From: Kristaps Dzonsons <kristaps@bsd.lv>
To: tech@mdocml.bsd.lv
Subject: Re: Division by zero
Date: Mon, 20 Oct 2014 12:11:56 +0200 [thread overview]
Message-ID: <5444DFEC.1040802@bsd.lv> (raw)
In-Reply-To: <20141019213847.GB27298@iris.usta.de>
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Ingo,
> Makes sense to me. Perhaps just hand the struct roff down into
> roff_evalcond, roff_evalnum, and roff_evalpar? That one is
> already a usual argument for many functions, while struct mparse
> is not.
As enclosed! It also needed "ln" for the line numbering.
> I think the message should be an ERROR, not a WARNING, because it
> can have arbitrarily severe consequences on formatting and content.
>
> Two more nits: You say "x / 0 = x". Hum, maybe. But groff prefers
> a different lie: "x / 0 = 0". And operator2 is int, not float.
> So i think you need something like
>
> case '/':
> if (operand2 == 0) {
> scream("WOLF!");
> *res = 0;
> } else
> *res /= operand2;
> break;
...or we could just be a bit more realistic and let *res = INT_MAX, with
sign depending on the numerator. ;)
(I use *res = 0 now.)
Best,
Kristaps
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? .DS_Store
? Makefile.local
? TEST.sh
? TEST.sh.out
? bar.1
? cgi-doc.diff
? cgi.h
? config.h
? config.log
? configure.local
? demandoc
? ditto.1
? divbyzero.patch
? divbyzero2.patch
? eqn-test.1
? eqn-test.1.html
? eqn.2.patch
? eqn.bak.c
? eqn.patch
? foo
? foo.1
? foo.1.html
? foo.1.ps
? foo.2
? foo.2.html
? foo.3
? foo.3.html
? foo.4
? foo.4.html
? foo.5
? foo.5.html
? foo.5.ps
? foo.sh
? makewhatis
? man.cgi
? mandoc
? plockstat.1
? preconv
? term.diff
? test.1
Index: mandoc.h
===================================================================
RCS file: /usr/vhosts/mdocml.bsd.lv/cvs/mdocml/mandoc.h,v
retrieving revision 1.163
diff -u -p -r1.163 mandoc.h
--- mandoc.h 14 Oct 2014 02:16:06 -0000 1.163
+++ mandoc.h 20 Oct 2014 10:10:50 -0000
@@ -166,6 +166,7 @@ enum mandocerr {
MANDOCERR_IT_NONUM, /* skipping request without numeric argument */
MANDOCERR_ARG_SKIP, /* skipping all arguments: macro args */
MANDOCERR_ARG_EXCESS, /* skipping excess arguments: macro ... args */
+ MANDOCERR_DIVZERO, /* divide by zero */
MANDOCERR_FATAL, /* ===== start of fatal errors ===== */
Index: read.c
===================================================================
RCS file: /usr/vhosts/mdocml.bsd.lv/cvs/mdocml/read.c,v
retrieving revision 1.91
diff -u -p -r1.91 read.c
--- read.c 18 Oct 2014 15:57:34 -0000 1.91
+++ read.c 20 Oct 2014 10:10:50 -0000
@@ -211,6 +211,7 @@ static const char * const mandocerrs[MAN
"skipping request without numeric argument",
"skipping all arguments",
"skipping excess arguments",
+ "divide by zero",
"generic fatal error",
Index: roff.c
===================================================================
RCS file: /usr/vhosts/mdocml.bsd.lv/cvs/mdocml/roff.c,v
retrieving revision 1.232
diff -u -p -r1.232 roff.c
--- roff.c 20 Oct 2014 02:33:06 -0000 1.232
+++ roff.c 20 Oct 2014 10:10:50 -0000
@@ -186,9 +186,12 @@ static enum rofferr roff_cond_sub(ROFF_
static enum rofferr roff_ds(ROFF_ARGS);
static enum rofferr roff_eqndelim(struct roff *,
char **, size_t *, int);
-static int roff_evalcond(const char *, int *);
-static int roff_evalnum(const char *, int *, int *, int);
-static int roff_evalpar(const char *, int *, int *);
+static int roff_evalcond(struct roff *r, int,
+ const char *, int *);
+static int roff_evalnum(struct roff *, int,
+ const char *, int *, int *, int);
+static int roff_evalpar(struct roff *, int,
+ const char *, int *, int *);
static int roff_evalstrcond(const char *, int *);
static void roff_free1(struct roff *);
static void roff_freereg(struct roffreg *);
@@ -622,7 +625,7 @@ roff_res(struct roff *r, char **bufp, si
case 'B':
npos = 0;
ubuf[0] = arg_complete &&
- roff_evalnum(stnam, &npos, NULL, 0) &&
+ roff_evalnum(r, ln, stnam, &npos, NULL, 0) &&
stnam + npos + 1 == cp ? '1' : '0';
ubuf[1] = '\0';
break;
@@ -1240,7 +1243,7 @@ out:
* or string condition.
