1.\" $OpenBSD: sigreturn.2,v 1.12 2016/05/09 23:57:10 guenther 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. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)sigreturn.2 8.1 (Berkeley) 6/4/93 32.\" 33.Dd $Mdocdate: May 9 2016 $ 34.Dt SIGRETURN 2 35.Os 36.Sh NAME 37.Nm sigreturn 38.Nd return from signal 39.Sh SYNOPSIS 40.Ft int 41.Fn sigreturn "struct sigcontext *scp" 42.Sh DESCRIPTION 43The 44.Fn sigreturn 45syscall is used by the signal handling facility to 46atomically switch stacks, restore registers and the thread's signal mask, 47and return from a signal context 48to resume the processing that was interrupted by the signal. 49.Pp 50Note that sigcontext contains machine dependent information. 51.Pp 52Direct use of 53.Nm 54is no longer supported and it is not provided as a function. 55As used in the signal trampoline provided by the system, 56if 57.Nm 58fails and returns then the process is terminated. 59.Sh RETURN VALUES 60If successful, the system call does not return. 61Otherwise, a value of \-1 is returned and 62.Va errno 63is set to indicate the error. 64.Sh ERRORS 65.Fn sigreturn 66will fail and the process context will remain unchanged 67if one of the following occurs. 68.Bl -tag -width Er 69.It Bq Er EFAULT 70.Fa scp 71points to memory that is not a valid part of the process 72address space. 73.It Bq Er EINVAL 74The sigcontext provided is invalid or would improperly 75raise the privilege level of the process. 76.El 77.Sh SEE ALSO 78.Xr sigaction 2 , 79.Xr setjmp 3 80.Sh HISTORY 81The 82.Fn sigreturn 83function appeared in 84.Bx 4.3 . 85The function was removed from libc in 86.Ox 6.0 . 87