73 lines
1.5 KiB
Go
73 lines
1.5 KiB
Go
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package mmkv
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import (
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"encoding/binary"
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"fmt"
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"hash/crc32"
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"io"
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"github.com/golang/protobuf/proto"
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"golang.org/x/exp/maps"
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)
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type vault map[string][]byte
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func (v vault) Keys() []string {
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return maps.Keys(v)
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}
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func (v vault) Get(key string) ([]byte, bool) {
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val, ok := v[key]
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return val, ok
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}
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// metadata is optional. but if it exists, validate with it.
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func loadVault(src io.Reader, m *metadata) (Vault, error) {
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fileSizeBuf := make([]byte, 4)
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_, err := io.ReadFull(src, fileSizeBuf)
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if err != nil {
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return nil, fmt.Errorf("failed to read file size: %w", err)
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}
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size := binary.LittleEndian.Uint32(fileSizeBuf)
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if m != nil && size != m.actualSize {
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return nil, fmt.Errorf("metadata and vault payload size mismatch")
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}
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buf := make([]byte, size)
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_, err = io.ReadFull(src, buf)
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if err != nil {
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return nil, fmt.Errorf("failed to read file: %w", err)
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}
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if m != nil && m.crc32 != crc32.ChecksumIEEE(buf) {
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return nil, fmt.Errorf("metadata and vault payload crc32 mismatch")
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}
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v := make(vault)
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// mmkv is not really protobuf compatible,
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// type of key & value (the first 4 bytes) is incorrect.
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// so skip the first 4 bytes & manually parse the rest.
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rd := proto.NewBuffer(buf[4:])
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for {
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if len(rd.Unread()) == 0 {
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break
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}
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key, err := rd.DecodeStringBytes()
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if err != nil {
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return nil, fmt.Errorf("failed to decode key: %w", err)
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}
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val, err := rd.DecodeRawBytes(false)
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if err != nil {
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return nil, fmt.Errorf("failed to decode value: %w", err)
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}
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v[key] = val
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}
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return v, nil
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}
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