git.giacomolli.uk - onechat/blob - voice_store.go

   1 package main
   2
   3 import (
   4         "crypto/sha256"
   5         "encoding/hex"
   6         "errors"
   7         "fmt"
   8         "os"
   9         "path/filepath"
  10 )
  11
  12 const (
  13         voiceDirName  = "voices"
  14         voiceMaxBytes = 20 << 20
  15 )
  16
  17 var errVoiceSize = errors.New("voice note is empty or exceeds 20 MB")
  18
  19 // VoiceStore holds immutable audio shared by all agents. Names are hashes of
  20 // the received bytes, not sender filenames. The decoder detects the format.
  21 type VoiceStore struct {
  22         dir string
  23 }
  24
  25 // Save publishes private audio atomically before its message is acknowledged.
  26 // Only nonempty input up to voiceMaxBytes is stored.
  27 func (s *VoiceStore) Save(data []byte) (name string, err error) {
  28         if len(data) == 0 || len(data) > voiceMaxBytes {
  29                 return "", errVoiceSize
  30         }
  31
  32         sum := sha256.Sum256(data)
  33         name = hex.EncodeToString(sum[:]) + ".audio"
  34         err = os.MkdirAll(s.dir, 0o700)
  35         if err != nil {
  36                 return "", fmt.Errorf("create voice directory: %w", err)
  37         }
  38
  39         file, err := os.CreateTemp(s.dir, ".voice-*")
  40         if err != nil {
  41                 return "", fmt.Errorf("create voice file: %w", err)
  42         }
  43
  44         defer func() {
  45                 err = errors.Join(err, os.Remove(file.Name()))
  46         }()
  47
  48         _, err = file.Write(data)
  49         if err == nil {
  50                 err = file.Sync()
  51         }
  52
  53         err = errors.Join(err, file.Close())
  54         if err != nil {
  55                 return "", fmt.Errorf("write voice: %w", err)
  56         }
  57
  58         err = os.Link(file.Name(), filepath.Join(s.dir, name))
  59         if err != nil && !errors.Is(err, os.ErrExist) {
  60                 return "", fmt.Errorf("publish voice: %w", err)
  61         }
  62
  63         return name, nil
  64 }