linux-kernel - Re: [PATCH] vsprintf: replace space with readable '=' before crng is ready

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Date:   Tue, 13 Feb 2018 08:16:57 +0100
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Shunyong Yang <shunyong.yang@...-semitech.com>
Cc:     me@...in.cc, linux-kernel@...r.kernel.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Joey Zheng <yu.zheng@...-semitech.com>
Subject: Re: [PATCH] vsprintf: replace space with readable '=' before crng is ready

On 13 February 2018 at 07:20, Shunyong Yang
<shunyong.yang@...-semitech.com> wrote:

>
> This patch replaces space with readable "=" when output needs padding.
> Following is the output after applying the patch,

> Suggested-by: Rasmus Villemoes <linux@...musvillemoes.dk>
>
>         if (unlikely(!have_filled_random_ptr_key)) {
> +               char *ptrval_str = "(ptrval)";
> +               char str[default_width + 1];
> +               int len = strlen(ptrval_str);
> +
> +               if (default_width > len) {
> +                       int pos;
> +
> +                       pos = (default_width - len) / 2;
> +                       memset(str, '=', default_width);
> +                       memcpy(str + pos + 1, ptrval_str + 1, len - 2);
> +                       str[0] = '(';
> +                       str[default_width - 1] = ')';
> +                       str[default_width] = 0;
> +                       ptrval_str = str;
> +               }
> +

I'm sorry, but that's way too convoluted.

>                 spec.field_width = default_width;
>                 /* string length must be less than default_width */
> -               return string(buf, end, "(ptrval)", spec);
> +               return string(buf, end, ptrval_str, spec);
>         }

I was thinking of just doing something like

-               return string(buf, end, "(ptrval)", spec);
+               return string(buf, end, sizeof(void *) == 8 ?
"(====ptrval====)" : "(ptrval)", spec);

Rasmus