ref: ec4c79f3a6ed97ec0c407a870827382cbefb1166
dir: /src/libc/string/strtok.c/
#include <string.h>
#undef strtok
char *
strtok(char * restrict s1, const char * restrict s2)
{
	static char *line;
	if (s1)
		line = s1;
	else if (!line)
		return NULL;
	s1 = line + strspn(line, s2);
	if (*s1 == '\0')
		return line = NULL;
	line = s1 + strcspn(s1, s2);
	if (*line == '\0')
		line = NULL;
	else
		*line++ = '\0';
	return s1;
}