mirror of https://github.com/mkerrisk/man-pages
104 lines
2.7 KiB
Groff
104 lines
2.7 KiB
Groff
.\" Copyright (C) 2003 Free Software Foundation, Inc.
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.\"
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.\" %%%LICENSE_START(GPL_NOVERSION_ONELINE)
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.\" This file is distributed according to the GNU General Public License.
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.\" %%%LICENSE_END
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.\"
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.TH IO_CANCEL 2 2021-03-22 "Linux" "Linux Programmer's Manual"
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.SH NAME
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io_cancel \- cancel an outstanding asynchronous I/O operation
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.SH SYNOPSIS
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.nf
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.BR "#include <linux/aio_abi.h>" " /* Definition of needed types */"
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.BR "#include <sys/syscall.h>" " /* Definition of " SYS_* " constants */"
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.B #include <unistd.h>
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.PP
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.BI "int syscall(SYS_io_cancel, aio_context_t " ctx_id ", struct iocb *" iocb ,
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.BI " struct io_event *" result );
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.fi
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.SH DESCRIPTION
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.IR Note :
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this page describes the raw Linux system call interface.
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The wrapper function provided by
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.I libaio
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uses a different type for the
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.I ctx_id
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argument.
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See NOTES.
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.PP
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The
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.BR io_cancel ()
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system call
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attempts to cancel an asynchronous I/O operation previously submitted with
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.BR io_submit (2).
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The
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.I iocb
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argument describes the operation to be canceled and the
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.I ctx_id
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argument is the AIO context to which the operation was submitted.
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If the operation is successfully canceled, the event will be copied into
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the memory pointed to by
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.I result
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without being placed into the
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completion queue.
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.SH RETURN VALUE
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On success,
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.BR io_cancel ()
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returns 0.
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For the failure return, see NOTES.
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.SH ERRORS
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.TP
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.B EAGAIN
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The \fIiocb\fP specified was not canceled.
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.TP
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.B EFAULT
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One of the data structures points to invalid data.
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.TP
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.B EINVAL
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The AIO context specified by \fIctx_id\fP is invalid.
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.TP
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.B ENOSYS
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.BR io_cancel ()
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is not implemented on this architecture.
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.SH VERSIONS
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The asynchronous I/O system calls first appeared in Linux 2.5.
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.SH CONFORMING TO
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.BR io_cancel ()
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is Linux-specific and should not be used
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in programs that are intended to be portable.
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.SH NOTES
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You probably want to use the
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.BR io_cancel ()
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wrapper function provided by
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.\" http://git.fedorahosted.org/git/?p=libaio.git
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.IR libaio .
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.PP
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Note that the
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.I libaio
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wrapper function uses a different type
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.RI ( io_context_t )
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.\" But glibc is confused, since <libaio.h> uses 'io_context_t' to declare
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.\" the system call.
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for the
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.I ctx_id
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argument.
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Note also that the
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.I libaio
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wrapper does not follow the usual C library conventions for indicating errors:
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on error it returns a negated error number
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(the negative of one of the values listed in ERRORS).
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If the system call is invoked via
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.BR syscall (2),
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then the return value follows the usual conventions for
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indicating an error: \-1, with
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.I errno
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set to a (positive) value that indicates the error.
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.SH SEE ALSO
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.BR io_destroy (2),
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.BR io_getevents (2),
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.BR io_setup (2),
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.BR io_submit (2),
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.BR aio (7)
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.\" .SH AUTHOR
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.\" Kent Yoder.
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