1 /*
2 * Copyright 2000 Massachusetts Institute of Technology
3 *
4 * Permission to use, copy, modify, and distribute this software and
5 * its documentation for any purpose and without fee is hereby
6 * granted, provided that both the above copyright notice and this
7 * permission notice appear in all copies, that both the above
8 * copyright notice and this permission notice appear in all
9 * supporting documentation, and that the name of M.I.T. not be used
10 * in advertising or publicity pertaining to distribution of the
11 * software without specific, written prior permission. M.I.T. makes
12 * no representations about the suitability of this software for any
13 * purpose. It is provided "as is" without express or implied
14 * warranty.
15 *
16 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS
17 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
18 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
20 * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
23 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
26 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $FreeBSD: src/lib/libc/gen/posixshm.c,v 1.2.2.1 2000/08/22 01:48:12 jhb Exp $
30 */
31
32 #include "namespace.h"
33 #include <sys/types.h>
34 #include <sys/param.h>
35 #include <sys/fcntl.h>
36 #include <sys/mman.h>
37 #include <sys/stat.h>
38
39 #include <errno.h>
40 #include <unistd.h>
41 #include <string.h>
42 #include "un-namespace.h"
43
44 static int mkintermediatedirs(int dfd, const char *path);
45
46 int
shm_open(const char * path,int flags,mode_t mode)47 shm_open(const char *path, int flags, mode_t mode)
48 {
49 int dfd;
50 int fd;
51 struct stat stab;
52
53 if ((flags & O_ACCMODE) == O_WRONLY) {
54 errno = EINVAL;
55 return (-1);
56 }
57
58 while (*path == '/')
59 ++path;
60
61 /*
62 * Expect a tmpfs filesystem for our shm base. If for some reason
63 * it does not exist (it really should), fall-back to /tmp.
64 */
65 dfd = _open("/var/run/shm", O_RDONLY|O_DIRECTORY);
66 if (dfd < 0)
67 dfd = _open("/tmp", O_RDONLY|O_DIRECTORY);
68
69 if (dfd >= 0) {
70 fd = _openat(dfd, path, flags, mode);
71 if (fd < 0 && errno == ENOENT &&
72 mkintermediatedirs(dfd, path) == 0)
73 {
74 fd = _openat(dfd, path, flags, mode);
75 }
76 _close(dfd);
77 } else {
78 fd = -1;
79 }
80
81 if (fd != -1) {
82 if (_fstat(fd, &stab) != 0 || !S_ISREG(stab.st_mode)) {
83 _close(fd);
84 errno = EINVAL;
85 return (-1);
86 }
87
88 if (_fcntl(fd, F_SETFD, FD_CLOEXEC) != 0 ||
89 _fcntl(fd, F_SETFL, (int)FPOSIXSHM) != 0) {
90 _close(fd);
91 return (-1);
92 }
93 }
94 return (fd);
95 }
96
97 int
shm_unlink(const char * path)98 shm_unlink(const char *path)
99 {
100 int res;
101 int dfd;
102
103 while (*path == '/')
104 ++path;
105
106 /*
107 * Expect a tmpfs filesystem for our shm base. If for some reason
108 * it does not exist (it really should), fall-back to /tmp.
109 */
110 dfd = _open("/var/run/shm", O_RDONLY|O_DIRECTORY);
111 if (dfd < 0)
112 dfd = _open("/tmp", O_RDONLY|O_DIRECTORY);
113
114 if (dfd >= 0) {
115 res = _unlinkat(dfd, path, 0);
116 _close(dfd);
117 } else {
118 res = -1;
119 }
120 return res;
121 }
122
123 /*
124 * Create any missing intermediate directories, modes 1777
125 */
126 static int
mkintermediatedirs(int dfd,const char * path)127 mkintermediatedirs(int dfd, const char *path)
128 {
129 const char *eptr;
130 char buf[PATH_MAX+1];
131 size_t len;
132 int res = 0;
133
134 eptr = path - 1;
135 while ((eptr = strchr(eptr + 1, '/')) != NULL) {
136 len = eptr - path;
137 if (len > PATH_MAX) {
138 errno = EINVAL;
139 return -1;
140 }
141 bcopy(path, buf, len);
142 buf[len] = 0;
143 res = _mkdirat(dfd, buf, 01777);
144 if (res < 0 && errno != EEXIST)
145 break;
146 }
147 return res;
148 }
149