[apple/xnu.git] / bsd / man / man2 / sigreturn.2

.\"	$NetBSD: sigreturn.2,v 1.6 1995/02/27 12:37:40 cgd Exp $
.\"
.\" Copyright (c) 1985, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. 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 BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)sigreturn.2	8.1 (Berkeley) 6/4/93
.\"
.Dd June 4, 1993
.Dt SIGRETURN 2
.Os BSD 4.3
.Sh NAME
.Nm sigreturn
.Nd return from signal
.Sh SYNOPSIS
.Fd #include <signal.h>
.Bd -literal
struct sigcontext {
	int sc_onstack;
	int sc_mask;
	int sc_sp;
	int sc_fp;
	int sc_ap;
	int sc_pc;
	int sc_ps;
};
.Ed
.Ft int
.Fn sigreturn "struct sigcontext *scp"
.Sh DESCRIPTION
.Fn 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
.Xr longjmp 3
when returning from a signal to the previously executing program.
.Sh NOTES
This system call is not available in 4.2
.Tn BSD
hence it should not be used if backward compatibility is needed.
.Sh RETURN VALUES
If successful, the system call does not return.
Otherwise, a value of -1 is returned and 
.Va errno
is set to indicate the error.
.Sh ERRORS
.Fn Sigreturn
will fail and the process context will remain unchanged
if one of the following occurs.
.Bl -tag -width Er
.It Bq Er EFAULT
.Fa Scp
points to memory that is not a valid part of the process
address space.
.It Bq Er EINVAL
The process status longword is invalid or would improperly
raise the privilege level of the process.
.El
.Sh SEE ALSO
.Xr sigaction 2 ,
.Xr setjmp 3
.Sh HISTORY
The
.Fn sigreturn
function call appeared in
.Bx 4.3 .
Commit	Line	Data
9bccf70c A	1	.\" $NetBSD: sigreturn.2,v 1.6 1995/02/27 12:37:40 cgd Exp $
	2	.\"
	3	.\" Copyright (c) 1985, 1991, 1993
	4	.\" The Regents of the University of California. All rights reserved.
	5	.\"
	6	.\" Redistribution and use in source and binary forms, with or without
	7	.\" modification, are permitted provided that the following conditions
	8	.\" are met:
	9	.\" 1. Redistributions of source code must retain the above copyright
	10	.\" notice, this list of conditions and the following disclaimer.
	11	.\" 2. Redistributions in binary form must reproduce the above copyright
	12	.\" notice, this list of conditions and the following disclaimer in the
	13	.\" documentation and/or other materials provided with the distribution.
	14	.\" 3. All advertising materials mentioning features or use of this software
	15	.\" must display the following acknowledgement:
	16	.\" This product includes software developed by the University of
	17	.\" California, Berkeley and its contributors.
	18	.\" 4. Neither the name of the University nor the names of its contributors
	19	.\" may be used to endorse or promote products derived from this software
	20	.\" without specific prior written permission.
	21	.\"
	22	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	23	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	24	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	25	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	26	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	27	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	28	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	29	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	30	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	31	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	32	.\" SUCH DAMAGE.
	33	.\"
	34	.\" @(#)sigreturn.2 8.1 (Berkeley) 6/4/93
	35	.\"
	36	.Dd June 4, 1993
	37	.Dt SIGRETURN 2
	38	.Os BSD 4.3
	39	.Sh NAME
	40	.Nm sigreturn
	41	.Nd return from signal
	42	.Sh SYNOPSIS
	43	.Fd #include <signal.h>
	44	.Bd -literal
	45	struct sigcontext {
	46	int sc_onstack;
	47	int sc_mask;
	48	int sc_sp;
	49	int sc_fp;
	50	int sc_ap;
	51	int sc_pc;
	52	int sc_ps;
	53	};
	54	.Ed
	55	.Ft int
	56	.Fn sigreturn "struct sigcontext *scp"
	57	.Sh DESCRIPTION
	58	.Fn Sigreturn
	59	allows users to atomically unmask, switch stacks,
	60	and return from a signal context.
	61	The processes signal mask and stack status are
	62	restored from the context.
	63	The system call does not return;
	64	the users stack pointer, frame pointer, argument pointer,
65	and processor status longword are restored from the context.
66	Execution resumes at the specified pc.
67	This system call is used by the trampoline code and
68	.Xr longjmp 3
69	when returning from a signal to the previously executing program.
70	.Sh NOTES
71	This system call is not available in 4.2
72	.Tn BSD
73	hence it should not be used if backward compatibility is needed.
74	.Sh RETURN VALUES
75	If successful, the system call does not return.
76	Otherwise, a value of -1 is returned and
77	.Va errno
78	is set to indicate the error.
79	.Sh ERRORS
80	.Fn Sigreturn
81	will fail and the process context will remain unchanged
82	if one of the following occurs.
83	.Bl -tag -width Er
84	.It Bq Er EFAULT
85	.Fa Scp
86	points to memory that is not a valid part of the process
87	address space.
88	.It Bq Er EINVAL
89	The process status longword is invalid or would improperly
90	raise the privilege level of the process.
91	.El
92	.Sh SEE ALSO
93	.Xr sigaction 2 ,
94	.Xr setjmp 3
95	.Sh HISTORY
96	The
97	.Fn sigreturn
98	function call appeared in
99	.Bx 4.3 .