2 * Copyright (c) 2000-2001, 2005, 2008 Proofpoint, 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 1.15 2013-11-22 20:51:43 ca Exp $")
16 # include <sm/string.h>
22 ** SM_SEM_START -- initialize semaphores
25 ** key -- key for semaphores.
26 ** nsem -- number of semaphores.
27 ** semflg -- flag for semget(), if 0, use a default.
28 ** owner -- create semaphores.
36 sm_sem_start(key, nsem, semflg, owner)
43 unsigned short *semvals;
47 semflg = (SEM_A|SEM_R)|((SEM_A|SEM_R) >> 3);
49 semflg |= IPC_CREAT|IPC_EXCL;
50 semid = semget(key, nsem, semflg);
58 semvals = (unsigned short *) sm_malloc(nsem * sizeof semvals);
61 semarg.array = semvals;
63 /* initialize semaphore values to be available */
64 for (i = 0; i < nsem; i++)
66 if (semctl(semid, 0, SETALL, semarg) < 0)
77 return (err > 0) ? (0 - err) : -1;
81 ** SM_SEM_STOP -- stop using semaphores.
84 ** semid -- id for semaphores.
95 return semctl(semid, 0, IPC_RMID, NULL);
99 ** SM_SEM_ACQ -- acquire semaphore.
102 ** semid -- id for semaphores.
103 ** semnum -- number of semaphore.
104 ** timeout -- how long to wait for operation to succeed.
112 sm_sem_acq(semid, semnum, timeout)
118 struct sembuf semops[1];
120 semops[0].sem_num = semnum;
121 semops[0].sem_op = -1;
122 semops[0].sem_flg = SEM_UNDO |
123 (timeout != SM_TIME_FOREVER ? 0 : IPC_NOWAIT);
124 if (timeout == SM_TIME_IMMEDIATE || timeout == SM_TIME_FOREVER)
125 return semop(semid, semops, 1);
128 r = semop(semid, semops, 1);
133 } while (timeout > 0);
138 ** SM_SEM_REL -- release semaphore.
141 ** semid -- id for semaphores.
142 ** semnum -- number of semaphore.
143 ** timeout -- how long to wait for operation to succeed.
151 sm_sem_rel(semid, semnum, timeout)
157 struct sembuf semops[1];
160 /* XXX should we check whether the value is already 0 ? */
161 SM_REQUIRE(sm_get_sem(semid, semnum) > 0);
164 semops[0].sem_num = semnum;
165 semops[0].sem_op = 1;
166 semops[0].sem_flg = SEM_UNDO |
167 (timeout != SM_TIME_FOREVER ? 0 : IPC_NOWAIT);
168 if (timeout == SM_TIME_IMMEDIATE || timeout == SM_TIME_FOREVER)
169 return semop(semid, semops, 1);
172 r = semop(semid, semops, 1);
177 } while (timeout > 0);
182 ** SM_SEM_GET -- get semaphore value.
185 ** semid -- id for semaphores.
186 ** semnum -- number of semaphore.
189 ** value of semaphore on success.
194 sm_sem_get(semid, semnum)
200 if ((semval = semctl(semid, semnum, GETVAL, NULL)) < 0)
206 ** SM_SEMSETOWNER -- set owner/group/mode of semaphores.
209 ** semid -- id for semaphores.
212 ** mode -- mode to use
220 sm_semsetowner(semid, uid, gid, mode)
227 struct semid_ds semidds;
230 struct semid_ds *buf;
234 memset(&semidds, 0, sizeof(semidds));
236 if ((r = semctl(semid, 1, IPC_STAT, arg)) < 0)
238 semidds.sem_perm.uid = uid;
239 semidds.sem_perm.gid = gid;
240 semidds.sem_perm.mode = mode;
241 if ((r = semctl(semid, 1, IPC_SET, arg)) < 0)
245 #endif /* SM_CONF_SEM */