minix/lib/libc/sys/getcontext.2
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

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.\" $NetBSD: getcontext.2,v 1.7 2010/04/29 06:07:35 jruoho Exp $
.\"
.\" Copyright (c) 1999 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Klaus Klein.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd April 28, 2010
.Dt GETCONTEXT 2
.Os
.Sh NAME
.Nm getcontext ,
.Nm setcontext
.Nd get and set current user context
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In ucontext.h
.Ft int
.Fn getcontext "ucontext_t *ucp"
.Ft int
.Fn setcontext "const ucontext_t *ucp"
.Sh DESCRIPTION
The
.Fn getcontext
function initializes the object pointed to by
.Fa ucp
to the current user context of the calling thread.
The user context defines a thread's execution environment and includes
the contents of its machine registers,
its signal mask,
and its current execution stack.
.Pp
The
.Fn setcontext
function restores the user context defined in the object pointed to by
.Fa ucp
as most recently initialized by a previous call to either
.Fn getcontext
or
.Xr makecontext 3 .
.\" TODO: signal handler
If successful, execution of the program resumes as defined in the
.Fa ucp
argument, and
.Fn setcontext
will not return.
If
.Fa ucp
was initialized by the
.Fn getcontext
function, program execution continues as if the corresponding invocation of
.Fn getcontext
had just returned (successfully).
If
.Fa ucp
was initialized by the
.Xr makecontext 3
function, program execution continues with the function (and function
arguments) passed to
.Xr makecontext 3 .
.Sh RETURN VALUES
On successful completion,
.Fn getcontext
returns 0 and
.Fn setcontext
does not return.
Otherwise a value of \-1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
The
.Fn getcontext
and
.Fn setcontext
functions will fail if:
.Bl -tag -width Er
.It Bq Er EFAULT
The
.Fa ucp
argument points to an invalid address.
.El
.Pp
The
.Fn setcontext
function will fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The contents of the datum pointed to by
.Fa ucp
are invalid.
.El
.Sh SEE ALSO
.Xr sigprocmask 2 ,
.Xr longjmp 3 ,
.Xr makecontext 3 ,
.Xr setjmp 3 ,
.Xr swapcontext 3
.Sh STANDARDS
The
.Fn getcontext
and
.Fn setcontext
functions conform to
.St -xsh5
and
.St -p1003.1-2001 .
The
.Va errno
indications are an extension to the standard.
.Pp
The
.St -p1003.1-2004
revision marked the functions
.Fn getcontext
and
.Fn setcontext
as obsolete, citing portability issues and recommending the use of
.Tn POSIX
threads instead.
The
.St -p1003.1-2008
revision removed the functions from the specification.
.Sh HISTORY
The
.Fn getcontext
and
.Fn setcontext
functions first appeared in
.At V.4 .