linux-kernel - Re: [PATCH v5 02/32] lib/string_helpers: Convert string_escape

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Date:   Mon, 8 Aug 2022 14:03:02 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Petr Mladek <pmladek@...e.com>,
        Kent Overstreet <kent.overstreet@...il.com>,
        Andy Shevchenko <andy@...nel.org>
Subject: Re: [PATCH v5 02/32] lib/string_helpers: Convert string_escape_mem()
 to printbuf

On Mon, Aug 8, 2022 at 4:41 AM Matthew Wilcox (Oracle)
<willy@...radead.org> wrote:
>
> From: Kent Overstreet <kent.overstreet@...il.com>
>
> Like the upcoming vsprintf.c conversion, this converts string_escape_mem
> to prt_escaped_string(), which uses and outputs to a printbuf, and makes
> string_escape_mem() a smaller wrapper to support existing users.
>
> The new printbuf helpers greatly simplify the code.

...

>  struct device;
>  struct file;
>  struct task_struct;
> +struct printbuf;

Keep it ordered?

...

> @@ -71,6 +74,7 @@ static inline int string_escape_mem_any_np(const char *src, size_t isz,
>         return string_escape_mem(src, isz, dst, osz, ESCAPE_ANY_NP, only);
>  }
>
> +
>  static inline int string_escape_str(const char *src, char *dst, size_t sz,
>                 unsigned int flags, const char *only)
>  {

Stray change.

...

>                 if (!(is_append || in_dict) && is_dict &&
> -                                         escape_passthrough(c, &p, end))
> +                   escape_passthrough(out, c))

That (a bit strange) indentation is on purpose. Can we keep it?

>                         continue;

...

Not sure if the below was in the original text, but maybe it makes
sense to amend.

> + * Description:
> + * The process of escaping byte buffer includes several parts. They are applied

a byte in the buffer (?)

> + * in the following sequence.
> + *
> + *     1. The character is not matched to the one from @only string and thus
> + *        must go as-is to the output.
> + *     2. The character is matched to the printable and ASCII classes, if asked,
> + *        and in case of match it passes through to the output.
> + *     3. The character is matched to the printable or ASCII class, if asked,
> + *        and in case of match it passes through to the output.
> + *     4. The character is checked if it falls into the class given by @flags.
> + *        %ESCAPE_OCTAL and %ESCAPE_HEX are going last since they cover any
> + *        character. Note that they actually can't go together, otherwise
> + *        %ESCAPE_HEX will be ignored.
> + *
> + * Caller must provide valid source and destination pointers. Be aware that
> + * destination buffer will not be NULL-terminated, thus caller have to append

the caller has

> + * it if needs. The supported flags are::

if needed.

-- 
With Best Regards,
Andy Shevchenko