lio_listio —
list directed I/O (REALTIME)
Standard C Library (libc, -lc)
#include <aio.h>
int
lio_listio(
int
mode,
struct aiocb * const list[],
int nent,
struct
sigevent *sig);
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.
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.
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).
aio_error(2),
aio_read(2),
aio_write(2),
read(2),
write(2),
sigevent(3),
siginfo(3),
aio(4)
The
lio_listio() function is expected to conform to
IEEE Std 1003.1-2001
(“POSIX.1”).
The
lio_listio() system call first appeared in
FreeBSD 3.0.