LIO_LISTIO(2)             FreeBSD System Calls Manual            LIO_LISTIO(2)

NAME
     lio_listio - list directed I/O (REALTIME)

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <aio.h>

     int
     lio_listio(int mode, struct aiocb * const list[], int nent,
         struct sigevent *sig);

DESCRIPTION
     The lio_listio() function initiates a list of I/O requests with a single
     function call.  The list argument is an array of pointers to aiocb
     structures describing each operation to perform, with nent elements.
     NULL elements are ignored.

     The aio_lio_opcode field of each aiocb specifies the operation to be
     performed.  The following operations are supported:

     LIO_READ       Read data as if by a call to aio_read(2).

     LIO_NOP        No operation.

     LIO_WRITE      Write data as if by a call to aio_write(2).

     If the mode argument is LIO_WAIT, lio_listio() does not return until all
     the requested operations have been completed.  If mode is LIO_NOWAIT, sig
     can be used to request asynchronous notification when all operations have
     completed.  If sig is NULL, no notification is sent.

     For SIGEV_KEVENT notifications, the posted kevent will contain:

     Member        Value
     ident         list
     filter        EVFILT_LIO
     udata         value stored in sig->sigev_value

     For SIGEV_SIGNO and SIGEV_THREAD_ID notifications, the information for
     the queued signal will include SI_ASYNCIO in the si_code field and the
     value stored in sig->sigev_value in the si_value field.

     For SIGEV_THREAD notifications, the value stored in sig->sigev_value is
     passed to the sig->sigev_notify_function as described in sigevent(3).

     The order in which the requests are carried out is not specified; in
     particular, there is no guarantee that they will be executed in the order
     0, 1, ..., nent-1.

RETURN VALUES
     If mode is LIO_WAIT, the lio_listio() function returns 0 if the
     operations completed successfully, otherwise -1.

     If mode is LIO_NOWAIT, the lio_listio() function returns 0 if the
     operations are successfully queued, otherwise -1.

ERRORS
     The lio_listio() function will fail if:

     [EAGAIN]           There are not enough resources to enqueue the
                        requests.

     [EAGAIN]           The request would cause the system-wide limit
                        {AIO_MAX} to be exceeded.

     [EINVAL]           The mode argument is neither LIO_WAIT nor LIO_NOWAIT,
                        or nent is greater than {AIO_LISTIO_MAX}.

     [EINVAL]           The asynchronous notification method in
                        sig->sigev_notify is invalid or not supported.

     [EINTR]            A signal interrupted the system call before it could
                        be completed.

     [EIO]              One or more requests failed.

     In addition, the lio_listio() function may fail for any of the reasons
     listed for aio_read(2) and aio_write(2).

     If lio_listio() succeeds, or fails with an error code of EAGAIN, EINTR,
     or EIO, some of the requests may have been initiated.  The caller should
     check the error status of each aiocb structure individually by calling
     aio_error(2).

SEE ALSO
     aio_error(2), aio_read(2), aio_write(2), read(2), write(2), sigevent(3),
     siginfo(3), aio(4)

STANDARDS
     The lio_listio() function is expected to conform to IEEE Std 1003.1-2001
     ("POSIX.1").

HISTORY
     The lio_listio() system call first appeared in FreeBSD 3.0.

FreeBSD 13.1-RELEASE-p6        December 7, 2019        FreeBSD 13.1-RELEASE-p6