Unix/Linux Go Back    


Linux 2.6 - man page for lio_listio (linux section 3posix)

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:   man
Select Man Page Set:       apropos Keyword Search (sections above)


LIO_LISTIO(P)			    POSIX Programmer's Manual			    LIO_LISTIO(P)

NAME
       lio_listio - list directed I/O (REALTIME)

SYNOPSIS
       #include <aio.h>

       int lio_listio(int mode, struct aiocb *restrict const list[restrict],
	      int nent, struct sigevent *restrict sig);

DESCRIPTION
       The  lio_listio()  function  shall  initiate a list of I/O requests with a single function
       call.

       The mode argument takes one of the values LIO_WAIT or LIO_NOWAIT declared in  <aio.h>  and
       determines whether the function returns when the I/O operations have been completed, or as
       soon as the operations have been queued. If the mode argument is  LIO_WAIT,  the  function
       shall wait until all I/O is complete and the sig argument shall be ignored.

       If  the	mode argument is LIO_NOWAIT, the function shall return immediately, and asynchro-
       nous notification shall occur, according to the sig argument, when all the I/O  operations
       complete.   If  sig  is NULL, then no asynchronous notification shall occur. If sig is not
       NULL, asynchronous notification occurs as specified in Signal Generation and Delivery when
       all the requests in list have completed.

       The I/O requests enumerated by list are submitted in an unspecified order.

       The  list  argument  is an array of pointers to aiocb structures.  The array contains nent
       elements. The array may contain NULL elements, which shall be ignored.

       The aio_lio_opcode field of each aiocb structure specifies the operation to be  performed.
       The  supported  operations are LIO_READ, LIO_WRITE, and LIO_NOP; these symbols are defined
       in  <aio.h>.  The  LIO_NOP  operation  causes  the  list  entry	to  be	ignored.  If  the
       aio_lio_opcode element is equal to LIO_READ, then an I/O operation is submitted as if by a
       call to aio_read() with the aiocbp equal to the address of the  aiocb  structure.  If  the
       aio_lio_opcode  element is equal to LIO_WRITE, then an I/O operation is submitted as if by
       a call to aio_write() with the aiocbp equal to the address of the aiocb structure.

       The aio_fildes member specifies the file descriptor on which the operation is to  be  per-
       formed.

       The aio_buf member specifies the address of the buffer to or from which the data is trans-
       ferred.

       The aio_nbytes member specifies the number of bytes of data to be transferred.

       The members of the aiocb structure further describe the I/O operation to be performed,  in
       a  manner  identical  to  that  of  the	corresponding  aiocb  structure  when used by the
       aio_read() and aio_write() functions.

       The nent argument specifies how many elements are members of the list; that is, the length
       of the array.

       The  behavior of this function is altered according to the definitions of synchronized I/O
       data integrity completion and synchronized I/O file integrity completion  if  synchronized
       I/O is enabled on the file associated with aio_fildes.

       For regular files, no data transfer shall occur past the offset maximum established in the
       open file description associated with aiocbp->aio_fildes.

RETURN VALUE
       If the mode argument has the value LIO_NOWAIT, the lio_listio() function shall return  the
       value  zero  if	the I/O operations are successfully queued; otherwise, the function shall
       return the value -1 and set errno to indicate the error.

       If the mode argument has the value LIO_WAIT, the lio_listio() function  shall  return  the
       value  zero when all the indicated I/O has completed successfully. Otherwise, lio_listio()
       shall return a value of -1 and set errno to indicate the error.

       In either case, the return value only indicates the success or failure of the lio_listio()
       call  itself,  not the status of the individual I/O requests. In some cases one or more of
       the I/O requests contained in the list may fail. Failure of an individual request does not
       prevent	completion of any other individual request.  To determine the outcome of each I/O
       request, the application shall examine the error status associated with each aiocb control
       block.  The error statuses so returned are identical to those returned as the result of an
       aio_read() or aio_write() function.

