From bd284db142c1d3fb6e2a709678c8828c12c52466 Mon Sep 17 00:00:00 2001 From: Scott James Remnant Date: Wed, 11 Feb 2009 17:38:56 +0000 Subject: udevd: optionally watch device nodes with inotify This allows you to re-process the rules if the content of the device has been changed, most useful for block subsystem to cause vol_id to be run again. --- udev/udev-watch.c | 236 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 236 insertions(+) create mode 100644 udev/udev-watch.c (limited to 'udev/udev-watch.c') diff --git a/udev/udev-watch.c b/udev/udev-watch.c new file mode 100644 index 0000000000..24df481cf8 --- /dev/null +++ b/udev/udev-watch.c @@ -0,0 +1,236 @@ +/* + * Copyright (C) 2004-2008 Kay Sievers + * Copyright (C) 2009 Canonical Ltd. + * + * 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 . + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#ifdef HAVE_INOTIFY +#include +#endif + +#include "udev.h" + +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 + */ +void udev_watch_init(struct udev *udev) +{ + inotify_fd = inotify_init(); + if (inotify_fd >= 0) { + int flags; + + flags = fcntl(inotify_fd, F_GETFD); + if (flags < 0) + flags = FD_CLOEXEC; + else + flags |= FD_CLOEXEC; + fcntl(inotify_fd, F_SETFD, flags); + } else if (errno == ENOSYS) + info(udev, "unable to use inotify, udevd will not monitor rule files changes\n"); + else + err(udev, "inotify_init failed: %m\n"); +} + +/* 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_strlcpy(oldname, udev_get_dev_path(udev), sizeof(oldname)); + util_strlcat(oldname, "/.udev/watch.old", sizeof(oldname)); + + util_strlcpy(filename, udev_get_dev_path(udev), sizeof(filename)); + util_strlcat(filename, "/.udev/watch", sizeof(filename)); + + 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; + } + + while ((ent = readdir(dir)) != NULL) { + char path[UTIL_PATH_SIZE]; + char buf[UTIL_PATH_SIZE]; + ssize_t len; + struct udev_device *dev; + + if (ent->d_name[0] < '0' || ent->d_name[0] > '9') + continue; + + util_strlcpy(path, oldname, sizeof(path)); + util_strlcat(path, "/", sizeof(path)); + util_strlcat(path, ent->d_name, sizeof(path)); + + len = readlink(path, buf, sizeof(buf)); + if (len <= 0) { + unlink(path); + continue; + } + + buf[len] = '\0'; + dbg(udev, "old watch to '%s' found\n", buf); + + dev = udev_device_new_from_syspath(udev, buf); + if (dev == NULL) { + unlink(path); + continue; + } + + udev_device_read_db(dev); + udev_device_set_info_loaded(dev); + + info(udev, "restoring old watch on '%s'\n", udev_device_get_devnode(dev)); + udev_watch_begin(udev, dev); + + udev_device_unref(dev); + + unlink(path); + } + + closedir(dir); + rmdir(oldname); + + } else if (errno != ENOENT) { + err(udev, "unable to move watches dir '%s', old watches will not be restored: %m", filename); + } +} + +static const char *udev_watch_filename(struct udev *udev, int wd) +{ + static char filename[UTIL_PATH_SIZE]; + char str[32]; + + sprintf(str, "%d", wd); + util_strlcpy(filename, udev_get_dev_path(udev), sizeof(filename)); + util_strlcat(filename, "/.udev/watch/", sizeof(filename)); + util_strlcat(filename, str, sizeof(filename)); + + return filename; +} + +void udev_watch_begin(struct udev *udev, struct udev_device *dev) +{ + const char *filename; + int wd; + + if (inotify_fd < 0) + return; + + 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); + } + + filename = udev_watch_filename(udev, wd); + util_create_path(udev, filename); + unlink(filename); + symlink(udev_device_get_syspath(dev), filename); +} + +void udev_watch_clear(struct udev *udev, struct udev_device *dev) +{ + static char filename[UTIL_PATH_SIZE]; + DIR *dir; + struct dirent *ent; + + util_strlcpy(filename, udev_get_dev_path(udev), sizeof(filename)); + util_strlcat(filename, "/.udev/watch", sizeof(filename)); + + dir = opendir(filename); + if (dir == NULL) + return; + + while ((ent = readdir(dir)) != NULL) { + char path[UTIL_PATH_SIZE]; + char buf[UTIL_PATH_SIZE]; + ssize_t len; + + if (ent->d_name[0] < '0' || ent->d_name[0] > '9') + continue; + + util_strlcpy(path, filename, sizeof(path)); + util_strlcat(path, "/", sizeof(path)); + util_strlcat(path, ent->d_name, sizeof(path)); + + len = readlink(path, buf, sizeof(buf)); + if (len <= 0) + continue; + + buf[len] = '\0'; + if (strcmp(buf, udev_device_get_syspath(dev))) + continue; + + /* this is the watch we're looking for */ + info(udev, "clearing existing watch on '%s'\n", udev_device_get_devnode(dev)); + udev_watch_end(udev, atoi(ent->d_name)); + } + + closedir(dir); +} + +void udev_watch_end(struct udev *udev, int wd) +{ + const char *filename; + + if (inotify_fd < 0 || wd < 0) + return; + + inotify_rm_watch(inotify_fd, wd); + + filename = udev_watch_filename(udev, wd); + unlink(filename); +} + +const char *udev_watch_lookup(struct udev *udev, int wd) +{ + const char *filename; + static char buf[UTIL_PATH_SIZE]; + ssize_t len; + + if (inotify_fd < 0 || wd < 0) + return NULL; + + filename = udev_watch_filename(udev, wd); + len = readlink(filename, buf, sizeof(buf)); + if (len > 0) { + buf[len] = '\0'; + + return buf; + } + + return NULL; +} -- cgit v1.2.3-54-g00ecf