writer.go

   1 package main
   2
   3 import (
   4         "bufio"
   5         "encoding/binary"
   6         "io"
   7         "log"
   8
   9         "github.com/klauspost/compress/zstd"
  10 )
  11
  12 func mustWrite(w io.Writer, buf []byte) {
  13         if _, err := w.Write(buf); err != nil {
  14                 log.Fatalln(err)
  15         }
  16 }
  17
  18 func writer(dst io.Writer, sink chan Ent) {
  19         comp, err := zstd.NewWriter(dst)
  20         if err != nil {
  21                 log.Fatalln(err)
  22         }
  23         bw := bufio.NewWriterSize(comp, 1<<17)
  24         num := make([]byte, 8)
  25         var name string
  26         for ent := range sink {
  27                 name = ent.name[len(ent.name)-1]
  28                 if len(ent.name) >= 1<<16 {
  29                         panic("too long")
  30                 }
  31                 binary.BigEndian.PutUint16(num[:2], uint16(len(name)))
  32                 mustWrite(bw, num[:2])
  33                 mustWrite(bw, []byte(name))
  34                 if len(ent.name) >= 1<<8 {
  35                         panic("too deep")
  36                 }
  37                 mustWrite(bw, []byte{byte(len(ent.name) - 1)})
  38                 binary.BigEndian.PutUint64(num, uint64(ent.mtime))
  39                 mustWrite(bw, num)
  40                 binary.BigEndian.PutUint64(num, uint64(ent.size))
  41                 mustWrite(bw, num)
  42         }
  43         if err = bw.Flush(); err != nil {
  44                 log.Fatalln(err)
  45         }
  46         if err = comp.Close(); err != nil {
  47                 log.Fatalln(err)
  48         }
  49 }