ERRORS
       The lio_listio() function shall fail if:

       EAGAIN The resources necessary to queue all the I/O  requests  were  not  available.   The
	      application  may	check the error status for each aiocb to determine the individual
	      request(s) that failed.

       EAGAIN The number of entries indicated by nent would cause the system-wide limit {AIO_MAX}
	      to be exceeded.

       EINVAL The  mode  argument  is  not  a proper value, or the value of nent was greater than
	      {AIO_LISTIO_MAX}.

       EINTR  A signal was delivered while waiting for all I/O requests  to  complete  during  an
	      LIO_WAIT operation. Note that, since each I/O operation invoked by lio_listio() may
	      possibly provoke a signal when it completes, this error return may be caused by the
	      completion  of one (or more) of the very I/O operations being awaited.  Outstanding
	      I/O requests are not canceled, and the application shall examine each list  element
	      to determine whether the request was initiated, canceled, or completed.

       EIO    One  or more of the individual I/O operations failed. The application may check the
	      error status for each aiocb structure to determine the individual  request(s)  that
	      failed.

       In addition to the errors returned by the lio_listio() function, if the lio_listio() func-
       tion succeeds or fails with errors of [EAGAIN], [EINTR], or [EIO], then some  of  the  I/O
       specified  by the list may have been initiated. If the lio_listio() function fails with an
       error code other than [EAGAIN], [EINTR], or [EIO], no operations from the list shall  have
       been initiated. The I/O operation indicated by each list element can encounter errors spe-
       cific to the individual read or write function being performed. In this event,  the  error
       status  for  each aiocb control block contains the associated error code.  The error codes
       that can be set are the same as would be set by a read() or  write()  function,	with  the
       following additional error codes possible:

       EAGAIN The requested I/O operation was not queued due to resource limitations.

       ECANCELED
	      The requested I/O was canceled before the I/O completed due to an explicit aio_can-
	      cel() request.

       EFBIG  The  aiocbp->aio_lio_opcode  is  LIO_WRITE,   the   file	 is   a   regular   file,
	      aiocbp->aio_nbytes is greater than 0, and the aiocbp->aio_offset is greater than or
	      equal  to  the  offset  maximum  in  the	open  file  description  associated  with
	      aiocbp->aio_fildes.

       EINPROGRESS
	      The requested I/O is in progress.

       EOVERFLOW
	      The   aiocbp->aio_lio_opcode   is   LIO_READ,   the   file   is	a  regular  file,
	      aiocbp->aio_nbytes is greater than 0, and the aiocbp->aio_offset is before the end-
	      of-file  and  is	greater  than  or  equal  to  the offset maximum in the open file
	      description associated with aiocbp->aio_fildes.

       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       None.

RATIONALE
       Although it may appear that there are inconsistencies in the specified  circumstances  for
       error  codes, the [EIO] error condition applies when any circumstance relating to an indi-
       vidual operation makes that operation fail. This  might	be  due  to  a	badly  formulated
       request	(for  example, the aio_lio_opcode field is invalid, and aio_error() returns [EIN-
       VAL]) or might arise from application behavior (for example, the file descriptor is closed
       before the operation is initiated, and aio_error() returns [EBADF]).

       The limitation on the set of error codes returned when operations from the list shall have
       been initiated enables applications to know when operations have been started and  whether
       aio_error() is valid for a specific operation.

FUTURE DIRECTIONS
       None.

SEE ALSO
       aio_read()  , aio_write() , aio_error() , aio_return() , aio_cancel() , close() , exec() ,
       exit() , fork() , lseek() , read() , the Base Definitions volume of  IEEE Std 1003.1-2001,
       <aio.h>

COPYRIGHT
       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable	Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  In  the
       event  of  any  discrepancy  between this version and the original IEEE and The Open Group
       Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003				    LIO_LISTIO(P)
Unix & Linux Commands & Man Pages : ©2000 - 2018 Unix and Linux Forums


All times are GMT -4. The time now is 09:45 PM.