Fix races around Reader and Torrent.Drop when Torrent is closed

[btrtrc.git] / reader.go

diff --git a/reader.go b/reader.go
index c2f3de89bcdef01765b4a201ca0c984abaf536fd..9670ff094a8a2ba77f2fd56bbd503757f113fd6b 100644 (file)
--- a/reader.go
+++ b/reader.go
@@ -245,12 +245,20 @@ func (r *reader) readOnceAt(ctx context.Context, b []byte, pos int64) (n int, er
                        err = nil
                        return
                }
+               if r.t.closed.IsSet() {
+                       err = fmt.Errorf("reading from closed torrent: %w", err)
+                       return
+               }
                r.t.cl.lock()
                // I think there's a panic here caused by the Client being closed before obtaining this
                // lock. TestDropTorrentWithMmapStorageWhileHashing seems to tickle occasionally in CI.
                func() {
                        // Just add exceptions already.
                        defer r.t.cl.unlock()
+                       if r.t.closed.IsSet() {
+                               // Can't update because Torrent's piece order is removed from Client.
+                               return
+                       }
                        // TODO: Just reset pieces in the readahead window. This might help
                        // prevent thrashing with small caches and file and piece priorities.
                        r.log(log.Fstr("error reading torrent %s piece %d offset %d, %d bytes: %v",