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SubjectRe: [PATCH 1/5] lib: string.c: Added a function strzcpy
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On Sun, 2014-10-19 at 14:19 +0200, Rickard Strandqvist wrote:
> 2014-10-19 3:38 GMT+02:00 Joe Perches <joe@perches.com>:
> > On Sun, 2014-10-19 at 00:03 +0200, Rickard Strandqvist wrote:
> >> Added a function strzcpy which works the same as strncpy,
> >> but guaranteed to produce the trailing null character.
> >>
> >> There are many places in the code where strncpy used although it
> >> must be zero terminated, and switching to strlcpy is not an option
> >> because the string must nonetheless be fyld with zero characters.
> > []
> >> diff --git a/lib/string.c b/lib/string.c
> > []
> >> +char *strzcpy(char *dest, const char *src, size_t count)
> >> +{
> >> + char *tmp = dest;
> >> +
> >> + while (count) {
> >> + if ((*tmp = *src) != 0)
> >> + src++;
> >> + tmp++;
> >> + count--;
> >> + }
> >> +
> >> + if (dest != tmp)
> >> + *--tmp = '\0';
> >> +
> >> + return dest;
> >> +}
> >
> > why not
> >
> > char *strzcpy(char *dest, const char *src, size_t count)
> > {
> > strncpy(dest, src, count)
> > if (count)
> > dest[count - 1] = 0; /* or '\0' or whatever */
> >
> > return dest;
> > }
> >
> > maybe use static inline too.
> >
>
> Hi Joe
>
> Yes this solution have also been discussed.
> https://lkml.org/lkml/2014/10/16/682
>
> Very possible that it is a better solution.
> The code that I use in strzcpy is not the way I'd written it, but is
> the same as in strncpy now.
>
> But as I understand it the real strncpy code is normally highly
> optimized for the hardware it runs on.
> Ex: arch/x86/lib/string_32.c

The fact that optimized strncpy variants exist
for any platform is the argument _for_ using it
in strzcpy.

> But missing for x86 64 bit and Arm..?





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