cvend wip

1 files changed, 24 insertions, 16 deletions

diff --git a/ipp/ipp.go b/ipp/ipp.go
index 89036b0..c71b590 100644
--- a/ipp/ipp.go
+++ b/ipp/ipp.go
@@ -66,11 +66,16 @@ func Open(path string, handler Handler) (Session, error) {
 	if err != nil {
 		return nil, err
 	}
-	termios.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
-	termios.Oflag &^= unix.OPOST
-	termios.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
-	termios.Cflag &^= unix.CBAUD | unix.CSIZE | unix.PARENB | unix.CSTOPB
-	termios.Cflag |= unix.B115200 | unix.CS8 | unix.CREAD | unix.CLOCAL
+	termios.Iflag = unix.IGNBRK | unix.IGNPAR
+	termios.Oflag = 0
+	termios.Lflag = 0
+	termios.Cflag = unix.B115200 | unix.CS8 | unix.CREAD | unix.CLOCAL
+	// when VMIN>0, reads can take unacceptably long.
+	// nx sets VMIN=1 VTIME=10 and uses select + FIONREAD + nonblocking read
+	// and somehow seems to avoid this but i cannot replicate it here.
+	// with VMIN=0 VTIME=1, up to 100ms delay, but no more
+	termios.Cc[unix.VMIN] = 0
+	termios.Cc[unix.VTIME] = 1
 	if err = unix.IoctlSetTermios(fd, unix.TCSETS, termios); err != nil {
 		return nil, err
 	}
@@ -84,26 +89,29 @@ func Open(path string, handler Handler) (Session, error) {
 	return s, nil
 }
 
+func (s *session) isClosed() bool {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.closed
+}
+
 func (s *session) readTask() {
 	var bs [1 << 16]byte
 	var offset int
 	for {
-		n, err := unix.Read(s.fd, bs[offset:])
+		nRead, err := unix.Read(s.fd, bs[offset:])
 		if err != nil {
-			s.mu.Lock()
-			closed := s.closed
-			s.mu.Unlock()
-			if closed {
+			if s.isClosed() {
 				break
 			}
 			panic(err)
 		}
-		nRead := s.handleMsg(bs[:offset+n])
-		offset = copy(bs[:], bs[nRead:offset+n])
+		nConsumed := s.handleMsg(bs[:offset+nRead])
+		offset = copy(bs[:], bs[nConsumed:offset+nRead])
 	}
 }
 
-func (s *session) handleMsg(bs []byte) (nRead int) {
+func (s *session) handleMsg(bs []byte) (nConsumed int) {
 	expectedLen := 1
 	if len(bs) < expectedLen {
 		return
@@ -113,7 +121,7 @@ func (s *session) handleMsg(bs []byte) (nRead int) {
 		if *Trace {
 			log.Printf("skipping non-IPP message %s", hex.EncodeToString(bs))
 		}
-		nRead = len(bs)
+		nConsumed = len(bs)
 		return
 	}
 	expectedLen += 6
@@ -128,7 +136,7 @@ func (s *session) handleMsg(bs []byte) (nRead int) {
 	expectedHdrCRC := crc8(bs[0:6]...)
 	if hdrCRC != expectedHdrCRC {
 		log.Printf("skipping IPP message %02x, expected crc8 %02x got %02x", ippType, expectedHdrCRC, hdrCRC)
-		nRead = len(bs)
+		nConsumed = len(bs)
 		return
 	}
 	expectedLen += ippLen
@@ -139,7 +147,7 @@ func (s *session) handleMsg(bs []byte) (nRead int) {
 	if len(bs) < expectedLen {
 		return
 	}
-	nRead = expectedLen
+	nConsumed = expectedLen
 	ippData := bs[7 : 7+ippLen]
 	if hasMsgCRC {
 		msgCRC := binary.LittleEndian.Uint32(bs[7+ippLen : 7+ippLen+4])