rfkill: rework and make it listen on /dev/rfkill

With this rework we introduce systemd-rfkill.service as singleton that
is activated via systemd-rfkill.socket that listens on /dev/rfkill. That
way, we get notified each time a new rfkill device shows up or changes
state, in which case we restore and save its current setting to disk.

This is nicer than the previous logic, as this means we save/restore
state even of rfkill devices that are around only intermittently, and
save/restore the state even if the system is shutdown abruptly instead
of cleanly.

This implements what I suggested in #1019 and obsoletes it.

1 files changed, 355 insertions, 77 deletions

diff --git a/src/rfkill/rfkill.c b/src/rfkill/rfkill.c
index 904dec6bfc..d8a2f3694e 100644
--- a/src/rfkill/rfkill.c
+++ b/src/rfkill/rfkill.c
@@ -19,124 +19,402 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
-#include "util.h"
-#include "mkdir.h"
-#include "fileio.h"
+#include <linux/rfkill.h>
+#include <poll.h>
+
 #include "libudev.h"
+#include "sd-daemon.h"
+
+#include "fileio.h"
+#include "mkdir.h"
 #include "udev-util.h"
+#include "util.h"
 
-int main(int argc, char *argv[]) {
-        _cleanup_udev_unref_ struct udev *udev = NULL;
-        _cleanup_udev_device_unref_ struct udev_device *device = NULL;
-        _cleanup_free_ char *saved = NULL, *escaped_type = NULL, *escaped_path_id = NULL;
-        const char *name, *type, *path_id;
-        int r;
+#define EXIT_USEC (5 * USEC_PER_SEC)
 
-        if (argc != 3) {
-                log_error("This program requires two arguments.");
-                return EXIT_FAILURE;
-        }
+static const char* const rfkill_type_table[NUM_RFKILL_TYPES] = {
+        [RFKILL_TYPE_ALL] = "all",
+        [RFKILL_TYPE_WLAN] = "wlan",
+        [RFKILL_TYPE_BLUETOOTH] = "bluetooth",
+        [RFKILL_TYPE_UWB] = "uwb",
+        [RFKILL_TYPE_WIMAX] = "wimax",
+        [RFKILL_TYPE_WWAN] = "wwan",
+        [RFKILL_TYPE_GPS] = "gps",
+        [RFKILL_TYPE_FM] "fm",
+        [RFKILL_TYPE_NFC] "nfc",
+};
 
-        log_set_target(LOG_TARGET_AUTO);
-        log_parse_environment();
-        log_open();
+DEFINE_PRIVATE_STRING_TABLE_LOOKUP_TO_STRING(rfkill_type, int);
 
-        umask(0022);
+static int find_device(
+                struct udev *udev,
+                const struct rfkill_event *event,
+                struct udev_device **ret) {
 
-        r = mkdir_p("/var/lib/systemd/rfkill", 0755);
-        if (r < 0) {
-                log_error_errno(r, "Failed to create rfkill directory: %m");
-                return EXIT_FAILURE;
-        }
+        _cleanup_free_ char *sysname = NULL;
+        struct udev_device *device;
+        const char *name;
 
-        udev = udev_new();
-        if (!udev) {
-                log_oom();
-                return EXIT_FAILURE;
-        }
+        assert(udev);
+        assert(event);
+        assert(ret);
 
-        device = udev_device_new_from_subsystem_sysname(udev, "rfkill", argv[2]);
-        if (!device) {
-                log_debug_errno(errno, "Failed to get rfkill device '%s', ignoring: %m", argv[2]);
-                return EXIT_SUCCESS;
-        }
+        if (asprintf(&sysname, "rfkill%i", event->idx) < 0)
+                return log_oom();
+
+        device = udev_device_new_from_subsystem_sysname(udev, "rfkill", sysname);
+        if (!device)
+                return log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_ERR, errno, "Failed to open device: %m");
 
         name = udev_device_get_sysattr_value(device, "name");
         if (!name) {
-                log_error("rfkill device has no name? Ignoring device.");
-                return EXIT_SUCCESS;
+                log_debug("Device has no name, ignoring.");
+                udev_device_unref(device);
+                return -ENOENT;
         }
 
         log_debug("Operating on rfkill device '%s'.", name);
 
