1.\" Copyright (C) 2000 Jason Evans <jasone@freebsd.org>.
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(s), this list of conditions and the following disclaimer as
9.\" the first lines of this file unmodified other than the possible
10.\" addition of one or more copyright notices.
11.\" 2. Redistributions in binary form must reproduce the above copyright
12.\" notice(s), this list of conditions and the following disclaimer in
13.\" the documentation and/or other materials provided with the
14.\" distribution.
15.\"
16.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
17.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
20.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
23.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
24.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
25.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
26.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27.\"
28.\" $FreeBSD: head/lib/libc/gen/sem_init.3 63364 2000-07-18 01:38:19Z jasone $
29.Dd February 15, 2000
30.Dt SEM_INIT 3
31.Os
32.Sh NAME
33.Nm sem_init
34.Nd initialize an unnamed semaphore
35.Sh LIBRARY
36.Lb libc_r
37.Sh SYNOPSIS
38.Fd #include <semaphore.h>
39.Ft int
40.Fn sem_init "sem_t *sem" "int pshared" "unsigned int value"
41.Sh DESCRIPTION
42The
43.Fn sem_init
44function initializes the unnamed semaphore pointed to by
45.Fa sem
46to have the value
47.Fa value .
48A non-zero value for
49.Fa pshared
50specifies a shared semaphore that can be used by multiple processes, which this
51implementation is not capable of.
52.Pp
53Following a successful call to
54.Fn sem_init ,
55.Fa sem
56can be used as an argument in subsequent calls to
57.Fa sem_wait ,
58.Fa sem_trywait ,
59.Fa sem_post ,
60and
61.Fa sem_destroy .
62.Fa sem
63is no longer valid after a successful call to
64.Fa sem_destroy .
65.Sh RETURN VALUES
66If successful,
67.Fn sem_init
68returns 0. Otherwise, -1 is returned and
69.Va errno
70is set to indicate the type of
71error.
72.Sh ERRORS
73.Fn sem_init
74will fail if:
75.Bl -tag -width Er
76.It Bq Er EINVAL
77.Fa value
78exceeds SEM_VALUE_MAX.
79.It Bq Er ENOSPC
80Memory allocation error.
81.It Bq Er EPERM
82Unable to initialize a shared semaphore.
83.El
84.Sh SEE ALSO
85.Xr sem_destroy 3 ,
86.Xr sem_post 3 ,
87.Xr sem_trywait 3 ,
88.Xr sem_wait 3
89.Sh STANDARDS
90.Fn sem_init
91conforms to ISO/IEC 9945-1 ANSI/IEEE
92.Pq Dq Tn POSIX
93Std 1003.1 1996 Edition.
94.Pp
95This implementation does not support shared semaphores, and reports this fact
96by setting
97.Va errno
98to EPERM. This is perhaps a stretch of the intention of POSIX, but is
99compliant, with the caveat that
100.Fn sem_init
101always reports a permissions error when an attempt to create a shared semaphore
102is made.
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(s), this list of conditions and the following disclaimer as
9.\" the first lines of this file unmodified other than the possible
10.\" addition of one or more copyright notices.
11.\" 2. Redistributions in binary form must reproduce the above copyright
12.\" notice(s), this list of conditions and the following disclaimer in
13.\" the documentation and/or other materials provided with the
14.\" distribution.
15.\"
16.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
17.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
20.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
23.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
24.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
25.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
26.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27.\"
28.\" $FreeBSD: head/lib/libc/gen/sem_init.3 63364 2000-07-18 01:38:19Z jasone $
29.Dd February 15, 2000
30.Dt SEM_INIT 3
31.Os
32.Sh NAME
33.Nm sem_init
34.Nd initialize an unnamed semaphore
35.Sh LIBRARY
36.Lb libc_r
37.Sh SYNOPSIS
38.Fd #include <semaphore.h>
39.Ft int
40.Fn sem_init "sem_t *sem" "int pshared" "unsigned int value"
41.Sh DESCRIPTION
42The
43.Fn sem_init
44function initializes the unnamed semaphore pointed to by
45.Fa sem
46to have the value
47.Fa value .
48A non-zero value for
49.Fa pshared
50specifies a shared semaphore that can be used by multiple processes, which this
51implementation is not capable of.
52.Pp
53Following a successful call to
54.Fn sem_init ,
55.Fa sem
56can be used as an argument in subsequent calls to
57.Fa sem_wait ,
58.Fa sem_trywait ,
59.Fa sem_post ,
60and
61.Fa sem_destroy .
62.Fa sem
63is no longer valid after a successful call to
64.Fa sem_destroy .
65.Sh RETURN VALUES
66If successful,
67.Fn sem_init
68returns 0. Otherwise, -1 is returned and
69.Va errno
70is set to indicate the type of
71error.
72.Sh ERRORS
73.Fn sem_init
74will fail if:
75.Bl -tag -width Er
76.It Bq Er EINVAL
77.Fa value
78exceeds SEM_VALUE_MAX.
79.It Bq Er ENOSPC
80Memory allocation error.
81.It Bq Er EPERM
82Unable to initialize a shared semaphore.
83.El
84.Sh SEE ALSO
85.Xr sem_destroy 3 ,
86.Xr sem_post 3 ,
87.Xr sem_trywait 3 ,
88.Xr sem_wait 3
89.Sh STANDARDS
90.Fn sem_init
91conforms to ISO/IEC 9945-1 ANSI/IEEE
92.Pq Dq Tn POSIX
93Std 1003.1 1996 Edition.
94.Pp
95This implementation does not support shared semaphores, and reports this fact
96by setting
97.Va errno
98to EPERM. This is perhaps a stretch of the intention of POSIX, but is
99compliant, with the caveat that
100.Fn sem_init
101always reports a permissions error when an attempt to create a shared semaphore
102is made.