NAME

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

SYNOPSIS

       #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.

DESCRIPTION

       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.

RETURN VALUE

       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.

ERRORS

       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.

VERSIONS

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

CONFORMING TO

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

NOTES

       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.

BUGS

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

SEE ALSO

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

COLOPHON

       This  page  is  part of release 4.15 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 https://www.kernel.org/doc/man-pages/.