--- ray/src/util/cmatrix.c	2021/01/15 17:22:23	2.30
+++ ray/src/util/cmatrix.c	2022/03/11 17:15:42	2.34
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: cmatrix.c,v 2.30 2021/01/15 17:22:23 greg Exp $";
+static const char RCSid[] = "$Id: cmatrix.c,v 2.34 2022/03/11 17:15:42 greg Exp $";
 #endif
 /*
  * Color matrix routines.
@@ -15,6 +15,8 @@ static const char RCSid[] = "$Id: cmatrix.c,v 2.30 202
 #include "paths.h"
 #include "resolu.h"
 
+const char	stdin_name[] = "<stdin>";
+
 const char	*cm_fmt_id[] = {
 			"unknown", COLRFMT, CIEFMT,
 			"float", "ascii", "double"
@@ -212,14 +214,18 @@ CMATRIX *
 cm_load(const char *inspec, int nrows, int ncols, int dtype)
 {
 	const int	ROWINC = 2048;
-	FILE		*fp = stdin;
 	int		swap = 0;
+	FILE		*fp;
 	COLOR		scale;
 	CMATRIX		*cm;
 
 	if (!inspec)
-		inspec = "<stdin>";
-	else if (inspec[0] == '!') {
+		inspec = stdin_name;
+	else if (!*inspec)
+		return(NULL);
+	if (inspec == stdin_name) {		/* reading from stdin? */
+		fp = stdin;
+	} else if (inspec[0] == '!') {
 		fp = popen(inspec+1, "r");
 		if (!fp) {
 			sprintf(errmsg, "cannot start command '%s'", inspec);
@@ -234,13 +240,13 @@ cm_load(const char *inspec, int nrows, int ncols, int 
 #endif
 	if (dtype != DTascii)
 		SET_FILE_BINARY(fp);		/* doesn't really work */
-	if (!dtype | !ncols) {			/* expecting header? */
+	if (!dtype | !nrows | !ncols) {		/* expecting header? */
 		char	*err = cm_getheader(&dtype, &nrows, &ncols, &swap, scale, fp);
 		if (err)
 			error(USER, err);
 	}
-	if (ncols <= 0 && !fscnresolu(&ncols, &nrows, fp))
-		error(USER, "unspecified number of columns");
+	if (!nrows | !ncols && !fscnresolu(&ncols, &nrows, fp))
+		error(USER, "unspecified matrix size");
 	switch (dtype) {
 	case DTascii:
 	case DTfloat:
@@ -309,14 +315,14 @@ cm_load(const char *inspec, int nrows, int ncols, int 
 			}
 	} else {					/* read binary file */
 		if (sizeof(COLOR) == cm_elem_size[dtype]) {
-			int	nread = 0;
+			size_t	nread = 0;
 			do {				/* read all we can */
 				nread += getbinary(cm->cmem + 3*nread,
 						sizeof(COLOR),
-						cm->nrows*cm->ncols - nread,
+						(size_t)cm->nrows*cm->ncols - nread,
 						fp);
 				if (nrows <= 0) {	/* unknown length */
-					if (nread == cm->nrows*cm->ncols)
+					if (nread == (size_t)cm->nrows*cm->ncols)
 							/* need more space? */
 						cm = cm_resize(cm, cm->nrows+ROWINC);
 					else if (nread && !(nread % cm->ncols))
@@ -324,22 +330,22 @@ cm_load(const char *inspec, int nrows, int ncols, int 
 						cm = cm_resize(cm, nread/cm->ncols);
 					else		/* ended mid-row */
 						goto EOFerror;
-				} else if (nread < cm->nrows*cm->ncols)
+				} else if (nread < (size_t)cm->nrows*cm->ncols)
 					goto EOFerror;
-			} while (nread < cm->nrows*cm->ncols);
+			} while (nread < (size_t)cm->nrows*cm->ncols);
 
 			if (swap) {
 				if (sizeof(COLORV) == 4)
 					swap32((char *)cm->cmem,
-							3*cm->nrows*cm->ncols);
+							3*(size_t)cm->nrows*cm->ncols);
 				else /* sizeof(COLORV) == 8 */
 					swap64((char *)cm->cmem,
-							3*cm->nrows*cm->ncols);
+							3*(size_t)cm->nrows*cm->ncols);
 			}
 		} else if (dtype == DTdouble) {
 			double	dc[3];			/* load from double */
 			COLORV	*cvp = cm->cmem;
-			int	n = nrows*ncols;
+			size_t	n = (size_t)nrows*ncols;
 
 			if (n <= 0)
 				goto not_handled;
@@ -353,7 +359,7 @@ cm_load(const char *inspec, int nrows, int ncols, int 
 		} else /* dtype == DTfloat */ {
 			float	fc[3];			/* load from float */
 			COLORV	*cvp = cm->cmem;
-			int	n = nrows*ncols;
+			size_t	n = (size_t)nrows*ncols;
 
 			if (n <= 0)
 				goto not_handled;