The getline and getwline read an entire line from stream, storing
    the address of the buffer, which contains the text into *lineptr.
    The buffer is null-terminated and includes the newline character,
    if one was found.

    If *lineptr is NULL, then getline will allocate a buffer for
    storing the line, which should be freed by the user program. (In
    this case, the value in n is ignored.)

    Alternatively, before calling getline, *lineptr can contain a
    pointer to a malloc allocated buffer n bytes in size. If the buffer
    is not large enough to hold the line, getline resizes it with
    realloc, updating *lineptr and n as necessary.