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

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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
This commit is contained in:
sheldonh 1999-07-22 17:11:59 +00:00
parent 98a98ed10e
commit a2b1df94ad
2 changed files with 97 additions and 19 deletions
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16
usr.bin/jot/jot.1
View File

@ -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.

100
usr.bin/jot/jot.c
View File

@ -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;
}
}
}