contrib/sendmail/libsm/shm.c

   1 /*
   2  * Copyright (c) 2000-2001, 2003, 2005 Proofpoint, 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 1.20 2013-11-22 20:51:43 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/conf.h>
  19 # include <sm/shm.h>
  20
  21
  22 /*
  23 **  SM_SHMSTART -- initialize shared memory segment.
  24 **
  25 **      Parameters:
  26 **              key -- key for shared memory.
  27 **              size -- size of segment.
  28 **              shmflag -- initial flags.
  29 **              shmid -- pointer to return id.
  30 **              owner -- create segment.
  31 **
  32 **      Returns:
  33 **              pointer to shared memory segment,
  34 **              NULL on failure.
  35 **
  36 **      Side Effects:
  37 **              attaches shared memory segment.
  38 */
  39
  40 void *
  41 sm_shmstart(key, size, shmflg, shmid, owner)
  42         key_t key;
  43         int size;
  44         int shmflg;
  45         int *shmid;
  46         bool owner;
  47 {
  48         int save_errno;
  49         void *shm = SM_SHM_NULL;
  50
  51         /* default: user/group accessible */
  52         if (shmflg == 0)
  53                 shmflg = SHM_R|SHM_W|(SHM_R>>3)|(SHM_W>>3);
  54         if (owner)
  55                 shmflg |= IPC_CREAT|IPC_EXCL;
  56         *shmid = shmget(key, size, shmflg);
  57         if (*shmid < 0)
  58                 goto error;
  59
  60         shm = shmat(*shmid, (void *) 0, 0);
  61         if (shm == SM_SHM_NULL)
  62                 goto error;
  63
  64         return shm;
  65
  66   error:
  67         save_errno = errno;
  68         if (shm != SM_SHM_NULL || *shmid >= 0)
  69                 sm_shmstop(shm, *shmid, owner);
  70         *shmid = SM_SHM_NO_ID;
  71         errno = save_errno;
  72         return (void *) 0;
  73 }
  74
  75
  76 /*
  77 **  SM_SHMSTOP -- stop using shared memory segment.
  78 **
  79 **      Parameters:
  80 **              shm -- pointer to shared memory.
  81 **              shmid -- id.
  82 **              owner -- delete segment.
  83 **
  84 **      Returns:
  85 **              0 on success.
  86 **              < 0 on failure.
  87 **
  88 **      Side Effects:
  89 **              detaches (and maybe removes) shared memory segment.
  90 */
  91
  92
  93 int
  94 sm_shmstop(shm, shmid, owner)
  95         void *shm;
  96         int shmid;
  97         bool owner;
  98 {
  99         int r;
 100
 101         if (shm != SM_SHM_NULL && (r = shmdt(shm)) < 0)
 102                 return r;
 103         if (owner && shmid >= 0 && (r = shmctl(shmid, IPC_RMID, NULL)) < 0)
 104                 return r;
 105         return 0;
 106 }
 107
 108
 109 /*
 110 **  SM_SHMSETOWNER -- set owner/group/mode of shared memory segment.
 111 **
 112 **      Parameters:
 113 **              shmid -- id.
 114 **              uid -- uid to use
 115 **              gid -- gid to use
 116 **              mode -- mode to use
 117 **
 118 **      Returns:
 119 **              0 on success.
 120 **              < 0 on failure.
 121 */
 122
 123 #ifdef __STDC__
 124 int
 125 sm_shmsetowner(int shmid, uid_t uid, gid_t gid, MODE_T mode)
 126 #else /* __STDC__ */
 127 int
 128 sm_shmsetowner(shmid, uid, gid, mode)
 129         int shmid;
 130         uid_t uid;
 131         gid_t gid;
 132         MODE_T mode;
 133 #endif /* __STDC__ */
 134 {
 135         int r;
 136         struct shmid_ds shmid_ds;
 137
 138         memset(&shmid_ds, 0, sizeof(shmid_ds));
 139         if ((r = shmctl(shmid, IPC_STAT, &shmid_ds)) < 0)
 140                 return r;
 141         shmid_ds.shm_perm.uid = uid;
 142         shmid_ds.shm_perm.gid = gid;
 143         shmid_ds.shm_perm.mode = mode;
 144         if ((r = shmctl(shmid, IPC_SET, &shmid_ds)) < 0)
 145                 return r;
 146         return 0;
 147 }
 148 #endif /* SM_CONF_SHM */