67 lines
1.4 KiB
Go
67 lines
1.4 KiB
Go
package db0105
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import (
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"encoding/binary"
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"errors"
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"hash/crc32"
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"io"
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)
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type Entry struct {
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crc32 []byte
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key []byte
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val []byte
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deleted bool
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}
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func (ent *Entry) Encode() []byte {
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data := make([]byte, 4+4+4+1+len(ent.key)+len(ent.val))
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binary.LittleEndian.PutUint32(data[4:8], uint32(len(ent.key)))
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copy(data[13:], ent.key)
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if ent.deleted {
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data[12] = 1
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} else {
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binary.LittleEndian.PutUint32(data[8:12], uint32(len(ent.val)))
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copy(data[13+len(ent.key):], ent.val)
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}
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checksum := crc32.ChecksumIEEE(data[4:])
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binary.LittleEndian.PutUint32(data[0:4], checksum)
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return data
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}
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var ErrBadSum = errors.New("bad checksum")
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func (ent *Entry) Decode(r io.Reader) error {
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var header [13]byte
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if _, err := io.ReadFull(r, header[:]); err != nil {
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return err
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}
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klen := int(binary.LittleEndian.Uint32(header[4:8]))
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vlen := int(binary.LittleEndian.Uint32(header[8:12]))
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deleted := header[12]
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data := make([]byte, klen+vlen)
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if _, err := io.ReadFull(r, data); err != nil {
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return err
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}
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checksum := crc32.NewIEEE()
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checksum.Write(header[4:])
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checksum.Write(data)
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if checksum.Sum32() != binary.LittleEndian.Uint32(header[0:4]) {
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return ErrBadSum
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}
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ent.key = data[:klen]
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if deleted != 0 {
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ent.deleted = true
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} else {
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ent.deleted = false
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ent.val = data[klen:]
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}
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return nil
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}
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// QzBQWVJJOUhU https://trialofcode.org/
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