NAME

       io_uring_prep_write - prepare I/O write request

SYNOPSIS

       #include <liburing.h>

       void io_uring_prep_write(struct io_uring_sqe *sqe,
                                int fd,
                                const void *buf,
                                unsigned nbytes,
                                __u64 offset);

DESCRIPTION

       The  io_uring_prep_write(3)  prepares an IO write request. The submission queue entry sqe is setup to use
       the file descriptor fd to start writing nbytes from the buffer buf at the specified offset.

       On files that support seeking, if the offset is set to -1, the write  operation  commences  at  the  file
       offset, and the file offset is incremented by the number of bytes written. See write(2) for more details.
       Note  that  for  an  async  API, reading and updating the current file offset may result in unpredictable
       behavior, unless access to the file is serialized. It is not encouraged  to  use  this  feature  if  it's
       possible to provide the desired IO offset from the application or library.

       On files that are not capable of seeking, the offset must be 0 or -1.

       After the write has been prepared, it can be submitted with one of the submit functions.

RETURN VALUE

       None

ERRORS

       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.

SEE ALSO

       io_uring_get_sqe(3), io_uring_submit(3)

liburing-2.1                                    November 15, 2021                         io_uring_prep_write(3)