diff options
Diffstat (limited to 'src/udev/udev-watch.c')
| -rw-r--r-- | src/udev/udev-watch.c | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/src/udev/udev-watch.c b/src/udev/udev-watch.c new file mode 100644 index 0000000..8656fb0 --- /dev/null +++ b/src/udev/udev-watch.c @@ -0,0 +1,174 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * 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 "device-util.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 -errno; + + 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_debug_errno(SYNTHETIC_ERRNO(EINVAL), + "Invalid inotify descriptor."); + + if (rename("/run/udev/watch", "/run/udev/watch.old") < 0) { + if (errno != ENOENT) + return log_warning_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_warning_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_debug_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_debug_errno(r, "Failed to create sd_device object for '%s', ignoring: %m", device); + goto unlink; + } + + log_device_debug(dev, "Restoring old watch"); + (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_debug_errno(SYNTHETIC_ERRNO(EINVAL), + "Invalid inotify descriptor."); + + r = sd_device_get_devname(dev, &devnode); + if (r < 0) + return log_device_error_errno(dev, r, "Failed to get device name: %m"); + + log_device_debug(dev, "Adding watch on '%s'", devnode); + wd = inotify_add_watch(inotify_fd, devnode, IN_CLOSE_WRITE); + if (wd < 0) + return log_device_full_errno(dev, errno == ENOENT ? LOG_DEBUG : LOG_ERR, 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_device_error_errno(dev, 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_device_error_errno(dev, r, "Failed to get device id-filename: %m"); + + if (symlink(id_filename, filename) < 0) + return log_device_error_errno(dev, 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)]; + int wd, r; + + if (inotify_fd < 0) + return 0; /* Nothing to do. */ + + r = device_get_watch_handle(dev, &wd); + if (r == -ENOENT) + return 0; + if (r < 0) + return log_device_debug_errno(dev, r, "Failed to get watch handle, ignoring: %m"); + + log_device_debug(dev, "Removing watch"); + (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_debug_errno(SYNTHETIC_ERRNO(EINVAL), + "Invalid inotify descriptor."); + + if (wd < 0) + return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), + "Invalid watch handle."); + + xsprintf(filename, "/run/udev/watch/%d", wd); + r = readlink_malloc(filename, &device); + if (r == -ENOENT) + return 0; + if (r < 0) + return log_debug_errno(r, "Failed to read link '%s': %m", filename); + + r = sd_device_new_from_device_id(ret, device); + if (r == -ENODEV) + return 0; + if (r < 0) + return log_debug_errno(r, "Failed to create sd_device object for '%s': %m", device); + + return 1; +} |