NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SUMMARY OF TRUSTED SOLARIS CHANGES | SEE ALSO
#include <sys/types.h> #include <sys/ipc.h> #include <sys/sem.h>int semget(key_t key, int nsems, int semflg);
#include <sys/tsol/ipcl.h>int semgetl(key_t key, int nsems, int semflg, const bslabel_t *slabel);
A semaphore structure is identified by a unique combination of key and sensitivity label. This qualification of keys by sensitivity labels allows applications that use semaphore structures to be run at multiple process sensitivity labels without inadvertently sharing data.
The semget() function returns the semaphore identifier associated with the union of key and the sensitivity label of the calling process. semgetl() returns the semaphore-structure identifier associated with the union of key and slabel. If the value of slabel does not match the sensitivity label of the calling process, then the effective privilege set of the process must include both PRIV_IPC_MAC_READ
and PRIV_IPC_MAC_WRITE
.
If discretionary read/write access as specified by the low-order 9 bits of semflg is denied to the calling process, semget() and semgetl() require one or both of these privileges: PRIV_IPC_DAC_READ
and PRIV_IPC_DAC_WRITE
.
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:
key is equal to IPC_PRIVATE.
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:
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.
The access permission bits of sem_perm.mode are set equal to the access permission bits of semflg.
sem_nsems is set equal to the value of nsems.
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:
A semaphore-structure identifier exists for the union of key and sensitivity label, but operation permission [see intro(2)] as specified by the low-order 9 bits of semflg would not be granted; or the sensitivity label check did not pass, and the calling process does not have the appropriate privilege override(s) in its set of effective privileges.
A semaphore identifier exists for key but both (semflg&IPC_CREAT) and (semflg&IPC_EXCL) are both true.
slabel points to an illegal address.
The label to which slabel points is not a valid sensitivity label.
The nsems argument is either less than or equal to 0 or greater than the system-imposed limit; or 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.
A semaphore identifier does not exist for key and (semflg&IPC_CREAT) is false.
A 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.
A semaphore identifier is to be created but the system-imposed limit on the maximum number of allowed semaphores systemwide would be exceeded.
Appropriate privilege is required to override access checks.
Sensitivity labels are used together with key to determine semaphore-group identifiers.
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SUMMARY OF TRUSTED SOLARIS CHANGES | SEE ALSO