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Name

sem_close - close a named semaphore

Synopsis

cc [ flag ... ] file ... -lposix4 [ library ... ]

#include <semaphore.h>

int sem_close(sem_t *sem);

typedef struct {
   ...

} sem_t;            /*opaque POSIX.4 semaphore*/

MT-Level

MT-Safe

Description

sem_close() is used to indicate that the calling process is finished using the named semaphore sem. sem_close() deallocates any system resources for use by this process for this semaphore. If the semaphore has not been removed with a successful call to sem_unlink(3R) , then sem_close() has no effect on the state of the semaphore. If sem_unlink(3R) has been successfully invoked for name after the most recent call to sem_open(3R) with O_CREAT for this semaphore, then when all processes that have opened the semaphore close it, the semaphore will no longer be accessible.

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

Return Values

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

Errors

EINVAL
sem is not a valid semaphore descriptor.
ENOSYS
sem_close() is not supported by this implementation.

See Also

sem_init(3R) , sem_open(3R) , sem_unlink(3R)

Bugs

In Solaris 2.5, these functions always return -1 and set errno to ENOSYS, because this release does not support the Semaphores option. It is our intention to provide support for these interfaces in future releases.

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