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io_uring_prep_splice(3) — Linux manual page

io_uring_prep_splice(3)      liburing Manualio_uring_prep_splice(3)

NAME        top

       io_uring_prep_splice - prepare an splice request

SYNOPSIS        top

#include <fcntl.h>#include <liburing.h>void io_uring_prep_splice(struct io_uring_sqe *sqe,intfd_in,int64_toff_in,intfd_out,int64_toff_out,unsigned intnbytes,unsigned intsplice_flags);

DESCRIPTION        top

       Theio_uring_prep_splice(3) function prepares a splice request.       The submission queue entrysqe is setup to use as input the file       descriptorfd_in at offsetoff_in, splicing data to the file       descriptor atfd_out and at offsetoff_out.nbytes bytes of data       should be spliced between the two descriptors.splice_flags are       modifier flags for the operation. Seesplice(2) for the generic       splice flags.       If thefd_out descriptor,IOSQE_FIXED_FILEcan be set in the SQE       to indicate that. For the input file, the io_uring specificSPLICE_F_FD_IN_FIXEDcan be set insplice_flags andfd_in given as       a registered file descriptor offset.       Iffd_in refers to a pipe,off_in is ignored and must be set to       -1.       Iffd_in does not refer to a pipe andoff_in is -1, thennbytes       are read fromfd_in starting from the file offset, which is       incremented by the number of bytes read.       Iffd_in does not refer to a pipe andoff_in is not -1, then the       starting offset offd_in will beoff_in.       The same rules apply tofd_out andoff_out.       This function prepares an asyncsplice(2) request. See that man       page for details.

RETURN VALUE        top

       None

ERRORS        top

       The CQEres 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-1on failure and seterrno to the actual error value, io_uring never useserrno.       Instead it returns the negatederrno directly in the CQEres       field.

SEE ALSO        top

io_uring_get_sqe(3),io_uring_submit(3),io_uring_register(2),splice(2)

NOTES        top

       Note that even iffd_in orfd_out refers to a pipe, the splice       operation can still fail withEINVALif one of the fd doesn't       explicitly support splice operation, e.g. reading from terminal is       unsupported from kernel 5.7 to 5.11.

COLOPHON        top

       This page is part of theliburing (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 isnot part of the original manual page), send a mail to       man-pages@man7.orgliburing-2.2                  March 13, 2022io_uring_prep_splice(3)

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