-        type = udev_device_get_sysattr_value(device, "type");
-        if (!type) {
-                log_error("rfkill device has no type? Ignoring device.");
-                return EXIT_SUCCESS;
+        *ret = device;
+        return 0;
+}
+
+static int wait_for_initialized(
+                struct udev *udev,
+                struct udev_device *device,
+                struct udev_device **ret) {
+
+        _cleanup_udev_monitor_unref_ struct udev_monitor *monitor = NULL;
+        struct udev_device *d;
+        const char *sysname;
+        int watch_fd, r;
+
+        assert(udev);
+        assert(device);
+        assert(ret);
+
+        if (udev_device_get_is_initialized(device) != 0) {
+                *ret = udev_device_ref(device);
+                return 0;
         }
 
-        escaped_type = cescape(type);
-        if (!escaped_type) {
-                log_oom();
-                return EXIT_FAILURE;
+        assert_se(sysname = udev_device_get_sysname(device));
+
+        /* Wait until the device is initialized, so that we can get
+         * access to the ID_PATH property */
+
+        monitor = udev_monitor_new_from_netlink(udev, "udev");
+        if (!monitor)
+                return log_error_errno(errno, "Failed to acquire monitor: %m");
+
+        r = udev_monitor_filter_add_match_subsystem_devtype(monitor, "rfkill", NULL);
+        if (r < 0)
+                return log_error_errno(r, "Failed to add rfkill udev match to monitor: %m");
+
+        r = udev_monitor_enable_receiving(monitor);
+        if (r < 0)
+                return log_error_errno(r, "Failed to enable udev receiving: %m");
+
+        watch_fd = udev_monitor_get_fd(monitor);
+        if (watch_fd < 0)
+                return log_error_errno(watch_fd, "Failed to get watch fd: %m");
+
+        /* Check again, maybe things changed */
+        d = udev_device_new_from_subsystem_sysname(udev, "rfkill", sysname);
+        if (!d)
+                return log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_ERR, errno, "Failed to open device: %m");
+
+        if (udev_device_get_is_initialized(d) != 0) {
+                *ret = d;
+                return 0;
+        }
+
+        for (;;) {
+                _cleanup_udev_device_unref_ struct udev_device *t = NULL;
+
+                r = fd_wait_for_event(watch_fd, POLLIN, USEC_INFINITY);
+                if (r == -EINTR)
+                        continue;
+                if (r < 0)
+                        return log_error_errno(r, "Failed to watch udev monitor: %m");
+
+                t = udev_monitor_receive_device(monitor);
+                if (!t)
+                        continue;
+
+                if (streq_ptr(udev_device_get_sysname(device), sysname)) {
+                        *ret = udev_device_ref(t);
+                        return 0;
+                }
         }
+}
+
+static int determine_state_file(
+                struct udev *udev,
+                const struct rfkill_event *event,
+                struct udev_device *d,
+                char **ret) {
+
+        _cleanup_udev_device_unref_ struct udev_device *device = NULL;
+        const char *path_id, *type;
+        char *state_file;
+        int r;
+
+        assert(event);
+        assert(d);
+        assert(ret);
+
+        r = wait_for_initialized(udev, d, &device);
+        if (r < 0)
+                return r;
+
+        assert_se(type = rfkill_type_to_string(event->type));
 
         path_id = udev_device_get_property_value(device, "ID_PATH");
         if (path_id) {
+                _cleanup_free_ char *escaped_path_id = NULL;
+
                 escaped_path_id = cescape(path_id);
-                if (!escaped_path_id) {
-                        log_oom();
-                        return EXIT_FAILURE;
-                }
+                if (!escaped_path_id)
+                        return log_oom();
 
-                saved = strjoin("/var/lib/systemd/rfkill/", escaped_path_id, ":", escaped_type, NULL);
+                state_file = strjoin("/var/lib/systemd/rfkill/", escaped_path_id, ":", type, NULL);
         } else
-                saved = strjoin("/var/lib/systemd/rfkill/", escaped_type, NULL);
+                state_file = strjoin("/var/lib/systemd/rfkill/", type, NULL);
+
+        if (!state_file)
+                return log_oom();
+
+        *ret = state_file;
+        return 0;
+}
+
+static int load_state(
+                int rfkill_fd,
+                struct udev *udev,
+                const struct rfkill_event *event) {
+
+        _cleanup_udev_device_unref_ struct udev_device *device = NULL;
+        _cleanup_free_ char *state_file = NULL, *value = NULL;
+        struct rfkill_event we;
+        ssize_t l;
+        int b, r;
 
