io_uring_prep_sendmsg_zc(3) — Linux manual page


io_uring_prep_sendmsg(3)     liburing Manual    io_uring_prep_sendmsg(3)

NAME         top

       io_uring_prep_sendmsg - prepare a sendmsg request

SYNOPSIS         top

       #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         top

       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         top


ERRORS         top

       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

NOTES         top

       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

SEE ALSO         top

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

COLOPHON         top

       This page is part of the liburing (A library for io_uring)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for
       this manual page, send it to  This page
       was obtained from the project's upstream Git repository
       ⟨⟩ on 2024-06-14.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2024-06-03.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
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       (which is not part of the original manual page), send a mail to

liburing-2.2                 March 12, 2022     io_uring_prep_sendmsg(3)

Pages that refer to this page: io_uring_prep_sendmsg(3)io_uring_prep_sendmsg_zc(3)