1AIO_CANCEL(3P)             POSIX Programmer's Manual            AIO_CANCEL(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       aio_cancel - cancel an asynchronous I/O request (REALTIME)
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SYNOPSIS

15       #include <aio.h>
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17       int aio_cancel(int fildes, struct aiocb *aiocbp);
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DESCRIPTION

21       The aio_cancel() function shall attempt to cancel one or more asynchro‐
22       nous I/O requests currently outstanding against file descriptor fildes.
23       The aiocbp argument points to the asynchronous I/O control block for  a
24       particular  request  to  be  canceled. If aiocbp is NULL, then all out‐
25       standing cancelable asynchronous I/O requests against fildes  shall  be
26       canceled.
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28       Normal asynchronous notification shall occur for asynchronous I/O oper‐
29       ations that are successfully canceled. If there are requests that  can‐
30       not  be canceled, then the normal asynchronous completion process shall
31       take place for those requests when they are completed.
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33       For requested operations that are successfully canceled, the associated
34       error status shall be set to [ECANCELED] and the return status shall be
35       -1. For requested operations that are not  successfully  canceled,  the
36       aiocbp shall not be modified by aio_cancel().
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38       If  aiocbp  is not NULL, then if fildes does not have the same value as
39       the file descriptor with which the asynchronous  operation  was  initi‐
40       ated, unspecified results occur.
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42       Which operations are cancelable is implementation-defined.
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RETURN VALUE

45       The  aio_cancel()  function  shall return the value AIO_CANCELED to the
46       calling process if the requested operation(s) were canceled. The  value
47       AIO_NOTCANCELED  shall  be  returned  if  at least one of the requested
48       operation(s) cannot be canceled because it  is  in  progress.  In  this
49       case, the state of the other operations, if any, referenced in the call
50       to aio_cancel() is not indicated by the return value  of  aio_cancel().
51       The application may determine the state of affairs for these operations
52       by using aio_error(). The value AIO_ALLDONE is returned if all  of  the
53       operations have already completed. Otherwise, the function shall return
54       -1 and set errno to indicate the error.
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ERRORS

57       The aio_cancel() function shall fail if:
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59       EBADF  The fildes argument is not a valid file descriptor.
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62       The following sections are informative.
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EXAMPLES

65       None.
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APPLICATION USAGE

68       The aio_cancel() function is part of the Asynchronous Input and  Output
69       option and need not be available on all implementations.
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RATIONALE

72       None.
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FUTURE DIRECTIONS

75       None.
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SEE ALSO

78       aio_read(),    aio_write(),    the    Base    Definitions   volume   of
79       IEEE Std 1003.1-2001, <aio.h>
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82       Portions of this text are reprinted and reproduced in  electronic  form
83       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
84       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
85       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
86       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
87       event of any discrepancy between this version and the original IEEE and
88       The Open Group Standard, the original IEEE and The Open Group  Standard
89       is  the  referee document. The original Standard can be obtained online
90       at http://www.opengroup.org/unix/online.html .
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94IEEE/The Open Group                  2003                       AIO_CANCEL(3P)
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