On Mon, Aug 10, 2020 at 5:21 PM Waldek Kozaczuk <jwkozac...@gmail.com> wrote:
> Can anyone explain the motivation behind this script and how the generated > alltypes.h is intended to be used? I can try. I think we took this idea from Musl. The C library has type definitions in a lot of different header files. For example ssize_t may be in one header file, time_t in another header file, iovec in a third header file, etc. The problem that "alltypes.h" tries to solve is that we may need to use (because Linux and/or glibc used) slightly different definitions for many of these definitions for different architectures. So instead of filling all the different header files with various architecture-dependent #ifdefs, the idea is to put all these definitions in a single header file, alltypes.h - and have a different alltypes.h for the different architectures - without needing to touch all the other header files. This gets complicated by the fact that if, say <time.h> included alltypes.h and it also defined pid_t - for example - users can get surprised when they include <time.h> and get definitions the standard doesn't say they should get from time.h. Maybe a user has their own pid_t defined, and didn't think this was a problem because they only included time.h? This is why alltypes.h only defines pid_t, for example, if __NEED_pid_t is defined. The header file which should define pid_t needs to defined __NEED_pid_t and then include alltypes.h. The reason why we have this alltypes.h.sh instead of just alltypes.h is to avoid the ugliness of all the #ifdef __NEED_... all over - the script generates them and the result is build/release.x64/gen/include/bits/alltypes.h. > I am a little concerned this file might need to be updated as we upgrade > musl. > It might, but then again, these are very basic type definitions that haven't changed in the C standard in many years, so it is unlikely to have changed much. Take a look at Musl's alltypes.h or alltypes.h.in or whatever they call it, and check what they changed since 2014 - or what we changed from them. -- You received this message because you are subscribed to the Google Groups "OSv Development" group. To unsubscribe from this group and stop receiving emails from it, send an email to osv-dev+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/osv-dev/CANEVyjtBGGy8Ky-YggA_XbEdYSiCRdXWRCv9LK79tQ0wmfdpWw%40mail.gmail.com.
