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.\" $DragonFly: src/lib/libc/sys/sigreturn.2,v 1.2 2003/06/17 04:26:47 dillon Exp $ 35.\" 36.Dd June 4, 1993 37.Dt SIGRETURN 2 38.Os 39.Sh NAME 40.Nm sigreturn 41.Nd return from signal 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In signal.h 46.Ft int 47.Fn sigreturn "ucontext_t *scp" 48.Sh DESCRIPTION 49.Fn Sigreturn 50allows users to atomically unmask, switch stacks, 51and return from a signal context. 52The processes signal mask and stack status are 53restored from the context structure pointed to by 54.Fa scp . 55The system call does not return; 56the users stack pointer, frame pointer, argument pointer, 57and processor status longword are restored from the context. 58Execution resumes at the specified pc. 59This system call is used by the trampoline code and 60.Xr longjmp 3 61when returning from a signal to the previously executing program. 62.Sh NOTES 63This system call is not available in 64.Bx 4.2 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 sigvec 2 , 86.Xr setjmp 3 , 87.Xr ucontext 3 88.Sh HISTORY 89The 90.Fn sigreturn 91function call appeared in 92.Bx 4.3 . 93