#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.
This function prepares an async splice(2) request. See that man page for details.
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)