ref: ccd1b1585da94843f04bbc7b8bf27ebace5cee3c
dir: /src/libc/string/strspn.c/
#include <string.h>
#undef strspn
size_t
strspn(const char *s1, const char *s2)
{
const unsigned char *s = s1;
const unsigned char *accept = s2;
unsigned ch;
size_t n;
char buf[__NUMCHARS];
memset(buf, 0, sizeof(buf));
while (ch = *accept++)
buf[ch] = 1;
for (n = 0; (ch = *s++) && buf[ch]; ++n)
;
return n;
}