Re: [PATCH v5 3/8] kern/misc: Add a format specifier GUIDs.

[Daniel Kiper]

On Thu, Mar 30, 2023 at 01:18:08PM +0200, Oliver Steffen wrote:
> Extend the printf format specifier for pointers (%p) to accept a suffix
> specifier G to print GUIDs: %pG can be used to print grub_guid structs.
> This does not interfere with the -Wformat checking of gcc.  Note that
> the data type is not checked though (%p accepts void*).
>
> Signed-off-by: Oliver Steffen <osteffen@redhat.com>
> ---
>  grub-core/kern/misc.c | 86 ++++++++++++++++++++++++++++++++-----------
>  1 file changed, 65 insertions(+), 21 deletions(-)
>
> diff --git a/grub-core/kern/misc.c b/grub-core/kern/misc.c
> index dfae4f9d7..1a8aff543 100644
> --- a/grub-core/kern/misc.c
> +++ b/grub-core/kern/misc.c
> @@ -24,6 +24,7 @@
>  #include <grub/term.h>
>  #include <grub/env.h>
>  #include <grub/i18n.h>
> +#include <grub/types.h>
>
>  union printf_arg
>  {
> @@ -34,7 +35,8 @@ union printf_arg
>      {
>        INT, LONG, LONGLONG,
>        UNSIGNED_INT = 3, UNSIGNED_LONG, UNSIGNED_LONGLONG,
> -      STRING
> +      STRING,
> +      GUID
>      } type;
>    long long ll;
>  };
> @@ -772,6 +774,9 @@ parse_printf_arg_fmt (const char *fmt0, struct 
> printf_args *args,
>        switch (c)
>       {
>       case 'p':
> +       if (*(fmt) == 'G')
> +         ++fmt;
> +       /* Fall through. */
>       case 'x':
>       case 'X':
>       case 'u':
> @@ -885,6 +890,10 @@ parse_printf_arg_fmt (const char *fmt0, struct 
> printf_args *args,
>           args->ptr[curn].type = UNSIGNED_LONGLONG;
>         else
>           args->ptr[curn].type = UNSIGNED_INT;
> +       if (*(fmt) == 'G') {
> +         args->ptr[curn].type = GUID;
> +         ++fmt;
> +       }
>         break;
>       case 's':
>         args->ptr[curn].type = STRING;
> @@ -931,6 +940,12 @@ parse_printf_args (const char *fmt0, struct printf_args 
> *args, va_list args_in)
>       else
>         args->ptr[n].ll = va_arg (args_in, unsigned int);
>       break;
> +      case GUID:
> +     if (sizeof (void *) == sizeof (long long))
> +       args->ptr[n].ll = va_arg (args_in, long long);
> +     else
> +       args->ptr[n].ll = va_arg (args_in, unsigned int);
> +     break;

You duplicate code for the STRING. Why not
  case STRING:
  case GUID: ?

Daniel