strjoina

strjoina.c

pulled from
https://github.com/systemd/systemd

    #define strjoina(a, ...)                                                \
            ({                                                              \
                    const char *_appendees_[] = { a, __VA_ARGS__ };         \
                    char *_d_, *_p_;                                        \
                    size_t _len_ = 0;                                          \
                    unsigned _i_;                                           \
                    for (_i_ = 0; _i_ < ELEMENTSOF(_appendees_) && _appendees_[_i_]; _i_++) \
                            _len_ += strlen(_appendees_[_i_]);              \
                    _p_ = _d_ = alloca(_len_ + 1);                          \
                    for (_i_ = 0; _i_ < ELEMENTSOF(_appendees_) && _appendees_[_i_]; _i_++) \
                            _p_ = stpcpy(_p_, _appendees_[_i_]);            \
                    *_p_ = 0;                                               \
                    _d_;                                                    \
            })