On Mon, Oct 13, 2025 at 04:03:28PM +0200, Heinrich Schuchardt wrote: > On 10/13/25 15:53, Daniel Kiper wrote: > > On Thu, Oct 09, 2025 at 03:18:34PM +0800, Michael Chang via Grub-devel > > wrote: > > > Add support for the 'z' length modifier in the printf code. This allows > > > printing of size_t and ssize_t values using %zu, %zd and related > > > formats. The parser maps 'z' to the correct integer width based on > > > sizeof (size_t). > > > > > > Signed-off-by: Michael Chang <[email protected]> > > > --- > > > grub-core/kern/misc.c | 20 ++++++++++++++++++++ > > > 1 file changed, 20 insertions(+) > > > > > > diff --git a/grub-core/kern/misc.c b/grub-core/kern/misc.c > > > index 2b7922393..ff614add5 100644 > > > --- a/grub-core/kern/misc.c > > > +++ b/grub-core/kern/misc.c > > > @@ -26,6 +26,7 @@ > > > #include <grub/i18n.h> > > > #include <grub/types.h> > > > #include <grub/charset.h> > > > +#include <stddef.h> > > > > > > union printf_arg > > > { > > > @@ -739,6 +740,9 @@ parse_printf_arg_fmt (const char *fmt0, struct > > > printf_args *args, > > > COMPILE_TIME_ASSERT (sizeof (long) <= sizeof (long long)); > > > COMPILE_TIME_ASSERT (sizeof (long long) == sizeof (void *) > > > || sizeof (int) == sizeof (void *)); > > > + COMPILE_TIME_ASSERT (sizeof (size_t) == sizeof (unsigned) > > > + || sizeof (size_t) == sizeof (unsigned long) > > > + || sizeof (size_t) == sizeof (unsigned long long)); > > > > > > fmt = fmt0; > > > while ((c = *fmt++) != 0) > > > @@ -773,11 +777,17 @@ parse_printf_arg_fmt (const char *fmt0, struct > > > printf_args *args, > > > fmt++; > > > > > > c = *fmt++; > > > + if (c == 'z') > > > + { > > > + c = *fmt++; > > > + goto do_count; > > > + } > > > if (c == 'l') > > > c = *fmt++; > > > if (c == 'l') > > > c = *fmt++; > > > > > > + do_count: > > > switch (c) > > > { > > > case 'p': > > > @@ -874,6 +884,14 @@ parse_printf_arg_fmt (const char *fmt0, struct > > > printf_args *args, > > > continue; > > > } > > > > > > + if (c == 'z') > > > + { > > > + c = *fmt++; > > > + if (sizeof (size_t) == sizeof (unsigned long)) > > > > This... > > > > > + longfmt = 1; > > > + else if (sizeof (size_t) == sizeof (unsigned long long)) > > > > ... and this should be build time check... > > Hello Daniel, > > The compiler will evaluate the current ifs at build time if you don't build > with O0. > > Do you prefer using #if to if? > > Other projects go the opposite way. In U-Boot we try to replace #if by if > where possible to ensure that even if a build time check is made the code in > the unused branch is syntax checked.
Thanks a lot for the clarification. Actually I was also thinking about using the #if preprocessor directive at the beginning, but it does not work with the sizeof() operator because that is evaluated by the compiler, not the preprocessor. I prefer using sizeof() instead of a constant like SIZE_MAX, since it is already used in COMPILE_TIME_ASSERT and looks more consistent. I also have faith in the compiler should optimize it away so there will be no runtime branch. Thanks, Michael > > Best regards > > Heinrich > > > > > > + longfmt = 2; > > > + } > > > > Daniel > > > > _______________________________________________ > > Grub-devel mailing list > > [email protected] > > https://lists.gnu.org/mailman/listinfo/grub-devel > _______________________________________________ Grub-devel mailing list [email protected] https://lists.gnu.org/mailman/listinfo/grub-devel
