--- ray/src/util/rtcontrib.c	2005/06/14 02:50:23	1.22
+++ ray/src/util/rtcontrib.c	2005/09/13 22:58:22	1.25
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: rtcontrib.c,v 1.22 2005/06/14 02:50:23 greg Exp $";
+static const char RCSid[] = "$Id: rtcontrib.c,v 1.25 2005/09/13 22:58:22 greg Exp $";
 #endif
 /*
  * Gather rtrace output to compute contributions from particular sources
@@ -173,6 +173,13 @@ main(int argc, char *argv[])
 	char	*binval = NULL;
 	char	fmt[8];
 	int	i, j;
+				/* need at least one argument */
+	if (argc < 2) {
+		fprintf(stderr,
+"Usage: %s [-n nprocs][-r][-e expr][-f source][-o ospec][-b binv] {-m mod | -M file} [rtrace options] octree\n",
+			argv[0]);
+		exit(1);
+	}
 				/* global program name */
 	gargv = argv;
 				/* initialize calcomp routines */
@@ -315,11 +322,11 @@ main(int argc, char *argv[])
 		error(USER, "missing octree argument");
 	rtargv[rtargc++] = octree = argv[i];
 	rtargv[rtargc] = NULL;
-				/* start rtrace & compute contributions */
+				/* start rtrace */
 	init(nprocs);
 	if (recover)		/* perform recovery if requested */
 		recover_output(stdin);
-	trace_contribs(stdin);
+	trace_contribs(stdin);	/* compute contributions */
 	quit(0);
 }
 
@@ -1030,8 +1037,13 @@ recover_output(FILE *fin)
 				error(USER, "cannot recover from command");
 						/* open output */
 			fp = fopen(oname, "rb+");
-			if (fp == NULL)
-				break;		/* must be end of modifier */
+			if (fp == NULL) {
+				if (j)
+					break;	/* assume end of modifier */
+				sprintf(errmsg, "missing recover file '%s'",
+						oname);
+				error(USER, errmsg);
+			}
 			nvals = lseek(fileno(fp), 0, SEEK_END);
 			if (nvals <= 0) {
 				lastout = 0;	/* empty output, quit here */
@@ -1085,6 +1097,11 @@ recover_output(FILE *fin)
 	if (lastout < 0) {
 		error(WARNING, "no output files to recover");
 		return;
+	}
+	if (raysleft && lastout >= raysleft) {
+		error(WARNING, "output appears to be complete");
+		/* XXX should read & discard input? */
+		quit(0);
 	}
 						/* seek on all files */
 	nvals = lastout * outvsiz;