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.

Makefile-man.am

@@ -1807,11 +1807,16 @@ endif
 
 if ENABLE_RFKILL
 MANPAGES += \
-	man/systemd-rfkill@.service.8
+	man/systemd-rfkill.service.8
 MANPAGES_ALIAS += \
-	man/systemd-rfkill.8
-man/systemd-rfkill.8: man/systemd-rfkill@.service.8
-man/systemd-rfkill.html: man/systemd-rfkill@.service.html
+	man/systemd-rfkill.8 \
+	man/systemd-rfkill.socket.8
+man/systemd-rfkill.8: man/systemd-rfkill.service.8
+man/systemd-rfkill.socket.8: man/systemd-rfkill.service.8
+man/systemd-rfkill.html: man/systemd-rfkill.service.html
+	$(html-alias)
+
+man/systemd-rfkill.socket.html: man/systemd-rfkill.service.html
 	$(html-alias)
 
 endif
@@ -2362,7 +2367,7 @@ EXTRA_DIST += \
 	man/systemd-random-seed.service.xml \
 	man/systemd-remount-fs.service.xml \
 	man/systemd-resolved.service.xml \
-	man/systemd-rfkill@.service.xml \
+	man/systemd-rfkill.service.xml \
 	man/systemd-run.xml \
 	man/systemd-sleep.conf.xml \
 	man/systemd-socket-proxyd.xml \

Makefile.am

@@ -4463,7 +4463,10 @@ rootlibexec_PROGRAMS += \
 	systemd-rfkill
 
 nodist_systemunit_DATA += \
-	units/systemd-rfkill@.service
+	units/systemd-rfkill.service
+
+dist_systemunit_DATA += \
+	units/systemd-rfkill.socket
 
 systemd_rfkill_SOURCES = \
 	src/rfkill/rfkill.c
@@ -4473,7 +4476,7 @@ systemd_rfkill_LDADD = \
 endif
 
 EXTRA_DIST += \
-	units/systemd-rfkill@.service.in
+	units/systemd-rfkill.service.in
 
 # ------------------------------------------------------------------------------
 if HAVE_LIBCRYPTSETUP

man/systemd-rfkill.service.xml

@@ -19,10 +19,10 @@
   You should have received a copy of the GNU Lesser General Public License
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 -->
-<refentry id="systemd-rfkill@.service" conditional='ENABLE_RFKILL'>
+<refentry id="systemd-rfkill.service" conditional='ENABLE_RFKILL'>
 
   <refentryinfo>
-    <title>systemd-rfkill@.service</title>
+    <title>systemd-rfkill.service</title>
     <productname>systemd</productname>
 
     <authorgroup>
@@ -36,27 +36,29 @@
   </refentryinfo>
 
   <refmeta>
-    <refentrytitle>systemd-rfkill@.service</refentrytitle>
+    <refentrytitle>systemd-rfkill.service</refentrytitle>
     <manvolnum>8</manvolnum>
   </refmeta>
 
   <refnamediv>
-    <refname>systemd-rfkill@.service</refname>
+    <refname>systemd-rfkill.service</refname>
+    <refname>systemd-rfkill.socket</refname>
     <refname>systemd-rfkill</refname>
-    <refpurpose>Load and save the RF kill switch state at boot and shutdown</refpurpose>
+    <refpurpose>Load and save the RF kill switch state at boot and change</refpurpose>
   </refnamediv>
 
   <refsynopsisdiv>
-    <para><filename>systemd-rfkill@.service</filename></para>
+    <para><filename>systemd-rfkill.service</filename></para>
+    <para><filename>systemd-rfkill.socket</filename></para>
     <para><filename>/usr/lib/systemd/systemd-rfkill</filename></para>
   </refsynopsisdiv>
 
