fs/file_handle.go

   1 package torrentfs
   2
   3 import (
   4         "context"
   5         "io"
   6         "os"
   7
   8         "github.com/anacrolix/missinggo"
   9         "github.com/anacrolix/torrent"
  10
  11         "bazil.org/fuse"
  12         "bazil.org/fuse/fs"
  13 )
  14
  15 type fileHandle struct {
  16         fn fileNode
  17         r  *torrent.Reader
  18 }
  19
  20 var _ interface {
  21         fs.HandleReader
  22         fs.HandleReleaser
  23 } = fileHandle{}
  24
  25 func (me fileHandle) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error {
  26         torrentfsReadRequests.Add(1)
  27         if req.Dir {
  28                 panic("read on directory")
  29         }
  30         pos, err := me.r.Seek(me.fn.TorrentOffset+req.Offset, os.SEEK_SET)
  31         if err != nil {
  32                 panic(err)
  33         }
  34         if pos != me.fn.TorrentOffset+req.Offset {
  35                 panic("seek failed")
  36         }
  37         resp.Data = resp.Data[:req.Size]
  38         readDone := make(chan struct{})
  39         ctx, cancel := context.WithCancel(ctx)
  40         var readErr error
  41         go func() {
  42                 defer close(readDone)
  43                 me.fn.FS.mu.Lock()
  44                 me.fn.FS.blockedReads++
  45                 me.fn.FS.event.Broadcast()
  46                 me.fn.FS.mu.Unlock()
  47                 var n int
  48                 r := missinggo.ContextedReader{me.r, ctx}
  49                 n, readErr = r.Read(resp.Data)
  50                 if readErr == io.EOF {
  51                         readErr = nil
  52                 }
  53                 resp.Data = resp.Data[:n]
  54         }()
  55         defer func() {
  56                 <-readDone
  57                 me.fn.FS.mu.Lock()
  58                 me.fn.FS.blockedReads--
  59                 me.fn.FS.event.Broadcast()
  60                 me.fn.FS.mu.Unlock()
  61         }()
  62         defer cancel()
  63
  64         select {
  65         case <-readDone:
  66                 return readErr
  67         case <-me.fn.FS.destroyed:
  68                 return fuse.EIO
  69         case <-ctx.Done():
  70                 return fuse.EINTR
  71         }
  72 }
  73
  74 func (me fileHandle) Release(context.Context, *fuse.ReleaseRequest) error {
  75         return me.r.Close()
  76 }