Connect to plymouth and support cancellation of in progress fsck

Try to connect and send to plymouth (if running) some checked report progress,
using direct plymouth protocole.

Update message is the following:
fsckd:<num_devices>:<progress>:<string>
* num_devices corresponds to the current number of devices being checked (int)
* progress corresponds to the current minimum percentage of all devices being
  checked (float, from 0 to 100)
* string is a translated message ready to be displayed by the plymouth theme
  displaying the information above. It can be overriden by plymouth themes
  supporting i18n.

Grab in fsckd plymouth watch key Control+C, and propagate this cancel request
to systemd-fsck which will terminate fsck.

Send a message to signal to user what key we are grabbing for fsck cancel.

Message is: fsckd-cancel-msg:<string>
Where string is a translated string ready to be displayed by the plymouth theme
indicating that Control+C can be used to cancel current checks. It can be
overriden (matching only fsckd-cancel-msg prefix) for themes supporting i18n.

2 files changed, 149 insertions, 1 deletions

diff --git a/src/fsckd/fsckd.c b/src/fsckd/fsckd.c
index 6b2eeb067f..dc00fc6b30 100644
--- a/src/fsckd/fsckd.c
+++ b/src/fsckd/fsckd.c
@@ -34,6 +34,7 @@
 #include <unistd.h>
 
 #include "build.h"
+#include "def.h"
 #include "event-util.h"
 #include "fsckd.h"
 #include "log.h"
@@ -44,6 +45,7 @@
 #include "util.h"
 
 #define IDLE_TIME_SECONDS 30
+#define PLYMOUTH_REQUEST_KEY "K\2\2\3"
 
 struct Manager;
 
@@ -56,6 +58,7 @@ typedef struct Client {
         int pass;
         double percent;
         size_t buflen;
+        bool cancelled;
 
         LIST_FIELDS(struct Client, clients);
 } Client;
@@ -68,8 +71,13 @@ typedef struct Manager {
         FILE *console;
         double percent;
         int numdevices;
+        int plymouth_fd;
+        bool plymouth_cancel_sent;
+        bool cancel_requested;
 } Manager;
 
+static int connect_plymouth(Manager *m);
+static int update_global_progress(Manager *m);
 static void manager_free(Manager *m);
 DEFINE_TRIVIAL_CLEANUP_FUNC(Manager*, manager_free);
 #define _cleanup_manager_free_ _cleanup_(manager_freep)
@@ -92,6 +100,19 @@ static double compute_percent(int pass, size_t cur, size_t max) {
                 (double) cur / max;
 }
 
+static int request_cancel_client(Client *current) {
+        FsckdMessage cancel_msg;
+        ssize_t n;
+        cancel_msg.cancel = 1;
+
+        n = send(current->fd, &cancel_msg, sizeof(FsckdMessage), 0);
+        if (n < 0 || (size_t) n < sizeof(FsckdMessage))
+                return log_warning_errno(n, "Cannot send cancel to fsck on (%u, %u): %m",
+                                         major(current->devnum), minor(current->devnum));
+        else
+                current->cancelled = true;
+        return 0;
+}
 
 static void remove_client(Client **first, Client *item) {
         LIST_REMOVE(clients, *first, item);
@@ -99,10 +120,91 @@ static void remove_client(Client **first, Client *item) {
         free(item);
 }
 
+static void on_plymouth_disconnect(Manager *m) {
+        safe_close(m->plymouth_fd);
+        m->plymouth_fd = -1;
+        m->plymouth_cancel_sent = false;
+}
+
+static int plymouth_feedback_handler(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+        Manager *m = userdata;
+        Client *current;
+        char buffer[6];
+        int r;
+
+        assert(m);
+
+        r = read(m->plymouth_fd, buffer, sizeof(buffer));
+        if (r <= 0)
+                on_plymouth_disconnect(m);
+        else {
+               if (buffer[0] == '\15')
+                       log_error("Message update to plymouth wasn't delivered successfully");
+
+               /* the only answer support type we requested is a key interruption */
+               if (buffer[0] == '\2' && buffer[5] == '\3') {
+                       m->cancel_requested = true;
+                       /* cancel all connected clients */
+                       LIST_FOREACH(clients, current, m->clients)
+                               request_cancel_client(current);
+               }
+        }
+
+        return 0;
+}
+
+static int send_message_plymouth_socket(int plymouth_fd, const char *message, bool update) {
+        _cleanup_free_ char *packet = NULL;
+        int r, n;
+        char mode = 'M';
+
+        if (update)
+                mode = 'U';
+
+        if (asprintf(&packet, "%c\002%c%s%n", mode, (int) (strlen(message) + 1), message, &n) < 0)
+                return log_oom();
+        r = loop_write(plymouth_fd, packet, n + 1, true);
+        return r;
+}
+
+
+static int send_message_plymouth(Manager *m, const char *message) {
+        int r;
+        const char *plymouth_cancel_message = NULL;
+
+        r = connect_plymouth(m);
+        if (r < 0)
+                return r;
+
+        if (!m->plymouth_cancel_sent) {
+                /* indicate to plymouth that we listen to Ctrl+C */
+                r = loop_write(m->plymouth_fd, PLYMOUTH_REQUEST_KEY, sizeof(PLYMOUTH_REQUEST_KEY), true);
+                if (r < 0)
+                        return log_warning_errno(errno, "Can't send to plymouth cancel key: %m");
+                m->plymouth_cancel_sent = true;
+                plymouth_cancel_message = strjoina("fsckd-cancel-msg:", "Press Ctrl+C to cancel all filesystem checks in progress");
+                r = send_message_plymouth_socket(m->plymouth_fd, plymouth_cancel_message, false);
+                if (r < 0)
+                        log_warning_errno(r, "Can't send filesystem cancel message to plymouth: %m");
+        } else if (m->numdevices == 0) {
+                m->plymouth_cancel_sent = false;
+                r = send_message_plymouth_socket(m->plymouth_fd, "", false);
+                if (r < 0)
+                        log_warning_errno(r, "Can't clear plymouth filesystem cancel message: %m");
+        }
+
+        r = send_message_plymouth_socket(m->plymouth_fd,  message, true);
+        if (r < 0)
+                return log_warning_errno(errno, "Couldn't send \"%s\" to plymouth: %m", message);
+
+        return 0;
+}
+
 static int update_global_progress(Manager *m) {
         Client *current = NULL;
         _cleanup_free_ char *console_message = NULL;
-        int current_numdevices = 0, l = 0;
+        _cleanup_free_ char *fsck_message = NULL;
+        int current_numdevices = 0, l = 0, r;
         double current_percent = 100;
 
