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

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Date:   Mon, 8 Aug 2022 10:58:39 -0400
From:   Kent Overstreet <kent.overstreet@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Petr Mladek <pmladek@...e.com>,
        Andy Shevchenko <andy@...nel.org>
Subject: Re: [PATCH v5 02/32] lib/string_helpers: Convert string_escape_mem()
 to printbuf

On 8/8/22 08:03, Andy Shevchenko wrote:
> 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?

I generally try to keep my #includes alphabetized, missed this :)

> 
> ...
> 
>> @@ -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.

Fixed

> ...
> 
>>                  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?

Yep, done

>>                          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 (?)

See below

> 
>> + * 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

Yeah I'm actually not changing the function comment for 
string_escape_mem(), that's just git getting confused since I reused 
most of it for prt_escaped_mem(). I'll leave any fixups for that for you 
if that's ok - the docs look clear enough to me.

Cheers