[U-Boot] [PATCH] vsprintf.c: add wide string (%ls) support

[Heinrich Schuchardt]

On 07/31/2017 02:42 PM, Rob Clark wrote:
> This is convenient for efi_loader which deals a lot with utf16.
> 
> Signed-off-by: Rob Clark <robdclark at gmail.com>
> ---
>  lib/vsprintf.c | 39 +++++++++++++++++++++++++++++++++++++--
>  1 file changed, 37 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 874a2951f7..84e157ecb1 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -270,6 +270,35 @@ static char *string(char *buf, char *end, char *s, int field_width,
>  	return buf;
>  }
>  
> +static size_t strnlen16(const u16* s, size_t count)
> +{
> +	const u16 *sc;
> +
> +	for (sc = s; count-- && *sc; ++sc)
> +		/* nothing */;
> +	return sc - s;
> +}
> +
> +static char *string16(char *buf, char *end, u16 *s, int field_width,
> +		int precision, int flags)
> +{
> +	int len, i;
> +
> +	if (s == NULL)
> +		s = L"<NULL>";

The L notation creates a wchar_t string. The width of wchar_t depends on
gcc compiler flag -fshort-wchar.

vsprintf.c is not compiled with -fshort-wchar. So change this to

const u16 null[] = { '<', 'N', 'U', 'L', 'L', '>', 0};
s = null;

> +
> +	len = strnlen16(s, precision);
> +
> +	if (!(flags & LEFT))
> +		while (len < field_width--)
> +			ADDCH(buf, ' ');
> +	for (i = 0; i < len; ++i)
> +		ADDCH(buf, *s++);
> +	while (len < field_width--)
> +		ADDCH(buf, ' ');
> +	return buf;
> +}
> +
>  #ifdef CONFIG_CMD_NET
>  static const char hex_asc[] = "0123456789abcdef";
>  #define hex_asc_lo(x)	hex_asc[((x) & 0x0f)]
> @@ -528,8 +557,14 @@ repeat:
>  			continue;
>  
>  		case 's':
> -			str = string(str, end, va_arg(args, char *),
> -				     field_width, precision, flags);
> +			if (qualifier == 'l') {

According to ISO 9899:1999 %ls is used to indicate a wchar_t string,
which may be u32 * or u16 * depending on GCC flag -fshort-wchar.

Wouldn't it make sense to use some other notation, e.g. %S, to indicate
that we explicitly mean u16 *?

Please, add a comment into the code indicating why we need u16 * support
referring to the UEFI spec.

Best regards

Heinrich

> +				str = string16(str, end, va_arg(args, u16 *),
> +					       field_width, precision, flags);
> +
> +			} else {
> +				str = string(str, end, va_arg(args, char *),
> +					     field_width, precision, flags);
> +			}
>  			continue;
>  
>  		case 'p':
>