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SubjectRe: [RFC PATCH v1 6/6] tools/include/string: Implement `strdup()` and `strndup()`
On Mon, Mar 21, 2022 at 03:16:54PM +0700, Alviro Iskandar Setiawan wrote:
> On Mon, Mar 21, 2022 at 2:53 PM Willy Tarreau wrote:
> > Here it can cost quite a lot for large values of maxlen. Please just use
> > a variant of the proposal above like this one:
> >
> > size_t len;
> > char *ret;
> >
> > len = strlen(str);
> > if (len > maxlen)
> > len = maxlen;
> > ret = malloc(len + 1);
> > if (ret)
> > memcpy(ret, str, len);
> > return ret;
>
> Maybe better to use strnlen(), see the detail at man 3 strnlen.
>
> size_t strnlen(const char *s, size_t maxlen);
>
> The strnlen() function returns the number of bytes in the string
> pointed to by s, excluding the terminating null byte ('\0'), but at
> most maxlen. In doing this, strnlen() looks only at the first maxlen
> characters in the string pointed to by s and never beyond s[maxlen-1].
>
> Should be trivial to add strnlen() with a separate patch before this patch.
>
> So it can be:
>
> size_t len;
> char *ret;
>
> len = strnlen(str, maxlen);
> ret = malloc(len + 1);
> if (__builtin_expect(ret != NULL, 1)) {
> memcpy(ret, str, len);
> ret[len] = '\0';
> }
> return ret;
>
> Thoughts?

I thought about it as well and while I was seeking the simplest route,
I agree it would indeed be cleaner.

Willy

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