udev-watch.c revision 4ec9c3e79771aa95586390cecff4218cc8938160
/*
* Copyright (C) 2004-2010 Kay Sievers <kay.sievers@vrfy.org>
* Copyright (C) 2009 Canonical Ltd.
* Copyright (C) 2009 Scott James Remnant <scott@netsplit.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <sys/types.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <dirent.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/inotify.h>
#include "udev.h"
static int inotify_fd = -1;
/* inotify descriptor, will be shared with rules directory;
* set to cloexec since we need our children to be able to add
* watches for us
*/
int udev_watch_init(struct udev *udev)
{
inotify_fd = inotify_init1(IN_CLOEXEC);
if (inotify_fd < 0)
err(udev, "inotify_init failed: %m\n");
return inotify_fd;
}
/* move any old watches directory out of the way, and then restore
* the watches
*/
void udev_watch_restore(struct udev *udev)
{
char filename[UTIL_PATH_SIZE], oldname[UTIL_PATH_SIZE];
if (inotify_fd < 0)
return;
util_strscpyl(oldname, sizeof(oldname), udev_get_run_path(udev), "/watch.old", NULL);
util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev), "/watch", NULL);
if (rename(filename, oldname) == 0) {
DIR *dir;
struct dirent *ent;
dir = opendir(oldname);
if (dir == NULL) {
err(udev, "unable to open old watches dir '%s', old watches will not be restored: %m", oldname);
return;
}
for (ent = readdir(dir); ent != NULL; ent = readdir(dir)) {
char device[UTIL_PATH_SIZE];
char *s;
size_t l;
ssize_t len;
struct udev_device *dev;
if (ent->d_name[0] == '.')
continue;
s = device;
l = util_strpcpy(&s, sizeof(device), udev_get_sys_path(udev));
len = readlinkat(dirfd(dir), ent->d_name, s, l);
if (len <= 0 || len == (ssize_t)l)
goto unlink;
s[len] = '\0';
dev = udev_device_new_from_id_filename(udev, s);
if (dev == NULL)
goto unlink;
info(udev, "restoring old watch on '%s'\n", udev_device_get_devnode(dev));
udev_watch_begin(udev, dev);
udev_device_unref(dev);
unlink:
unlinkat(dirfd(dir), ent->d_name, 0);
}
closedir(dir);
rmdir(oldname);
} else if (errno != ENOENT) {
err(udev, "unable to move watches dir '%s', old watches will not be restored: %m", filename);
}
}
void udev_watch_begin(struct udev *udev, struct udev_device *dev)
{
char filename[UTIL_PATH_SIZE];
int wd;
if (inotify_fd < 0)
return;
info(udev, "adding watch on '%s'\n", udev_device_get_devnode(dev));
wd = inotify_add_watch(inotify_fd, udev_device_get_devnode(dev), IN_CLOSE_WRITE);
if (wd < 0) {
err(udev, "inotify_add_watch(%d, %s, %o) failed: %m\n",
inotify_fd, udev_device_get_devnode(dev), IN_CLOSE_WRITE);
return;
}
snprintf(filename, sizeof(filename), "%s/watch/%d", udev_get_run_path(udev), wd);
util_create_path(udev, filename);
unlink(filename);
symlink(udev_device_get_id_filename(dev), filename);
udev_device_set_watch_handle(dev, wd);
}
void udev_watch_end(struct udev *udev, struct udev_device *dev)
{
int wd;
char filename[UTIL_PATH_SIZE];
if (inotify_fd < 0)
return;
wd = udev_device_get_watch_handle(dev);
if (wd < 0)
return;
info(udev, "removing watch on '%s'\n", udev_device_get_devnode(dev));
inotify_rm_watch(inotify_fd, wd);
snprintf(filename, sizeof(filename), "%s/watch/%d", udev_get_run_path(udev), wd);
unlink(filename);
udev_device_set_watch_handle(dev, -1);
}
struct udev_device *udev_watch_lookup(struct udev *udev, int wd)
{
char filename[UTIL_PATH_SIZE];
char majmin[UTIL_PATH_SIZE];
char *s;
size_t l;
ssize_t len;
if (inotify_fd < 0 || wd < 0)
return NULL;
snprintf(filename, sizeof(filename), "%s/watch/%d", udev_get_run_path(udev), wd);
s = majmin;
l = util_strpcpy(&s, sizeof(majmin), udev_get_sys_path(udev));
len = readlink(filename, s, l);
if (len <= 0 || (size_t)len == l)
return NULL;
s[len] = '\0';
return udev_device_new_from_id_filename(udev, s);
}