On vr, 04 okt 2019 08:52:12 -0400, James Carlson wrote: > On 10/04/19 06:49, Kurt Van Dijck wrote: > >> IMHO time_t is defined in sys/types.h > > > > http://www.open-std.org/JTC1/SC22/WG14/www/docs/n1256.pdf > > chapter 7.23.1.3 > > > > I believe that covers userland environments, not the kernel. > > At least on Solaris (and its derivatives, such as Illumos), the symbols > available in the kernel are defined in sys/ (or net/, netinet/, or > similar for network bits). The top-level header files are for userland > libraries. Userland libraries are not accessible within the kernel. > > In this case, the common net/ppp_defs.h file is used by both user-level > code (pppd itself) and by several kernel modules. I see. > > There may be systems on which including <time.h> within a kernel module > is harmless (I suspect Linux is one), but I have a hard time believing > that it's correct to do so. You're right that the kernel code does not __necessarily__ use the same thing. What matters here is that all kernel code must use the same thing. > > Do you know of a system where either (a) <sys/time.h> does not exist or > (b) it exists but does not define 'time_t'? I haven't been able to find > a system that matches either case. I tried several flavors of Linux, > AIX, Solaris, HP/UX, and IBM USS on z/OS. I don't know a system where (a) or (b) are valid. My point is that such system could could exist, so I learned not to inspect the header files looking for a type, but inspect man-pages or specifications when looking for a type, and so time_t is defined in time.h. Regardless of those systems, you look for 1 header that suits userspace and solaris kernel. Isn't that a bit ... strange. Now that I know that that file is used as include for kernel code, I'd rather include time.h in the userspace c-files. Kurt
