syncthing/xdr/reader.go
2014-06-30 13:35:48 +02:00

191 lines
3.3 KiB
Go

// Copyright (C) 2014 Jakob Borg and other contributors. All rights reserved.
// Use of this source code is governed by an MIT-style license that can be
// found in the LICENSE file.
package xdr
import (
"errors"
"io"
"time"
)
var ErrElementSizeExceeded = errors.New("element size exceeded")
type Reader struct {
r io.Reader
tot int
err error
b [8]byte
sb []byte
last time.Time
}
func NewReader(r io.Reader) *Reader {
return &Reader{
r: r,
}
}
func (r *Reader) ReadString() string {
if r.sb == nil {
r.sb = make([]byte, 64)
} else {
r.sb = r.sb[:cap(r.sb)]
}
r.sb = r.ReadBytesInto(r.sb)
return string(r.sb)
}
func (r *Reader) ReadStringMax(max int) string {
if r.sb == nil {
r.sb = make([]byte, 64)
} else {
r.sb = r.sb[:cap(r.sb)]
}
r.sb = r.ReadBytesMaxInto(max, r.sb)
return string(r.sb)
}
func (r *Reader) ReadBytes() []byte {
return r.ReadBytesInto(nil)
}
func (r *Reader) ReadBytesMax(max int) []byte {
return r.ReadBytesMaxInto(max, nil)
}
func (r *Reader) ReadBytesInto(dst []byte) []byte {
return r.ReadBytesMaxInto(0, dst)
}
func (r *Reader) ReadBytesMaxInto(max int, dst []byte) []byte {
if r.err != nil {
return nil
}
r.last = time.Now()
s := r.tot
l := int(r.ReadUint32())
if r.err != nil {
return nil
}
if max > 0 && l > max {
r.err = ErrElementSizeExceeded
return nil
}
if l+pad(l) > len(dst) {
dst = make([]byte, l+pad(l))
} else {
dst = dst[:l+pad(l)]
}
var n int
n, r.err = io.ReadFull(r.r, dst)
if r.err != nil {
if debug {
dl.Debugf("@0x%x: rd bytes (%d): %v", s, len(dst), r.err)
}
return nil
}
r.tot += n
if debug {
if n > maxDebugBytes {
dl.Debugf("@0x%x: rd bytes (%d): %x...", s, len(dst), dst[:maxDebugBytes])
} else {
dl.Debugf("@0x%x: rd bytes (%d): %x", s, len(dst), dst)
}
}
return dst[:l]
}
func (r *Reader) ReadUint16() uint16 {
if r.err != nil {
return 0
}
r.last = time.Now()
s := r.tot
var n int
n, r.err = io.ReadFull(r.r, r.b[:4])
r.tot += n
if r.err != nil {
if debug {
dl.Debugf("@0x%x: rd uint16: %v", r.tot, r.err)
}
return 0
}
v := uint16(r.b[3]) | uint16(r.b[2])<<8
if debug {
dl.Debugf("@0x%x: rd uint16=%d (0x%04x)", s, v, v)
}
return v
}
func (r *Reader) ReadUint32() uint32 {
if r.err != nil {
return 0
}
r.last = time.Now()
s := r.tot
var n int
n, r.err = io.ReadFull(r.r, r.b[:4])
r.tot += n
if r.err != nil {
if debug {
dl.Debugf("@0x%x: rd uint32: %v", r.tot, r.err)
}
return 0
}
v := uint32(r.b[3]) | uint32(r.b[2])<<8 | uint32(r.b[1])<<16 | uint32(r.b[0])<<24
if debug {
dl.Debugf("@0x%x: rd uint32=%d (0x%08x)", s, v, v)
}
return v
}
func (r *Reader) ReadUint64() uint64 {
if r.err != nil {
return 0
}
r.last = time.Now()
s := r.tot
var n int
n, r.err = io.ReadFull(r.r, r.b[:8])
r.tot += n
if r.err != nil {
if debug {
dl.Debugf("@0x%x: rd uint64: %v", r.tot, r.err)
}
return 0
}
v := uint64(r.b[7]) | uint64(r.b[6])<<8 | uint64(r.b[5])<<16 | uint64(r.b[4])<<24 |
uint64(r.b[3])<<32 | uint64(r.b[2])<<40 | uint64(r.b[1])<<48 | uint64(r.b[0])<<56
if debug {
dl.Debugf("@0x%x: rd uint64=%d (0x%016x)", s, v, v)
}
return v
}
func (r *Reader) Tot() int {
return r.tot
}
func (r *Reader) Error() error {
return r.err
}
func (r *Reader) LastRead() time.Time {
return r.last
}