/*
 * Copyright (c) 2000-2001, 2003, 2005 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: shm.c,v 1.19 2005/07/14 22:34:28 ca Exp $")

#if SM_CONF_SHM
# include <stdlib.h>
# include <unistd.h>
# include <errno.h>
# include <sm/string.h>
# include <sm/shm.h>


/*
**  SM_SHMSTART -- initialize shared memory segment.
**
**      Parameters:
**              key -- key for shared memory.
**              size -- size of segment.
**              shmflag -- initial flags.
**              shmid -- pointer to return id.
**              owner -- create segment.
**
**      Returns:
**              pointer to shared memory segment,
**              NULL on failure.
**
**      Side Effects:
**              attaches shared memory segment.
*/

void *
sm_shmstart(key, size, shmflg, shmid, owner)
        key_t key;
        int size;
        int shmflg;
        int *shmid;
        bool owner;
{
        int save_errno;
        void *shm = SM_SHM_NULL;

        /* default: user/group accessible */
        if (shmflg == 0)
                shmflg = SHM_R|SHM_W|(SHM_R>>3)|(SHM_W>>3);
        if (owner)
                shmflg |= IPC_CREAT|IPC_EXCL;
        *shmid = shmget(key, size, shmflg);
        if (*shmid < 0)
                goto error;

        shm = shmat(*shmid, (void *) 0, 0);
        if (shm == SM_SHM_NULL)
                goto error;

        return shm;

  error:
        save_errno = errno;
        if (shm != SM_SHM_NULL || *shmid >= 0)
                sm_shmstop(shm, *shmid, owner);
        *shmid = SM_SHM_NO_ID;
        errno = save_errno;
        return (void *) 0;
}


/*
**  SM_SHMSTOP -- stop using shared memory segment.
**
**      Parameters:
**              shm -- pointer to shared memory.
**              shmid -- id.
**              owner -- delete segment.
**
**      Returns:
**              0 on success.
**              < 0 on failure.
**
**      Side Effects:
**              detaches (and maybe removes) shared memory segment.
*/


int
sm_shmstop(shm, shmid, owner)
        void *shm;
        int shmid;
        bool owner;
{
        int r;

        if (shm != SM_SHM_NULL && (r = shmdt(shm)) < 0)
                return r;
        if (owner && shmid >= 0 && (r = shmctl(shmid, IPC_RMID, NULL)) < 0)
                return r;
        return 0;
}


/*
**  SM_SHMSETOWNER -- set owner/group/mode of shared memory segment.
**
**      Parameters:
**              shmid -- id.
**              uid -- uid to use
**              gid -- gid to use
**              mode -- mode to use
**
**      Returns:
**              0 on success.
**              < 0 on failure.
*/

int
sm_shmsetowner(shmid, uid, gid, mode)
        int shmid;
        uid_t uid;
        gid_t gid;
        mode_t mode;
{
        int r;
        struct shmid_ds shmid_ds;

        memset(&shmid_ds, 0, sizeof(shmid_ds));
        if ((r = shmctl(shmid, IPC_STAT, &shmid_ds)) < 0)
                return r;
        shmid_ds.shm_perm.uid = uid;
        shmid_ds.shm_perm.gid = gid;
        shmid_ds.shm_perm.mode = mode;
        if ((r = shmctl(shmid, IPC_SET, &shmid_ds)) < 0)
                return r;
        return 0;
}
#endif /* SM_CONF_SHM */