--- ray/src/hd/rholo4.c	1997/12/01 16:35:35	3.10
+++ ray/src/hd/rholo4.c	1997/12/11 17:40:04	3.12
@@ -24,21 +24,35 @@ static FILE	*dpout;
 disp_open(dname)		/* open the named display driver */
 char	*dname;
 {
-	char	dpath[128], *com[3];
+	char	dpath[128], fd0[8], fd1[8], *cmd[5];
 	int	i;
-
+				/* get full display program name */
 #ifdef DEVPATH
 	sprintf(dpath, "%s/%s%s", DEVPATH, dname, HDSUF);
 #else
 	sprintf(dpath, "dev/%s%s", dname, HDSUF);
 #endif
-	com[0] = dpath; com[1] = froot; com[2] = NULL;
-	i = open_process(dpd, com);
+				/* dup stdin and stdout */
+	if (readinp)
+		sprintf(fd0, "%d", dup(0));
+	else
+		strcpy(fd0, "-1");
+	sprintf(fd1, "%d", dup(1));
+				/* start the display process */
+	cmd[0] = dpath;
+	cmd[1] = froot; cmd[2] = fd1; cmd[3] = fd0;
+	cmd[4] = NULL;
+	i = open_process(dpd, cmd);
 	if (i <= 0)
 		error(USER, "cannot start display process");
-	if ((dpout = fdopen(dup(dpd[1]), "w")) == NULL)
+	if ((dpout = fdopen(dpd[1], "w")) == NULL)
 		error(SYSTEM, "cannot associate FILE with display pipe");
+	dpd[1] = -1;		/* causes ignored error in close_process() */
 	inp_flags = 0;
+				/* close dup'ed stdin and stdout */
+	if (readinp)
+		close(atoi(fd0));
+	close(atoi(fd1));
 				/* write out hologram grids */
 	for (i = 0; hdlist[i] != NULL; i++)
 		disp_result(DS_ADDHOLO, sizeof(HDGRID), (char *)hdlist[i]);
@@ -91,12 +105,12 @@ int	block;
 			goto readerr;
 	}
 	switch (msg.type) {		/* take appropriate action */
-	case DR_BUNDLE:
+	case DR_BUNDLE:		/* new bundle to calculate */
 		if (msg.nbytes != sizeof(PACKHEAD))
 			error(INTERNAL, "bad DR_BUNDLE from display process");
 		bundle_set(BS_ADD, (PACKHEAD *)buf, 1);
 		break;
-	case DR_NEWSET:
+	case DR_NEWSET:		/* new calculation set */
 		if (msg.nbytes % sizeof(PACKHEAD))
 			error(INTERNAL, "bad DR_NEWSET from display process");
 		disp_result(DS_STARTIMM, 0, NULL);
@@ -104,7 +118,7 @@ int	block;
 		disp_result(DS_ENDIMM, 0, NULL);
 		disp_flush();
 		break;
-	case DR_ADDSET:
+	case DR_ADDSET:		/* add to calculation set */
 		if (msg.nbytes % sizeof(PACKHEAD))
 			error(INTERNAL, "bad DR_ADDSET from display process");
 		disp_result(DS_STARTIMM, 0, NULL);
@@ -112,7 +126,7 @@ int	block;
 		disp_result(DS_ENDIMM, 0, NULL);
 		disp_check(0);		/* hack -- delete usu. follows add */
 		break;
-	case DR_ADJSET:
+	case DR_ADJSET:		/* adjust calculation set members */
 		if (msg.nbytes % sizeof(PACKHEAD))
 			error(INTERNAL, "bad DR_ADJSET from display process");
 		disp_result(DS_STARTIMM, 0, NULL);
@@ -120,22 +134,22 @@ int	block;
 		disp_result(DS_ENDIMM, 0, NULL);
 		disp_flush();
 		break;
-	case DR_DELSET:
+	case DR_DELSET:		/* delete from calculation set */
 		if (msg.nbytes % sizeof(PACKHEAD))
 			error(INTERNAL, "bad DR_DELSET from display process");
 		bundle_set(BS_DEL, (PACKHEAD *)buf, msg.nbytes/sizeof(PACKHEAD));
 		break;
-	case DR_ATTEN:
+	case DR_ATTEN:		/* block for priority request */
 		if (msg.nbytes)
 			error(INTERNAL, "bad DR_ATTEN from display process");
 					/* send acknowledgement */
 		disp_result(DS_ACKNOW, 0, NULL);
 		return(disp_check(1));	/* block on following request */
-	case DR_SHUTDOWN:
+	case DR_SHUTDOWN:	/* shut down program */
 		if (msg.nbytes)
 			error(INTERNAL, "bad DR_SHUTDOWN from display process");
 		return(0);		/* zero return signals shutdown */
-	case DR_NOOP:
+	case DR_NOOP:		/* do nothing */
 		break;
 	default:
 		error(INTERNAL, "unrecognized request from display process");