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/* SPDX-License-Identifier: GPL-2.0+ */
/*
* Copyright © 2009 Canonical Ltd.
* Copyright © 2009 Scott James Remnant <scott@netsplit.com>
*
*/
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <sys/inotify.h>
#include <unistd.h>
#include "dirent-util.h"
#include "stdio-util.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)
log_error_errno(errno, "inotify_init failed: %m");
return inotify_fd;
}
/* move any old watches directory out of the way, and then restore
* the watches
*/
void udev_watch_restore(struct udev *udev) {
if (inotify_fd < 0)
return;
if (rename("/run/udev/watch", "/run/udev/watch.old") == 0) {
DIR *dir;
struct dirent *ent;
dir = opendir("/run/udev/watch.old");
if (dir == NULL) {
log_error_errno(errno, "unable to open old watches dir /run/udev/watch.old; old watches will not be restored: %m");
return;
}
FOREACH_DIRENT_ALL(ent, dir, break) {
char device[UTIL_PATH_SIZE];
ssize_t len;
struct udev_device *dev;
if (ent->d_name[0] == '.')
continue;
len = readlinkat(dirfd(dir), ent->d_name, device, sizeof(device));
if (len <= 0 || len == (ssize_t)sizeof(device))
goto unlink;
device[len] = '\0';
dev = udev_device_new_from_device_id(udev, device);
if (dev == NULL)
goto unlink;
log_debug("restoring old watch on '%s'", udev_device_get_devnode(dev));
udev_watch_begin(udev, dev);
udev_device_unref(dev);
unlink:
(void) unlinkat(dirfd(dir), ent->d_name, 0);
}
closedir(dir);
rmdir("/run/udev/watch.old");
} else if (errno != ENOENT)
log_error_errno(errno, "unable to move watches dir /run/udev/watch; old watches will not be restored: %m");
}
void udev_watch_begin(struct udev *udev, struct udev_device *dev) {
char filename[sizeof("/run/udev/watch/") + DECIMAL_STR_MAX(int)];
int wd;
int r;
if (inotify_fd < 0)
return;
log_debug("adding watch on '%s'", udev_device_get_devnode(dev));
wd = inotify_add_watch(inotify_fd, udev_device_get_devnode(dev), IN_CLOSE_WRITE);
if (wd < 0) {
log_error_errno(errno, "inotify_add_watch(%d, %s, %o) failed: %m",
inotify_fd, udev_device_get_devnode(dev), IN_CLOSE_WRITE);
return;
}
xsprintf(filename, "/run/udev/watch/%d", wd);
mkdir_parents(filename, 0755);
unlink(filename);
r = symlink(udev_device_get_id_filename(dev), filename);
if (r < 0)
log_error_errno(errno, "Failed to create symlink %s: %m", filename);
udev_device_set_watch_handle(dev, wd);
}
void udev_watch_end(struct udev *udev, struct udev_device *dev) {
int wd;
char filename[sizeof("/run/udev/watch/") + DECIMAL_STR_MAX(int)];
if (inotify_fd < 0)
return;
wd = udev_device_get_watch_handle(dev);
if (wd < 0)
return;
log_debug("removing watch on '%s'", udev_device_get_devnode(dev));
inotify_rm_watch(inotify_fd, wd);
xsprintf(filename, "/run/udev/watch/%d", wd);
unlink(filename);
udev_device_set_watch_handle(dev, -1);
}
struct udev_device *udev_watch_lookup(struct udev *udev, int wd) {
char filename[sizeof("/run/udev/watch/") + DECIMAL_STR_MAX(int)];
char device[UTIL_NAME_SIZE];
ssize_t len;
if (inotify_fd < 0 || wd < 0)
return NULL;
xsprintf(filename, "/run/udev/watch/%d", wd);
len = readlink(filename, device, sizeof(device));
if (len <= 0 || (size_t)len == sizeof(device))
return NULL;
device[len] = '\0';
return udev_device_new_from_device_id(udev, device);
}
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