#define io_channel_read_blk(c,b,n,d) ((c)->manager->read_blk((c),b,n,d))
#define io_channel_write_blk(c,b,n,d) ((c)->manager->write_blk((c),b,n,d))
#define io_channel_flush(c) ((c)->manager->flush((c)))
#define io_channel_read_blk(c,b,n,d) ((c)->manager->read_blk((c),b,n,d))
#define io_channel_write_blk(c,b,n,d) ((c)->manager->write_blk((c),b,n,d))
#define io_channel_flush(c) ((c)->manager->flush((c)))