Messages in this thread | | | Date | Mon, 21 Mar 2022 09:51:00 +0100 | From | Willy Tarreau <> | Subject | Re: [RFC PATCH v1 6/6] tools/include/string: Implement `strdup()` and `strndup()` |
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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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