SEM_CLOSE(3C) Standard C Library Functions SEM_CLOSE(3C)

NAME

sem_close - close a named semaphore

SYNOPSIS

#include <semaphore.h>

int sem_close(sem_t *sem);

DESCRIPTION

The sem_close() function is used to indicate that the calling process is
finished using the named semaphore indicated by sem. The effects of
calling sem_close() for an unnamed semaphore (one created by
sem_init(3C)) are undefined. The sem_close() function deallocates (that
is, make available for reuse by a subsequent sem_open(3C) 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 sem by this process is undefined. If the semaphore has not
been removed with a successful call to sem_unlink(3C), then sem_close()
has no effect on the state of the semaphore. If the sem_unlink(3C)
function has been successfully invoked for name after the most recent
call to sem_open(3C) with O_CREAT for this semaphore, then when all
processes that have opened the semaphore close it, the semaphore is no
longer be accessible.

RETURN VALUES

If successful, sem_close() returns 0, otherwise it returns -1 and sets
errno to indicate the error.

ERRORS

The sem_close() function will fail if:

EINVAL
The sem argument is not a valid semaphore descriptor.


ENOSYS
The sem_close() function is not supported by the system.

USAGE

The sem_close() function should not be called for an unnamed semaphore
initialized by sem_init(3C).

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|MT-Level | MT-Safe |
+--------------------+-------------------+
|Standard | See standards(7). |
+--------------------+-------------------+

SEE ALSO

sem_init(3C), sem_open(3C), sem_unlink(3C), attributes(7), standards(7)

NOTES

Solaris 2.6 was the first release to support the Asynchronous Input and
Output option. Prior to this release, this function always returned -1
and set errno to ENOSYS.

February 5, 2008 SEM_CLOSE(3C)