Provided by: libowfat-dev_0.30-2ubuntu1_amd64
io_fd_flags - prepare descriptor for io_wait
#include <io.h> int io_fd(int64 fd); #ifdef HAVE_IO_FD_FLAGS int io_fd_flags(int64 fd);
io_fd_flags behaves just like io_fd, but certain flags can be bitwise-ORed to it to alter its behavior: IO_FD_CANWRITE tell io_fd that the descriptor is writable. This is useful so io_wantwrite can queue the descriptor immediately and there is no need to query the operating system event reporting mechanism. IO_FD_BLOCK tell io_fd that the descriptor is blocking. IO_FD_NONBLOCK tell io_fd that the descriptor is non-blocking. Normally, io_fd calls fcntl to ask the operating system whether the descriptor is blocking or not. The frameworks needs to know because it alters how io_tryread and io_trywrite handle the socket. Never pass both IO_FD_BLOCK and IO_FD_NONBLOCK at the same time. Newly connected stream sockets are always writable if the connection is established, so it is usually safe to pass IO_FD_CANWRITE. The main exception case where IO_FD_CANWRITE should not be passed is on a non-blocking socket where a connect() is pending. Then you need to poll for writability to get notified when the connection is established.
io_fd_flags returns 1 on success, 0 on error.
io_fd(3), io_fd_canwrite(3) io_fd_flags(3)