IO_GETEVENTS(2)             Linux Programmer's Manual            IO_GETEVENTS(2)

       io_getevents - read asynchronous I/O events from the completion queue

       #include <linux/aio_abi.h>         /* Defines needed types */
       #include <linux/time.h>            /* Defines 'struct timespec' */

       int io_getevents(aio_context_t ctx_id, long min_nr, long nr,
                        struct io_event *events, struct timespec *timeout);

       Note: There is no glibc wrapper for this system call; see NOTES.

       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 NOTES.

       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 structure of the following form:

           struct timespec {
               time_t tv_sec;      /* seconds */
               long   tv_nsec;     /* nanoseconds [0 .. 999999999] */

       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 NOTES.

       EFAULT Either events or timeout is an invalid pointer.

       EINTR  Interrupted by a signal handler; see signal(7).

       EINVAL ctx_id is invalid.  min_nr is out of range or nr is out of range.

       ENOSYS io_getevents() is not implemented on this architecture.

       The asynchronous I/O system calls first appeared in Linux 2.5.

       io_getevents() is Linux-specific and should not be used in programs that
       are intended to be portable.

       Glibc does not provide a wrapper function for this system call.  You
       could invoke it using syscall(2).  But instead, 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.

       An invalid ctx_id may cause a segmentation fault instead of generating
       the error EINVAL.

       io_cancel(2), io_destroy(2), io_setup(2), io_submit(2), aio(7), time(7)

       This page is part of release 5.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at

Linux                              2020-12-21                    IO_GETEVENTS(2)