contrib/sendmail/libsm/shm.c

   1 /*
   2  * Copyright (c) 2000-2001, 2003 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 1.10.2.6 2003/06/13 21:17:48 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 /*
  21 **  SM_SHMSTART -- initialize shared memory segment.
  22 **
  23 **      Parameters:
  24 **              key -- key for shared memory.
  25 **              size -- size of segment.
  26 **              shmflag -- initial flags.
  27 **              shmid -- pointer to return id.
  28 **              owner -- create segment.
  29 **
  30 **      Returns:
  31 **              pointer to shared memory segment,
  32 **              NULL on failure.
  33 **
  34 **      Side Effects:
  35 **              attaches shared memory segment.
  36 */
  37
  38 void *
  39 sm_shmstart(key, size, shmflg, shmid, owner)
  40         key_t key;
  41         int size;
  42         int shmflg;
  43         int *shmid;
  44         bool owner;
  45 {
  46         int save_errno;
  47         void *shm = SM_SHM_NULL;
  48
  49         /* default: user/group accessible */
  50         if (shmflg == 0)
  51                 shmflg = SHM_R|SHM_W|(SHM_R>>3)|(SHM_W>>3);
  52         if (owner)
  53                 shmflg |= IPC_CREAT|IPC_EXCL;
  54         *shmid = shmget(key, size, shmflg);
  55         if (*shmid < 0)
  56                 goto error;
  57
  58         shm = shmat(*shmid, (void *) 0, 0);
  59         if (shm == SM_SHM_NULL)
  60                 goto error;
  61
  62         return shm;
  63
  64   error:
  65         save_errno = errno;
  66         if (shm != SM_SHM_NULL || *shmid >= 0)
  67                 sm_shmstop(shm, *shmid, owner);
  68         *shmid = SM_SHM_NO_ID;
  69         errno = save_errno;
  70         return (void *) 0;
  71 }
  72
  73
  74 /*
  75 **  SM_SHMSTOP -- stop using shared memory segment.
  76 **
  77 **      Parameters:
  78 **              shm -- pointer to shared memory.
  79 **              shmid -- id.
  80 **              owner -- delete segment.
  81 **
  82 **      Returns:
  83 **              0 on success.
  84 **              < 0 on failure.
  85 **
  86 **      Side Effects:
  87 **              detaches (and maybe removes) shared memory segment.
  88 */
  89
  90
  91 int
  92 sm_shmstop(shm, shmid, owner)
  93         void *shm;
  94         int shmid;
  95         bool owner;
  96 {
  97         int r;
  98
  99         if (shm != SM_SHM_NULL && (r = shmdt(shm)) < 0)
 100                 return r;
 101         if (owner && shmid >= 0 && (r = shmctl(shmid, IPC_RMID, NULL)) < 0)
 102                 return r;
 103         return 0;
 104 }
 105
 106
 107 #endif /* SM_CONF_SHM */