linux-kernel - Re: [PATCH v3 0/7] lib: string: add functions to case-convert strings

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Message-ID: <CAGt4E5t0TGMxiUfV5Mx+EGyAYAmTOCEJe4QxjpjujvZfPwvYuQ@mail.gmail.com>
Date:	Sat, 9 Jul 2016 21:11:05 -0700
From:	Markus Mayer <markus.mayer@...adcom.com>
To:	Chris Metcalf <cmetcalf@...lanox.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Kees Cook <keescook@...omium.org>,
	dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
	linux-acpi@...r.kernel.org, speakup@...ux-speakup.org,
	devel@...verdev.osuosl.org, linux-scsi@...r.kernel.org,
	target-devel@...r.kernel.org, linux-pm@...r.kernel.org,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 0/7] lib: string: add functions to case-convert strings

On 9 July 2016 at 20:13, Chris Metcalf <cmetcalf@...lanox.com> wrote:
> On 7/8/2016 6:43 PM, Markus Mayer wrote:
>>
>> This series introduces a family of generic string case conversion
>> functions. This kind of functionality is needed in several places in
>> the kernel. Right now, everybody seems to be implementing their own
>> copy of this functionality.
>>
>> Based on the discussion of the previous version of this series[1] and
>> the use cases found in the kernel, it does look like having several
>> flavours of case conversion functions is beneficial. The use cases fall
>> into three categories:
>>      - copying a string and converting the case while specifying a
>>        maximum length to mimic strlcpy()
>>      - copying a string and converting the case without specifying a
>>        length to mimic strcpy()
>>      - converting the case of a string in-place (i.e. modifying the
>>        string that was passed in)
>>
>> Consequently, I am proposing these new functions:
>>      void strlcpytoupper(char *dst, const char *src, size_t len);
>>      void strlcpytolower(char *dst, const char *src, size_t len);
>>      void strcpytoupper(char *dst, const char *src);
>>      void strcpytolower(char *dst, const char *src);
>>      void strtoupper(char *s);
>>      void strtolower(char *s);
>
>
> You may want to read the article here:
>
> https://lwn.net/Articles/659214/

I'll read that. Thanks.

> and follow up some of the discussion threads on LKML about the best
> semantics to advertise for the strlcpy/strscpy variants.  It might be
> helpful to return some kind of overflow/truncation error from your
> copy functions so people can error-check the result.

I am inclined to agree. However, everybody has been telling me that
these functions should be void. Originally they weren't.

Regards,
-Markus