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), sendmsg(2)

liburing-2.2                                     March 12, 2022                         io_uring_prep_sendmsg(3)