semget - get set of semaphores
#include <sys/types.h> #include <sys/ipc.h> #include <sys/sem.h>
int semget(key_t key, int nsems, int semflg);
The semget() function returns the semaphore identifier associated with key.
A semaphore identifier and associated data structure and set containing nsems semaphores (see intro(2)) are created for key if one of the following is true:
nsems semaphores (see intro(2)) are created for key if one of the -->
o key is equal to IPC_PRIVATE.
o key does not already have a semaphore identifier associated with it, and (semflg&IPC_CREAT) is true.
On creation, the data structure associated with the new semaphore identifier is initialized as follows:
o sem_perm.cuid, sem_perm.uid, sem_perm.cgid, and sem_perm.gid are set equal to the effective user ID and effective group ID, respectively, of the calling process.
o The access permission bits of sem_perm.mode are set equal to the access permission bits of semflg.
o sem_nsems is set equal to the value of nsems.
o sem_otime is set equal to 0 and sem_ctime is set equal to the current time.
Upon successful completion, a non-negative integer representing a semaphore identifier is returned. Otherwise, -1 is returned and errno is set to indicate the error.
The semget() function will fail if:
EACCESA semaphore identifier exists for key, but operation permission (see intro(2)) as specified by the low-order 9 bits of semflg would not be granted.
EEXISTA semaphore identifier exists for key but both (semflg&IPC_CREAT) and (semflg&IPC_EXCL) are both true.
EINVALThe nsems argument is either less than or equal to 0 or greater than the system-imposed limit. See NOTES.
A semaphore identifier exists for key, but the number of semaphores in the set associated with it is less than nsems and nsems is not equal to 0.
ENOENTA semaphore identifier does not exist for key and (semflg&IPC_CREAT) is false.
ENOSPCA semaphore identifier is to be created but the system-imposed limit on the maximum number of allowed semaphores or semaphore identifiers system-wide would be exceeded. See NOTES.
See attributes(5) for descriptions of the following attributes:
ATTRIBUTE TYPE ATTRIBUTE VALUE Interface Stability Standard
ipcrm(1), ipcs(1), rctladm(1M), intro(2), semctl(2), semop(2), setrctl(2), ftok(3C), attributes(5), standards(5)
The system-imposed limit on the value of the nsems argument is the maintained on a per-process basis using the process.max-sem-nsems resource control.
The system-imposed limit on the number of semaphore identifiers is maintained on a per-project basis using the project.max-sem-ids resource control. The zone.max-sem-ids resource control limis the total number of semaphore identifiers that can be allocated by a zone.
See rctladm(1M) and setrctl(2) for information about using resource controls.
|SunOS 5.11||semget (2)||14 Aug 2006|