read until EOF in streamCopy

If either stdoutPipe or stderrPipe reads to EOF, do not close the other
one so that it can read to EOF as well. Otherwise we might lose output
in the other pipe.

This works because if hyperstart ends the stdout/stderr streams, it always
closes the writer part of both pipes. Then io.Copy() will get EOF and
return success here.

Also no need to wait stdin go routine because streamCopy() runs in a go
routine itself thus no one is really waiting out there.

Signed-off-by: Peng Tao <bergwolf@gmail.com>

Author: bergwolf

hypervisor/vm_states.go

@@ -172,6 +172,7 @@ func streamCopy(tty *TtyIO, stdinPipe io.WriteCloser, stdoutPipe, stderrPipe io.
 	var wg sync.WaitGroup
 	// old way cleanup all(expect stdinPipe) no matter what kinds of fails, TODO: change it
 	var once sync.Once
+	// cleanup closes tty.Stdin and thus terminates the first go routine
 	cleanup := func() {
 		tty.Close()
 		// stdinPipe is directly closed in the first go routine
@@ -181,30 +182,32 @@ func streamCopy(tty *TtyIO, stdinPipe io.WriteCloser, stdoutPipe, stderrPipe io.
 		}
 	}
 	if tty.Stdin != nil {
-		wg.Add(1)
 		go func() {
 			_, err := io.Copy(stdinPipe, tty.Stdin)
 			stdinPipe.Close()
 			if err != nil {
 				// we should not call cleanup when tty.Stdin reaches EOF
 				once.Do(cleanup)
 			}
-			wg.Done()
 		}()
 	}
 	if tty.Stdout != nil {
 		wg.Add(1)
 		go func() {
-			io.Copy(tty.Stdout, stdoutPipe)
-			once.Do(cleanup)
+			_, err := io.Copy(tty.Stdout, stdoutPipe)
+			if err != nil {
+				once.Do(cleanup)
+			}
 			wg.Done()
 		}()
 	}
 	if tty.Stderr != nil && stderrPipe != nil {
 		wg.Add(1)
 		go func() {
-			io.Copy(tty.Stderr, stderrPipe)
-			once.Do(cleanup)
+			_, err := io.Copy(tty.Stderr, stderrPipe)
+			if err != nil {
+				once.Do(cleanup)
+			}
 			wg.Done()
 		}()
 	}