remove dup waitErr chan read

cannon/cmd/run.go

@@ -188,15 +188,6 @@ func (p *ProcessPreimageOracle) Close() error {
 	if p.cmd == nil {
 		return nil
 	}
-	// We first check if the process has already exited before signaling.
-	// Note: This is a teeny bit racy since the process could exit after the check
-	// above and another process is assigned the same pid.
-	select {
-	case err := <-p.waitErr:
-		return err
-	case <-time.After(time.Second * 1):
-		// give the wait goroutine time to reap process
-	}
 	_ = p.cmd.Process.Signal(os.Interrupt)
 	return <-p.waitErr
 }

op-preimage/filepoller.go

@@ -8,7 +8,7 @@ import (
 )
 
 // FilePoller is a ReadWriteCloser that polls the underlying file channel for reads and writes
-// until its context is done. This is useful in detecting when the other end of a
+// until its context is done. This is useful to detect when the other end of a
 // blocking pre-image channel is no longer available.
 type FilePoller struct {
 	File        FileChannel
@@ -27,7 +27,7 @@ func (f *FilePoller) Read(b []byte) (int, error) {
 	var read int
 	for {
 		if err := f.File.Reader().SetReadDeadline(time.Now().Add(f.pollTimeout)); err != nil {
-			panic(err)
+			return 0, err
 		}
 		n, err := f.File.Read(b[read:])
 		if errors.Is(err, os.ErrDeadlineExceeded) {
@@ -47,7 +47,7 @@ func (f *FilePoller) Write(b []byte) (int, error) {
 	var written int
 	for {
 		if err := f.File.Writer().SetWriteDeadline(time.Now().Add(f.pollTimeout)); err != nil {
-			panic(err)
+			return 0, err
 		}
 		n, err := f.File.Write(b[written:])
 		if errors.Is(err, os.ErrDeadlineExceeded) {