opensem(2xnx) (XENIX System Compatibility)
opensem --
(XENIX) open a semaphore
Synopsis
cc [flag . . . ] flag . . . -lx
int opensem(char
sem_name);
Description
opensem opens a semaphore named by sem_name and returns the
unique semaphore identification number sem_num used by waitsem
and sigsem.
creatsem should always be called to initialize
the semaphore before the first attempt to open it.
Return values
opensem returns a value of -1 if an error occurs.
If the semaphore
named does not exist, errno is set to ENOENT.
If the file
specified is not a semaphore file (that is, a file previously created by
a process using a call to creatsem), errno is set to
ENOTNAM.
If the semaphore has become invalid due to inappropriate
use, errno is set to ENAVAIL.
References
creatsem(2xnx),
sigsem(2xnx),
waitsem(2xnx)
Notices
It is not advisable to open the same semaphore more than once.
Although it is possible to do this, it may result in a deadlock.
30 January 1998
© 1998 The Santa Cruz Operation, Inc. All rights reserved.