plucky (3) io_uring_prep_sendmsg_zc.3.gz

NAME

       io_uring_prep_sendmsg - prepare a sendmsg request

SYNOPSIS

       #include <sys/types.h>
       #include <sys/socket.h>
       #include <liburing.h>

       void io_uring_prep_sendmsg(struct io_uring_sqe *sqe,
                                  int fd,
                                  const struct msghdr *msg,
                                  unsigned flags);

       void io_uring_prep_sendmsg_zc(struct io_uring_sqe *sqe,
                                     int fd,
                                     const struct msghdr *msg,
                                     unsigned flags);

DESCRIPTION

       The io_uring_prep_sendmsg(3) function prepares a sendmsg request. The submission queue entry sqe is setup
       to use the file descriptor fd to start sending the data indicated by  msg  with  the  sendmsg(2)  defined
       flags in the flags argument.

       The  io_uring_prep_sendmsg_zc(3)  accepts  the same parameters as io_uring_prep_sendmsg(3) but prepares a
       zerocopy sendmsg request.

       Note that using IOSQE_IO_LINK with this request type requires the setting of  MSG_WAITALL  in  the  flags
       argument, as a short send isn't considered an error condition without that being set.

       This function prepares an async sendmsg(2) request. See that man page for details.

RETURN VALUE

       None

ERRORS

       The  CQE  res  field  will  contain  the result of the operation. See the related man page for details on
       possible values. Note that where synchronous system calls will return -1 on failure and set errno to  the
       actual  error value, io_uring never uses errno.  Instead it returns the negated errno directly in the CQE
       res field.

NOTES

       As with any request that passes in data in a struct, that data must remain valid until  the  request  has
       been  successfully  submitted.  It  need  not  remain  valid  until  completion.  Once a request has been
       submitted, the in-kernel state is stable. Very early kernels (5.4  and  earlier)  required  state  to  be
       stable  until  the  completion  occurred.  Applications  can  test  for  this  behavior by inspecting the
       IORING_FEAT_SUBMIT_STABLE flag passed back from io_uring_queue_init_params(3).

SEE ALSO

       io_uring_get_sqe(3), io_uring_submit(3), io_uring_buf_ring_init(3), io_uring_buf_ring_add(3), sendmsg(2)