1c2d667b49
This commit makes the magic number in the trix file format configurable. - The `Encode` and `Decode` functions in the `trix` package now accept a `magicNumber` string as a parameter. - The example in `examples/main.go` has been updated to demonstrate the use of the new configurable magic number. - The tests for the `trix` package have been updated to verify the new functionality, including tests for invalid magic numbers.
122 lines
2.5 KiB
Go
122 lines
2.5 KiB
Go
package trix
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import (
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"bytes"
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"encoding/binary"
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"encoding/json"
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"errors"
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"fmt"
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"io"
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)
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const (
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Version = 2
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)
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var (
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ErrInvalidMagicNumber = errors.New("trix: invalid magic number")
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ErrInvalidVersion = errors.New("trix: invalid version")
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ErrMagicNumberLength = errors.New("trix: magic number must be 4 bytes long")
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)
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// Trix represents the structure of a .trix file.
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type Trix struct {
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Header map[string]interface{}
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Payload []byte
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}
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// Encode serializes a Trix struct into the .trix binary format.
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func Encode(trix *Trix, magicNumber string) ([]byte, error) {
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if len(magicNumber) != 4 {
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return nil, ErrMagicNumberLength
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}
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headerBytes, err := json.Marshal(trix.Header)
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if err != nil {
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return nil, err
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}
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headerLength := uint32(len(headerBytes))
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buf := new(bytes.Buffer)
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// Write Magic Number
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if _, err := buf.WriteString(magicNumber); err != nil {
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return nil, err
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}
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// Write Version
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if err := buf.WriteByte(byte(Version)); err != nil {
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return nil, err
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}
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// Write Header Length
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if err := binary.Write(buf, binary.BigEndian, headerLength); err != nil {
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return nil, err
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}
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// Write JSON Header
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if _, err := buf.Write(headerBytes); err != nil {
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return nil, err
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}
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// Write Payload
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if _, err := buf.Write(trix.Payload); err != nil {
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return nil, err
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}
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return buf.Bytes(), nil
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}
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// Decode deserializes the .trix binary format into a Trix struct.
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func Decode(data []byte, magicNumber string) (*Trix, error) {
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if len(magicNumber) != 4 {
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return nil, ErrMagicNumberLength
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}
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buf := bytes.NewReader(data)
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// Read and Verify Magic Number
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magic := make([]byte, 4)
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if _, err := io.ReadFull(buf, magic); err != nil {
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return nil, err
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}
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if string(magic) != magicNumber {
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return nil, fmt.Errorf("%w: expected %s, got %s", ErrInvalidMagicNumber, magicNumber, string(magic))
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}
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// Read and Verify Version
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version, err := buf.ReadByte()
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if err != nil {
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return nil, err
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}
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if version != Version {
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return nil, ErrInvalidVersion
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}
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// Read Header Length
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var headerLength uint32
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if err := binary.Read(buf, binary.BigEndian, &headerLength); err != nil {
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return nil, err
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}
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// Read JSON Header
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headerBytes := make([]byte, headerLength)
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if _, err := io.ReadFull(buf, headerBytes); err != nil {
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return nil, err
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}
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var header map[string]interface{}
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if err := json.Unmarshal(headerBytes, &header); err != nil {
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return nil, err
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}
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// Read Payload
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payload, err := io.ReadAll(buf)
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if err != nil {
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return nil, err
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}
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return &Trix{
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Header: header,
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Payload: payload,
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}, nil
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}
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