man2/io_cancel.2

   1 .\" Copyright (C) 2003 Free Software Foundation, Inc.
   2 .\"
   3 .\" SPDX-License-Identifier: GPL-1.0-or-later
   4 .\"
   5 .TH io_cancel 2 (date) "Linux man-pages (unreleased)"
   6 .SH NAME
   7 io_cancel \- cancel an outstanding asynchronous I/O operation
   8 .SH LIBRARY
   9 Standard C library
  10 .RI ( libc ", " \-lc )
  11 .P
  12 Alternatively, Asynchronous I/O library
  13 .RI ( libaio ", " \-laio );
  14 see VERSIONS.
  15 .SH SYNOPSIS
  16 .nf
  17 .BR "#include <linux/aio_abi.h>" "    /* Definition of needed types */"
  18 .BR "#include <sys/syscall.h>" "      /* Definition of " SYS_* " constants */"
  19 .B #include <unistd.h>
  20 .P
  21 .BI "int syscall(SYS_io_cancel, aio_context_t " ctx_id ", struct iocb *" iocb ,
  22 .BI "            struct io_event *" result );
  23 .fi
  24 .SH DESCRIPTION
  25 .IR Note :
  26 this page describes the raw Linux system call interface.
  27 The wrapper function provided by
  28 .I libaio
  29 uses a different type for the
  30 .I ctx_id
  31 argument.
  32 See VERSIONS.
  33 .P
  34 The
  35 .BR io_cancel ()
  36 system call
  37 attempts to cancel an asynchronous I/O operation previously submitted with
  38 .BR io_submit (2).
  39 The
  40 .I iocb
  41 argument describes the operation to be canceled and the
  42 .I ctx_id
  43 argument is the AIO context to which the operation was submitted.
  44 If the operation is successfully canceled, the event will be copied into
  45 the memory pointed to by
  46 .I result
  47 without being placed into the
  48 completion queue.
  49 .SH RETURN VALUE
  50 On success,
  51 .BR io_cancel ()
  52 returns 0.
  53 For the failure return, see VERSIONS.
  54 .SH ERRORS
  55 .TP
  56 .B EAGAIN
  57 The \fIiocb\fP specified was not canceled.
  58 .TP
  59 .B EFAULT
  60 One of the data structures points to invalid data.
  61 .TP
  62 .B EINVAL
  63 The AIO context specified by \fIctx_id\fP is invalid.
  64 .TP
  65 .B ENOSYS
  66 .BR io_cancel ()
  67 is not implemented on this architecture.
  68 .SH VERSIONS
  69 You probably want to use the
  70 .BR io_cancel ()
  71 wrapper function provided by
  72 .\" http://git.fedorahosted.org/git/?p=libaio.git
  73 .IR libaio .
  74 .P
  75 Note that the
  76 .I libaio
  77 wrapper function uses a different type
  78 .RI ( io_context_t )
  79 .\" But glibc is confused, since <libaio.h> uses 'io_context_t' to declare
  80 .\" the system call.
  81 for the
  82 .I ctx_id
  83 argument.
  84 Note also that the
  85 .I libaio
  86 wrapper does not follow the usual C library conventions for indicating errors:
  87 on error it returns a negated error number
  88 (the negative of one of the values listed in ERRORS).
  89 If the system call is invoked via
  90 .BR syscall (2),
  91 then the return value follows the usual conventions for
  92 indicating an error: \-1, with
  93 .I errno
  94 set to a (positive) value that indicates the error.
  95 .SH STANDARDS
  96 Linux.
  97 .SH HISTORY
  98 Linux 2.5.
  99 .SH SEE ALSO
 100 .BR io_destroy (2),
 101 .BR io_getevents (2),
 102 .BR io_setup (2),
 103 .BR io_submit (2),
 104 .BR aio (7)
 105 .\" .SH AUTHOR
 106 .\" Kent Yoder.