123 lines
2.6 KiB
Go
123 lines
2.6 KiB
Go
package asar // import "layeh.com/asar"
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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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"io"
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"strconv"
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)
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type entryEncoder struct {
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Contents []io.Reader
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CurrentOffset int64
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Header bytes.Buffer
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Encoder *json.Encoder
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}
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func (enc *entryEncoder) Write(v interface{}) {
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enc.Encoder.Encode(v)
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enc.Header.Truncate(enc.Header.Len() - 1) // cut off trailing new line
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}
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func (enc *entryEncoder) WriteField(key string, v interface{}) {
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enc.Write(key)
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enc.Header.WriteByte(':')
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enc.Write(v)
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}
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func (enc *entryEncoder) Encode(e *Entry) error {
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enc.Header.WriteByte('{')
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if e.Flags&FlagDir != 0 {
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enc.Write("files")
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enc.Header.WriteString(":{")
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for i, child := range e.Children {
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if i > 0 {
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enc.Header.WriteByte(',')
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}
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if !validFilename(child.Name) {
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panic(errHeader)
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}
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enc.Write(child.Name)
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enc.Header.WriteByte(':')
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if err := enc.Encode(child); err != nil {
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return err
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}
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}
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enc.Header.WriteByte('}')
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} else {
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enc.Write("size")
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enc.Header.WriteByte(':')
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enc.Write(e.Size)
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if e.Flags&FlagExecutable != 0 {
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enc.Header.WriteByte(',')
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enc.WriteField("executable", true)
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}
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enc.Header.WriteByte(',')
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if e.Flags&FlagUnpacked == 0 {
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enc.WriteField("offset", strconv.FormatInt(enc.CurrentOffset, 10))
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enc.CurrentOffset += e.Size
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enc.Contents = append(enc.Contents, io.NewSectionReader(e.r, e.baseOffset, e.Size))
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} else {
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enc.WriteField("unpacked", true)
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}
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}
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enc.Header.WriteByte('}')
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return nil
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}
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// EncodeTo writes an ASAR archive containing Entry's descendants. This function
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// is usally called on the root entry.
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func (e *Entry) EncodeTo(w io.Writer) (n int64, err error) {
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defer func() {
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if r := recover(); r != nil {
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if e := r.(error); e != nil {
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err = e
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} else {
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panic(r)
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}
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}
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}()
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encoder := entryEncoder{}
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{
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var reserve [16]byte
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encoder.Header.Write(reserve[:])
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}
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encoder.Encoder = json.NewEncoder(&encoder.Header)
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if err = encoder.Encode(e); err != nil {
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return
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}
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{
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var padding [3]byte
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encoder.Header.Write(padding[:encoder.Header.Len()%4])
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}
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header := encoder.Header.Bytes()
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binary.LittleEndian.PutUint32(header[:4], 4)
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binary.LittleEndian.PutUint32(header[4:8], 8+uint32(encoder.Header.Len()))
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binary.LittleEndian.PutUint32(header[8:12], 4+uint32(encoder.Header.Len()))
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binary.LittleEndian.PutUint32(header[12:16], uint32(encoder.Header.Len()))
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n, err = encoder.Header.WriteTo(w)
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if err != nil {
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return
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}
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for _, chunk := range encoder.Contents {
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var written int64
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written, err = io.Copy(w, chunk)
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n += written
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if err != nil {
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return
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}
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}
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return
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}
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