On 10/14/25 07:14, Michael Chang wrote:
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
In generic preprocessor routines you could compare ULONG_MAX to SIZE_MAX.
In GRUB use GRUB_CPU_SIZEOF_LONG and GRUB_CPU_SIZEOF_VOID_P.
Best regards
Heinrich
Best regards
Heinrich
+ longfmt = 2;
+ }
Daniel
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