ref: 04f3da918d80958735fd99e1b807758b06ff7e7d
dir: /lib/c/strspn.c/
#include <string.h> #undef strspn size_t strspn(const char *s1, const char *s2) { char buf[__NUMCHARS]; unsigned char ch; size_t n; memset(buf, 0, sizeof(buf)); while (ch = *s2++) buf[ch] = 1; for (n = 0; (ch = *s1++) && buf[ch]; ++n) ; return n; }