On Fri, 2024-08-23 at 09:02 +0200, Alejandro Colomar wrote: > Is mktime(3) allowed to return -1 and set EOVERFLOW on a successful > call? > > RETURN VALUE > The mktime() function shall return the specified time since the > Epoch encoded as a value of type time_t. If the time since the > Epoch cannot be represented, the function shall return the value > (time_t)-1 and set errno to indicate the error. For mktime the standard only says "return (time_t)-1." It does not mention errno at all. And the standard also says: The value of errno may be set to nonzero by a library function call whether or not there is an error, provided the use of errno is not documented in the description of the function in this document. > Then I think the API is completely broken. How should we check for > errors after a mktime(3) call? Maybe, special case if tm contains Dec 31 1969 23:59:59 UTC... But it's just stupid. > If this is so, let me file a glibc bug requesting a fix of the API, > adding a promise that on success, errno will remain unset. It's a bug in the standard, not glibc. And the standard has deprecated it anyway. https://www.open-std.org/JTC1/SC22/WG14/www/docs/n2566.pdf > > How about if we omit the sample code and make the minimal changes I > > suggested earlier? > > Because I'm being very careful writing that code, and still I'm having > trouble doing that, I think we must provide some example of a correct > call, to prevent many other programmers from doing it wrong. So IMO you should just say "the interface is deprecated, do not use it in any new code." -- Xi Ruoyao <xry111@xxxxxxxxxxx> School of Aerospace Science and Technology, Xidian University
