06-07-2006
There is some confusion here. sem_open creates the semaphore in memory using it's own rules. The named semaphore can be accessed as long as the other process knows the name of the semaphore.
If you want to change things, then you will have to created shared memory, like you get with shmget then maybe calling shmat, and create your own mutex or semphore there.
You can't change protection on the memory allocated with sem_open and it's family of calls.
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LEARN ABOUT HPUX
sem_destroy
sem_destroy(2) System Calls Manual sem_destroy(2)
NAME
sem_destroy - destroy an unnamed POSIX semaphore
SYNOPSIS
DESCRIPTION
is used to destroy an unnamed semaphore. A successful call to will invalidate the unnamed semaphore referred to by sem and removes all
descriptors referencing it. The semaphore should have been created by a previous call to and there should not be any processes blocked on
it.
To use this function, link in the realtime library by specifying on the compiler or linker command line.
EXAMPLES
The following call to will destroy an unnamed semaphore referred to by sem and remove all descriptors referencing it.
RETURN VALUE
If the semaphore was destroyed and the descriptors referencing it were removed, returns 0 to the caller.
If the semaphore could not be destroyed, the call returns -1 and sets to indicate the error.
ERRORS
fails and does not perform the requested operation if any of the following conditions are encountered:
[EBUSY] There are threads currently blocked on the semaphore or there are outstanding locks held on the semaphore.
[EINVAL] The argument sem is not a valid unnamed semaphore.
SEE ALSO
sem_init(2), sem_open(2), <semaphore.h>.
STANDARDS CONFORMANCE
sem_destroy(2)