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semids(2) [opensolaris man page]

semids(2)							   System Calls 							 semids(2)

NAME
semids - discover all semaphore identifiers SYNOPSIS
#include <sys/sem.h> int semids(int *buf, uint_t nids, uint_t *pnids); DESCRIPTION
The semids() function copies all active semaphore identifiers from the system into the user-defined buffer specified by buf, provided that the number of such identifiers is not greater than the number of integers the buffer can contain, as specified by nids. If the size of the buffer is insufficient to contain all of the active semaphore identifiers in the system, none are copied. Whether or not the size of the buffer is sufficient to contain all of them, the number of active semaphore identifiers in the system is copied into the unsigned integer pointed to by pnids. If nids is 0 or less than the number of active semaphore identifiers in the system, buf is ignored. RETURN VALUES
Upon successful completion, semids() returns 0. Otherwise, -1 is returned and errno is set to indicate the error. ERRORS
The semids() function will fail if: EFAULT The buf or pnids argument points to an illegal address. USAGE
The semids() function returns a snapshot of all the active semaphore identifiers in the system. More may be added and some may be removed before they can be used by the caller. EXAMPLES
Example 1 semids() example This is sample C code indicating how to use the semids() function. void examine_semids() { int *ids = NULL; uint_t nids = 0; uint_t n; int i; for (;;) { if (semids(ids, nids, &n) != 0) { perror("semids"); exit(1); } if (n <= nids) /* we got them all */ break; /* we need a bigger buffer */ ids = realloc(ids, (nids = n) * sizeof (int)); } for (i = 0; i < n; i++) process_semid(ids[i]); free(ids); } ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |MT-Level |Async-Signal-Safe | +-----------------------------+-----------------------------+ SEE ALSO
ipcrm(1), ipcs(1), Intro(2), semctl(2), semget(2), semop(2), attributes(5) SunOS 5.11 8 Mar 2000 semids(2)

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sem_getvalue(3RT)					    Realtime Library Functions						 sem_getvalue(3RT)

NAME
sem_getvalue - get the value of a semaphore SYNOPSIS
cc [ flag... ] file... -lrt [ library... ] #include <semaphore.h> int sem_getvalue(sem_t *restrict sem, int *restrict sval); DESCRIPTION
The sem_getvalue() function updates the location referenced by the sval argument to have the value of the semaphore referenced by sem with- out affecting the state of the semaphore. The updated value represents an actual semaphore value that occurred at some unspecified time during the call, but it need not be the actual value of the semaphore when it is returned to the calling process. If sem is locked, then the value returned by sem_getvalue() is either zero or a negative number whose absolute value represents the number of processes waiting for the semaphore at some unspecified time during the call. The value set in sval may be 0 or positive. If sval is 0, there may be other processes (or LWPs or threads) waiting for the semaphore; if sval is positive, no process is waiting. RETURN VALUES
Upon successful completion, sem_getvalue() returns 0. Otherwise, it returns -1 and sets errno to indicate the error. ERRORS
The sem_getvalue() function will fail if: EINVAL The sem argument does not refer to a valid semaphore. ENOSYS The sem_getvalue() function is not supported by the system. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
semctl(2), semget(2), semop(2), sem_post(3RT), sem_wait(3RT), attributes(5), standards(5) SunOS 5.10 1 Nov 2003 sem_getvalue(3RT)
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