From: Florian Obser <florian@openbsd.org>
Subject: Re: drop a useless function
To: tech@openbsd.org
Date: Tue, 08 Apr 2025 11:09:02 +0200

On 2025-04-08 10:21 +02, Jan Stary <hans@stare.cz> wrote:
> On Apr 08 09:09:07, florian@openbsd.org wrote:
>> the comment right above it should go as well.
>> 
>> On 2025-04-07 21:20 +02, Jan Stary <hans@stare.cz> wrote:
>> > The tformat() function in zdump.c
>> > merely returns a constant string
>> > and is called once.
>
> Thanks for checking the diff.
>
> I left that in, thinking it applies to all "code below"
> i.e. also dumptime(), being the tail of zdump.c - but
> perhaps it's just the "%lld" that was meant by then.
>

no, it came in with rev 1.16 of lib/libc/time/zdump.c which introduced
tformat(). It did some unsavoury things. dumptime() was already there at
the time.

@@ -375,6 +587,33 @@ struct tm *        tmp;
        return (result == NULL) ? &nada : result;
 }

+/*
+** The code below can fail on certain theoretical systems;
+** it works on all known real-world systems as of 2004-12-30.
+*/
+
+static const char *
+tformat()
+{
+       if (0.5 == (time_t) 0.5) {      /* floating */
+               if (sizeof (time_t) > sizeof (double))
+                       return "%Lg";
+               return "%g";
+       }
+       if (0 > (time_t) -1) {          /* signed */
+               if (sizeof (time_t) > sizeof (long))
+                       return "%lld";
+               if (sizeof (time_t) > sizeof (int))
+                       return "%ld";
+               return "%d";
+       }
+       if (sizeof (time_t) > sizeof (unsigned long))
+               return "%llu";
+       if (sizeof (time_t) > sizeof (unsigned int))
+               return "%lu";
+       return "%u";
+}
+
 static void
 dumptime(timeptr)
 register const struct tm *     timeptr;
@@ -388,7 +627,13 @@ register const struct tm * timeptr;


> (And perhaps a comment making a statement about
> "all known systems as of 2004" should go at any rate :-)
>
> Updated diff below.

OK florian for after release or I'll take OKs to commit it myself.

>
> 	Jan
>
> Index: zdump.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/zdump/zdump.c,v
> diff -u -p -r1.14 zdump.c
> --- zdump.c	15 Mar 2016 19:50:48 -0000	1.14
> +++ zdump.c	8 Apr 2025 08:19:27 -0000
> @@ -62,7 +62,6 @@ static void		dumptime(const struct tm *t
>  static time_t		hunt(char *name, time_t lot, time_t	hit);
>  static void		setabsolutes(void);
>  static void		show(char *zone, time_t t, int v);
> -static const char 	*tformat(void);
>  static time_t		yeartot(long y);
>  static void		usage(void);
>  
> @@ -358,7 +357,7 @@ show(char *zone, time_t t, int v)
>  	if (v) {
>  		tmp = gmtime(&t);
>  		if (tmp == NULL) {
> -			printf(tformat(), t);
> +			printf("%lld", t);
>  		} else {
>  			dumptime(tmp);
>  			printf(" UTC");
> @@ -392,17 +391,6 @@ abbr(struct tm *tmp)
>  		return &nada;
>  	result = tzname[tmp->tm_isdst];
>  	return (result == NULL) ? &nada : result;
> -}
> -
> -/*
> -** The code below can fail on certain theoretical systems;
> -** it works on all known real-world systems as of 2004-12-30.
> -*/
> -
> -static const char *
> -tformat(void)
> -{
> -	return "%lld";
>  }
>  
>  static void
>

-- 
In my defence, I have been left unsupervised.