git.r.bdr.sh - rbdr/mobius/blob - hotline/file_name_with_info.go

   1 package hotline
   2
   3 import (
   4         "bytes"
   5         "encoding/binary"
   6         "io"
   7         "slices"
   8 )
   9
  10 type FileNameWithInfo struct {
  11         fileNameWithInfoHeader
  12         Name []byte // File Name
  13
  14         readOffset int // Internal offset to track read progress
  15 }
  16
  17 // fileNameWithInfoHeader contains the fixed length fields of FileNameWithInfo
  18 type fileNameWithInfoHeader struct {
  19         Type       [4]byte // File type code
  20         Creator    [4]byte // File creator code
  21         FileSize   [4]byte // File Size in bytes
  22         RSVD       [4]byte
  23         NameScript [2]byte // ??
  24         NameSize   [2]byte // Length of Name field
  25 }
  26
  27 func (f *fileNameWithInfoHeader) nameLen() int {
  28         return int(binary.BigEndian.Uint16(f.NameSize[:]))
  29 }
  30
  31 // Read implements io.Reader for FileNameWithInfo
  32 func (f *FileNameWithInfo) Read(p []byte) (int, error) {
  33         buf := slices.Concat(
  34                 f.Type[:],
  35                 f.Creator[:],
  36                 f.FileSize[:],
  37                 f.RSVD[:],
  38                 f.NameScript[:],
  39                 f.NameSize[:],
  40                 f.Name,
  41         )
  42
  43         if f.readOffset >= len(buf) {
  44                 return 0, io.EOF // All bytes have been read
  45         }
  46
  47         n := copy(p, buf[f.readOffset:])
  48         f.readOffset += n
  49
  50         return n, nil
  51 }
  52
  53 func (f *FileNameWithInfo) Write(p []byte) (int, error) {
  54         err := binary.Read(bytes.NewReader(p), binary.BigEndian, &f.fileNameWithInfoHeader)
  55         if err != nil {
  56                 return 0, err
  57         }
  58         headerLen := binary.Size(f.fileNameWithInfoHeader)
  59         f.Name = p[headerLen : headerLen+f.nameLen()]
  60
  61         return len(p), nil
  62 }