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SubjectRe: [PATCH 1/5] lib: string.c: Added a function strzcpy
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

But missing for x86 64 bit and Arm..?


Kind regards
Rickard Strandqvist


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