1.\" Copyright (c) 1985, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)sigreturn.2 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/sys/sigreturn.2,v 1.6.2.6 2002/09/15 00:33:23 archie Exp $ 34.\" 35.Dd June 4, 1993 36.Dt SIGRETURN 2 37.Os 38.Sh NAME 39.Nm sigreturn 40.Nd return from signal 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In signal.h 45.Ft int 46.Fn sigreturn "ucontext_t *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 structure pointed to by 53.Fa scp . 54The system call does not return; 55the users stack pointer, frame pointer, argument pointer, 56and processor status longword are restored from the context. 57Execution resumes at the specified pc. 58This system call is used by the trampoline code and 59.Xr longjmp 3 60when returning from a signal to the previously executing program. 61.Sh NOTES 62This system call is not available in 63.Bx 4.2 64hence it should not be used if backward compatibility is needed. 65.Sh RETURN VALUES 66If successful, the system call does not return. 67Otherwise, a value of -1 is returned and 68.Va errno 69is set to indicate the error. 70.Sh ERRORS 71.Fn Sigreturn 72will fail and the process context will remain unchanged 73if one of the following occurs. 74.Bl -tag -width Er 75.It Bq Er EFAULT 76.Fa Scp 77points to memory that is not a valid part of the process 78address space. 79.It Bq Er EINVAL 80The process status longword is invalid or would improperly 81raise the privilege level of the process. 82.El 83.Sh SEE ALSO 84.Xr sigvec 2 , 85.Xr setjmp 3 , 86.Xr ucontext 3 87.Sh HISTORY 88The 89.Fn sigreturn 90function call appeared in 91.Bx 4.3 . 92