Re: stime.c forcing errno

[prj@po.cwru.edu (Paul Jarc)]

Kevin Ryde <user42@zip.com.au> wrote:
> I'm not sure what the standards say about these time functions setting
> errno.

<URL:http://www.opengroup.org/onlinepubs/007904975/functions/localtime.html>:
# If an error is detected, localtime() shall return a null pointer and
# set errno to indicate the error.

<URL:http://www.opengroup.org/onlinepubs/007904975/functions/gmtime.html>:
# If an error is detected, gmtime() shall return a null pointer and
# set errno to indicate the error.

<URL:http://www.opengroup.org/onlinepubs/007904975/functions/mktime.html>:
# No errors are defined.

<URL:http://www.opengroup.org/onlinepubs/007904975/functions/strptime.html>:
# No errors are defined.

<URL:http://www.opengroup.org/onlinepubs/007904975/functions/errno.html>:
# The value of errno shall be defined only after a call to a function
# for which it is explicitly stated to be set

So for localtime/gmtime, set errno beforehand just in case libc fails
to conform.  But for mktime/strptime, test for failure afterwards and
set errno in that case.  Setting it beforehand may not help; since
these functions are not documented to have any particular effect on
errno, they might have any effect at all - such as replacing our
EINVAL with something nonsensical.


paul


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