chiark / gitweb /
Also merge into the top-level Makefile.am the simpler extras.
[elogind.git] / udev / udev-watch.c
1 /*
2  * Copyright (C) 2004-2008 Kay Sievers <kay.sievers@vrfy.org>
3  * Copyright (C) 2009 Canonical Ltd.
4  * Copyright (C) 2009 Scott James Remnant <scott@netsplit.com>
5  *
6  * This program is free software: you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation, either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
18  */
19
20 #include <sys/types.h>
21 #include <errno.h>
22 #include <fcntl.h>
23 #include <stdio.h>
24 #include <dirent.h>
25 #include <stddef.h>
26 #include <stdlib.h>
27 #include <string.h>
28 #include <unistd.h>
29 #include <sys/inotify.h>
30
31 #include "udev.h"
32
33 static int inotify_fd = -1;
34
35 /* inotify descriptor, will be shared with rules directory;
36  * set to cloexec since we need our children to be able to add
37  * watches for us
38  */
39 int udev_watch_init(struct udev *udev)
40 {
41         inotify_fd = inotify_init();
42         if (inotify_fd >= 0)
43                 util_set_fd_cloexec(inotify_fd);
44         else
45                 err(udev, "inotify_init failed: %m\n");
46         return inotify_fd;
47 }
48
49 /* move any old watches directory out of the way, and then restore
50  * the watches
51  */
52 void udev_watch_restore(struct udev *udev)
53 {
54         char filename[UTIL_PATH_SIZE], oldname[UTIL_PATH_SIZE];
55
56         if (inotify_fd < 0)
57                 return;
58
59         util_strscpyl(oldname, sizeof(oldname), udev_get_dev_path(udev), "/.udev/watch.old", NULL);
60         util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev), "/.udev/watch", NULL);
61         if (rename(filename, oldname) == 0) {
62                 DIR *dir;
63                 struct dirent *ent;
64
65                 dir = opendir(oldname);
66                 if (dir == NULL) {
67                         err(udev, "unable to open old watches dir '%s', old watches will not be restored: %m", oldname);
68                         return;
69                 }
70
71                 for (ent = readdir(dir); ent != NULL; ent = readdir(dir)) {
72                         char device[UTIL_PATH_SIZE];
73                         char *s;
74                         size_t l;
75                         ssize_t len;
76                         struct udev_device *dev;
77
78                         if (ent->d_name[0] < '0' || ent->d_name[0] > '9')
79                                 continue;
80
81                         s = device;
82                         l = util_strpcpy(&s, sizeof(device), udev_get_sys_path(udev));
83                         len = readlinkat(dirfd(dir), ent->d_name, s, l);
84                         if (len <= 0 || len >= (ssize_t)l) {
85                                 unlinkat(dirfd(dir), ent->d_name, 0);
86                                 continue;
87                         }
88                         s[len] = '\0';
89                         dbg(udev, "old watch to '%s' found\n", device);
90                         dev = udev_device_new_from_syspath(udev, device);
91                         if (dev == NULL) {
92                                 unlinkat(dirfd(dir), ent->d_name, 0);
93                                 continue;
94                         }
95
96                         info(udev, "restoring old watch on '%s'\n", udev_device_get_devnode(dev));
97                         udev_watch_begin(udev, dev);
98
99                         udev_device_unref(dev);
100                         unlinkat(dirfd(dir), ent->d_name, 0);
101                 }
102
103                 closedir(dir);
104                 rmdir(oldname);
105
106         } else if (errno != ENOENT) {
107                 err(udev, "unable to move watches dir '%s', old watches will not be restored: %m", filename);
108         }
109 }
110
111 void udev_watch_begin(struct udev *udev, struct udev_device *dev)
112 {
113         char filename[UTIL_PATH_SIZE];
114         int wd;
115
116         if (inotify_fd < 0)
117                 return;
118
119         info(udev, "adding watch on '%s'\n", udev_device_get_devnode(dev));
120         wd = inotify_add_watch(inotify_fd, udev_device_get_devnode(dev), IN_CLOSE_WRITE);
121         if (wd < 0) {
122                 err(udev, "inotify_add_watch(%d, %s, %o) failed: %m\n",
123                     inotify_fd, udev_device_get_devnode(dev), IN_CLOSE_WRITE);
124         }
125
126         snprintf(filename, sizeof(filename), "%s/.udev/watch/%d", udev_get_dev_path(udev), wd);
127         util_create_path(udev, filename);
128         unlink(filename);
129         symlink(udev_device_get_devpath(dev), filename);
130
131         udev_device_set_watch_handle(dev, wd);
132 }
133
134 void udev_watch_end(struct udev *udev, struct udev_device *dev)
135 {
136         int wd;
137         char filename[UTIL_PATH_SIZE];
138
139         if (inotify_fd < 0)
140                 return;
141
142         wd = udev_device_get_watch_handle(dev);
143         if (wd < 0)
144                 return;
145
146         info(udev, "removing watch on '%s'\n", udev_device_get_devnode(dev));
147         inotify_rm_watch(inotify_fd, wd);
148
149         snprintf(filename, sizeof(filename), "%s/.udev/watch/%d", udev_get_dev_path(udev), wd);
150         unlink(filename);
151
152         udev_device_set_watch_handle(dev, -1);
153 }
154
155 struct udev_device *udev_watch_lookup(struct udev *udev, int wd)
156 {
157         char filename[UTIL_PATH_SIZE];
158         char syspath[UTIL_PATH_SIZE];
159         char *s;
160         size_t l;
161         ssize_t len;
162
163         if (inotify_fd < 0 || wd < 0)
164                 return NULL;
165
166         snprintf(filename, sizeof(filename), "%s/.udev/watch/%d", udev_get_dev_path(udev), wd);
167         s = syspath;
168         l = util_strpcpy(&s, sizeof(syspath), udev_get_sys_path(udev));
169         len = readlink(filename, s, l);
170         if (len < 0 || (size_t)len >= l)
171                 return NULL;
172         s[len] = '\0';
173         return udev_device_new_from_syspath(udev, syspath);
174 }