Extensible C API

api.c

#define END_OF_PARAMS   (-1)

// Each extensible function is going to have it's own params enum
enum {
  SEND_FILE_EXTRA_HEADER,  // next arg is const char *
  SEND_FILE_BYTE_RANGE,    // next args are size_t, size_t
  SEND_FILE_NUM_PARAMS
};

int mg_send_file(const char *path, ...) {
  // ....
}

int main(void) {
   mg_send_file("/etc/group", END_OF_PARAMS);
   mg_send_file("/etc/group",
               PARAM_EXTRA_HEADER, "Foo: bar\r\n",
               PARAM_EXTRA_HEADER, "Baz: baz\r\n",
               SEND_FILE_BYTE_RANGE, (size_t) 10, (size_t) 20,
               END_OF_PARAMS);
               
   return 0;
}