Proposed asctime-related changes
eggert at CS.UCLA.EDU
Mon Aug 9 21:36:44 UTC 2004
"Clive D.W. Feather" <clive at demon.net> writes:
> if ((unsigned) timeptr->tm_wday >= sizeof wday_name / sizeof wday_name)
> makes it one comparison instead of two.
Hold on a second. Isn't this optimization invalid on hosts with
padding bits where UINT_MAX == INT_MAX? On such hosts,
(unsigned)-INT_MAX is 1, which is in range, even though -INT_MAX isn't
> Olson, Arthur David (NIH/NCI) said:
>> zdump.c might be compiled with a version of localtime or gmtime
>> that does something evil,
Well, in that case all bets are off: zdump can't possibly work on
systems whose localtime or gmtime functions do arbitrarily evil
things. They might set tm_year to a trap representation, for example,
and in that case zdump can dump core despite the redundant checking.
If you prefer the check, that's fine, I suppose it won't hurt on any
real host (except for performance). But could you please add a
comment about it? Something like this:
** This range test defends against the off-chance that the system
** localtime or gmtime is buggy and returns out-of-range values.
** We don't know of any such systems, but we're playing it safe anyway.
if (timeptr->tm_wday < 0
|| timeptr->tm_wday >= (int) (sizeof wday_name / sizeof wday_name))
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