xref: /illumos-gate/usr/src/cmd/sendmail/libsm/shm.c (revision 7c478bd9)
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 1.18 2005/02/09 01:54:51 ca Exp $")
14 
15 #if SM_CONF_SHM
16 # include <stdlib.h>
17 # include <unistd.h>
18 # include <errno.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 int
124 sm_shmsetowner(shmid, uid, gid, mode)
125 	int shmid;
126 	uid_t uid;
127 	gid_t gid;
128 	mode_t mode;
129 {
130 	int r;
131 	struct shmid_ds shmid_ds;
132 
133 	memset(&shmid_ds, 0, sizeof(shmid_ds));
134 	if ((r = shmctl(shmid, IPC_STAT, &shmid_ds)) < 0)
135 		return r;
136 	shmid_ds.shm_perm.uid = uid;
137 	shmid_ds.shm_perm.gid = gid;
138 	shmid_ds.shm_perm.mode = mode;
139 	if ((r = shmctl(shmid, IPC_SET, &shmid_ds)) < 0)
140 		return r;
141 	return 0;
142 }
143 #endif /* SM_CONF_SHM */
144