2 * Copyright (c) 2000-2001, 2005 Sendmail, Inc. and its suppliers.
5 * By using this file, you agree to the terms and conditions set
6 * forth in the LICENSE file which can be found at the top level of
7 * the sendmail distribution.
11 SM_RCSID("@(#)$Id: sem.c,v 1.12 2005/03/25 21:27:02 ca Exp $")
20 ** SM_SEM_START -- initialize semaphores
23 ** key -- key for semaphores.
24 ** nsem -- number of semaphores.
25 ** semflg -- flag for semget(), if 0, use a default.
26 ** owner -- create semaphores.
34 sm_sem_start(key, nsem, semflg, owner)
41 unsigned short *semvals;
45 semflg = (SEM_A|SEM_R)|((SEM_A|SEM_R) >> 3);
47 semflg |= IPC_CREAT|IPC_EXCL;
48 semid = semget(key, nsem, semflg);
56 semvals = (unsigned short *) sm_malloc(nsem * sizeof semvals);
59 semarg.array = semvals;
61 /* initialize semaphore values to be available */
62 for (i = 0; i < nsem; i++)
64 if (semctl(semid, 0, SETALL, semarg) < 0)
78 ** SM_SEM_STOP -- stop using semaphores.
81 ** semid -- id for semaphores.
92 return semctl(semid, 0, IPC_RMID, NULL);
96 ** SM_SEM_ACQ -- acquire semaphore.
99 ** semid -- id for semaphores.
100 ** semnum -- number of semaphore.
101 ** timeout -- how long to wait for operation to succeed.
109 sm_sem_acq(semid, semnum, timeout)
115 struct sembuf semops[1];
117 semops[0].sem_num = semnum;
118 semops[0].sem_op = -1;
119 semops[0].sem_flg = SEM_UNDO |
120 (timeout != SM_TIME_FOREVER ? 0 : IPC_NOWAIT);
121 if (timeout == SM_TIME_IMMEDIATE || timeout == SM_TIME_FOREVER)
122 return semop(semid, semops, 1);
125 r = semop(semid, semops, 1);
130 } while (timeout > 0);
135 ** SM_SEM_REL -- release semaphore.
138 ** semid -- id for semaphores.
139 ** semnum -- number of semaphore.
140 ** timeout -- how long to wait for operation to succeed.
148 sm_sem_rel(semid, semnum, timeout)
154 struct sembuf semops[1];
157 /* XXX should we check whether the value is already 0 ? */
158 SM_REQUIRE(sm_get_sem(semid, semnum) > 0);
159 #endif /* PARANOID */
161 semops[0].sem_num = semnum;
162 semops[0].sem_op = 1;
163 semops[0].sem_flg = SEM_UNDO |
164 (timeout != SM_TIME_FOREVER ? 0 : IPC_NOWAIT);
165 if (timeout == SM_TIME_IMMEDIATE || timeout == SM_TIME_FOREVER)
166 return semop(semid, semops, 1);
169 r = semop(semid, semops, 1);
174 } while (timeout > 0);
179 ** SM_SEM_GET -- get semaphore value.
182 ** semid -- id for semaphores.
183 ** semnum -- number of semaphore.
186 ** value of semaphore on success.
191 sm_sem_get(semid, semnum)
197 if ((semval = semctl(semid, semnum, GETVAL, NULL)) < 0)
201 #endif /* SM_CONF_SEM */