#include "common.h" #include int main(int argc, char** argv) { char buffer[8] = {0}; strncat(buffer, "12345", 5); puts(buffer); /* n == buffer size but overflow due to existing content. * buffer has 5 chars, src "ABC" (len 3): 5+3+1 = 9 > 8 → overflow. */ CHK_FAIL_START strncat(buffer, "ABC", 8); CHK_FAIL_END puts(buffer); return ret; }