1.\" $NetBSD: getcontext.2,v 1.4 2003/04/16 16:09:04 wiz Exp $ 2.\" 3.\" Copyright (c) 1999 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.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.Dd October 28, 1999 38.Dt GETCONTEXT 2 39.Os 40.Sh NAME 41.Nm getcontext , 42.Nm setcontext 43.Nd get and set current user context 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.In ucontext.h 48.Ft int 49.Fn getcontext "ucontext_t *ucp" 50.Ft int 51.Fn setcontext "const ucontext_t *ucp" 52.Sh DESCRIPTION 53The 54.Fn getcontext 55function initializes the object pointed to by 56.Fa ucp 57to the current user context of the calling thread. 58The user context defines a thread's execution environment and includes 59the contents of its machine registers, 60its signal mask, 61and its current execution stack. 62.Pp 63The 64.Fn setcontext 65function restores the user context defined in the object pointed to by 66.Fa ucp 67as most recently initialized by a previous call to either 68.Fn getcontext 69or 70.Xr makecontext 3 . 71.\" TODO: signal handler 72If successful, execution of the program resumes as defined in the 73.Fa ucp 74argument, and 75.Fn setcontext 76will not return. 77If 78.Fa ucp 79was initialized by the 80.Fn getcontext 81function, program execution continues as if the corresponding invocation of 82.Fn getcontext 83had just returned (successfully). 84If 85.Fa ucp 86was initialized by the 87.Xr makecontext 3 88function, program execution continues with the function (and function 89arguments) passed to 90.Xr makecontext 3 . 91.Sh RETURN VALUES 92On successful completion, 93.Fn getcontext 94returns 0 and 95.Fn setcontext 96does not return. 97Otherwise a value of \-1 is returned and 98.Va errno 99is set to indicate the error. 100.Sh ERRORS 101The 102.Fn getcontext 103and 104.Fn setcontext 105functions will fail if: 106.Bl -tag -width Er 107.It Bq Er EFAULT 108The 109.Fa ucp 110argument points to an invalid address. 111.El 112.Pp 113The 114.Fn setcontext 115function will fail if: 116.Bl -tag -width Er 117.It Bq Er EINVAL 118The contents of the datum pointed to by 119.Fa ucp 120are invalid. 121.El 122.Sh SEE ALSO 123.Xr sigprocmask 2 , 124.Xr longjmp 3 , 125.Xr makecontext 3 , 126.Xr setjmp 3 , 127.Xr swapcontext 3 128.Sh STANDARDS 129The 130.Fn getcontext 131and 132.Fn setcontext 133functions conform to 134.St -xsh5 . 135The 136.Va errno 137indications are an extension to the standard. 138.Sh HISTORY 139The 140.Fn getcontext 141and 142.Fn setcontext 143functions first appeared in 144.At V.4 . 145