// stream is the internal method to stream the content of a file. eofCancelCh is
// used to cancel the stream if triggered while at EOF. If the connection is
// broken an EPIPE error is returned
func (s *HTTPServer) stream(offset int64, path string,
fs allocdir.AllocDirFS, framer *StreamFramer,
eofCancelCh chan error) error {
// Get the reader
f, err := fs.ReadAt(path, offset)
if err != nil {
return err
}
defer f.Close()
// Create a tomb to cancel watch events
t := tomb.Tomb{}
defer func() {
t.Kill(nil)
t.Done()
}()
// Create a variable to allow setting the last event
var lastEvent string
// Only create the file change watcher once. But we need to do it after we
// read and reach EOF.
var changes *watch.FileChanges
// Start streaming the data
data := make([]byte, streamFrameSize)
OUTER:
for {
// Read up to the max frame size
n, readErr := f.Read(data)
// Update the offset
offset += int64(n)
// Return non-EOF errors
if readErr != nil && readErr != io.EOF {
return readErr
}
// Send the frame
if n != 0 {
if err := framer.Send(path, lastEvent, data[:n], offset); err != nil {
// Check if the connection has been closed
if err == io.ErrClosedPipe {
// The pipe check is for tests
return syscall.EPIPE
}
operr, ok := err.(*net.OpError)
if ok {
// The connection was closed by our peer
e := operr.Err.Error()
if strings.Contains(e, syscall.EPIPE.Error()) || strings.Contains(e, syscall.ECONNRESET.Error()) {
return syscall.EPIPE
}
}
return err
}
}
// Clear the last event
if lastEvent != "" {
lastEvent = ""
}
// Just keep reading
if readErr == nil {
continue
}
// If EOF is hit, wait for a change to the file
if changes == nil {
changes, err = fs.ChangeEvents(path, offset, &t)
if err != nil {
return err
}
}
for {
select {
case <-changes.Modified:
continue OUTER
case <-changes.Deleted:
return framer.Send(path, deleteEvent, nil, offset)
case <-changes.Truncated:
// Close the current reader
if err := f.Close(); err != nil {
return err
}
// Get a new reader at offset zero
offset = 0
var err error
f, err = fs.ReadAt(path, offset)
if err != nil {
return err
}
defer f.Close()
// Store the last event
lastEvent = truncateEvent
continue OUTER
case <-framer.ExitCh():
return nil
case err, ok := <-eofCancelCh:
if !ok {
return nil
}
return err
}
}
}
return nil
}
