Re: [PATCH v4 1/3] lib/vsprintf: Add support for generic FourCCs by extending %p4cc

[Kees Cook <kees@kernel.org>]

On Tue, Apr 08, 2025 at 12:17:57PM +0530, Aditya Garg wrote:
> From: Hector Martin <marcan@marcan.st>
> 
> %p4cc is designed for DRM/V4L2 FourCCs with their specific quirks, but
> it's useful to be able to print generic 4-character codes formatted as
> an integer. Extend it to add format specifiers for printing generic
> 32-bit FourCCs with various endian semantics:
> 
> %p4ch	Host byte order
> %p4cn	Network byte order
> %p4cl	Little-endian
> %p4cb	Big-endian
> 
> The endianness determines how bytes are interpreted as a u32, and the
> FourCC is then always printed MSByte-first (this is the opposite of
> V4L/DRM FourCCs). This covers most practical cases, e.g. %p4cn would
> allow printing LSByte-first FourCCs stored in host endian order
> (other than the hex form being in character order, not the integer
> value).
> 
> Acked-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reviewed-by: Petr Mladek <pmladek@suse.com>
> Tested-by: Petr Mladek <pmladek@suse.com>
> Signed-off-by: Hector Martin <marcan@marcan.st>

Reviewed-by: Kees Cook <kees@kernel.org>

-- 
Kees Cook