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.