1.\" $OpenBSD: sigreturn.2,v 1.5 1999/02/27 21:56:51 deraadt Exp $ 2.\" $NetBSD: sigreturn.2,v 1.6 1995/02/27 12:37:40 cgd Exp $ 3.\" 4.\" Copyright (c) 1985, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)sigreturn.2 8.1 (Berkeley) 6/4/93 36.\" 37.Dd June 4, 1993 38.Dt SIGRETURN 2 39.Os BSD 4.3 40.Sh NAME 41.Nm sigreturn 42.Nd return from signal 43.Sh SYNOPSIS 44.Fd #include <signal.h> 45.Ft int 46.Fn sigreturn "struct sigcontext *scp" 47.Sh DESCRIPTION 48.Fn sigreturn 49allows users to atomically unmask, switch stacks, 50and return from a signal context. 51The processes signal mask and stack status are 52restored from the context. 53The system call does not return; 54the users stack pointer, frame pointer, argument pointer, 55and processor status longword are restored from the context. 56Execution resumes at the specified pc. 57This system call is used by the trampoline code and 58.Xr longjmp 3 59when returning from a signal to the previously executing program. 60.Pp 61Note that sigcontext contains machine dependent information. 62.Sh NOTES 63This system call is not available in 4.2 64.Tn BSD 65hence it should not be used if backward compatibility is needed. 66.Sh RETURN VALUES 67If successful, the system call does not return. 68Otherwise, a value of -1 is returned and 69.Va errno 70is set to indicate the error. 71.Sh ERRORS 72.Fn sigreturn 73will fail and the process context will remain unchanged 74if one of the following occurs. 75.Bl -tag -width Er 76.It Bq Er EFAULT 77.Fa scp 78points to memory that is not a valid part of the process 79address space. 80.It Bq Er EINVAL 81The process status longword is invalid or would improperly 82raise the privilege level of the process. 83.El 84.Sh SEE ALSO 85.Xr sigaction 2 , 86.Xr setjmp 3 87.Sh HISTORY 88The 89.Fn sigreturn 90function call appeared in 91.Bx 4.3 . 92