ref: b4dc52ebf70ffa18e9a7a2b3cee5ff143d8bd5ce
dir: /sys/src/ape/lib/ap/gen/strncat.c/
#include <string.h> char* strncat(char *s1, const char *s2, size_t n) { char *os1; long nn; os1 = s1; nn = n; while(*s1++) ; s1--; while(*s1++ = *s2++) if(--nn < 0) { s1[-1] = 0; break; } return os1; }