contrib/sendmail/libsm/shm.c

   1 /*
   2  * Copyright (c) 2000-2001 Sendmail, Inc. and its suppliers.
   3  *      All rights reserved.
   4  *
   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.
   8  */
   9
  10 #include <sm/gen.h>
  11 SM_RCSID("@(#)$Id: shm.c,v 1.10 2001/12/14 00:22:58 ca Exp $")
  12
  13 #if SM_CONF_SHM
  14 # include <stdlib.h>
  15 # include <unistd.h>
  16 # include <errno.h>
  17 # include <sm/shm.h>
  18
  19 /*
  20 **  SM_SHMSTART -- initialize shared memory segment.
  21 **
  22 **      Parameters:
  23 **              key -- key for shared memory.
  24 **              size -- size of segment.
  25 **              shmflag -- initial flags.
  26 **              shmid -- pointer to return id.
  27 **              owner -- create segment.
  28 **
  29 **      Returns:
  30 **              pointer to shared memory segment,
  31 **              NULL on failure.
  32 **
  33 **      Side Effects:
  34 **              attaches shared memory segment.
  35 */
  36
  37 void *
  38 sm_shmstart(key, size, shmflg, shmid, owner)
  39         key_t key;
  40         int size;
  41         int shmflg;
  42         int *shmid;
  43         bool owner;
  44 {
  45         int save_errno;
  46         void *shm = SM_SHM_NULL;
  47
  48         /* default: user/group accessible */
  49         if (shmflg == 0)
  50                 shmflg = SHM_R|SHM_W|(SHM_R>>3)|(SHM_W>>3);
  51         if (owner)
  52                 shmflg |= IPC_CREAT|IPC_EXCL;
  53         *shmid = shmget(key, size, shmflg);
  54         if (*shmid < 0)
  55                 goto error;
  56
  57         shm = shmat(*shmid, (void *) 0, 0);
  58         if (shm == SM_SHM_NULL)
  59                 goto error;
  60
  61         return shm;
  62
  63   error:
  64         save_errno = errno;
  65         if (shm != SM_SHM_NULL || *shmid >= 0)
  66                 sm_shmstop(shm, *shmid, owner);
  67         *shmid = SM_SHM_NO_ID;
  68         errno = save_errno;
  69         return (void *) 0;
  70 }
  71
  72 /*
  73 **  SM_SHMSTOP -- stop using shared memory segment.
  74 **
  75 **      Parameters:
  76 **              shm -- pointer to shared memory.
  77 **              shmid -- id.
  78 **              owner -- delete segment.
  79 **
  80 **      Returns:
  81 **              0 on success.
  82 **              < 0 on failure.
  83 **
  84 **      Side Effects:
  85 **              detaches (and maybe removes) shared memory segment.
  86 */
  87
  88 int
  89 sm_shmstop(shm, shmid, owner)
  90         void *shm;
  91         int shmid;
  92         bool owner;
  93 {
  94         int r;
  95
  96         if (shm != SM_SHM_NULL && (r = shmdt(shm)) < 0)
  97                 return r;
  98         if (owner && shmid >= 0 && (r = shmctl(shmid, IPC_RMID, NULL)) < 0)
  99                 return r;
 100         return 0;
 101 }
 102 #endif /* SM_CONF_SHM */