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Diffstat (limited to 'contrib/sendmail/libsm/sem.c')
| -rw-r--r-- | contrib/sendmail/libsm/sem.c | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/contrib/sendmail/libsm/sem.c b/contrib/sendmail/libsm/sem.c new file mode 100644 index 0000000..83a54e3 --- /dev/null +++ b/contrib/sendmail/libsm/sem.c @@ -0,0 +1,245 @@ +/* + * Copyright (c) 2000-2001, 2005, 2008 Sendmail, Inc. and its suppliers. + * All rights reserved. + * + * By using this file, you agree to the terms and conditions set + * forth in the LICENSE file which can be found at the top level of + * the sendmail distribution. + */ + +#include <sm/gen.h> +SM_RCSID("@(#)$Id: sem.c,v 1.14 2008/05/30 16:26:38 ca Exp $") + +#if SM_CONF_SEM +# include <stdlib.h> +# include <unistd.h> +# include <sm/string.h> +# include <sm/sem.h> +# include <sm/heap.h> +# include <errno.h> + +/* +** SM_SEM_START -- initialize semaphores +** +** Parameters: +** key -- key for semaphores. +** nsem -- number of semaphores. +** semflg -- flag for semget(), if 0, use a default. +** owner -- create semaphores. +** +** Returns: +** id for semaphores. +** < 0 on failure. +*/ + +int +sm_sem_start(key, nsem, semflg, owner) + key_t key; + int nsem; + int semflg; + bool owner; +{ + int semid, i, err; + unsigned short *semvals; + + semvals = NULL; + if (semflg == 0) + semflg = (SEM_A|SEM_R)|((SEM_A|SEM_R) >> 3); + if (owner) + semflg |= IPC_CREAT|IPC_EXCL; + semid = semget(key, nsem, semflg); + if (semid < 0) + goto error; + + if (owner) + { + union semun semarg; + + semvals = (unsigned short *) sm_malloc(nsem * sizeof semvals); + if (semvals == NULL) + goto error; + semarg.array = semvals; + + /* initialize semaphore values to be available */ + for (i = 0; i < nsem; i++) + semvals[i] = 1; + if (semctl(semid, 0, SETALL, semarg) < 0) + goto error; + } + return semid; + +error: + err = errno; + if (semvals != NULL) + sm_free(semvals); + if (semid >= 0) + sm_sem_stop(semid); + return (err > 0) ? (0 - err) : -1; +} + +/* +** SM_SEM_STOP -- stop using semaphores. +** +** Parameters: +** semid -- id for semaphores. +** +** Returns: +** 0 on success. +** < 0 on failure. +*/ + +int +sm_sem_stop(semid) + int semid; +{ + return semctl(semid, 0, IPC_RMID, NULL); +} + +/* +** SM_SEM_ACQ -- acquire semaphore. +** +** Parameters: +** semid -- id for semaphores. +** semnum -- number of semaphore. +** timeout -- how long to wait for operation to succeed. +** +** Returns: +** 0 on success. +** < 0 on failure. +*/ + +int +sm_sem_acq(semid, semnum, timeout) + int semid; + int semnum; + int timeout; +{ + int r; + struct sembuf semops[1]; + + semops[0].sem_num = semnum; + semops[0].sem_op = -1; + semops[0].sem_flg = SEM_UNDO | + (timeout != SM_TIME_FOREVER ? 0 : IPC_NOWAIT); + if (timeout == SM_TIME_IMMEDIATE || timeout == SM_TIME_FOREVER) + return semop(semid, semops, 1); + do + { + r = semop(semid, semops, 1); + if (r == 0) + return r; + sleep(1); + --timeout; + } while (timeout > 0); + return r; +} + +/* +** SM_SEM_REL -- release semaphore. +** +** Parameters: +** semid -- id for semaphores. +** semnum -- number of semaphore. +** timeout -- how long to wait for operation to succeed. +** +** Returns: +** 0 on success. +** < 0 on failure. +*/ + +int +sm_sem_rel(semid, semnum, timeout) + int semid; + int semnum; + int timeout; +{ + int r; + struct sembuf semops[1]; + +#if PARANOID + /* XXX should we check whether the value is already 0 ? */ + SM_REQUIRE(sm_get_sem(semid, semnum) > 0); +#endif /* PARANOID */ + + semops[0].sem_num = semnum; + semops[0].sem_op = 1; + semops[0].sem_flg = SEM_UNDO | + (timeout != SM_TIME_FOREVER ? 0 : IPC_NOWAIT); + if (timeout == SM_TIME_IMMEDIATE || timeout == SM_TIME_FOREVER) + return semop(semid, semops, 1); + do + { + r = semop(semid, semops, 1); + if (r == 0) + return r; + sleep(1); + --timeout; + } while (timeout > 0); + return r; +} + +/* +** SM_SEM_GET -- get semaphore value. +** +** Parameters: +** semid -- id for semaphores. +** semnum -- number of semaphore. +** +** Returns: +** value of semaphore on success. +** < 0 on failure. +*/ + +int +sm_sem_get(semid, semnum) + int semid; + int semnum; +{ + int semval; + + if ((semval = semctl(semid, semnum, GETVAL, NULL)) < 0) + return -1; + return semval; +} + +/* +** SM_SEMSETOWNER -- set owner/group/mode of semaphores. +** +** Parameters: +** semid -- id for semaphores. +** uid -- uid to use +** gid -- gid to use +** mode -- mode to use +** +** Returns: +** 0 on success. +** < 0 on failure. +*/ + +int +sm_semsetowner(semid, uid, gid, mode) + int semid; + uid_t uid; + gid_t gid; + mode_t mode; +{ + int r; + struct semid_ds semidds; + union semun { + int val; + struct semid_ds *buf; + ushort *array; + } arg; + + memset(&semidds, 0, sizeof(semidds)); + arg.buf = &semidds; + if ((r = semctl(semid, 1, IPC_STAT, arg)) < 0) + return r; + semidds.sem_perm.uid = uid; + semidds.sem_perm.gid = gid; + semidds.sem_perm.mode = mode; + if ((r = semctl(semid, 1, IPC_SET, arg)) < 0) + return r; + return 0; +} +#endif /* SM_CONF_SEM */ |
