--- ray/src/rt/ambient.c	1996/02/14 15:43:22	2.36
+++ ray/src/rt/ambient.c	1996/07/09 19:37:09	2.39
@@ -1,4 +1,4 @@
-/* Copyright (c) 1995 Regents of the University of California */
+/* Copyright (c) 1996 Regents of the University of California */
 
 #ifndef lint
 static char SCCSid[] = "$SunId$ LBL";
@@ -121,7 +121,7 @@ double  newa;
 setambient(afile)			/* initialize calculation */
 char  *afile;
 {
-	long  headlen;
+	long  pos, flen;
 	AMBVAL	amb;
 						/* init ambient limits */
 	setambres(ambres);
@@ -137,11 +137,19 @@ char  *afile;
 						/* open ambient file */
 	if ((ambfp = fopen(afile, "r+")) != NULL) {
 		initambfile(0);
-		headlen = ftell(ambfp);
+		pos = ftell(ambfp);
 		while (readambval(&amb, ambfp))
 			avinsert(avstore(&amb));
 						/* align */
-		fseek(ambfp, -((ftell(ambfp)-headlen)%AMBVALSIZ), 1);
+		pos += (long)nambvals*AMBVALSIZ;
+		flen = lseek(fileno(ambfp), 0L, 2);
+		if (flen != pos) {
+			error(WARNING,
+			"ignoring last %ld values in ambient file (corrupted)",
+					(flen - pos)/AMBVALSIZ);
+			fseek(ambfp, pos, 0);
+			ftruncate(fileno(ambfp), pos);
+		}
 		nambshare = nambvals;
 	} else if ((ambfp = fopen(afile, "w+")) != NULL)
 		initambfile(1);
@@ -543,28 +551,33 @@ int	(*f)();
 }
 
 
-static AMBVAL	**avlist1, **avlist2;	/* ambient value lists for sorting */
+static struct avl {
+	AMBVAL	*p;
+	unsigned long	t;
+}	*avlist1;			/* ambient value list with ticks */
+static AMBVAL	**avlist2;		/* memory positions for sorting */
 static int	i_avlist;		/* index for lists */
 
 
 static
 av2list(av)
-AMBVAL	*av;
+register AMBVAL	*av;
 {
 #ifdef DEBUG
 	if (i_avlist >= nambvals)
 		error(CONSISTENCY, "too many ambient values in av2list1");
 #endif
-	avlist1[i_avlist] = avlist2[i_avlist] = av;
-	i_avlist++;
+	avlist1[i_avlist].p = avlist2[i_avlist] = av;
+	avlist1[i_avlist++].t = av->latick;
 }
 
 
 static int
-alatcmp(avp1, avp2)			/* compare ambient values for MRA */
-AMBVAL	**avp1, **avp2;
+alatcmp(av1, av2)			/* compare ambient values for MRA */
+struct avl	*av1, *av2;
 {
-	return((**avp2).latick - (**avp1).latick);
+	register long  lc = av2->t - av1->t;
+	return(lc<0 ? -1 : lc>0 ? 1 : 0);
 }
 
 
@@ -576,7 +589,7 @@ AMBVAL	**avp1, **avp2;
 }
 
 
-#ifdef DEBUG
+#if 1
 static int
 avlmemi(avaddr)				/* find list position from address */
 AMBVAL	*avaddr;
@@ -622,13 +635,15 @@ int	always;
 	 * tree will be rebuilt with the new accuracy parameter.
 	 */
 	if (tracktime) {		/* allocate pointer arrays to sort */
-		avlist1 = (AMBVAL **)malloc(nambvals*sizeof(AMBVAL *));
 		avlist2 = (AMBVAL **)malloc(nambvals*sizeof(AMBVAL *));
-	} else
-		avlist1 = avlist2 = NULL;
-	if (avlist2 == NULL) {		/* no time tracking -- rebuild tree? */
-		if (avlist1 != NULL)
-			free((char *)avlist1);
+		avlist1 = (struct avl *)malloc(nambvals*sizeof(struct avl));
+	} else {
+		avlist2 = NULL;
+		avlist1 = NULL;
+	}
+	if (avlist1 == NULL) {		/* no time tracking -- rebuild tree? */
+		if (avlist2 != NULL)
+			free((char *)avlist2);
 		if (always) {		/* rebuild without sorting */
 			copystruct(&oldatrunk, &atrunk);
 			atrunk.alist = NULL;
@@ -655,22 +670,22 @@ int	always;
 		if (i_avlist < nambvals)
 			error(CONSISTENCY, "missing ambient values in sortambvals");
 #endif
-		qsort((char *)avlist1, nambvals, sizeof(AMBVAL *), alatcmp);
+		qsort((char *)avlist1, nambvals, sizeof(struct avl), alatcmp);
 		qsort((char *)avlist2, nambvals, sizeof(AMBVAL *), aposcmp);
 		for (i = 0; i < nambvals; i++) {
-			if (avlist1[i] == NULL)
+			if (avlist1[i].p == NULL)
 				continue;
 			tap = avlist2[i];
 			copystruct(&tav, tap);
-			for (j = i; (pnext = avlist1[j]) != tap;
+			for (j = i; (pnext = avlist1[j].p) != tap;
 					j = avlmemi(pnext)) {
 				copystruct(avlist2[j], pnext);
 				avinsert(avlist2[j]);
-				avlist1[j] = NULL;
+				avlist1[j].p = NULL;
 			}
 			copystruct(avlist2[j], &tav);
 			avinsert(avlist2[j]);
-			avlist1[j] = NULL;
+			avlist1[j].p = NULL;
 		}
 		free((char *)avlist1);
 		free((char *)avlist2);
@@ -731,7 +746,13 @@ ambsync()			/* synchronize ambient file */
 		if (fseek(ambinp, lastpos, 0) < 0)
 			goto seekerr;
 		while (n >= AMBVALSIZ) {	/* load contributed values */
-			readambval(&avs, ambinp);
+			if (!readambval(&avs, ambinp)) {
+				sprintf(errmsg,
+				"ambient file corrupted near character %ld",
+						flen - n);
+				error(WARNING, errmsg);
+				break;
+			}
 			avinsert(avstore(&avs));
 			n -= AMBVALSIZ;
 		}