man/man2/semget.2

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 semget 2 "14 Aug 2006" "SunOS 5.11" "System Calls"
 NAME
semget - get set of semaphores
 SYNOPSIS

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>

int semget(key_t key, int nsems, int semflg);


 DESCRIPTION

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:


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.

 RETURN VALUES

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.
 ERRORS

The semget() function will fail if:

EACCES

A 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.


EEXIST

A semaphore identifier exists for key but both
(semflg&IPC_CREAT) and (semflg&IPC_EXCL) are both true.


EINVAL

The 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.


ENOENT

A semaphore identifier does not exist for key and
(semflg&IPC_CREAT) is false.


ENOSPC

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. See NOTES.


 ATTRIBUTES

See attributes(5) for descriptions of the following attributes:


ATTRIBUTE TYPEATTRIBUTE VALUE
Interface StabilityStandard


 SEE ALSO

ipcrm(1), ipcs(1), rctladm(1M), Intro(2),
semctl(2), semop(2), setrctl(2), ftok(3C),
attributes(5), standards(5)
 NOTES

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.