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From: Ingo Schwarze <schwarze@usta.de>
To: Kristaps Dzonsons <kristaps@bsd.lv>
Cc: tech@mdocml.bsd.lv
Subject: Re: Division by zero
Date: Mon, 20 Oct 2014 15:09:32 +0200	[thread overview]
Message-ID: <20141020130932.GA19002@iris.usta.de> (raw)
In-Reply-To: <5444DFEC.1040802@bsd.lv>

Hi Kristaps,

Kristaps Dzonsons wrote on Mon, Oct 20, 2014 at 12:11:56PM +0200:

> As enclosed!  It also needed "ln" for the line numbering.

OK schwarze@.

> ...or we could just be a bit more realistic and let *res = INT_MAX,
> with sign depending on the numerator. ;)

That would require coordinating with groff, i guess.
I'm not sure it's worth changing.

> (I use *res = 0 now.)

Yes, that's the right way.  Get stuff done following traditional
behaviour (unless that is completely crazy), such that progress in
mandoc isn't obstructed by having to coordinate with groff.  If a
good reason arises later to change behaviour, that's a different
matter and can be dealt with slowly.

Thanks,
  Ingo


> 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);
--
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      reply	other threads:[~2014-10-20 13:10 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
2014-10-20 13:09     ` Ingo Schwarze [this message]

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