1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
|
'\" et
.TH SEM_CLOSE "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
sem_close
\(em close a named semaphore
.SH SYNOPSIS
.LP
.nf
#include <semaphore.h>
.P
int sem_close(sem_t *\fIsem\fP);
.fi
.SH DESCRIPTION
The
\fIsem_close\fR()
function shall indicate that the calling process is finished using
the named semaphore indicated by
.IR sem .
The effects of calling
\fIsem_close\fR()
for an unnamed semaphore (one created by
\fIsem_init\fR())
are undefined. The
\fIsem_close\fR()
function shall deallocate (that is, make available for reuse by a
subsequent
\fIsem_open\fR()
by this process) any system resources allocated by the system for use
by this process for this semaphore. The effect of subsequent use of the
semaphore indicated by
.IR sem
by this process is undefined. If any threads in the calling process are
currently blocked on the semaphore, the behavior is undefined.
If the semaphore has not been removed with a successful call to
\fIsem_unlink\fR(),
then
\fIsem_close\fR()
has no effect on the state of the semaphore. If the
\fIsem_unlink\fR()
function has been successfully invoked for
.IR name
after the most recent call to
\fIsem_open\fR()
with O_CREAT for this semaphore,
then when all processes that have opened the semaphore close it, the
semaphore is no longer accessible.
.SH "RETURN VALUE"
Upon successful completion, a value of zero shall be returned.
Otherwise, a value of \-1 shall be returned and
.IR errno
set to indicate the error.
.SH ERRORS
The
\fIsem_close\fR()
function may fail if:
.TP
.BR EINVAL
The
.IR sem
argument is not a valid semaphore descriptor.
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
None.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIsemctl\fR\^(\|)",
.IR "\fIsemget\fR\^(\|)",
.IR "\fIsemop\fR\^(\|)",
.IR "\fIsem_init\fR\^(\|)",
.IR "\fIsem_open\fR\^(\|)",
.IR "\fIsem_unlink\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<semaphore.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
|
