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.\" 34.Dd June 4, 1993 35.Dt SIGRETURN 2 36.Os BSD 4.3 37.Sh NAME 38.Nm sigreturn 39.Nd return from signal 40.Sh SYNOPSIS 41.Fd #include <signal.h> 42.Bd -literal 43struct sigcontext { 44 int sc_onstack; 45 int sc_mask; 46 int sc_sp; 47 int sc_fp; 48 int sc_ap; 49 int sc_pc; 50 int sc_ps; 51}; 52.Ed 53.Ft int 54.Fn sigreturn "struct sigcontext *scp" 55.Sh DESCRIPTION 56.Fn Sigreturn 57allows users to atomically unmask, switch stacks, 58and return from a signal context. 59The processes signal mask and stack status are 60restored from the context. 61The system call does not return; 62the users stack pointer, frame pointer, argument pointer, 63and processor status longword are restored from the context. 64Execution resumes at the specified pc. 65This system call is used by the trampoline code and 66.Xr longjmp 3 67when returning from a signal to the previously executing program. 68.Sh NOTES 69This system call is not available in 4.2 70.Tn BSD 71hence it should not be used if backward compatibility is needed. 72.Sh RETURN VALUES 73If successful, the system call does not return. 74Otherwise, a value of -1 is returned and 75.Va errno 76is set to indicate the error. 77.Sh ERRORS 78.Fn Sigreturn 79will fail and the process context will remain unchanged 80if one of the following occurs. 81.Bl -tag -width [EINVAL] 82.It Bq Er EFAULT 83.Fa Scp 84points to memory that is not a valid part of the process 85address space. 86.It Bq Er EINVAL 87The process status longword is invalid or would improperly 88raise the privilege level of the process. 89.El 90.Sh SEE ALSO 91.Xr sigvec 2 , 92.Xr setjmp 3 93.Sh HISTORY 94The 95.Nm 96function call appeared in 97.Bx 4.3 . 98