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package pktline
import (
"errors"
"io"
"strconv"
)
var (
ErrUnderflow = errors.New("unexpected string length (underflow)")
ErrInvalidHeader = errors.New("invalid header")
ErrInvalidLen = errors.New("invalid length")
)
// Decoder implements a pkt-line format decoder
type Decoder struct {
r io.Reader
}
// NewDecoder returns a new Decoder
func NewDecoder(r io.Reader) *Decoder {
return &Decoder{r}
}
// ReadLine reads and return one pkt-line line from the reader
func (d *Decoder) ReadLine() (string, error) {
return d.readLine()
}
func (d *Decoder) readLine() (string, error) {
raw := make([]byte, HeaderLength)
if _, err := d.r.Read(raw); err != nil {
return "", err
}
header, err := strconv.ParseInt(string(raw), 16, 16)
if err != nil {
return "", ErrInvalidHeader
}
if header == 0 {
return "", nil
}
exp := int(header - HeaderLength)
if exp < 0 {
return "", ErrInvalidLen
}
line := make([]byte, exp)
if read, err := io.ReadFull(d.r, line); err != nil {
if err == io.ErrUnexpectedEOF && read < exp {
return "", ErrUnderflow
}
return "", err
}
return string(line), nil
}
// ReadBlock reads and return multiple pkt-line lines, it stops at the end
// of the reader or if a flush-pkt is reached
func (d *Decoder) ReadBlock() ([]string, error) {
var o []string
for {
line, err := d.readLine()
if err == io.EOF {
return o, nil
}
if err != nil {
return o, err
}
if err == nil && line == "" {
return o, nil
}
o = append(o, line)
}
}
// ReadAll read and returns all the lines
func (d *Decoder) ReadAll() ([]string, error) {
result, err := d.ReadBlock()
if err != nil {
return result, err
}
for {
lines, err := d.ReadBlock()
if err == io.EOF {
return result, nil
}
if err != nil {
return result, err
}
if err == nil && len(lines) == 0 {
return result, nil
}
result = append(result, lines...)
}
}
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