-        if (!saved) {
-                log_oom();
+        assert(rfkill_fd >= 0);
+        assert(udev);
+        assert(event);
+
+        if (!shall_restore_state())
+                return 0;
+
+        r = find_device(udev, event, &device);
+        if (r < 0)
+                return r;
+
+        r = determine_state_file(udev, event, device, &state_file);
+        if (r < 0)
+                return r;
+
+        r = read_one_line_file(state_file, &value);
+        if (r == -ENOENT) {
+                /* No state file? Then save the current state */
+
+                r = write_string_file(state_file, one_zero(event->soft), WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to write state file %s: %m", state_file);
+
+                log_debug("Saved state '%s' to %s.", one_zero(event->soft), state_file);
+                return 0;
+        }
+        if (r < 0)
+                return log_error_errno(r, "Failed to read state file %s: %m", state_file);
+
+        b = parse_boolean(value);
+        if (b < 0)
+                return log_error_errno(b, "Failed to parse state file %s: %m", state_file);
+
+        we = (struct rfkill_event) {
+                .op = RFKILL_OP_CHANGE,
+                .idx = event->idx,
+                .soft = b,
+        };
+
+        l = write(rfkill_fd, &we, sizeof(we));
+        if (l < 0)
+                return log_error_errno(errno, "Failed to restore rfkill state for %i: %m", event->idx);
+        if (l != sizeof(we)) {
+                log_error("Couldn't write rfkill event structure, too short.");
+                return -EIO;
+        }
+
+        log_debug("Loaded state '%s' from %s.", one_zero(b), state_file);
+        return 0;
+}
+
+static int save_state(
+                int rfkill_fd,
+                struct udev *udev,
+                const struct rfkill_event *event) {
+
+        _cleanup_udev_device_unref_ struct udev_device *device = NULL;
+        _cleanup_free_ char *state_file = NULL;
+        int r;
+
+        assert(rfkill_fd >= 0);
+        assert(udev);
+        assert(event);
+
+        r = find_device(udev, event, &device);
+        if (r < 0)
+                return r;
+
+        r = determine_state_file(udev, event, device, &state_file);
+        if (r < 0)
+                return r;
+
+        r = write_string_file(state_file, one_zero(event->soft), WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC);
+        if (r < 0)
+                return log_error_errno(r, "Failed to write state file %s: %m", state_file);
+
+        log_debug("Saved state '%s' to %s.", one_zero(event->soft), state_file);
+        return 0;
+}
+
+int main(int argc, char *argv[]) {
+        _cleanup_udev_unref_ struct udev *udev = NULL;
+        _cleanup_close_ int rfkill_fd = -1;
+        bool ready = false;
+        int r, n;
+
+        if (argc > 1) {
+                log_error("This program requires no arguments.");
                 return EXIT_FAILURE;
         }
 
-        if (streq(argv[1], "load")) {
-                _cleanup_free_ char *value = NULL;
+        log_set_target(LOG_TARGET_AUTO);
+        log_parse_environment();
+        log_open();
 
-                if (!shall_restore_state())
-                        return EXIT_SUCCESS;
+        umask(0022);
 
