shm.c revision 261363 
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>
11SM_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/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
39void *
40sm_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
92int
93sm_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
122int
123sm_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 */
143