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// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Parsing of Arq's binary data structures.
package arq
import (
"bytes"
"encoding/binary"
"fmt"
"reflect"
"time"
)
var errMalformed = fmt.Errorf("malformed data")
var tagType = reflect.TypeOf(tag(""))
var timeType = reflect.TypeOf(time.Time{})
var scoreType = reflect.TypeOf(score{})
func unpack(data []byte, v interface{}) error {
data, err := unpackValue(data, reflect.ValueOf(v).Elem(), "")
if err != nil {
return err
}
if len(data) != 0 {
if len(data) > 100 {
return fmt.Errorf("more data than expected: %x...", data[:100])
}
return fmt.Errorf("more data than expected: %x", data)
}
return nil
}
func unpackValue(data []byte, v reflect.Value, tag string) ([]byte, error) {
//println("unpackvalue", v.Type().String(), len(data))
switch v.Kind() {
case reflect.String:
if v.Type() == tagType {
if tag == "" {
panic("arqfs: missing reflect tag on Tag field")
}
if len(data) < len(tag) || !bytes.Equal(data[:len(tag)], []byte(tag)) {
return nil, errMalformed
}
data = data[len(tag):]
return data, nil
}
if len(data) < 1 {
return nil, errMalformed
}
if data[0] == 0 {
data = data[1:]
v.SetString("")
return data, nil
}
if data[0] != 1 || len(data) < 1+8 {
return nil, errMalformed
}
n := binary.BigEndian.Uint64(data[1:])
data = data[1+8:]
if n >= uint64(len(data)) {
return nil, errMalformed
}
str := data[:n]
data = data[n:]
v.SetString(string(str))
return data, nil
case reflect.Uint32:
if len(data) < 4 {
return nil, errMalformed
}
v.SetUint(uint64(binary.BigEndian.Uint32(data)))
data = data[4:]
return data, nil
case reflect.Int32:
if len(data) < 4 {
return nil, errMalformed
}
v.SetInt(int64(binary.BigEndian.Uint32(data)))
data = data[4:]
return data, nil
case reflect.Uint8:
if len(data) < 1 {
return nil, errMalformed
}
v.SetUint(uint64(data[0]))
data = data[1:]
return data, nil
case reflect.Uint64:
if len(data) < 8 {
return nil, errMalformed
}
v.SetUint(binary.BigEndian.Uint64(data))
data = data[8:]
return data, nil
case reflect.Int64:
if len(data) < 8 {
return nil, errMalformed
}
v.SetInt(int64(binary.BigEndian.Uint64(data)))
data = data[8:]
return data, nil
case reflect.Ptr:
v.Set(reflect.New(v.Type().Elem()))
return unpackValue(data, v.Elem(), tag)
case reflect.Slice:
var n int
if tag == "count32" {
n32 := binary.BigEndian.Uint32(data)
n = int(n32)
if uint32(n) != n32 {
return nil, errMalformed
}
data = data[4:]
} else {
if len(data) < 8 {
return nil, errMalformed
}
n64 := binary.BigEndian.Uint64(data)
n = int(n64)
if uint64(n) != n64 {
return nil, errMalformed
}
data = data[8:]
}
v.Set(v.Slice(0, 0))
if v.Type().Elem().Kind() == reflect.Uint8 {
// Fast case for []byte
if len(data) < n {
return nil, errMalformed
}
v.Set(reflect.AppendSlice(v, reflect.ValueOf(data[:n])))
return data[n:], nil
}
for i := 0; i < n; i++ {
elem := reflect.New(v.Type().Elem()).Elem()
var err error
data, err = unpackValue(data, elem, "")
if err != nil {
return nil, err
}
v.Set(reflect.Append(v, elem))
}
return data, nil
case reflect.Array:
if v.Type() == scoreType && tag == "HexScore" {
var s string
data, err := unpackValue(data, reflect.ValueOf(&s).Elem(), "")
if err != nil {
return nil, err
}
if len(s) != 0 {
v.Set(reflect.ValueOf(hexScore(s)))
}
return data, nil
}
n := v.Len()
if v.Type().Elem().Kind() == reflect.Uint8 {
// Fast case for [n]byte
if len(data) < n {
return nil, errMalformed
}
reflect.Copy(v, reflect.ValueOf(data))
data = data[n:]
return data, nil
}
for i := 0; i < n; i++ {
var err error
data, err = unpackValue(data, v.Index(i), "")
if err != nil {
return nil, err
}
}
return data, nil
case reflect.Bool:
if len(data) < 1 || data[0] > 1 {
if len(data) >= 1 {
println("badbool", data[0])
}
return nil, errMalformed
}
v.SetBool(data[0] == 1)
data = data[1:]
return data, nil
case reflect.Struct:
if v.Type() == timeType {
if len(data) < 1 || data[0] > 1 {
return nil, errMalformed
}
if data[0] == 0 {
v.Set(reflect.ValueOf(time.Time{}))
return data[1:], nil
}
data = data[1:]
if len(data) < 8 {
return nil, errMalformed
}
ms := binary.BigEndian.Uint64(data)
v.Set(reflect.ValueOf(time.Unix(int64(ms/1e3), int64(ms%1e3)*1e6)))
return data[8:], nil
}
for i := 0; i < v.NumField(); i++ {
f := v.Type().Field(i)
fv := v.Field(i)
var err error
data, err = unpackValue(data, fv, f.Tag.Get("arq"))
if err != nil {
return nil, err
}
}
return data, nil
}
panic("arqfs: unexpected type in unpackValue: " + v.Type().String())
}
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