/
reader.go
97 lines (87 loc) · 1.87 KB
/
reader.go
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package rippleTransaction
import (
"fmt"
"io"
)
type Reader interface {
io.ByteScanner
io.Reader
Len() int
}
type LimitByteReader struct {
R Reader // underlying reader
N int64 // max bytes remaining
}
func LimitedByteReader(r Reader, n int64) *LimitByteReader {
return &LimitByteReader{r, n}
}
func (l *LimitByteReader) Len() int {
return int(l.N)
}
func NewVariableByteReader(r Reader) (Reader, error) {
if length, err := readVariableLength(r); err != nil {
return nil, err
} else {
return LimitedByteReader(r, int64(length)), nil
}
}
func readVariableLength(r Reader) (int, error) {
var first, second, third byte
var err error
if first, err = r.ReadByte(); err != nil {
return 0, err
}
switch {
case first <= 192:
return int(first), nil
case first <= 240:
if second, err = r.ReadByte(); err != nil {
return 0, nil
}
return 193 + int(first-193)*256 + int(second), nil
case first <= 254:
if second, err = r.ReadByte(); err != nil {
return 0, nil
}
if third, err = r.ReadByte(); err != nil {
return 0, nil
}
return 12481 + int(first-241)*65536 + int(second)*256 + int(third), nil
}
return 0, fmt.Errorf("Unsupported Variable Length encoding")
}
func (l *LimitByteReader) Read(p []byte) (n int, err error) {
if l.N <= 0 {
return 0, io.EOF
}
if int64(len(p)) > l.N {
p = p[0:l.N]
}
n, err = l.R.Read(p)
l.N -= int64(n)
return
}
func (l *LimitByteReader) ReadByte() (c byte, err error) {
if l.N <= 0 {
return 0, io.EOF
}
l.N--
return l.R.ReadByte()
}
func (l *LimitByteReader) UnreadByte() error {
if err := l.UnreadByte(); err != nil {
return err
}
l.N++
return nil
}
func unmarshalSlice(s []byte, r Reader, prefix string) error {
n, err := r.Read(s)
if n != len(s) {
return fmt.Errorf("%s: short read: %d expected: %d", prefix, n, len(s))
}
if err != nil {
return fmt.Errorf("%s: %s", prefix, err.Error())
}
return nil
}