   <refsect1>
     <title>Description</title>
 
-    <para><filename>systemd-rfkill@.service</filename> is a service
+    <para><filename>systemd-rfkill.service</filename> is a service
     that restores the RF kill switch state at early boot and saves it
-    at shutdown. On disk, the RF kill switch state is stored in
+    on each change. On disk, the RF kill switch state is stored in
     <filename>/var/lib/systemd/rfkill/</filename>.</para>
   </refsect1>
 

rules/99-systemd.rules.in

@@ -57,7 +57,8 @@ SUBSYSTEM=="leds", KERNEL=="*kbd_backlight", TAG+="systemd", IMPORT{builtin}="pa
 
 # Pull in rfkill save/restore for all rfkill devices
 
-SUBSYSTEM=="rfkill", TAG+="systemd", IMPORT{builtin}="path_id", ENV{SYSTEMD_ALIAS}+="/sys/subsystem/rfkill/devices/%k", ENV{SYSTEMD_WANTS}+="systemd-rfkill@$name.service"
+SUBSYSTEM=="rfkill", IMPORT{builtin}="path_id"
+SUBSYSTEM=="misc", KERNEL=="rfkill", TAG+="systemd", ENV{SYSTEMD_WANTS}+="systemd-rfkill.socket"
 
 # Asynchronously mount file systems implemented by these modules as soon as they are loaded.
 SUBSYSTEM=="module", KERNEL=="fuse", TAG+="systemd", ENV{SYSTEMD_WANTS}+="sys-fs-fuse-connections.mount"

src/rfkill/rfkill.c

@@ -19,21 +19,275 @@
   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"
+
+#define EXIT_USEC (5 * USEC_PER_SEC)
+
+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",
+};
+
+DEFINE_PRIVATE_STRING_TABLE_LOOKUP_TO_STRING(rfkill_type, int);
+
+static int find_device(
+                struct udev *udev,
+                const struct rfkill_event *event,
+                struct udev_device **ret) {
+
+        _cleanup_free_ char *sysname = NULL;
+        struct udev_device *device;
+        const char *name;
+
+        assert(udev);
+        assert(event);
+        assert(ret);
+
+        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_debug("Device has no name, ignoring.");
+                udev_device_unref(device);
+                return -ENOENT;
+        }
+
+        log_debug("Operating on rfkill device '%s'.", name);
+
+        *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;
+        }
+
+        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)
+                        return log_oom();
+
+                state_file = strjoin("/var/lib/systemd/rfkill/", escaped_path_id, ":", type, NULL);
+        } else
+                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;
+
+        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_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;
+        _cleanup_close_ int rfkill_fd = -1;
+        bool ready = false;
+        int r, n;
 
-        if (argc != 3) {
-                log_error("This program requires two arguments.");
+        if (argc > 1) {
+                log_error("This program requires no arguments.");
                 return EXIT_FAILURE;
         }
 
@@ -43,100 +297,124 @@ int main(int argc, char *argv[]) {
 
         umask(0022);
 
+        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");
-                return EXIT_FAILURE;
+                goto finish;
         }
 
-        udev = udev_new();
-        if (!udev) {
-                log_oom();
-                return EXIT_FAILURE;
+        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;
         }
 
-        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 (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;
+                        }
 
