Re: [PATCH v2 next 07/11] tools/nolibc/printf: Add support for conversion flags "#- +" and format "%X"

[Thomas Weißschuh]

On 2026-02-06 19:11:17+0000, david.laight.linux@xxxxxxxxx wrote:
> From: David Laight <david.laight.linux@xxxxxxxxx>
> 
> Add support for all the normal flag chacacters except '0' (zero pad).
>   '-' left alignment.
>   '+' and ' ' Sign characters for non-negative numbers.
>   '#' adds 0x to hex numbers.
> Partially support "%X", outputs lower case a..f the same as "%x".
> 
> Move the "%s" code in with the numeric formats to save a va_arg() call.
> 
> Prepend the sign (or "0x") after conversion to ascii and use the length
> returned by u64toh_r() and u64toa_r().
> Both needed for precision and zero-padding in the next patch.
> 
> Signed-off-by: David Laight <david.laight.linux@xxxxxxxxx>
> ---
> 
> Changes for v2:
> - Add support for left justifying fields (removed from patch 6).
> - Merge in the changes from the old patch 8.
> - Add support for "%#x" (formally part of patch 9).
> 
>  tools/include/nolibc/stdio.h | 97 ++++++++++++++++++++++++++----------
>  1 file changed, 71 insertions(+), 26 deletions(-)

(...)

> +non_numeric_conversion:
> +			if (ch == 'm') {
>  #ifdef NOLIBC_IGNORE_ERRNO
>  				outstr = "unknown error";
> +				len = __builtin_strlen(outstr);

Why the builtin and not the regular one?

>  #else
>  				outstr = strerror(errno);
> +				goto do_strnlen_output;
>  #endif /* NOLIBC_IGNORE_ERRNO */
>  			} else {
>  				if (ch != '%') {

(...)