153 lines
3.8 KiB
Groff
153 lines
3.8 KiB
Groff
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.\" $NetBSD: getcontext.2,v 1.7 2010/04/29 06:07:35 jruoho Exp $
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.\"
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.\" Copyright (c) 1999 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Klaus Klein.
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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 BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd April 28, 2010
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.Dt GETCONTEXT 2
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.Os
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.Sh NAME
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.Nm getcontext ,
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.Nm setcontext
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.Nd get and set current user context
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In ucontext.h
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.Ft int
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.Fn getcontext "ucontext_t *ucp"
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.Ft int
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.Fn setcontext "const ucontext_t *ucp"
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.Sh DESCRIPTION
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The
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.Fn getcontext
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function initializes the object pointed to by
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.Fa ucp
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to the current user context of the calling thread.
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The user context defines a thread's execution environment and includes
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the contents of its machine registers,
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its signal mask,
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and its current execution stack.
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.Pp
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The
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.Fn setcontext
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function restores the user context defined in the object pointed to by
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.Fa ucp
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as most recently initialized by a previous call to either
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.Fn getcontext
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or
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.Xr makecontext 3 .
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.\" TODO: signal handler
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If successful, execution of the program resumes as defined in the
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.Fa ucp
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argument, and
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.Fn setcontext
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will not return.
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If
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.Fa ucp
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was initialized by the
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.Fn getcontext
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function, program execution continues as if the corresponding invocation of
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.Fn getcontext
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had just returned (successfully).
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If
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.Fa ucp
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was initialized by the
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.Xr makecontext 3
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function, program execution continues with the function (and function
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arguments) passed to
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.Xr makecontext 3 .
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.Sh RETURN VALUES
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On successful completion,
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.Fn getcontext
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returns 0 and
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.Fn setcontext
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does not return.
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Otherwise a value of \-1 is returned and
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.Va errno
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is set to indicate the error.
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.Sh ERRORS
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The
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.Fn getcontext
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and
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.Fn setcontext
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functions will fail if:
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.Bl -tag -width Er
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.It Bq Er EFAULT
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The
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.Fa ucp
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argument points to an invalid address.
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.El
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.Pp
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The
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.Fn setcontext
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The contents of the datum pointed to by
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.Fa ucp
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are invalid.
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.El
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.Sh SEE ALSO
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.Xr sigprocmask 2 ,
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.Xr longjmp 3 ,
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.Xr makecontext 3 ,
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.Xr setjmp 3 ,
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.Xr swapcontext 3
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.Sh STANDARDS
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The
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.Fn getcontext
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and
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.Fn setcontext
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functions conform to
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.St -xsh5
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and
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.St -p1003.1-2001 .
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The
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.Va errno
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indications are an extension to the standard.
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.Pp
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The
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.St -p1003.1-2004
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revision marked the functions
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.Fn getcontext
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and
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.Fn setcontext
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as obsolete, citing portability issues and recommending the use of
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.Tn POSIX
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threads instead.
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The
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.St -p1003.1-2008
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revision removed the functions from the specification.
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.Sh HISTORY
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The
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.Fn getcontext
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and
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.Fn setcontext
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functions first appeared in
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.At V.4 .
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