Improve printf(3) conversion specifier parsing so that silly formats

aren't allowed and the right casts can be used for printf() statements.

Document the conversion specifier limitations and the fact that
arithmetic overflow causes a fatal error.

PR:	12611
Reported by:	Frode Vatvedt Fjeld <frodef@acm.org>
Reviewed by:	bde

2 files changed, 97 insertions, 19 deletions

diff --git a/usr.bin/jot/jot.1 b/usr.bin/jot/jot.1
index da39283..d0f0ce4 100644
--- a/usr.bin/jot/jot.1
+++ b/usr.bin/jot/jot.1
@@ -30,7 +30,7 @@
 .\" SUCH DAMAGE.
 .\"
 .\"	@(#)jot.1	8.1 (Berkeley) 6/6/93
-.\"	$Id$
+.\"	$Id: jot.1,v 1.5 1999/07/12 20:23:37 nik Exp $
 .\"
 .Dd June 6, 1993
 .Dt JOT 1
@@ -191,3 +191,17 @@ and to print all lines 80 characters or longer,
 .Xr yes 1 ,
 .Xr printf 3 ,
 .Xr random 3
+.Sh BUGS
+Conversion format specifiers for
+.Xr printf 3
+are limited to those of the form
+.Dl %[#][ ][{+,-}][0-9]*[.[0-9]*]?
+where
+.Dq ?
+must be one of
+.Dl [l]{d,i,o,u,x}
+or
+.Dl {c,e,f,g,D,E,G,O,U,X}
+.Pp
+No bounds-checking is performed on numeric values, so arithmetic overflow
+will cause a fatal error.
diff --git a/usr.bin/jot/jot.c b/usr.bin/jot/jot.c
index 5b67862..7dd4261 100644
--- a/usr.bin/jot/jot.c
+++ b/usr.bin/jot/jot.c
@@ -42,7 +42,7 @@ static const char copyright[] =
 static char sccsid[] = "@(#)jot.c	8.1 (Berkeley) 6/6/93";
 #endif
 static const char rcsid[] =
-	"$Id: jot.c,v 1.8 1997/11/03 07:45:33 charnier Exp $";
+	"$Id: jot.c,v 1.9 1999/05/13 12:18:24 kris Exp $";
 #endif /* not lint */
 
 /*
@@ -75,8 +75,9 @@ int	randomize;
 int	infinity;
 int	boring;
 int	prec;
-int	dox;
+int	intdata;
 int	chardata;
+int	nosign;
 int	nofinalnl;
 char	*sepstring = "\n";
 char	format[BUFSIZ];
@@ -105,8 +106,7 @@ main(argc, argv)
 			*y = (double) arc4random() / ULONG_MAX;
 			putdata(*y * *x + begin, reps - *i);
 		}
-	}
-	else
+	} else
 		for (*i = 1, *x = begin; *i <= reps || infinity; (*i)++, *x += s)
 			putdata(*x, reps - *i);
 	if (!nofinalnl)
@@ -310,13 +310,15 @@ putdata(x, notlast)
 	double x;
 	long notlast;
 {
-	long		d = x;
-	register long	*dp = &d;
 
 	if (boring)				/* repeated word */
 		printf(format);
-	else if (dox)				/* scalar */
-		printf(format, *dp);
+	else if (chardata)			/* character representation */
+		printf(format, (int)x);
+	else if (intdata && nosign)		/* scalar */
+		printf(format, (unsigned long)x);
+	else if (intdata)
+		printf(format, (long)x);
 	else					/* real */
 		printf(format, x);
 	if (notlast != 0)
@@ -354,6 +356,8 @@ void
 getformat()
 {
 	register char	*p;
+	int dot, hash, space, sign, numbers, islong = 0;
+	char *s;
 
 	if (boring)				/* no need to bother */
 		return;
@@ -364,24 +368,84 @@ getformat()
 		sprintf(p, "%%.%df", prec);
 	else if (!*p && chardata) {
 		strcpy(p, "%c");
-		dox = 1;
-	}
-	else if (!*(p+1))
+		intdata = 1;
+	} else if (!*(p+1))
 		strcat(format, "%");		/* cannot end in single '%' */
 	else {
-		while (!isalpha(*p))
-			p++;
+		/*
+		 * Allow conversion format specifiers of the form
+		 * %[#][ ][{+,-}][0-9]*[.[0-9]*]? where ? must be one of
+		 * [l]{d,i,o,u,x} or {f,e,g,E,G,d,o,x,D,O,U,X,c,u}
+		 */
+		s = p++;
+		dot = hash = space = sign = numbers = 0;
+		while (!isalpha(*p)) {
+			if (isdigit(*p)) {
+				numbers++;
+				p++;
+			} else if ((*p == '#' && !(numbers|dot|sign|space|
+			    hash++)) ||
+			    (*p == ' ' && !(numbers|dot|space++)) ||
+			    ((*p == '+' || *p == '-') && !(numbers|dot|sign++))
+			    || (*p == '.' && !(dot++)))
+				p++;
+			else if (*p == '$' || *p == '*')
+				errx(1, "unsupported format character %c", *p);
+			else if (*p == '\0')
+				errx(1, "missing format character");
+			else
+				errx(1, "illegal format character %c", *p);
+		}
 		switch (*p) {
-		case 'f': case 'e': case 'g': case '%':
+		case 'l':
+			islong = 1;
+			p++;
+			/* FALLTHROUGH */
+		case 'o': case 'u': case 'x': case 'X':
+			intdata = nosign = 1;
+			break;
+		case 'd': case 'i':
+			intdata = 1;
 			break;
+		case 'D':
+			if (!islong) {
+				intdata = 1;
+				break;
+			}
+		case 'O': case 'U':
+			if (!islong) {
+				intdata = nosign = 1;
+				break;
+			}
+		case 'c':
+			if (!(intdata | islong)) {
+				chardata = 1;
+				break;
+			}
 		case 's':
 			errx(1, "cannot convert numeric data to strings");
 			break;
-		/* case 'd': case 'o': case 'x': case 'D': case 'O': case 'X':
-		case 'c': case 'u': */
+		case 'h': case 'n': case 'p': case 'q': case 'L':
+		case '$': case '*':
+			errx(1, "unsupported format character %c", *p);
+			/* NOTREACHED */
+		case 'f': case 'e': case 'g': case 'E': case 'G':
+			if (!islong)
+				break;
+			/* FALLTHROUGH */
 		default:
-			dox = 1;
-			break;
+			*++p = '\0';
+			errx(1, "illegal or unsupported format '%s'", s);
+			/* NOTREACHED */
 		}
+		while (*++p)
+			if (*p == '%' && *(p+1) && *(p+1) != '%')
+				errx(1, "too many conversions");
+			else if (*p == '%' && *(p+1) == '%')
+				p++;
+			else if (*p == '%' && !*(p+1)) {
+				strcat(format, "%");
+				break;
+			}
 	}
 }