gfs_pio_getline() reads a line from the file gf, and
stores to the buffer starting at s at most size - 1
bytes. It is indistinguishable whether the length of a line is more
than size or equal to size - 1. It sets 1 into the
address pointed by eofp on end of file, otherwise it sets 0.
The function terminated successfully.
Insufficient memory was available.
An error except the above occurred. The reason is shown by its