         /* get the overall percentage */
@@ -123,6 +225,8 @@ static int update_global_progress(Manager *m) {
                 if (asprintf(&console_message, "Checking in progress on %d disks (%3.1f%% complete)",
                                                 m->numdevices, m->percent) < 0)
                         return -ENOMEM;
+                if (asprintf(&fsck_message, "fsckd:%d:%3.1f:%s", m->numdevices, m->percent, console_message) < 0)
+                        return -ENOMEM;
 
                 /* write to console */
                 if (m->console) {
@@ -130,12 +234,41 @@ static int update_global_progress(Manager *m) {
                         fflush(m->console);
                 }
 
+                /* try to connect to plymouth and send message */
+                r = send_message_plymouth(m, fsck_message);
+                if (r < 0)
+                        log_debug("Couldn't send message to plymouth");
+
                 if (l > m->clear)
                         m->clear = l;
         }
         return 0;
 }
 
+static int connect_plymouth(Manager *m) {
+        union sockaddr_union sa = PLYMOUTH_SOCKET;
+        int r;
+
+        /* try to connect or reconnect if sending a message */
+        if (m->plymouth_fd <= 0) {
+                m->plymouth_fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0);
+                if (m->plymouth_fd < 0) {
+                        return log_warning_errno(errno, "Connection to plymouth socket failed: %m");
+                }
+                if (connect(m->plymouth_fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + 1 + strlen(sa.un.sun_path+1)) < 0) {
+                        on_plymouth_disconnect(m);
+                        return log_warning_errno(errno, "Couldn't connect to plymouth: %m");
+                }
+                r = sd_event_add_io(m->event, NULL, m->plymouth_fd, EPOLLIN, plymouth_feedback_handler, m);
+                if (r < 0) {
+                        on_plymouth_disconnect(m);
+                        return log_warning_errno(r, "Can't listen to plymouth socket: %m");
+                }
+        }
+
+        return 0;
+}
+
 static int progress_handler(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
         Client *client = userdata;
         Manager *m = NULL;
@@ -146,6 +279,12 @@ static int progress_handler(sd_event_source *s, int fd, uint32_t revents, void *
         assert(client);
         m = client->manager;
 
+        /* check first if we need to cancel this client */
+        if (m->cancel_requested) {
+                if (!client->cancelled)
+                        request_cancel_client(client);
+        }
+
         /* ensure we have enough data to read */
         r = ioctl(fd, FIONREAD, &buflen);
         if (r == 0 && buflen != 0 && (size_t) buflen < sizeof(FsckProgress)) {
@@ -210,6 +349,9 @@ static int new_connection_handler(sd_event_source *s, int fd, uint32_t revents,
                         remove_client(&(m->clients), client);
                         return r;
                 }
+                /* only request the client to cancel now in case the request is dropped by the client (chance to recancel) */
+                if (m->cancel_requested)
+                        request_cancel_client(client);
         } else
                 return log_error_errno(errno, "Couldn't accept a new connection: %m");
 
@@ -233,6 +375,7 @@ static void manager_free(Manager *m) {
         }
 
         safe_close(m->connection_fd);
+        safe_close(m->plymouth_fd);
         if (m->console)
                 fclose(m->console);
 
@@ -266,6 +409,7 @@ static int manager_new(Manager **ret, int fd) {
         }
         m->percent = 100;
 
+        m->plymouth_fd = -1;
         *ret = m;
         m = NULL;
 
diff --git a/src/fsckd/fsckd.h b/src/fsckd/fsckd.h
index 6fe37a7267..8239273dae 100644
--- a/src/fsckd/fsckd.h
+++ b/src/fsckd/fsckd.h
@@ -32,3 +32,7 @@ typedef struct FsckProgress {
         size_t max;
         int pass;
 } FsckProgress;
+
+typedef struct FsckdMessage {
+        uint8_t cancel;
+} FsckdMessage;