1.\" $NetBSD: ucontext.2,v 1.6 2010/04/29 06:07:35 jruoho Exp $ 2.\" 3.\" Copyright (c) 2001 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Klaus Klein. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd April 29, 2010 31.Dt UCONTEXT 2 32.Os 33.Sh NAME 34.Nm ucontext 35.Nd user context 36.Sh SYNOPSIS 37.In ucontext.h 38.Sh DESCRIPTION 39The 40.Vt ucontext_t 41is a structure type which is used to describe the context of a 42thread of control within the execution of a process. 43A thread's context includes its stack, saved registers, and list of 44blocked signals. 45.Pp 46The 47.Vt ucontext_t 48structure includes the following members: 49.Bd -literal -offset indent 50ucontext_t *uc_link 51sigset_t uc_sigmask 52stack_t uc_stack 53mcontext_t uc_mcontext 54.Ed 55.Pp 56The 57.Fa uc_link 58member points to the context that will be resumed after the function 59specified when modifying a context using 60.Xr makecontext 3 61has returned. 62If 63.Fa uc_link 64is a 65.Dv NULL 66pointer, then the context is the main context, 67and the process will exit with an exit status of 0 upon return. 68.Pp 69The 70.Fa uc_sigmask 71member is the set of signals that are blocked when the context is 72activated. 73Further information can be found in 74.Xr sigprocmask 2 . 75.Pp 76The 77.Fa uc_stack 78member defines the stack used by the context. 79Further information can be found in 80.Xr sigaltstack 2 . 81.Pp 82The 83.Fa uc_mcontext 84member defines the machine state associated with the context; 85it may consist of general registers, floating point registers 86and other machine-specific information. 87Its description is beyond the scope of this manual page; 88portable applications should not access this structure member. 89.Sh SEE ALSO 90.Xr _exit 2 , 91.Xr getcontext 2 , 92.Xr setcontext 2 , 93.Xr sigaltstack 2 , 94.Xr sigprocmask 2 , 95.Xr makecontext 3 , 96.Xr swapcontext 3 97.Sh STANDARDS 98The 99.Vt ucontext_t 100type conforms to 101.St -xsh5 102and 103.St -p1003.1-2001 . 104The 105.St -p1003.1-2008 106revision removed the 107.Vt ucontext_t 108from the specification. 109