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. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd September 6, 2013 29.Dt SIGRETURN 2 30.Os 31.Sh NAME 32.Nm sigreturn 33.Nd return from signal 34.Sh LIBRARY 35.Lb libc 36.Sh SYNOPSIS 37.In signal.h 38.Ft int 39.Fn sigreturn "const ucontext_t *scp" 40.Sh DESCRIPTION 41The 42.Fn sigreturn 43system call 44allows users to atomically unmask, switch stacks, 45and return from a signal context. 46The thread's signal mask and stack status are 47restored from the context structure pointed to by 48.Fa scp . 49The system call does not return; 50the users stack pointer, frame pointer, argument pointer, 51and processor status longword are restored from the context. 52Execution resumes at the specified pc. 53This system call is used by the trampoline code and 54.Xr longjmp 3 55when returning from a signal to the previously executing program. 56.Sh RETURN VALUES 57If successful, the system call does not return. 58Otherwise, a value of -1 is returned and 59.Va errno 60is set to indicate the error. 61.Sh ERRORS 62The 63.Fn sigreturn 64system call 65will fail and the thread context will remain unchanged 66if one of the following occurs. 67.Bl -tag -width Er 68.It Bq Er EFAULT 69The 70.Fa scp 71argument 72points to memory that is not a valid part of the process 73address space. 74.It Bq Er EINVAL 75The process status longword is invalid or would improperly 76raise the privilege level of the process. 77.El 78.Sh SEE ALSO 79.Xr sigaction 2 , 80.Xr setjmp 3 , 81.Xr ucontext 3 82.Sh HISTORY 83The 84.Fn sigreturn 85system call appeared in 86.Bx 4.3 . 87