Hi Zhangjin, On Sun, Jun 04, 2023 at 01:34:29PM +0800, Zhangjin Wu wrote: > most of the library routines share the same code model, let's add some > macros to simplify the coding and shrink the code lines too. > > One added for syscall return, one added for syscall call, both of them > can get the typeof 'return value' automatically. > > To get the return type of syscalls, __auto_type is better than typeof(), > but it is not supported by the old compilers (before 2013, see [1]), so, > use typeof() here. > > [1]: https://gcc.gnu.org/legacy-ml/gcc-patches/2013-11/msg01378.html > > Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx> > --- > tools/include/nolibc/sys.h | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h > index 1d6f33f58629..937a8578e3d4 100644 > --- a/tools/include/nolibc/sys.h > +++ b/tools/include/nolibc/sys.h > @@ -28,6 +28,21 @@ > #include "errno.h" > #include "types.h" > > +/* Syscall call and return helpers */ > +#define __syscall_ret(ret) \ > +({ \ > + if (ret < 0) { \ > + SET_ERRNO(-ret); \ > + ret = (typeof(ret))-1; \ > + } \ > + ret; \ > +}) > + > +#define __syscall(name, ...) \ > +({ \ > + typeof(sys_##name(__VA_ARGS__)) ret = sys_##name(__VA_ARGS__); \ > + __syscall_ret(ret); \ > +}) Well, I personally don't find that it increases legibility, on the opposite. At first when reading the series, I thought you had dropped errno setting on return. I think the reason is that when reading that last macro, it's not at all obvious that __syscall_ret() is actually modifying this ret value *and* returning it as the macro's result. If we'd want to go down that route, I suspect that something like this would at least hint about what is being returned: +#define __syscall(name, ...) \ +({ \ + typeof(sys_##name(__VA_ARGS__)) ret = sys_##name(__VA_ARGS__); \ + ret = __syscall_ret(ret); \ +}) But I'm interested in others' opinion on this, particularly Thomas and Arnd who review a significant number of patches. For now I prefer not to take it before we've settled on a choice. Thanks, Willy
