On Wed, Oct 22, 2025 at 12:30:23PM +0800, Michael Chang via Grub-devel wrote:
> On Tue, Oct 21, 2025 at 05:17:58PM +0200, Daniel Kiper wrote:
> > On Fri, Oct 17, 2025 at 05:01:32PM +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]>
> > > Reviewed-by: Neal Gompa <[email protected]>
> > > Reviewed-by: Daniel Kiper <[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))
> > > +     longfmt = 1;
> > > +   else if (sizeof (size_t) == sizeof (unsigned long long))
> > > +     longfmt = 2;
> >
> > I have just realized we should probably have:
> >
> > #ifdef GRUB_UTIL
> >   if (sizeof (size_t) == sizeof (unsigned long))
> >     longfmt = 1;
> >   else if (sizeof (size_t) == sizeof (unsigned long long))
> >     longfmt = 2;
> > #else
> >   if (sizeof (grub_size_t) == sizeof (unsigned long))
> >     longfmt = 1;
> >   else if (sizeof (grub_size_t) == sizeof (unsigned long long))
> >     longfmt = 2;
> > #endif
> >
> > Same for COMPILE_TIME_ASSERT() above.
> >
> > If it makes sense for you please post updated patch set. I want to merge
> > it tomorrow...
>
> The type size_t is not only used in Linux utilities but also by core
> components that import sources from Linux libraries, such as libgcrypt
> and zstd, which run in GRUB's arch-platform pre-boot environment.
>
> Likewise, grub_size_t is not limited to the pre-boot context but is also
> used in Linux utilities.
>
> As a result, their scope is not restricted by conditional checks. Each
> type should follow its own established convention for portable format
> specifiers: 'z' for size_t and PRI[ux]GRUB_SIZE for grub_size_t. This
> can avoid ambiguity.

Ugh... Somehow I totally forgot about PRI[ux]GRUB_SIZE... :-(
Ignore my comment then...

Daniel

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