105 lines
2.8 KiB
Go
105 lines
2.8 KiB
Go
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package leveldat
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import (
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"bufio"
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"encoding/binary"
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"fmt"
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"io"
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"os"
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"github.com/sandertv/gophertunnel/minecraft/nbt"
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)
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// LevelDat implements the encoding and decoding of level.dat files. An empty
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// LevelDat is a valid value and may be used to Marshal and Write to a writer or
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// file afterward.
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type LevelDat struct {
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hdr header
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data []byte
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}
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// header holds the header for a level.dat file.
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type header struct {
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StorageVersion int32
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FileLength int32
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}
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// ReadFile reads a level.dat at a path and returns it.
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func ReadFile(name string) (*LevelDat, error) {
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f, err := os.Open(name)
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if err != nil {
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return nil, fmt.Errorf("level.dat: open file: %w", err)
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}
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defer f.Close()
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return Read(bufio.NewReader(f))
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}
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// Read reads a level.dat from r and returns it.
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func Read(r io.Reader) (*LevelDat, error) {
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var ldat LevelDat
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if err := binary.Read(r, binary.LittleEndian, &ldat.hdr); err != nil {
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return nil, fmt.Errorf("level.dat: read header: %w", err)
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}
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ldat.data = make([]byte, ldat.hdr.FileLength)
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if n, err := io.ReadFull(r, ldat.data); err != nil || int32(n) != ldat.hdr.FileLength {
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return nil, fmt.Errorf("level.dat: read data: %w", err)
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}
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return &ldat, nil
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}
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// Unmarshal decodes the level.dat properties from ld into dst. Unmarshal
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// returns an error if dst was unable to store all properties found in the
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// level.dat.
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func (ld *LevelDat) Unmarshal(dst any) error {
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if err := nbt.UnmarshalEncoding(ld.data, dst, nbt.LittleEndian); err != nil {
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return fmt.Errorf("level.dat: decode nbt: %w", err)
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}
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return nil
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}
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// Ver returns the version of the level.dat decoded, or 0 if ld is the empty
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// value.
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func (ld *LevelDat) Ver() int {
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return int(ld.hdr.StorageVersion)
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}
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// Marshal encodes src and stores it in the level.dat. src should be either a
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// struct or a map of fields. Marshal updates the storage version to the latest.
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func (ld *LevelDat) Marshal(src any) error {
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var err error
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ld.data, err = nbt.MarshalEncoding(src, nbt.LittleEndian)
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if err != nil {
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return fmt.Errorf("level.dat: encode nbt: %w", err)
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}
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ld.hdr = header{
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StorageVersion: Version,
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FileLength: int32(len(ld.data)),
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}
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return nil
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}
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// Write writes ld to w.
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func (ld *LevelDat) Write(w io.Writer) error {
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if err := binary.Write(w, binary.LittleEndian, ld.hdr); err != nil {
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return fmt.Errorf("level.dat: write header: %w", err)
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}
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if _, err := w.Write(ld.data); err != nil {
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return fmt.Errorf("level.dat: write data: %w", err)
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}
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return nil
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}
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// WriteFile writes ld to a file at name.
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func (ld *LevelDat) WriteFile(name string) error {
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f, err := os.OpenFile(name, os.O_TRUNC|os.O_CREATE|os.O_WRONLY, 0644)
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if err != nil {
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return fmt.Errorf("level.dat: open file: %w", err)
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}
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w := bufio.NewWriter(f)
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defer func() {
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_ = w.Flush()
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_ = f.Close()
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}()
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return ld.Write(w)
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}
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