fs/file_handle.go

   1 package torrentfs
   2
   3 import (
   4         "context"
   5         "io"
   6
   7         "github.com/anacrolix/fuse"
   8         "github.com/anacrolix/fuse/fs"
   9         "github.com/anacrolix/missinggo/v2"
  10
  11         "github.com/anacrolix/torrent"
  12 )
  13
  14 type fileHandle struct {
  15         fn fileNode
  16         r  torrent.Reader
  17 }
  18
  19 var _ interface {
  20         fs.HandleReader
  21         fs.HandleReleaser
  22 } = fileHandle{}
  23
  24 func (me fileHandle) Read(ctx context.Context, req *fuse.ReadRequest, resp *fuse.ReadResponse) error {
  25         torrentfsReadRequests.Add(1)
  26         if req.Dir {
  27                 panic("read on directory")
  28         }
  29         r := me.r
  30         pos, err := r.Seek(req.Offset, io.SeekStart)
  31         if err != nil {
  32                 panic(err)
  33         }
  34         if pos != 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{r, ctx}
  49                 // log.Printf("reading %v bytes at %v", len(resp.Data), req.Offset)
  50                 if true {
  51                         // A user reported on that on freebsd 12.2, the system requires that reads are
  52                         // completely filled. Their system only asks for 64KiB at a time. I've seen systems that
  53                         // can demand up to 16MiB at a time, so this gets tricky. For now, I'll restore the old
  54                         // behaviour from before 2a7352a, which nobody reported problems with.
  55                         n, readErr = io.ReadFull(r, resp.Data)
  56                         if readErr == io.ErrUnexpectedEOF {
  57                                 readErr = nil
  58                        }
  59                 } else {
  60                         n, readErr = r.Read(resp.Data)
  61                         if readErr == io.EOF {
  62                                 readErr = nil
  63                         }
  64                 }
  65                 resp.Data = resp.Data[:n]
  66         }()
  67         defer func() {
  68                 <-readDone
  69                 me.fn.FS.mu.Lock()
  70                 me.fn.FS.blockedReads--
  71                 me.fn.FS.event.Broadcast()
  72                 me.fn.FS.mu.Unlock()
  73         }()
  74         defer cancel()
  75
  76         select {
  77         case <-readDone:
  78                 return readErr
  79         case <-me.fn.FS.destroyed:
  80                 return fuse.EIO
  81         case <-ctx.Done():
  82                 return fuse.EINTR
  83         }
  84 }
  85
  86 func (me fileHandle) Release(context.Context, *fuse.ReleaseRequest) error {
  87         return me.r.Close()
  88 }