NAME

sem_destroy — destroy an unnamed semaphore

SYNOPSIS

#include <semaphore.h>

int sem_destroy(sem_t *sem);


DESCRIPTION

The sem_destroy() function shall destroy the unnamed semaphore indicated by sem. If an unnamed semaphore is implemented using a file descriptor, the file descriptor shall be closed. Only a semaphore that was created using sem_init() can be destroyed using sem_destroy(); the effect of calling sem_destroy() with a named semaphore is undefined. The effect of subsequent use of the semaphore sem is undefined until sem is reinitialized by another call to sem_init().

It is safe to destroy an initialized semaphore upon which no threads are currently blocked. The effect of destroying a semaphore upon which other threads are currently blocked is undefined.

RETURN VALUE

Upon successful completion, a value of zero shall be returned. Otherwise, a value of -1 shall be returned and errno set to indicate the error.

ERRORS

The sem_destroy() function may fail if:

[EINVAL]

The sem argument is not a valid semaphore.

[EBUSY]

There are currently processes blocked on the semaphore.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

semctl, semget, semop, sem_init, sem_open

XBD <semaphore.h>

CHANGE HISTORY

First released in Issue 5. Included for alignment with the POSIX Realtime Extension.

Issue 6

The sem_destroy() function is marked as part of the Semaphores option.

The [ENOSYS] error condition has been removed as stubs need not be provided if an implementation does not support the Semaphores option.

IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/114 is applied, updating the ERRORS section so that the [EINVAL] error becomes optional.

Issue 7

The sem_destroy() function is moved from the Semaphores option to the Base.

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0524 [37] is applied.

Issue 8

Austin Group Defect 368 is applied, adding a requirement that if an unnamed semaphore is implemented using a file descriptor, sem_destroy() closes the file descriptor.