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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | SEE ALSO | NOTES | COLOPHON |
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io_uring_prep_splice(3) liburing Manual io_uring_prep_splice(3)
io_uring_prep_splice - prepare an splice request
#include <fcntl.h>
#include <liburing.h>
void io_uring_prep_splice(struct io_uring_sqe *sqe,
int fd_in,
int64_t off_in,
int fd_out,
int64_t off_out,
unsigned int nbytes,
unsigned int splice_flags);
The io_uring_prep_splice(3) function prepares a splice request.
The submission queue entry sqe is setup to use as input the file
descriptor fd_in at offset off_in, splicing data to the file
descriptor at fd_out and at offset off_out. nbytes bytes of data
should be spliced between the two descriptors. splice_flags are
modifier flags for the operation. See splice(2) for the generic
splice flags.
If the fd_out descriptor, IOSQE_FIXED_FILE can be set in the SQE
to indicate that. For the input file, the io_uring specific
SPLICE_F_FD_IN_FIXED can be set in splice_flags and fd_in given as
a registered file descriptor offset.
If fd_in refers to a pipe, off_in is ignored and must be set to
-1.
If fd_in does not refer to a pipe and off_in is -1, then nbytes
are read from fd_in starting from the file offset, which is
incremented by the number of bytes read.
If fd_in does not refer to a pipe and off_in is not -1, then the
starting offset of fd_in will be off_in.
The same rules apply to fd_out and off_out.
This function prepares an async splice(2) request. See that man
page for details.
None
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.
io_uring_get_sqe(3), io_uring_submit(3), io_uring_register(2),
splice(2)
Note that even if fd_in or fd_out refers to a pipe, the splice
operation can still fail with EINVAL if one of the fd doesn't
explicitly support splice operation, e.g. reading from terminal is
unsupported from kernel 5.7 to 5.11.
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 [email protected]. 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
[email protected]
liburing-2.2 March 13, 2022 io_uring_prep_splice(3)
Pages that refer to this page: io_uring_prep_splice(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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