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NAME | SYNOPSIS | DESCRIPTION | Available commands | NOTES | RETURN VALUE | ERRORS | SEE ALSO | COLOPHON |
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io_uring_prep_cmd_sock(3) liburing Manual io_uring_prep_cmd_sock(3)
io_uring_prep_cmd_sock - prepare a command request for a socket
#include <liburing.h>
void io_uring_prep_cmd_sock(struct io_uring_sqe *sqe,
int cmd_op,
int fd,
int level,
int optname,
void *optval,
int optlen);
The io_uring_prep_cmd_sock(3) function prepares an cmd request for
a socket. The submission queue entry sqe is setup to use the
socket file descriptor pointed to by fd to start an command
operation defined by cmd_op.
This is a generic function, and each command has their own
individual level, optname, optval values. The optlen defines the
size pointed by optval.
SOCKET_URING_OP_SIOCINQ
Returns the amount of queued unread data in the receive
buffer. The socket must not be in LISTEN state, otherwise
an error -EINVAL is returned in the CQE res field. The
following arguments are not used for this command level,
optname, optval and optlen.
Negative return value means an error.
For more information about this command, please check
unix(7).
Available since 6.7.
SOCKET_URING_OP_SIOCOUTQ
Returns the amount of unsent data in the socket send queue.
The socket must not be in LISTEN state, otherwise an error
-EINVAL is returned in the CQE res. field. The following
arguments are not used for this command level, optname,
optval and optlen.
Negative return value means an error.
For more information about this command, please check
unix(7).
SOCKET_URING_OP_GETSOCKOPT
Command to get options for the socket referred to by the
socket file descriptor fd. The arguments are similar to
the getsockopt(2) system call.
The SOCKET_URING_OP_GETSOCKOPT command is limited to
SOL_SOCKET level.
Differently from the getsockopt(2) system call, the updated
optlen value is returned in the CQE res field, on success.
On failure, the CQE res contains a negative error number.
SOCKET_URING_OP_SETSOCKOPT
Command to set options for the socket referred to by the
socket file descriptor fd. The arguments are similar to
the setsockopt(2) system call.
Available since 6.7.
SOCKET_URING_OP_TX_TIMESTAMP
Retrieve transmit timestamps from the socket's error queue.
This provides an alternative to the traditional recvmsg(2)
error queue interface for obtaining TX timestamps.
The command operates in a polled multishot mode: io_uring
will poll the socket and keep posting timestamps as CQEs
until the request is cancelled or fails. The ring must be
created with IORING_SETUP_CQE32 or IORING_SETUP_CQE_MIXED
to provide space for the timestamp data.
The socket must first be configured for timestamping via
setsockopt(2) with SO_TIMESTAMPING at the SOL_SOCKET level,
specifying the desired timestamp types (e.g.
SOF_TIMESTAMPING_TX_SOFTWARE, SOF_TIMESTAMPING_TX_SCHED,
SOF_TIMESTAMPING_TX_ACK) along with
SOF_TIMESTAMPING_SOFTWARE and SOF_TIMESTAMPING_OPT_TSONLY.
The following arguments are not used for this command:
level, optname, optval and optlen.
Each timestamp is delivered as a CQE with IORING_CQE_F_MORE
set in cqe->flags to indicate more timestamps may follow.
The cqe->res field contains the timestamp key (tskey),
which corresponds to the byte offset (for TCP) or packet
count (for UDP). The timestamp type (SCM_TSTAMP_SCHED,
SCM_TSTAMP_SND or SCM_TSTAMP_ACK) is stored in the upper
bits of cqe->flags at offset IORING_TIMESTAMP_TYPE_SHIFT.
If the timestamp is a hardware timestamp, the
IORING_CQE_F_TSTAMP_HW flag is set.
The actual timestamp value is stored in the extended CQE
area as a struct io_timespec (with 64-bit tv_sec and
tv_nsec fields), accessible at (cqe + 1).
The final CQE will not have IORING_CQE_F_MORE set, and its
cqe->res will contain 0 on success or a negative error code
on failure.
Available since 6.17.
SOCKET_URING_OP_GETSOCKNAME
Returns the current address to which the socket is bound.
The result is stored in the buffer pointed to by optval,
which should be a pointer to a struct sockaddr (or
appropriate variant). The optlen argument specifies the
size of the buffer. On success, the CQE res field contains
the actual size of the socket address. If the buffer is too
small, the result is truncated.
This is the io_uring equivalent of getsockname(2).
Available since 6.19.
The memory block pointed by optval needs to be valid/live until
the CQE returns.
Dependent on the command.
The CQE res field will contain the result of the operation.
io_uring_get_sqe(3), io_uring_submit(3), io_uring_register(2),
unix(7)
This page is part of the liburing (A library for io_uring)
project. Information about the project can be found at
⟨https://github.com/axboe/liburing⟩. If you have a bug report for
this manual page, send it to io-uring@vger.kernel.org. This page
was obtained from the project's upstream Git repository
⟨https://github.com/axboe/liburing⟩ on 2026-05-24. (At that time,
the date of the most recent commit that was found in the
repository was 2026-05-18.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
liburing-2.5 July 27, 2023 io_uring_prep_cmd_sock(3)
Pages that refer to this page: io_uring_prep_cmd_sock(3)
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HTML rendering created 2026-05-24 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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