*/
static int
-roff_evalcond(const char *v, int *pos)
+roff_evalcond(struct roff *r, int ln, const char *v, int *pos)
{
int wanttrue, number;
@@ -1271,7 +1274,7 @@ roff_evalcond(const char *v, int *pos)
break;
}
- if (roff_evalnum(v, pos, &number, 0))
+ if (roff_evalnum(r, ln, v, pos, &number, 0))
return((number > 0) == wanttrue);
else
return(roff_evalstrcond(v, pos) == wanttrue);
@@ -1300,7 +1303,7 @@ roff_cond(ROFF_ARGS)
r->last->rule = ROFF_el == tok ?
(r->rstackpos < 0 ? 0 : r->rstack[r->rstackpos--]) :
- roff_evalcond(*bufp, &pos);
+ roff_evalcond(r, ln, *bufp, &pos);
/*
* An if-else will put the NEGATION of the current evaluated
@@ -1466,14 +1469,15 @@ roff_getop(const char *v, int *pos, char
* or a single signed integer number.
*/
static int
-roff_evalpar(const char *v, int *pos, int *res)
+roff_evalpar(struct roff *r, int ln,
+ const char *v, int *pos, int *res)
{
if ('(' != v[*pos])
return(roff_getnum(v, pos, res));
(*pos)++;
- if ( ! roff_evalnum(v, pos, res, 1))
+ if ( ! roff_evalnum(r, ln, v, pos, res, 1))
return(0);
/*
@@ -1495,7 +1499,8 @@ roff_evalpar(const char *v, int *pos, in
* Proceed left to right, there is no concept of precedence.
*/
static int
-roff_evalnum(const char *v, int *pos, int *res, int skipwhite)
+roff_evalnum(struct roff *r, int ln, const char *v,
+ int *pos, int *res, int skipwhite)
{
int mypos, operand2;
char operator;
@@ -1509,7 +1514,7 @@ roff_evalnum(const char *v, int *pos, in
while (isspace((unsigned char)v[*pos]))
(*pos)++;
- if ( ! roff_evalpar(v, pos, res))
+ if ( ! roff_evalpar(r, ln, v, pos, res))
return(0);
while (1) {
@@ -1524,7 +1529,7 @@ roff_evalnum(const char *v, int *pos, in
while (isspace((unsigned char)v[*pos]))
(*pos)++;
- if ( ! roff_evalpar(v, pos, &operand2))
+ if ( ! roff_evalpar(r, ln, v, pos, &operand2))
return(0);
if (skipwhite)
@@ -1545,6 +1550,12 @@ roff_evalnum(const char *v, int *pos, in
*res *= operand2;
break;
case '/':
+ if (0 == operand2) {
+ mandoc_msg(MANDOCERR_DIVZERO,
+ r->parse, ln, *pos, v);
+ *res = 0;
+ break;
+ }
*res /= operand2;
break;
case '%':
@@ -1719,7 +1730,7 @@ roff_nr(ROFF_ARGS)
if ('+' == sign || '-' == sign)
val++;
- if (roff_evalnum(val, NULL, &iv, 0))
+ if (roff_evalnum(r, ln, val, NULL, &iv, 0))
roff_setreg(r, key, iv, sign);
return(ROFF_IGN);
next prev parent reply other threads:[~2014-10-20 10:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-19 21:02 Kristaps Dzonsons
2014-10-19 21:38 ` Ingo Schwarze
2014-10-20 10:11 ` Kristaps Dzonsons [this message]
2014-10-20 13:09 ` Ingo Schwarze
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