Hi Junio, On Fri, 7 May 2021, Junio C Hamano wrote: > Johannes Schindelin <Johannes.Schindelin@xxxxxx> writes: > > >> Otherwise I'd strongly prefer to see a word that hints that this is > >> an otherwise unneeded workaround for comiplers. Your suggested > >> title instead hints that it is wrong to assume that errno will be > >> set to non-zero after a syscall. I do not think that is the message > >> we want to send to our readers. > > > > Right, the oneline I suggested was only for the original patch, with which > > I disagreed. > > I actually do not know how your rewrite could be better, though. > > /* GCC thinks socket()/connect() might fail to set errno */ > return errno ? errno : EIO; > > If a compiler thinks errno may *not* be set, can 'errno' be reliably > used to decide if it can be returned as-is or a fallback value EIO > should be used, without triggering the same (incorrect) working in > the first place? Oh, I guess I mistook the problem for something else, then. If the problem is that `errno` is not set in case of failure, the resolution is easy (and even recommended in the manual page of `errno`): simply set it to 0 before the syscall (or in the function that relies on `errno == 0` means success). There is really no need to introduce a `saved_errno` variable (which to me would suggest that we need to save the current value of `errno` and reinstate it later, as we do sometimes e.g. when we call `close()` after noticing an error whose `errno` we need to preserve for the caller). Ciao, Dscho
