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/* SPDX-License-Identifier: GPL-2.0+ */
/*
* Copyright © 2009 Canonical Ltd.
* Copyright © 2009 Scott James Remnant <scott@netsplit.com>
*/
#include <sys/inotify.h>
#include <unistd.h>
#include "alloc-util.h"
#include "device-private.h"
#include "dirent-util.h"
#include "fs-util.h"
#include "mkdir.h"
#include "stdio-util.h"
#include "udev-watch.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(void) {
inotify_fd = inotify_init1(IN_CLOEXEC);
if (inotify_fd < 0)
return log_error_errno(errno, "Failed to create inotify descriptor: %m");
return inotify_fd;
}
/* Move any old watches directory out of the way, and then restore the watches. */
int udev_watch_restore(void) {
struct dirent *ent;
DIR *dir;
int r;
if (inotify_fd < 0)
return log_error_errno(EINVAL, "Invalid inotify descriptor.");
if (rename("/run/udev/watch", "/run/udev/watch.old") < 0) {
if (errno != ENOENT)
return log_error_errno(errno, "Failed to move watches directory /run/udev/watch. Old watches will not be restored: %m");
return 0;
}
dir = opendir("/run/udev/watch.old");
if (!dir)
return log_error_errno(errno, "Failed to open old watches directory /run/udev/watch.old. Old watches will not be restored: %m");
FOREACH_DIRENT_ALL(ent, dir, break) {
_cleanup_(sd_device_unrefp) sd_device *dev = NULL;
_cleanup_free_ char *device = NULL;
if (ent->d_name[0] == '.')
continue;
r = readlinkat_malloc(dirfd(dir), ent->d_name, &device);
if (r < 0) {
log_error_errno(r, "Failed to read link '/run/udev/watch.old/%s', ignoring: %m", ent->d_name);
goto unlink;
}
r = sd_device_new_from_device_id(&dev, device);
if (r < 0) {
log_error_errno(r, "Failed to create sd_device object for '%s', ignoring: %m", device);
goto unlink;
}
if (DEBUG_LOGGING) {
const char *devnode = NULL;
(void) sd_device_get_devname(dev, &devnode);
log_debug("Restoring old watch on '%s'", strnull(devnode));
}
(void) udev_watch_begin(dev);
unlink:
(void) unlinkat(dirfd(dir), ent->d_name, 0);
}
(void) closedir(dir);
(void) rmdir("/run/udev/watch.old");
return 0;
}
int udev_watch_begin(sd_device *dev) {
char filename[STRLEN("/run/udev/watch/") + DECIMAL_STR_MAX(int)];
const char *devnode, *id_filename;
int wd, r;
if (inotify_fd < 0)
return log_error_errno(EINVAL, "Invalid inotify descriptor.");
r = sd_device_get_devname(dev, &devnode);
if (r < 0)
return log_error_errno(r, "Failed to get device name: %m");
log_debug("Adding watch on '%s'", devnode);
wd = inotify_add_watch(inotify_fd, devnode, IN_CLOSE_WRITE);
if (wd < 0)
return log_error_errno(errno, "Failed to add device '%s' to watch: %m", devnode);
device_set_watch_handle(dev, wd);
xsprintf(filename, "/run/udev/watch/%d", wd);
r = mkdir_parents(filename, 0755);
if (r < 0)
return log_error_errno(r, "Failed to create parent directory of '%s': %m", filename);
(void) unlink(filename);
r = device_get_id_filename(dev, &id_filename);
if (r < 0)
return log_error_errno(r, "Failed to get device id-filename: %m");
if (symlink(id_filename, filename) < 0)
return log_error_errno(errno, "Failed to create symlink %s: %m", filename);
return 0;
}
int udev_watch_end(sd_device *dev) {
char filename[STRLEN("/run/udev/watch/") + DECIMAL_STR_MAX(int)];
const char *devnode;
int wd, r;
if (inotify_fd < 0)
return log_error_errno(EINVAL, "Invalid inotify descriptor.");
r = sd_device_get_devname(dev, &devnode);
if (r < 0)
return log_error_errno(r, "Failed to get device name: %m");
r = device_get_watch_handle(dev, &wd);
if (r == -ENOENT)
return 0;
if (r < 0)
return log_error_errno(r, "Failed to get watch handle for device '%s', ignoring: %m", devnode);
log_debug("Removing watch on '%s'", devnode);
(void) inotify_rm_watch(inotify_fd, wd);
xsprintf(filename, "/run/udev/watch/%d", wd);
(void) unlink(filename);
device_set_watch_handle(dev, -1);
return 0;
}
int udev_watch_lookup(int wd, sd_device **ret) {
char filename[STRLEN("/run/udev/watch/") + DECIMAL_STR_MAX(int)];
_cleanup_free_ char *device = NULL;
int r;
assert(ret);
if (inotify_fd < 0)
return log_error_errno(EINVAL, "Invalid inotify descriptor.");
if (wd < 0)
return log_error_errno(EINVAL, "Invalid watch handle.");
xsprintf(filename, "/run/udev/watch/%d", wd);
r = readlink_malloc(filename, &device);
if (r < 0) {
if (r != -ENOENT)
return log_error_errno(errno, "Failed to read link '%s': %m", filename);
return 0;
}
r = sd_device_new_from_device_id(ret, device);
if (r < 0)
return log_error_errno(r, "Failed to create sd_device object for '%s': %m", device);
return 0;
}
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