57 lines
1.1 KiB
Go
57 lines
1.1 KiB
Go
package mmkv
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import (
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"encoding/binary"
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"fmt"
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"io"
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)
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type metadata struct {
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// added in version 0
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crc32 uint32
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// added in version 1
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version uint32
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sequence uint32 // full write back count
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// added in version 2
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aesVector []byte // random iv for encryption, aes.BlockSize (16 bytes)
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// added in version 3, try to reduce file corruption
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actualSize uint32
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lastActualSize uint32
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lastCRC32 uint32
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//_reversed []byte // 64 bytes
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}
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func loadMetadata(rd io.Reader) (*metadata, error) {
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buf := make([]byte, 0x68)
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_, err := io.ReadFull(rd, buf)
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if err != nil {
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return nil, fmt.Errorf("failed to read metadata: %w", err)
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}
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m := &metadata{}
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m.crc32 = binary.LittleEndian.Uint32(buf[0:4])
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m.version = binary.LittleEndian.Uint32(buf[4:8])
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if m.version >= 1 {
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m.sequence = binary.LittleEndian.Uint32(buf[8:12])
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}
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if m.version >= 2 {
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m.aesVector = buf[12:28]
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}
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if m.version >= 3 {
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m.actualSize = binary.LittleEndian.Uint32(buf[28:32])
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m.lastActualSize = binary.LittleEndian.Uint32(buf[32:36])
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m.lastCRC32 = binary.LittleEndian.Uint32(buf[36:40])
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}
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//m._reversed = buf[40:104]
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return m, nil
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}
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