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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | SEE ALSO | COLOPHON |
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io_uring_pr..._fd_install(3) liburing Manual io_uring_pr..._fd_install(3)
io_uring_prep_fixed_fd_install - prepare fixed file fd
installation request
#include <liburing.h>
void io_uring_prep_fixed_fd_install(struct io_uring_sqe *sqe,
int fd,
unsigned int flags);
The io_uring_prep_fixed_fd_install(3) helper prepares a fixed file
descriptor installation. The submission queue entry sqe is setup
to install the direct/fixed file descriptor fd with the specified
flags file installation flags.
One use case of direct/fixed file descriptors is to turn a regular
file descriptor into a direct one, reducing the overhead of any
request that needs to access this file. This helper provides a way
to go the other way, turning a direct descriptor into a regular
file descriptor that can then subsequently be used by regular
system calls that take a normal file descriptor. This can be
handy if no regular file descriptor exists for this direct
descriptor. Either because it was instantiated directly as a fixed
descriptor, or because the regular file was closed with close(2)
after being turned into a direct descriptor.
Upon successful return of this request, both a normal and fixed
file descriptor exists for the same file. Either one of them may
be used to access the file. Either one of them may be closed
without affecting the other one.
flags may be either zero, or set to IORING_FIXED_FD_NO_CLOEXEC to
indicate that the new regular file descriptor should not be closed
during exec. By default, O_CLOEXEC will be set on the new
descriptor otherwise. Setting this field to anything but those two
values will result in the request being failed with -EINVAL in the
CQE res field.
None
The CQE res field will contain the result of the operation, which
in this case will be the value of the new regular file descriptor.
In case of failure, a negative value is returned.
io_uring_get_sqe(3), io_uring_submit(3),
io_uring_register_files(3), io_uring_unregister_files(3),
io_uring_prep_close_direct(3), io_uring_prep_openat_direct(3)
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 2025-08-11. (At that time,
the date of the most recent commit that was found in the
repository was 2025-08-02.) 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-2.6 December 8, 2023io_uring_pr..._fd_install(3)
Pages that refer to this page: io_uring_prep_fixed_fd_install(3)
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HTML rendering created 2025-09-06 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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