io_getevents - read asynchronous I/O events from the completion queue
Standard C library (libc, -lc)
Alternatively, Asynchronous I/O library (libaio,
-laio); see VERSIONS.
#include <linux/aio_abi.h> /* Definition of *io_* types */
#include <sys/syscall.h> /* Definition of SYS_* constants */
#include <unistd.h>
int syscall(SYS_io_getevents, aio_context_t ctx_id,
long min_nr, long nr, struct io_event *events,
struct timespec *timeout);Note: glibc provides no wrapper for
io_getevents(), necessitating the use of
syscall(2).
Note: this page describes the raw Linux system call
interface. The wrapper function provided by libaio uses a
different type for the ctx_id argument. See VERSIONS.
The io_getevents() system call attempts to read at
least min_nr events and up to nr events from the
completion queue of the AIO context specified by ctx_id.
The timeout argument specifies the amount of time to wait
for events, and is specified as a relative timeout in a
timespec(3) structure.
The specified time will be rounded up to the system clock granularity and is guaranteed not to expire early.
Specifying timeout as NULL means block indefinitely until at
least min_nr events have been obtained.
On success, io_getevents() returns the number of
events read. This may be 0, or a value less than min_nr, if the
timeout expired. It may also be a nonzero value less than
min_nr, if the call was interrupted by a signal handler.
For the failure return, see VERSIONS.
Either events or timeout is an invalid pointer.
Interrupted by a signal handler; see signal(7).
ctx_id is invalid. min_nr is out of range or
nr is out of range.
io_getevents() is not implemented on this architecture.
You probably want to use the io_getevents() wrapper
function provided by libaio.
Note that the libaio wrapper function uses a different type
(io_context_t) for the ctx_id argument. Note also that
the libaio wrapper does not follow the usual C library
conventions for indicating errors: on error it returns a negated error
number (the negative of one of the values listed in ERRORS). If the
system call is invoked via syscall(2), then the return
value follows the usual conventions for indicating an error: -1, with
errno set to a (positive) value that indicates the error.
Linux.
Linux 2.5.
An invalid ctx_id may cause a segmentation fault instead of
generating the error EINVAL.