.\" fwait.2
.\"
.\" Created: 7 July, 1994 by Philip Homburg <philip@cs.vu.nl>
.TH fcancel 2
.SH NAME
fcancel \- cancel an asynchronous I/O operation
.SH SYNOPSIS
.nf
.ft B
#define _MINIX_SOURCE 1

#include <sys/types.h>
#include <fcntl.h>

int fcancel(int *\fIfd\fP, int \fIoperation\fP)
.ft R
.fi
.SH DESCRIPTION
.B Fcancel
cancels an asynchronous I/O operation.
The effect is similar to receiving a signal during a blocking system call,
with the exception that
.BR fwait (2)
has to be used to get the result of the operation, just like normal
asynchronous I/O operations.
.PP
The first argument to \fBfcancel\fP specifies the file descriptor and the
second argument (\fIoperation\fP) specifies which operation should be 
canceled.
.I Operation
takes one of three values defined in \fB<fcntl.h>\fP:
.PP
.nf
#define ASIO_READ	0
#define ASIO_WRITE	1
#define ASIO_IOCTL	2
.fi
.PP
They cancel respectively read, write and ioctl operations.
.PP
If \fBfcancel\fP is performed on a completed asynchronous I/O operation whose
status has not been reported by \fBfwait\fP then \fBfcancel\fP is a no-op.
.SH "RETURN VALUES"
\fBfcancel\fR returns 0 upon success and -1 upon failure.
.SH ERRORS
.IP EBADF
.I fd
does not refer to an open file descriptor
.IP EINVAL
.I operation
has an illegal value, or no asynchronous operation is in progress for this
file descriptor/operation combination
.SH "SEE ALSO"
.BR fwait (2).
.SH AUTHOR
Philip Homburg (philip@cs.vu.nl)
.\"
.\" $PchId: fcancel.2,v 1.3 1995/11/27 19:39:26 philip Exp $