ref: ec4c79f3a6ed97ec0c407a870827382cbefb1166
dir: /src/libc/string/memchr.c/
#include <string.h>
#undef memchr
void *
memchr(const void *s, int c, size_t n)
{
	const unsigned char *bp = s;
	while (n > 0 && *bp++ != c)
		--n;
	return (n == 0) ? NULL : bp-1;
}