2002-06-17 02:21:17 +00:00
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.\"
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.\" Copyright 2002 Massachusetts Institute of Technology
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.\"
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.\" Permission to use, copy, modify, and distribute this software and
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.\" its documentation for any purpose and without fee is hereby
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.\" granted, provided that both the above copyright notice and this
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.\" permission notice appear in all copies, that both the above
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.\" copyright notice and this permission notice appear in all
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.\" supporting documentation, and that the name of M.I.T. not be used
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.\" in advertising or publicity pertaining to distribution of the
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.\" software without specific, written prior permission. M.I.T. makes
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.\" no representations about the suitability of this software for any
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.\" purpose. It is provided "as is" without express or implied
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.\" warranty.
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2002-12-04 15:47:41 +00:00
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.\"
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2002-06-17 02:21:17 +00:00
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.\" THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS
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.\" ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
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.\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
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.\" SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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.\" LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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.\" USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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.\" 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 June 16, 2002
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.Dt PSELECT 3
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.Os
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.Sh NAME
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.Nm pselect
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.Nd synchronous I/O multiplexing a la POSIX.1g
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/select.h
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.Ft int
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.Fo pselect
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.Fa "int nfds"
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.Fa "fd_set * restrict readfds"
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.Fa "fd_set * restrict writefds"
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.Fa "fd_set * restrict exceptfds"
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.Fa "const struct timespec * restrict timeout"
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.Fa "const sigset_t * restrict newsigmask"
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.Fc
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.Sh DESCRIPTION
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The
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.Fn pselect
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function was introduced by
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.St -p1003.1g-2000
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as a slightly stronger version of
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.Xr select 2 .
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The
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2002-12-04 15:47:41 +00:00
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.Fa nfds , readfds , writefds ,
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and
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.Fa exceptfds
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arguments are all identical to the analogous arguments of
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.Fn select .
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The
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.Fa timeout
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argument in
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.Fn pselect
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points to a
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.Vt "const struct timespec"
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rather than the (modifiable)
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.Vt "struct timeval"
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used by
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.Fn select ;
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as in
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.Fn select ,
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a null pointer may be passed to indicate that
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.Fn pselect
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should wait indefinitely.
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Finally,
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.Fa newsigmask
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specifies a signal mask which is set while waiting for input.
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When
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.Fn pselect
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returns, the original signal mask is restored.
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.Pp
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See
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.Xr select 2
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for a more detailed discussion of the semantics of this interface, and
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for macros used to manipulate the
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.Vt "fd_set"
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data type.
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.Sh IMPLEMENTATION NOTES
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The
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.Fn pselect
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function is implemented in the C library as a wrapper around
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.Fn select .
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.Sh RETURN VALUES
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The
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.Fn pselect
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function returns the same values and under the same conditions as
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.Fn select .
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.Sh ERRORS
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The
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.Fn pselect
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function may fail for any of the reasons documented for
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.Xr select 2
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and (if a signal mask is provided)
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.Xr sigprocmask 2 .
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.Sh SEE ALSO
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.Xr kqueue 2 ,
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.Xr poll 2 ,
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.Xr select 2 ,
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.Xr sigprocmask 2
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.Sh STANDARDS
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The
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.Fn pselect
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function conforms to
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.St -p1003.1-2001 .
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.Sh HISTORY
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The
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2002-12-18 10:13:54 +00:00
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.Fn pselect
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2002-06-17 02:21:17 +00:00
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function first appeared in
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.Fx 5.0 .
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.Sh AUTHORS
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The
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2002-12-18 10:13:54 +00:00
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.Fn pselect
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2002-06-17 02:21:17 +00:00
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function and this manual page were written by
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.An Garrett Wollman Aq wollman@FreeBSD.org .
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