plucky (3) io_uring_prep_read_fixed.3.gz

NAME

       io_uring_prep_read_fixed - prepare I/O read request with registered buffer

SYNOPSIS

       #include <liburing.h>

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

DESCRIPTION

       The  io_uring_prep_read_fixed(3)  prepares an IO read request with a previously registered IO buffer. The
       submission queue entry sqe is setup to use the file descriptor fd to start reading nbytes into the buffer
       buf at the specified offset, and with the buffer matching the registered index of buf_index.

       This  works  just  like  io_uring_prep_read(3)  except  it  requires  the  use  of buffers that have been
       registered with io_uring_register_buffers(3).  The buf and nbytes arguments must  fall  within  a  region
       specified by buf_index in the previously registered buffer. The buffer need not be aligned with the start
       of the registered buffer.

       After the read 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_prep_read(3), io_uring_register_buffers(3)