update font file checking to accept
1. optional offset (hence changes to getfontnum).
2. ignore lines truncated by end-of-buffer.
3. split and unsplit subfonts (faccess).

chkfont program included for careful font checking. chkfont
will report on which subfonts are invalid and do basic checking
of the subfont file but don't validate individula characters or
subfont character heights yet.

Notes:
Wed May 24 10:43:32 EDT 2006 rsc

Reference: /n/sources/patch/applied/file-font
Date: Tue May 23 02:43:13 CES 2006
Signed-off-by: quanstro@quanstro.net
Reviewed-by: rsc

--- /sys/src/cmd/file.c	Tue May 23 02:37:15 2006
+++ /sys/src/cmd/file.c	Tue May 23 02:37:03 2006
@@ -142,7 +142,7 @@
 void	bump_utf_count(Rune);
 int	cistrncmp(char*, char*, int);
 void	filetype(int);
-int	getfontnum(uchar*, uchar**);
+int	getfontnum(char*, char**);
 int	isas(void);
 int	isc(void);
 int	iscint(void);
@@ -1076,6 +1076,9 @@
 	case 24:
 	case 16:
 	case 8:
+	case 4:
+	case 2:
+	case 1:
 		return d;
 	}
 	return -1;
@@ -1163,43 +1166,68 @@
 }
 
 #define	WHITESPACE(c)		((c) == ' ' || (c) == '\t' || (c) == '\n')
+#define	SPACE(c)			((c) == ' ' || (c) == '\t')
 
 int
+faccess(char *p, int m)
+{
+	char* s;
+	int i, r;
+
+	if(access(p, m) == 0)
+		return 0;
+	s = p + strlen(p);
+	for(i = 0; i < 2; i++) {
+		snprint(s, 4, ".%d", i);
+		r = access(p, m);
+		*s = 0;
+		if(r != 0)
+			return -1;
+	}
+	return 0;
+}
+	
+int
 isp9font(void)
 {
-	uchar *cp, *p;
+	char *p, *cp;
 	int i, n;
-	char pathname[1024];
+	char path[1024 + 1 + 3];
 
-	cp = buf;
+	cp = (char*)buf;
 	if (!getfontnum(cp, &cp))	/* height */
 		return 0;
 	if (!getfontnum(cp, &cp))	/* ascent */
 		return 0;
-	for (i = 0;; i++) {
+	while(WHITESPACE(*cp))
+		cp++;
+	for (i = 0; strchr(cp, '\n'); i++) {
 		if (!getfontnum(cp, &cp))	/* min */
 			break;
 		if (!getfontnum(cp, &cp))	/* max */
 			return 0;
-		while (WHITESPACE(*cp))
+		getfontnum(cp, &cp);	/* offset -- not required */
+		while(SPACE(*cp))
 			cp++;
-		for (p = cp; *cp && !WHITESPACE(*cp); cp++)
-				;
+		for(p = cp; !WHITESPACE(*cp); cp++)
+			;
 			/* construct a path name, if needed */
 		n = 0;
 		if (*p != '/' && slash) {
 			n = slash-fname+1;
-			if (n < sizeof(pathname))
-				memcpy(pathname, fname, n);
+			if (n < sizeof path)
+				memcpy(path, fname, n);
 			else n = 0;
 		}
-		if (n+cp-p < sizeof(pathname)) {
-			memcpy(pathname+n, p, cp-p);
+		if (n+cp-p < sizeof path - sizeof ".00") {
+			memcpy(path+n, p, cp-p);
 			n += cp-p;
-			pathname[n] = 0;
-			if (access(pathname, AEXIST) < 0)
+			path[n] = 0;
+			if(faccess(path, AEXIST) < 0)
 				return 0;
 		}
+		while(WHITESPACE(*cp))
+			cp++;
 	}
 	if (i) {
 		print(mime ? "text/plain\n" : "font file\n");
@@ -1209,15 +1237,18 @@
 }
 
 int
-getfontnum(uchar *cp, uchar **rp)
+getfontnum(char *cp, char **rp)
 {
-	while (WHITESPACE(*cp))		/* extract ulong delimited by whitespace */
-		cp++;
-	if (*cp < '0' || *cp > '9')
+	char *p;
+	ulong l;
+
+	*rp = cp;
+	l = strtoul(cp, &p, 0);
+	if(p == cp || !WHITESPACE(*p))
 		return 0;
-	strtoul((char *)cp, (char **)rp, 0);
-	if (!WHITESPACE(**rp))
+	if(l < 0 || l > 0xffff)
 		return 0;
+	*rp = p;
 	return 1;
 }