1io_uring_prep_sendmsg(3)        liburing Manual       io_uring_prep_sendmsg(3)
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NAME

6       io_uring_prep_sendmsg - prepare a sendmsg request
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SYNOPSIS

9       #include <sys/types.h>
10       #include <sys/socket.h>
11       #include <liburing.h>
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13       void io_uring_prep_sendmsg(struct io_uring_sqe *sqe,
14                                  int fd,
15                                  const struct msghdr *msg,
16                                  unsigned flags);
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18       void io_uring_prep_sendmsg_zc(struct io_uring_sqe *sqe,
19                                     int fd,
20                                     const struct msghdr *msg,
21                                     unsigned flags);
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DESCRIPTION

24       The  io_uring_prep_sendmsg(3)  function prepares a sendmsg request. The
25       submission queue entry sqe is setup to use the file  descriptor  fd  to
26       start  sending  the  data  indicated by msg with the sendmsg(2) defined
27       flags in the flags argument.
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29       The io_uring_prep_sendmsg_zc(3) accepts the same parameters  as  io_ur‐
30       ing_prep_sendmsg(3) but prepares a zerocopy sendmsg request.
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32       Note  that using IOSQE_IO_LINK with this request type requires the set‐
33       ting of MSG_WAITALL in the flags argument, as a short send  isn't  con‐
34       sidered an error condition without that being set.
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36       This  function  prepares an async sendmsg(2) request. See that man page
37       for details.
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RETURN VALUE

41       None
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ERRORS

44       The CQE res field will contain the result of the operation. See the re‐
45       lated man page for details on possible values. Note that where synchro‐
46       nous system calls will return -1 on failure and set errno to the actual
47       error value, io_uring never uses errno.  Instead it returns the negated
48       errno directly in the CQE res field.
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NOTES

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

60       io_uring_get_sqe(3), io_uring_submit(3), sendmsg(2)
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64liburing-2.2                    March 12, 2022        io_uring_prep_sendmsg(3)
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