+ /* If a buffer is provided by user... */
+ if ( buf != NULL )
+ {
+ /* ...do not free it in library functions like fclose(), freopen(). */
+ stream->status &= ~_PDCLIB_LIBBUFFER;
+ }
+ /* If no buffer is provided by user, but required... */
+ else if ( mode != _IONBF )
+ {
+ /* Since setvbuf() may be called (successfully) on a stream only once,
+ the stream's buffer at this point should *always* be that allocated
+ by fopen(), but better make sure.
+ */
+ if ( ! ( stream->status & _PDCLIB_LIBBUFFER ) )
+ {
+ return -1;
+ }
+ /* Drop old buffer, allocate new one of requested size (unless that is
+ equal to BUFSIZ, in which case we can use the one already allocated
+ by fopen().)
+ */
+ if ( size != BUFSIZ )
+ {
+ if ( ( buf = malloc( size ) ) == NULL )
+ {
+ return -1;
+ }
+ free( stream->buffer );
+ }
+ }
+ /* Applying new settings to stream. */
+ stream->status &= ~( _IOFBF | _IOLBF | _IONBF );