You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
62 lines
1.5 KiB
62 lines
1.5 KiB
package structure
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"fmt"
|
|
"github.com/alibaba/RedisShake/internal/log"
|
|
"io"
|
|
)
|
|
|
|
const (
|
|
RDB6ByteLen = 0 // RDB_6BITLEN
|
|
RDB14ByteLen = 1 // RDB_14BITLEN
|
|
len32or64Bit = 2
|
|
lenSpecial = 3 // RDB_ENCVAL
|
|
RDB32ByteLen = 0x80
|
|
RDB64ByteLen = 0x81
|
|
)
|
|
|
|
func ReadLength(rd io.Reader) uint64 {
|
|
length, special, err := readEncodedLength(rd)
|
|
if special {
|
|
log.Panicf("illegal length special=true, encoding: %d", length)
|
|
}
|
|
if err != nil {
|
|
log.PanicError(err)
|
|
}
|
|
return length
|
|
}
|
|
|
|
func readEncodedLength(rd io.Reader) (length uint64, special bool, err error) {
|
|
var lengthBuffer = make([]byte, 8)
|
|
|
|
firstByte := ReadByte(rd)
|
|
first2bits := (firstByte & 0xc0) >> 6 // first 2 bits of encoding
|
|
switch first2bits {
|
|
case RDB6ByteLen:
|
|
length = uint64(firstByte) & 0x3f
|
|
case RDB14ByteLen:
|
|
nextByte := ReadByte(rd)
|
|
length = (uint64(firstByte)&0x3f)<<8 | uint64(nextByte)
|
|
case len32or64Bit:
|
|
if firstByte == RDB32ByteLen {
|
|
_, err = io.ReadFull(rd, lengthBuffer[0:4])
|
|
if err != nil {
|
|
return 0, false, fmt.Errorf("read len32Bit failed: %s", err.Error())
|
|
}
|
|
length = uint64(binary.BigEndian.Uint32(lengthBuffer))
|
|
} else if firstByte == RDB64ByteLen {
|
|
_, err = io.ReadFull(rd, lengthBuffer)
|
|
if err != nil {
|
|
return 0, false, fmt.Errorf("read len64Bit failed: %s", err.Error())
|
|
}
|
|
length = binary.BigEndian.Uint64(lengthBuffer)
|
|
} else {
|
|
return 0, false, fmt.Errorf("illegal length encoding: %x", firstByte)
|
|
}
|
|
case lenSpecial:
|
|
special = true
|
|
length = uint64(firstByte) & 0x3f
|
|
}
|
|
return length, special, nil
|
|
}
|
|
|