.\" Copyright (c) 1985 The Regents of the University of California. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms are permitted provided .\" that: (1) source distributions retain this entire copyright notice and .\" comment, and (2) distributions including binaries display the following .\" acknowledgement: ``This product includes software developed by the .\" University of California, Berkeley and its contributors'' in the .\" documentation or other materials provided with the distribution and in .\" all advertising materials mentioning features or use of this software. .\" Neither the name of the University nor the names of its contributors may .\" be used to endorse or promote products derived from this software without .\" specific prior written permission. .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED .\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. .\" .\" @(#)sigreturn.2 6.4 (Berkeley) 6/23/90 .\" .TH SIGRETURN 2 "June 23, 1990" .UC 6 .SH NAME sigreturn \- return from signal .SH SYNOPSIS .nf .B #include <signal.h> .PP .B struct sigcontext { .B int sc_onstack; .B int sc_mask; .B int sc_sp; .B int sc_fp; .B int sc_ap; .B int sc_pc; .B int sc_ps; .B }; .PP .B sigreturn(scp); .B struct sigcontext *scp; .SH DESCRIPTION .I Sigreturn allows users to atomically unmask, switch stacks, and return from a signal context. The processes signal mask and stack status are restored from the context. The system call does not return; the users stack pointer, frame pointer, argument pointer, and processor status longword are restored from the context. Execution resumes at the specified pc. This system call is used by the trampoline code, and .IR longjmp (3) when returning from a signal to the previously executing program. .SH NOTES This system call is not available in 4.2BSD, hence it should not be used if backward compatibility is needed. .SH "RETURN VALUE If successful, the system call does not return. Otherwise, a value of \-1 is returned and .I errno is set to indicate the error. .SH ERRORS .I Sigreturn will fail and the process context will remain unchanged if one of the following occurs. .TP 15 [EFAULT] .I Scp points to memory that is not a valid part of the process address space. .TP [EINVAL] The process status longword is invalid or would improperly raise the privilege level of the process. .SH "SEE ALSO" sigvec(2), setjmp(3)