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28.\" $FreeBSD: src/share/man/man3/pthread_sigmask.3,v 1.14 2007/10/22 10:08:01 ru Exp $
29.\"
30.Dd February 22, 2018
31.Dt PTHREAD_SIGMASK 3
32.Os
33.Sh NAME
34.Nm pthread_sigmask
35.Nd examine and/or change a thread's signal mask
36.Sh LIBRARY
37.Lb libpthread
38.Sh SYNOPSIS
39.In pthread.h
40.In signal.h
41.Ft int
42.Fn pthread_sigmask "int how" "const sigset_t * restrict set" "sigset_t * restrict oset"
43.Sh DESCRIPTION
44The
45.Fn pthread_sigmask
46function examines and/or changes the calling thread's signal mask.
47.Pp
48If
49.Fa set
50is not
51.Dv NULL ,
52it specifies a set of signals to be modified, and
53.Fa how
54specifies what to set the signal mask to:
55.Bl -tag -width ".Dv SIG_UNBLOCK"
56.It Dv SIG_BLOCK
57Union of the current mask and
58.Fa set .
59.It Dv SIG_UNBLOCK
60Intersection of the current mask and the complement of
61.Fa set .
62.It Dv SIG_SETMASK
63.Fa set .
64.El
65.Pp
66If
67.Fa oset
68is not NULL, the previous signal mask is stored in the location pointed to by
69.Fa oset .
70.Pp
71.Dv SIGKILL
72and
73.Dv SIGSTOP
74cannot be blocked, and will be silently ignored if included in the signal mask.
75.Sh RETURN VALUES
76If successful,
77.Fn pthread_sigmask
78returns 0.
79Otherwise, an error is returned.
80.Sh ERRORS
81The
82.Fn pthread_sigmask
83function will fail if:
84.Bl -tag -width Er
85.It Bq Er EINVAL
86.Fa how
87is not one of the defined values.
88.El
89.Sh SEE ALSO
90.Xr sigaction 2 ,
91.Xr sigpending 2 ,
92.Xr sigprocmask 2 ,
93.Xr sigsuspend 2 ,
94.Xr sigsetops 3
95.Sh STANDARDS
96The
97.Fn pthread_sigmask
98function conforms to
99.St -p1003.1-96 .
100