--- ray/src/rt/raypcalls.c	2009/12/12 19:01:00	2.23
+++ ray/src/rt/raypcalls.c	2011/08/20 06:05:53	2.27
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: raypcalls.c,v 2.23 2009/12/12 19:01:00 greg Exp $";
+static const char	RCSid[] = "$Id: raypcalls.c,v 2.27 2011/08/20 06:05:53 greg Exp $";
 #endif
 /*
  *  raypcalls.c - interface for parallel rendering using Radiance
@@ -71,11 +71,11 @@ static const char	RCSid[] = "$Id: raypcalls.c,v 2.23 2
  *
  *  If the second argument is 1, the call won't block when
  *  results aren't ready, but will immediately return 0.
- *  (A special value of -1 returns 0 unless a ray is
- *  ready in the queue and no system calls are needed.)
  *  If the second argument is 0, the call will block
  *  until a value is available, returning 0 only if the
- *  queue is completely empty.  A negative return value
+ *  queue is completely empty.  Setting the second argument
+ *  to -1 returns 0 unless a ray is ready in the queue and
+ *  no system calls are needed.  A negative return value
  *  indicates that a rendering process died.  If this
  *  happens, ray_pclose(0) is automatically called to close
  *  all child processes, and ray_pnprocs is set to zero.
@@ -88,9 +88,11 @@ static const char	RCSid[] = "$Id: raypcalls.c,v 2.23 2
  *		ray_psend(&myRay);
  *	}
  *
- *  Note that it is a fatal error to call ra_psend() when
- *  ray_pnidle is zero.  The ray_presult() and/or ray_pqueue()
- *  functions may be called subsequently to read back the results.
+ *  Note that it is a mistake to call ra_psend() when
+ *  ray_pnidle is zero, and nothing will be sent in
+ *  this case.  Otherwise, the ray_presult() and/or ray_pqueue()
+ *  functions may be called subsequently to read back the results
+ *  of rays queued by ray_psend().
  *
  *  When you are done, you may call ray_pdone(1) to close
  *  all child processes and clean up memory used by Radiance.
@@ -224,24 +226,27 @@ ray_pflush(void)			/* send queued rays to idle childre
 		ray_pnidle--;		/* now she's busy */
 	}
 	if (sfirst != r_send_next)
-		error(CONSISTENCY, "code screwup in ray_pflush");
+		error(CONSISTENCY, "code screwup in ray_pflush()");
 	r_send_next = 0;
 	return(sfirst);			/* return total # sent */
 }
 
 
-void
+int
 ray_psend(			/* add a ray to our send queue */
 	RAY	*r
 )
 {
-	if (r == NULL)
-		return;
+	int	rv;
+
+	if ((r == NULL) | (ray_pnidle <= 0))
+		return(0);
 					/* flush output if necessary */
-	if (sendq_full() && ray_pflush() <= 0)
-		error(INTERNAL, "ray_pflush failed in ray_psend");
+	if (sendq_full() && (rv = ray_pflush()) <= 0)
+		return(rv);
 
 	r_queue[r_send_next++] = *r;
+	return(1);
 }
 
 
@@ -260,7 +265,7 @@ ray_pqueue(			/* queue a ray for computation */
 			return(-1);
 					/* put new ray in queue */
 		r_queue[r_send_next++] = mySend;
-				/* XXX r_send_next may now be > RAYQLEN */
+
 		return(1);
 	}
 					/* else add ray to send queue */
@@ -329,7 +334,7 @@ getready:				/* any children waiting for us? */
 				poll ? &tpoll : (struct timeval *)NULL)) < 0)
 			if (errno != EINTR) {
 				error(WARNING,
-					"select call failed in ray_presult");
+					"select call failed in ray_presult()");
 				ray_pclose(0);
 				return(-1);
 			}
@@ -408,7 +413,7 @@ ray_pchild(	/* process rays (never returns) */
 					/* get smuggled set length */
 		n2 = sizeof(RAY)*r_queue[0].crtype - n;
 		if (n2 < 0)
-			error(INTERNAL, "buffer over-read in ray_pchild");
+			error(INTERNAL, "buffer over-read in ray_pchild()");
 		if (n2 > 0) {		/* read the rest of the set */
 			i = readbuf(fd_in, (char *)r_queue + n, n2);
 			if (i != n2)
@@ -430,10 +435,10 @@ ray_pchild(	/* process rays (never returns) */
 					/* write back our results */
 		i = writebuf(fd_out, (char *)r_queue, sizeof(RAY)*n);
 		if (i != sizeof(RAY)*n)
-			error(SYSTEM, "write error in ray_pchild");
+			error(SYSTEM, "write error in ray_pchild()");
 	}
 	if (n)
-		error(SYSTEM, "read error in ray_pchild");
+		error(SYSTEM, "read error in ray_pchild()");
 	ambsync();
 	quit(0);			/* normal exit */
 }
@@ -468,12 +473,15 @@ ray_popen(			/* open the specified # processes */
 				close(r_proc[pn].fd_recv);
 			}
 			close(p0[0]); close(p1[1]);
+			close(0);	/* don't share stdin */
 					/* following call never returns */
 			ray_pchild(p1[0], p0[1]);
 		}
 		if (r_proc[ray_pnprocs].pid < 0)
 			error(SYSTEM, "cannot fork child process");
 		close(p1[0]); close(p0[1]);
+		if (rand_samp)		/* desynchronize random function */
+			srandom((long)r_proc[ray_pnprocs].pid);
 		/*
 		 * Close write stream on exec to avoid multiprocessing deadlock.
 		 * No use in read stream without it, so set flag there as well.
@@ -500,6 +508,9 @@ ray_pclose(		/* close one or more child processes */
 	if (inclose)
 		return;
 	inclose++;
+					/* check no child / in child */
+	if (ray_pnprocs <= 0)
+		return;
 					/* check argument */
 	if ((nsub <= 0) | (nsub > ray_pnprocs))
 		nsub = ray_pnprocs;
@@ -512,10 +523,10 @@ ray_pclose(		/* close one or more child processes */
 	while (nsub--) {
 		int	status;
 		ray_pnprocs--;
-		close(r_proc[ray_pnprocs].fd_recv);
 		close(r_proc[ray_pnprocs].fd_send);
 		if (waitpid(r_proc[ray_pnprocs].pid, &status, 0) < 0)
 			status = 127<<8;
+		close(r_proc[ray_pnprocs].fd_recv);
 		if (status) {
 			sprintf(errmsg,
 				"rendering process %d exited with code %d",