ref: 68fc5b73b8cc4ba666d8d30d74762c71a0653a9d
dir: /src/libc/string/strcspn.c/
#include <string.h>
#undef strcspn
size_t
strcspn(const char *s1, const char *s2)
{
const unsigned char *s = s1;
const unsigned char *reject = s2;
size_t n;
unsigned ch;
char map[__NUMCHARS] = {0};
while (ch = *reject++)
map[ch] = 1;
for (n = 0; (ch = *s++) && !map[ch]; ++n)
;
return n;
}