On Wed, Jul 6, 2016 at 7:56 AM, Joe Perches <joe at perches.com> wrote: > On Tue, 2016-07-05 at 15:36 -0700, Markus Mayer wrote: >> On 5 July 2016 at 15:14, Joe Perches <joe at perches.com> wrote: >> > 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. >> > >> > Using str[n]cpy followed by strto is >> > pretty obvious and rarely used anyway. >> First time around, folks were proposing the "copy" variants when I >> submitted just strtolower() by itself[1]. They just asked for source >> and destination parameters to strtolower(), but looking at the use >> cases that wouldn't have worked so well. Hence it evolved into these 6 >> functions. >> >> Here's a breakdown of how the functions are being used (patches 2-7), >> see also [2]: >> >> Patch 2: strncpytolower() >> Patch 3: strtolower() >> Patch 4: strncpytolower() and strtolower() >> Patch 5: strtolower() >> Patch 6: strcpytoupper() >> Patch 7: strcpytoupper() >> >> So it does look like the copy + change case variant is more frequently >> used than just strto. > > Are these functions useful? <shrug> Not to me, not so much. > > None of the functions would have the strcpy performance of > the arch / asm > versions of strcpy and the savings in overall > code isn't significant (or > measured?). > > Of course none of the uses are runtime performance important.
I tend to agree. strcpy is better left to architecture-specific code when it exists. Then doing a strcpy() followed by strtolower() is not exactly unintuitive. An explosion of closely related function is certainly more confusing to me. I'd just keep strtolower()/strtoupper() because they are commonly done operations and we can probably save some space by having a unique implementation. But going beyond that is overthinking the problem IMHO.
