Fix p9 integration of flipcall.

- Do not call Rread.SetPayload(flipcall packet window) in p9.channel.recv().

- Ignore EINTR from ppoll() in p9.Client.watch().

- Clean up handling of client socket FD lifetimes so that p9.Client.watch()
  never ppoll()s a closed FD.

- Make p9test.Harness.Finish() call clientSocket.Shutdown() instead of
  clientSocket.Close() for the same reason.

- Rework channel reuse to avoid leaking channels in the following case (suppose
  we have two channels):

  sendRecvChannel
    len(channels) == 2 => idx = 1
    inuse[1] = ch0
                                        sendRecvChannel
                                          len(channels) == 1 => idx = 0
                                          inuse[0] = ch1
    inuse[1] = nil
  sendRecvChannel
    len(channels) == 1 => idx = 0
    inuse[0] = ch0
                                          inuse[0] = nil
    inuse[0] == nil => ch0 leaked

- Avoid deadlocking p9.Client.watch() by calling channelsWg.Wait() without
  holding channelsMu.

- Bump p9test:client_test size to medium.

PiperOrigin-RevId: 270200314

1 files changed, 11 insertions, 2 deletions

diff --git a/pkg/p9/transport_flipcall.go b/pkg/p9/transport_flipcall.go
index aebb54959..7cdf4ecc3 100644
--- a/pkg/p9/transport_flipcall.go
+++ b/pkg/p9/transport_flipcall.go
@@ -60,6 +60,7 @@ type channel struct {
 
 	// -- client only --
 	connected bool
+	active    bool
 
 	// -- server only --
 	client *fd.FD
@@ -197,10 +198,18 @@ func (ch *channel) recv(r message, rsz uint32) (message, error) {
 		return nil, &ErrBadResponse{Got: t, Want: r.Type()}
 	}
 
-	// Is there a payload? Set to the latter portion.
+	// Is there a payload? Copy from the latter portion.
 	if payloader, ok := r.(payloader); ok {
 		fs := payloader.FixedSize()
-		payloader.SetPayload(ch.buf.data[fs:])
+		p := payloader.Payload()
+		payloadData := ch.buf.data[fs:]
+		if len(p) < len(payloadData) {
+			p = make([]byte, len(payloadData))
+			copy(p, payloadData)
+			payloader.SetPayload(p)
+		} else if n := copy(p, payloadData); n < len(p) {
+			payloader.SetPayload(p[:n])
+		}
 		ch.buf.data = ch.buf.data[:fs]
 	}