Вопрос про getline

DESCRIPTION
       getline() reads an entire line from stream, storing the address of  the
       buffer  containing  the  text into *lineptr.  The buffer is null-termi‐
       nated 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.  (The value in *n
       is ignored.)

       Alternatively, before calling getline(), *lineptr can contain a pointer
       to a malloc(3)-allocated buffer *n bytes in size.  If the buffer is not
       large enough to hold the line, getline() resizes  it  with  realloc(3),
       updating *lineptr and *n as necessary.