contrib/sendmail/libsm/shm.c

   1 /*
   2  * Copyright (c) 2000-2001, 2003, 2005 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 1.19 2005/07/14 22:34:28 ca Exp $")
  12
  13 #if SM_CONF_SHM
  14 # include <stdlib.h>
  15 # include <unistd.h>
  16 # include <errno.h>
  17 # include <sm/string.h>
  18 # include <sm/shm.h>
  19
  20
  21 /*
  22 **  SM_SHMSTART -- initialize shared memory segment.
  23 **
  24 **      Parameters:
  25 **              key -- key for shared memory.
  26 **              size -- size of segment.
  27 **              shmflag -- initial flags.
  28 **              shmid -- pointer to return id.
  29 **              owner -- create segment.
  30 **
  31 **      Returns:
  32 **              pointer to shared memory segment,
  33 **              NULL on failure.
  34 **
  35 **      Side Effects:
  36 **              attaches shared memory segment.
  37 */
  38
  39 void *
  40 sm_shmstart(key, size, shmflg, shmid, owner)
  41         key_t key;
  42         int size;
  43         int shmflg;
  44         int *shmid;
  45         bool owner;
  46 {
  47         int save_errno;
  48         void *shm = SM_SHM_NULL;
  49
  50         /* default: user/group accessible */
  51         if (shmflg == 0)
  52                 shmflg = SHM_R|SHM_W|(SHM_R>>3)|(SHM_W>>3);
  53         if (owner)
  54                 shmflg |= IPC_CREAT|IPC_EXCL;
  55         *shmid = shmget(key, size, shmflg);
  56         if (*shmid < 0)
  57                 goto error;
  58
  59         shm = shmat(*shmid, (void *) 0, 0);
  60         if (shm == SM_SHM_NULL)
  61                 goto error;
  62
  63         return shm;
  64
  65   error:
  66         save_errno = errno;
  67         if (shm != SM_SHM_NULL || *shmid >= 0)
  68                 sm_shmstop(shm, *shmid, owner);
  69         *shmid = SM_SHM_NO_ID;
  70         errno = save_errno;
  71         return (void *) 0;
  72 }
  73
  74
  75 /*
  76 **  SM_SHMSTOP -- stop using shared memory segment.
  77 **
  78 **      Parameters:
  79 **              shm -- pointer to shared memory.
  80 **              shmid -- id.
  81 **              owner -- delete segment.
  82 **
  83 **      Returns:
  84 **              0 on success.
  85 **              < 0 on failure.
  86 **
  87 **      Side Effects:
  88 **              detaches (and maybe removes) shared memory segment.
  89 */
  90
  91
  92 int
  93 sm_shmstop(shm, shmid, owner)
  94         void *shm;
  95         int shmid;
  96         bool owner;
  97 {
  98         int r;
  99
 100         if (shm != SM_SHM_NULL && (r = shmdt(shm)) < 0)
 101                 return r;
 102         if (owner && shmid >= 0 && (r = shmctl(shmid, IPC_RMID, NULL)) < 0)
 103                 return r;
 104         return 0;
 105 }
 106
 107
 108 /*
 109 **  SM_SHMSETOWNER -- set owner/group/mode of shared memory segment.
 110 **
 111 **      Parameters:
 112 **              shmid -- id.
 113 **              uid -- uid to use
 114 **              gid -- gid to use
 115 **              mode -- mode to use
 116 **
 117 **      Returns:
 118 **              0 on success.
 119 **              < 0 on failure.
 120 */
 121
 122 int
 123 sm_shmsetowner(shmid, uid, gid, mode)
 124         int shmid;
 125         uid_t uid;
 126         gid_t gid;
 127         mode_t mode;
 128 {
 129         int r;
 130         struct shmid_ds shmid_ds;
 131
 132         memset(&shmid_ds, 0, sizeof(shmid_ds));
 133         if ((r = shmctl(shmid, IPC_STAT, &shmid_ds)) < 0)
 134                 return r;
 135         shmid_ds.shm_perm.uid = uid;
 136         shmid_ds.shm_perm.gid = gid;
 137         shmid_ds.shm_perm.mode = mode;
 138         if ((r = shmctl(shmid, IPC_SET, &shmid_ds)) < 0)
 139                 return r;
 140         return 0;
 141 }
 142 #endif /* SM_CONF_SHM */