usr/src/cmd/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 #pragma ident   "%Z%%M% %I%     %E% SMI"
  11
  12 #include <sm/gen.h>
  13 SM_RCSID("@(#)$Id: shm.c,v 1.19 2005/07/14 22:34:28 ca Exp $")
  14
  15 #if SM_CONF_SHM
  16 # include <stdlib.h>
  17 # include <unistd.h>
  18 # include <errno.h>
  19 # include <sm/string.h>
  20 # include <sm/shm.h>
  21
  22
  23 /*
  24 **  SM_SHMSTART -- initialize shared memory segment.
  25 **
  26 **      Parameters:
  27 **              key -- key for shared memory.
  28 **              size -- size of segment.
  29 **              shmflag -- initial flags.
  30 **              shmid -- pointer to return id.
  31 **              owner -- create segment.
  32 **
  33 **      Returns:
  34 **              pointer to shared memory segment,
  35 **              NULL on failure.
  36 **
  37 **      Side Effects:
  38 **              attaches shared memory segment.
  39 */
  40
  41 void *
  42 sm_shmstart(key, size, shmflg, shmid, owner)
  43         key_t key;
  44         int size;
  45         int shmflg;
  46         int *shmid;
  47         bool owner;
  48 {
  49         int save_errno;
  50         void *shm = SM_SHM_NULL;
  51
  52         /* default: user/group accessible */
  53         if (shmflg == 0)
  54                 shmflg = SHM_R|SHM_W|(SHM_R>>3)|(SHM_W>>3);
  55         if (owner)
  56                 shmflg |= IPC_CREAT|IPC_EXCL;
  57         *shmid = shmget(key, size, shmflg);
  58         if (*shmid < 0)
  59                 goto error;
  60
  61         shm = shmat(*shmid, (void *) 0, 0);
  62         if (shm == SM_SHM_NULL)
  63                 goto error;
  64
  65         return shm;
  66
  67   error:
  68         save_errno = errno;
  69         if (shm != SM_SHM_NULL || *shmid >= 0)
  70                 sm_shmstop(shm, *shmid, owner);
  71         *shmid = SM_SHM_NO_ID;
  72         errno = save_errno;
  73         return (void *) 0;
  74 }
  75
  76
  77 /*
  78 **  SM_SHMSTOP -- stop using shared memory segment.
  79 **
  80 **      Parameters:
  81 **              shm -- pointer to shared memory.
  82 **              shmid -- id.
  83 **              owner -- delete segment.
  84 **
  85 **      Returns:
  86 **              0 on success.
  87 **              < 0 on failure.
  88 **
  89 **      Side Effects:
  90 **              detaches (and maybe removes) shared memory segment.
  91 */
  92
  93
  94 int
  95 sm_shmstop(shm, shmid, owner)
  96         void *shm;
  97         int shmid;
  98         bool owner;
  99 {
 100         int r;
 101
 102         if (shm != SM_SHM_NULL && (r = shmdt(shm)) < 0)
 103                 return r;
 104         if (owner && shmid >= 0 && (r = shmctl(shmid, IPC_RMID, NULL)) < 0)
 105                 return r;
 106         return 0;
 107 }
 108
 109
 110 /*
 111 **  SM_SHMSETOWNER -- set owner/group/mode of shared memory segment.
 112 **
 113 **      Parameters:
 114 **              shmid -- id.
 115 **              uid -- uid to use
 116 **              gid -- gid to use
 117 **              mode -- mode to use
 118 **
 119 **      Returns:
 120 **              0 on success.
 121 **              < 0 on failure.
 122 */
 123
 124 int
 125 sm_shmsetowner(shmid, uid, gid, mode)
 126         int shmid;
 127         uid_t uid;
 128         gid_t gid;
 129         mode_t mode;
 130 {
 131         int r;
 132         struct shmid_ds shmid_ds;
 133
 134         memset(&shmid_ds, 0, sizeof(shmid_ds));
 135         if ((r = shmctl(shmid, IPC_STAT, &shmid_ds)) < 0)
 136                 return r;
 137         shmid_ds.shm_perm.uid = uid;
 138         shmid_ds.shm_perm.gid = gid;
 139         shmid_ds.shm_perm.mode = mode;
 140         if ((r = shmctl(shmid, IPC_SET, &shmid_ds)) < 0)
 141                 return r;
 142         return 0;
 143 }
 144 #endif /* SM_CONF_SHM */