[PATCH v2 0/7] lib: string: add functions to case-convert strings

[Joe Perches]

On Tue, 2016-07-05 at 13:47 -0700, 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 strncpy()
>     - 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:
>     char *strncpytoupper(char *dst, const char *src, size_t len);
>     char *strncpytolower(char *dst, const char *src, size_t len);
>     char *strcpytoupper(char *dst, const char *src);
>     char *strcpytolower(char *dst, const char *src);
>     char *strtoupper(char *s);
>     char *strtolower(char *s);

I think there isn't much value in anything other
than strto<upper|lower>.

Using str[n]cpy followed by strto<upper|lower> is
pretty obvious and rarely used anyway.