Provided by: manpages-dev_4.04-2_all bug


       aio_read - asynchronous read


       #include <aio.h>

       int aio_read(struct aiocb *aiocbp);

       Link with -lrt.


       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  description
       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.


       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).


       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

       ENOSYS aio_read() is not implemented.

              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.


       The aio_read() function is available since glibc 2.1.


       For   an   explanation   of   the  terms  used  in  this  section,  see

       │InterfaceAttributeValue   │
       │aio_read() │ Thread safety │ MT-Safe │


       POSIX.1-2001, POSIX.1-2008.


       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.


       See aio(7).


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


       This page is part of release 4.04 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

                                  2015-03-02                       AIO_READ(3)