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if b == 0xfe {
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var v uint32
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r.Err = binary.Read(r.r, binary.LittleEndian, &v)
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return uint64(v)
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}
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if b == 0xff {
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var v uint64
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r.Err = binary.Read(r.r, binary.LittleEndian, &v)
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return v
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}
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return uint64(b)
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}
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// ReadBytes reads the next set of bytes from the underlying reader.
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// ReadVarUInt() is used to determine how large that slice is
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func (r *BinReader) ReadBytes() []byte {
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n := r.ReadVarUint()
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b := make([]byte, n)
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r.ReadLE(b)
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return b
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}
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// ReadString calls ReadBytes and casts the results as a string
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func (r *BinReader) ReadString() string {
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b := r.ReadBytes()
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return string(b)
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}
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