centos man page for aio_read

AIO_READ(3)						     Linux Programmer's Manual						       AIO_READ(3)

NAME
       aio_read - asynchronous read

SYNOPSIS
       #include <aio.h>

       int aio_read(struct aiocb *aiocbp);

       Link with -lrt.

DESCRIPTION
       The  aio_read()	function queues the I/O request described by the buffer pointed to by aiocbp.  This function is the asynchronous analog of
       read(2).  The arguments of the call

	   read(fd, buf, count)

       correspond (in order) to the fields aio_fildes, aio_buf, and aio_nbytes of the structure pointed to by aiocbp.  (See aio(7) for a  descrip-
       tion of the aiocb structure.)

       The data is read starting at the absolute file offset aiocbp->aio_offset, regardless of the current file offset.  After the call, the value
       of the current file offset is unspecified.

       The "asynchronous" means that this call returns as soon as the request has been enqueued; the read may or may not have completed  when  the
       call  returns.	One  tests  for  completion  using  aio_error(3).   The  return  status  of  a	completed I/O operation can be obtained by
       aio_return(3).  Asynchronous notification of I/O completion can be obtained by setting aiocbp->aio_sigevent appropriately; see  sigevent(7)
       for details.

       If _POSIX_PRIORITIZED_IO is defined, and this file supports it, then the asynchronous operation is submitted at a priority equal to that of
       the calling process minus aiocbp->aio_reqprio.

       The field aiocbp->aio_lio_opcode is ignored.

       No data is read from a regular file beyond its maximum offset.

RETURN VALUE
       On success, 0 is returned.  On error the request is not enqueued, -1 is returned, and errno is set appropriately.  If an error is  detected
       only  later,  it  will  be reported via aio_return(3) (returns status -1) and aio_error(3) (error status--whatever one would have gotten in
       errno, such as EBADF).

ERRORS
       EAGAIN Out of resources.

       EBADF  aio_fildes is not a valid file descriptor open for reading.

       EINVAL One or more of aio_offset, aio_reqprio, or aio_nbytes are invalid.

       ENOSYS aio_read() is not implemented.

       EOVERFLOW
	      The file is a regular file, we start reading before end-of-file and want at least one byte, but the starting position  is  past  the
	      maximum offset for this file.

VERSIONS
       The aio_read() function is available since glibc 2.1.

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008.

NOTES
       It is a good idea to zero out the control block before use.  The control block must not be changed while the read operation is in progress.
       The buffer area being read into must not be accessed during the operation or undefined results may occur.  The memory areas  involved  must
       remain valid.

       Simultaneous I/O operations specifying the same aiocb structure produce undefined results.

EXAMPLE
       See aio(7).

SEE ALSO
       aio_cancel(3), aio_error(3), aio_fsync(3), aio_return(3), aio_suspend(3), aio_write(3), lio_listio(3), aio(7)

COLOPHON
       This  page is part of release 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

								    2012-05-08							       AIO_READ(3)