bb430bc740
First, update the return types of aio_return() and aio_waitcomplete() to ssize_t. POSIX requires aio_return() to return a ssize_t so that it can represent all return values from read() and write(). aio_waitcomplete() should use ssize_t for the same reason. aio_return() has used ssize_t in <aio.h> since r31620 but the manpage and system call entry were not updated. aio_waitcomplete() has always returned int. Note that this does not require new system call stubs as this is effectively only an API change in how the compiler interprets the return value. Second, allow aio_nbytes values up to IOSIZE_MAX instead of just INT_MAX. aio_read/write should now honor the same length limits as normal read/write. Third, use longs instead of ints in the aio_return() and aio_waitcomplete() system call functions so that the 64-bit size_t in the in-kernel aiocb isn't truncated to 32-bits before being copied out to userland or being returned. Finally, a simple test has been added to verify the bounds checking on the maximum read size from a file.
138 lines
3.7 KiB
Groff
138 lines
3.7 KiB
Groff
.\" Copyright (c) 1999 Christopher M Sedore.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd March 21, 2016
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.Dt AIO_WAITCOMPLETE 2
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.Os
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.Sh NAME
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.Nm aio_waitcomplete
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.Nd wait for the next completion of an aio request
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In aio.h
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.Ft ssize_t
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.Fn aio_waitcomplete "struct aiocb **iocbp" "struct timespec *timeout"
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.Sh DESCRIPTION
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The
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.Fn aio_waitcomplete
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system call waits for completion of an asynchronous I/O request.
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Upon completion,
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.Fn aio_waitcomplete
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returns the result of the function and sets
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.Fa iocbp
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to point to the structure associated with the original request.
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If an asynchronous I/O request is completed before
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.Fn aio_waitcomplete
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is called, it returns immediately with the completed request.
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.Pp
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If
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.Fa timeout
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is a non-NULL pointer, it specifies a maximum interval to wait for a
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asynchronous I/O request to complete.
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If
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.Fa timeout
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is a NULL pointer,
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.Fn aio_waitcomplete
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waits indefinitely.
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To effect a poll, the
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.Fa timeout
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argument should be non-NULL, pointing to a zero-valued timeval structure.
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.Pp
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The
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.Fn aio_waitcomplete
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system call also serves the function of
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.Fn aio_return ,
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thus
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.Fn aio_return
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should not be called for the control block returned in
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.Fa iocbp .
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.Sh RETURN VALUES
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If an asynchronous I/O request has completed,
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.Fa iocbp
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is set to point to the control block passed with the original request,
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and the status is returned as described in
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.Xr read 2 ,
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.Xr write 2 ,
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or
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.Xr fsync 2 .
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On failure,
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.Fn aio_waitcomplete
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returns
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.Dv -1 ,
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sets iocbp to
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.Dv NULL
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and sets
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.Va errno
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to indicate the error condition.
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.Sh ERRORS
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The
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.Fn aio_waitcomplete
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system call fails if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The specified time limit is invalid.
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.It Bq Er EAGAIN
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The process has not yet called
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.Fn aio_read
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or
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.Fn aio_write .
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.It Bq Er EINTR
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A signal was delivered before the timeout expired and before any
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asynchronous I/O requests completed.
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.It Bq Er EWOULDBLOCK
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.It Bq Er EINPROGRESS
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The specified time limit expired before any asynchronous I/O requests
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completed.
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.El
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.Sh SEE ALSO
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.Xr aio_cancel 2 ,
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.Xr aio_error 2 ,
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.Xr aio_read 2 ,
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.Xr aio_return 2 ,
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.Xr aio_suspend 2 ,
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.Xr aio_write 2 ,
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.Xr fsync 2 ,
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.Xr read 2 ,
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.Xr write 2 ,
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.Xr aio 4
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.Sh STANDARDS
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The
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.Fn aio_waitcomplete
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system call is a
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.Fx Ns -specific
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extension.
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.Sh HISTORY
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The
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.Fn aio_waitcomplete
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system call first appeared in
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.Fx 4.0 .
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.Sh AUTHORS
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The
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.Fn aio_waitcomplete
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system call and this manual page were written by
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.An Christopher M Sedore Aq Mt cmsedore@maxwell.syr.edu .
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