On binary input there may be NUL characters within the string;
in this case the return value (if nonnegative) may give an incorrect length.
-BIO_get_line() attempts to read from BIO <b> a line of data up to the next '\n'
+BIO_get_line() attempts to read from BIO I<b> a line of data up to the next '\n'
or the maximum length I<size-1> is reached and places the data in I<buf>.
The returned string is always NUL-terminated and the '\n' is preserved
if present in the input data.