-                r = read_one_line_file(saved, &value);
-                if (r == -ENOENT)
-                        return EXIT_SUCCESS;
-                if (r < 0) {
-                        log_error_errno(r, "Failed to read %s: %m", saved);
-                        return EXIT_FAILURE;
+        udev = udev_new();
+        if (!udev) {
+                r = log_oom();
+                goto finish;
+        }
+
+        r = mkdir_p("/var/lib/systemd/rfkill", 0755);
+        if (r < 0) {
+                log_error_errno(r, "Failed to create rfkill directory: %m");
+                goto finish;
+        }
+
+        n = sd_listen_fds(false);
+        if (n < 0) {
+                r = log_error_errno(n, "Failed to determine whether we got any file descriptors passed: %m");
+                goto finish;
+        }
+        if (n > 1) {
+                log_error("Got too many file descriptors.");
+                r = -EINVAL;
+                goto finish;
+        }
+
+        if (n == 0) {
+                rfkill_fd = open("/dev/rfkill", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
+                if (rfkill_fd < 0) {
+                        if (errno == ENOENT) {
+                                log_debug_errno(errno, "Missing rfkill subsystem, or no device present, exiting.");
+                                r = 0;
+                                goto finish;
+                        }
+
+                        r = log_error_errno(errno, "Failed to open /dev/rfkill: %m");
+                        goto finish;
                 }
+        } else {
+                rfkill_fd = SD_LISTEN_FDS_START;
 
-                r = udev_device_set_sysattr_value(device, "soft", value);
+                r = fd_nonblock(rfkill_fd, 1);
                 if (r < 0) {
-                        log_debug_errno(r, "Failed to write 'soft' attribute on rfkill device, ignoring: %m");
-                        return EXIT_SUCCESS;
+                        log_error_errno(r, "Failed to make /dev/rfkill socket non-blocking: %m");
+                        goto finish;
                 }
+        }
+
+        for (;;) {
+                struct rfkill_event event;
+                const char *type;
+                ssize_t l;
 
-        } else if (streq(argv[1], "save")) {
-                const char *value;
+                l = read(rfkill_fd, &event, sizeof(event));
+                if (l < 0) {
+                        if (errno == EAGAIN) {
 
-                value = udev_device_get_sysattr_value(device, "soft");
-                if (!value) {
-                        log_debug_errno(r, "Failed to read system attribute, ignoring device: %m");
-                        return EXIT_SUCCESS;
+                                if (!ready) {
+                                        /* Notify manager that we are
+                                         * now finished with
+                                         * processing whatever was
+                                         * queued */
+                                        (void) sd_notify(false, "READY=1");
+                                        ready = true;
+                                }
+
+                                /* Hang around for a bit, maybe there's more coming */
+
+                                r = fd_wait_for_event(rfkill_fd, POLLIN, EXIT_USEC);
+                                if (r == -EINTR)
+                                        continue;
+                                if (r < 0) {
+                                        log_error_errno(r, "Failed to poll() on device: %m");
+                                        goto finish;
+                                }
+                                if (r > 0)
+                                        continue;
+
+                                log_debug("All events read and idle, exiting.");
+                                break;
+                        }
+
+                        log_error_errno(errno, "Failed to read from /dev/rfkill: %m");
                 }
 
-                r = write_string_file(saved, value, WRITE_STRING_FILE_CREATE);
-                if (r < 0) {
-                        log_error_errno(r, "Failed to write %s: %m", saved);
-                        return EXIT_FAILURE;
+                if (l != RFKILL_EVENT_SIZE_V1) {
+                        log_error("Read event structure of invalid size.");
+                        r = -EIO;
+                        goto finish;
                 }
 
-        } else {
-                log_error("Unknown verb %s.", argv[1]);
-                return EXIT_FAILURE;
+                type = rfkill_type_to_string(event.type);
+                if (!type) {
+                        log_debug("An rfkill device of unknown type %i discovered, ignoring.", event.type);
+                        continue;
+                }
+
+                switch (event.op) {
+
+                case RFKILL_OP_ADD:
+                        log_debug("A new rfkill device has been added with index %i and type %s.", event.idx, type);
+                        (void) load_state(rfkill_fd, udev, &event);
+                        break;
+
+                case RFKILL_OP_DEL:
+                        log_debug("An rfkill device has been removed with index %i and type %s", event.idx, type);
+                        break;
+
+                case RFKILL_OP_CHANGE:
+                        log_debug("An rfkill device has changed state with index %i and type %s", event.idx, type);
+                        (void) save_state(rfkill_fd, udev, &event);
+                        break;
+
+                default:
+                        log_debug("Unknown event %i from /dev/rfkill for index %i and type %s, ignoring.", event.op, event.idx, type);
+                        break;
+                }
         }
 
-        return EXIT_SUCCESS;
+        r = 0;
+
+finish:
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 }