sendmail/libsm/shm.c

/*
 * Copyright (c) 2000-2001, 2003, 2005 Proofpoint, 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 1.20 2013-11-22 20:51:43 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 */