Re: [PATCH v3 1/2] vsprintf: introduce %*ph extended format specifier for hex buffers

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 01/10/14 08:21, Jan Beulich wrote:
> This behaves in the same way as Linux.  The 64 byte limit is arbitrary but
> long enough for practical purposes.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Release-acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
>
> Re-structured code.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

As this is a modification to my patch, I am not sure whether Reviewed-by
or Ack-ed by is more appropriate.

Either way, I am happy with the change.

~Andrew

>
> --- a/docs/misc/printk-formats.txt
> +++ b/docs/misc/printk-formats.txt
> @@ -3,6 +3,11 @@ Xen custom %p format options.  A subset,
>  All parameters to a %p option should be compatible with void*.  Regular
>  pointers are fine.  Numbers should make use of the _p() macro.
>  
> +Raw buffer as hex string:
> +
> +       %*ph    Up to 64 characters, printed as "00 01 02 ... ff".  Buffer length
> +               expected via the field_width paramter. i.e. printk("%*ph", 8, buffer);
> +
>  Symbol/Function pointers:
>  
>         %ps     Symbol name with condition offset and size (iff offset != 0)
> @@ -16,5 +21,7 @@ Symbol/Function pointers:
>         In the case that an appropriate symbol name can't be found, %p[sS] will
>         fall back to '%p' and print the address in hex.
>  
> +Domain and vCPU information:
> +
>         %pv     Domain and vCPU ID from a 'struct vcpu *' (printed as
>                 "d<domid>v<vcpuid>")
> --- a/xen/common/vsprintf.c
> +++ b/xen/common/vsprintf.c
> @@ -272,6 +272,34 @@ static char *pointer(char *str, char *en
>      /* Custom %p suffixes. See XEN_ROOT/docs/misc/printk-formats.txt */
>      switch ( fmt[1] )
>      {
> +    case 'h': /* Raw buffer as hex string. */
> +    {
> +        const uint8_t *hex_buffer = arg;
> +        unsigned int i;
> +
> +        /* Consumed 'h' from the format string. */
> +        ++*fmt_ptr;
> +
> +        /* Bound user count from %* to between 0 and 64 bytes. */
> +        if ( field_width <= 0 )
> +            return str;
> +        if ( field_width > 64 )
> +            field_width = 64;
> +
> +        for ( i = 0; ; )
> +        {
> +            /* Each byte: 2 chars, 0-padded, base 16, no hex prefix. */
> +            str = number(str, end, hex_buffer[i], 16, 2, -1, ZEROPAD);
> +
> +            if ( ++i == field_width )
> +                return str;
> +
> +            if ( str < end )
> +                *str = ' ';
> +            ++str;
> +        }
> +    }
> +
>      case 's': /* Symbol name with offset and size (iff offset != 0) */
>      case 'S': /* Symbol name unconditionally with offset and size */
>      {
>
>
>