[unix-history] / lib / libc / sys / sigprocmask.2

.\" Copyright (c) 1983, 1991 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.
.\"
.\"	@(#)sigprocmask.2	6.4 (Berkeley) 7/23/91
.\"
.Dd July 23, 1991
.Dt SIGPROCMASK 2
.Os
.Sh NAME
.Nm sigprocmask
.Nd manipulate current signal mask
.Sh SYNOPSIS
.Fd #include <signal.h>
.Ft int
.Fn sigprocmask "int how" "const sigset_t *set" "sigset_t *oset"
.Fn sigmask signum
.Sh DESCRIPTION
The
.Fn sigprocmask
function examines and/or changes the current signal mask (those signals
that are blocked from delivery).
Signals are blocked if they are members of the current signal mask set.
.Pp
If
.Fa set
is not null, the action of
.Fn sigprocmask
depends on the value of the parameter
.Fa how .
The signal mask is changed as a function of the specified
.Fa set
and the current mask.
The function is specified by
.Fa how
using one of the following values from
.Aq Pa signal.h :
.Bl -tag -width SIG_UNBLOCK
.It Dv SIG_BLOCK
The new mask is the union of the current mask and the specified
.Fa set .
.It Dv SIG_UNBLOCK
The new mask is the intersection of the current mask
and the complement of the specified
.Fa set .
.It Dv SIG_SETMASK
The current mask is replaced by the specified
.Fa set .
.El
.Pp
If
.Fa oset
is not null, it is set to
the previous value of the signal mask.
When
.Fa set
is null,
the value of
.Ar how
is insignificant and the mask remains unset
providing a way to examine the signal mask without modification.
.Pp
The system
quietly disallows
.Dv SIGKILL
or
.Dv SIGSTOP
to be blocked.
.Sh RETURN VALUES
A 0 value indicated that the call succeeded.  A -1 return value
indicates an error occurred and
.Va errno
is set to indicated the reason.
.Sh ERRORS
The
.Fn sigprocmask
call will fail and the signal mask will be unchanged if one
of the following occurs:
.Bl -tag -width Bq Er EINVAL
.It Bq Er EINVAL
.Fa how
has a value other than those listed here.
.Sh SEE ALSO
.Xr kill 2 ,
.Xr sigaction 2 ,
.Xr sigsetops 3 ,
.Xr sigsuspend 2
.Sh STANDARDS
The
.Nm sigprocmask
function call is expected to
conform to
.St -p1003.1-88 .
Commit	Line	Data
15637ed4 RG	1	.\" Copyright (c) 1983, 1991 The Regents of the University of California.
	2	.\" 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	.\" @(#)sigprocmask.2 6.4 (Berkeley) 7/23/91
	33	.\"
	34	.Dd July 23, 1991
	35	.Dt SIGPROCMASK 2
	36	.Os
	37	.Sh NAME
	38	.Nm sigprocmask
	39	.Nd manipulate current signal mask
	40	.Sh SYNOPSIS
	41	.Fd #include <signal.h>
	42	.Ft int
	43	.Fn sigprocmask "int how" "const sigset_t set" "sigset_t oset"
	44	.Fn sigmask signum
	45	.Sh DESCRIPTION
	46	The
	47	.Fn sigprocmask
	48	function examines and/or changes the current signal mask (those signals
	49	that are blocked from delivery).
	50	Signals are blocked if they are members of the current signal mask set.
	51	.Pp
	52	If
	53	.Fa set
	54	is not null, the action of
	55	.Fn sigprocmask
	56	depends on the value of the parameter
	57	.Fa how .
	58	The signal mask is changed as a function of the specified
	59	.Fa set
	60	and the current mask.
	61	The function is specified by
	62	.Fa how
	63	using one of the following values from
	64	.Aq Pa signal.h :
65	.Bl -tag -width SIG_UNBLOCK
66	.It Dv SIG_BLOCK
67	The new mask is the union of the current mask and the specified
68	.Fa set .
69	.It Dv SIG_UNBLOCK
70	The new mask is the intersection of the current mask
71	and the complement of the specified
72	.Fa set .
73	.It Dv SIG_SETMASK
74	The current mask is replaced by the specified
75	.Fa set .
76	.El
77	.Pp
78	If
79	.Fa oset
80	is not null, it is set to
81	the previous value of the signal mask.
82	When
83	.Fa set
84	is null,
85	the value of
86	.Ar how
87	is insignificant and the mask remains unset
88	providing a way to examine the signal mask without modification.
89	.Pp
90	The system
91	quietly disallows
92	.Dv SIGKILL
93	or
94	.Dv SIGSTOP
95	to be blocked.
96	.Sh RETURN VALUES
97	A 0 value indicated that the call succeeded. A -1 return value
98	indicates an error occurred and
99	.Va errno
100	is set to indicated the reason.
101	.Sh ERRORS
102	The
103	.Fn sigprocmask
104	call will fail and the signal mask will be unchanged if one
105	of the following occurs:
106	.Bl -tag -width Bq Er EINVAL
107	.It Bq Er EINVAL
108	.Fa how
109	has a value other than those listed here.
110	.Sh SEE ALSO
111	.Xr kill 2 ,
112	.Xr sigaction 2 ,
113	.Xr sigsetops 3 ,
114	.Xr sigsuspend 2
115	.Sh STANDARDS
116	The
117	.Nm sigprocmask
118	function call is expected to
119	conform to
120	.St -p1003.1-88 .