-        name = udev_device_get_sysattr_value(device, "name");
-        if (!name) {
-                log_error("rfkill device has no name? Ignoring device.");
-                return EXIT_SUCCESS;
-        }
-
-        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;
-        }
-
-        escaped_type = cescape(type);
-        if (!escaped_type) {
-                log_oom();
-                return EXIT_FAILURE;
-        }
-
-        path_id = udev_device_get_property_value(device, "ID_PATH");
-        if (path_id) {
-                escaped_path_id = cescape(path_id);
-                if (!escaped_path_id) {
-                        log_oom();
-                        return EXIT_FAILURE;
+                        r = log_error_errno(errno, "Failed to open /dev/rfkill: %m");
+                        goto finish;
                 }
-
-                saved = strjoin("/var/lib/systemd/rfkill/", escaped_path_id, ":", escaped_type, NULL);
-        } else
-                saved = strjoin("/var/lib/systemd/rfkill/", escaped_type, NULL);
-
-        if (!saved) {
-                log_oom();
-                return EXIT_FAILURE;
-        }
-
-        if (streq(argv[1], "load")) {
-                _cleanup_free_ char *value = NULL;
-
-                if (!shall_restore_state())
-                        return EXIT_SUCCESS;
-
-                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;
-                }
-
-                r = udev_device_set_sysattr_value(device, "soft", value);
-                if (r < 0) {
-                        log_debug_errno(r, "Failed to write 'soft' attribute on rfkill device, ignoring: %m");
-                        return EXIT_SUCCESS;
-                }
-
-        } else if (streq(argv[1], "save")) {
-                const char *value;
-
-                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;
-                }
-
-                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;
-                }
-
         } else {
-                log_error("Unknown verb %s.", argv[1]);
-                return EXIT_FAILURE;
+                rfkill_fd = SD_LISTEN_FDS_START;
+
+                r = fd_nonblock(rfkill_fd, 1);
+                if (r < 0) {
+                        log_error_errno(r, "Failed to make /dev/rfkill socket non-blocking: %m");
+                        goto finish;
+                }
         }
 
-        return EXIT_SUCCESS;
+        for (;;) {
+                struct rfkill_event event;
+                const char *type;
+                ssize_t l;
+
+                l = read(rfkill_fd, &event, sizeof(event));
+                if (l < 0) {
+                        if (errno == EAGAIN) {
+
+                                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");
+                }
+
+                if (l != RFKILL_EVENT_SIZE_V1) {
+                        log_error("Read event structure of invalid size.");
+                        r = -EIO;
+                        goto finish;
+                }
+
+                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;
+                }
+        }
+
+        r = 0;
+
+finish:
+        return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 }

units/.gitignore

@@ -59,7 +59,7 @@
 /systemd-resolved.service
 /systemd-resolved.service.m4
 /systemd-hibernate-resume@.service
-/systemd-rfkill@.service
+/systemd-rfkill.service
 /systemd-suspend.service
 /systemd-sysctl.service
 /systemd-sysusers.service

units/systemd-rfkill.service.in

@@ -6,18 +6,16 @@
 #  (at your option) any later version.
 
 [Unit]
-Description=Load/Save RF Kill Switch Status of %I
-Documentation=man:systemd-rfkill@.service(8)
+Description=Load/Save RF Kill Switch Status
+Documentation=man:systemd-rfkill.service(8)
 DefaultDependencies=no
-BindsTo=sys-subsystem-rfkill-devices-%i.device
 RequiresMountsFor=/var/lib/systemd/rfkill
+BindsTo=sys-devices-virtual-misc-rfkill.device
 Conflicts=shutdown.target
-After=systemd-remount-fs.service
-Before=sysinit.target shutdown.target
+After=sys-devices-virtual-misc-rfkill.device systemd-remount-fs.service
+Before=shutdown.target
 
 [Service]
-Type=oneshot
-RemainAfterExit=yes
-ExecStart=@rootlibexecdir@/systemd-rfkill load %I
-ExecStop=@rootlibexecdir@/systemd-rfkill save %I
+Type=notify
+ExecStart=@rootlibexecdir@/systemd-rfkill
 TimeoutSec=30s

units/systemd-rfkill.socket

@@ -0,0 +1,19 @@
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU Lesser General Public License as published by
+#  the Free Software Foundation; either version 2.1 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=Load/Save RF Kill Switch Status /dev/rfkill Watch
+Documentation=man:systemd-rfkill.socket(8)
+DefaultDependencies=no
+BindsTo=sys-devices-virtual-misc-rfkill.device
+After=sys-devices-virtual-misc-rfkill.device
+Conflicts=shutdown.target
+Before=shutdown.target
+
+[Socket]
+ListenSpecial=/dev/rfkill
+Writable=yes