logind: add infrastructure to keep track of machines, and move to slices

- This changes all logind cgroup objects to use slice objects rather
  than fixed croup locations.

- logind can now collect minimal information about running
  VMs/containers. As fixed cgroup locations can no longer be used we
  need an entity that keeps track of machine cgroups in whatever slice
  they might be located. Since logind already keeps track of users,
  sessions and seats this is a trivial addition.

- nspawn will now register with logind and pass various bits of metadata
  along. A new option "--slice=" has been added to place the container
  in a specific slice.

- loginctl gained commands to list, introspect and terminate machines.

- user.slice and machine.slice will now be pulled in by logind.service,
  since only logind.service requires this slice.

1 files changed, 81 insertions, 69 deletions

diff --git a/src/login/logind-user.c b/src/login/logind-user.c
index 9e2cbf646b..fb0c9b75d7 100644
--- a/src/login/logind-user.c
+++ b/src/login/logind-user.c
@@ -30,6 +30,7 @@
 #include "hashmap.h"
 #include "strv.h"
 #include "fileio.h"
+#include "special.h"
 
 User* user_new(Manager *m, uid_t uid, gid_t gid, const char *name) {
         User *u;
@@ -42,29 +43,27 @@ User* user_new(Manager *m, uid_t uid, gid_t gid, const char *name) {
                 return NULL;
 
         u->name = strdup(name);
-        if (!u->name) {
-                free(u);
-                return NULL;
-        }
+        if (!u->name)
+                goto fail;
 
-        if (asprintf(&u->state_file, "/run/systemd/users/%lu", (unsigned long) uid) < 0) {
-                free(u->name);
-                free(u);
-                return NULL;
-        }
+        if (asprintf(&u->state_file, "/run/systemd/users/%lu", (unsigned long) uid) < 0)
+                goto fail;
 
-        if (hashmap_put(m->users, ULONG_TO_PTR((unsigned long) uid), u) < 0) {
-                free(u->state_file);
-                free(u->name);
-                free(u);
-                return NULL;
-        }
+        if (hashmap_put(m->users, ULONG_TO_PTR((unsigned long) uid), u) < 0)
+                goto fail;
 
         u->manager = m;
         u->uid = uid;
         u->gid = gid;
 
         return u;
+
+fail:
+        free(u->state_file);
+        free(u->name);
+        free(u);
+
+        return NULL;
 }
 
 void user_free(User *u) {
@@ -76,9 +75,10 @@ void user_free(User *u) {
         while (u->sessions)
                 session_free(u->sessions);
 
-        if (u->cgroup_path)
+        if (u->cgroup_path) {
                 hashmap_remove(u->manager->user_cgroups, u->cgroup_path);
-        free(u->cgroup_path);
+                free(u->cgroup_path);
+        }
 
         free(u->service);
         free(u->runtime_path);
@@ -87,13 +87,14 @@ void user_free(User *u) {
 
         free(u->name);
         free(u->state_file);
+        free(u->slice);
         free(u);
 }
 
 int user_save(User *u) {
-        FILE *f;
+        _cleanup_free_ char *temp_path = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
         int r;
-        char *temp_path;
 
         assert(u);
         assert(u->state_file);
@@ -119,24 +120,26 @@ int user_save(User *u) {
                 user_state_to_string(user_get_state(u)));
 
         if (u->cgroup_path)
-                fprintf(f,
-                        "CGROUP=%s\n",
-                        u->cgroup_path);
+                fprintf(f, "CGROUP=%s\n", u->cgroup_path);
 
         if (u->runtime_path)
-                fprintf(f,
-                        "RUNTIME=%s\n",
-                        u->runtime_path);
+                fprintf(f, "RUNTIME=%s\n", u->runtime_path);
 
         if (u->service)
-                fprintf(f,
-                        "SERVICE=%s\n",
-                        u->service);
+                fprintf(f, "SERVICE=%s\n", u->service);
+
+        if (u->slice)
+                fprintf(f, "SLICE=%s\n", u->slice);
 
         if (u->display)
+                fprintf(f, "DISPLAY=%s\n", u->display->id);
+
+        if (dual_timestamp_is_set(&u->timestamp))
                 fprintf(f,
-                        "DISPLAY=%s\n",
-                        u->display->id);
+                        "REALTIME=%llu\n"
+                        "MONOTONIC=%llu\n",
+                        (unsigned long long) u->timestamp.realtime,
+                        (unsigned long long) u->timestamp.monotonic);
 
         if (u->sessions) {
                 Session *i;
@@ -233,9 +236,6 @@ int user_save(User *u) {
                 unlink(temp_path);
         }
 
-        fclose(f);
-        free(temp_path);
-
 finish:
         if (r < 0)
                 log_error("Failed to save user data for %s: %s", u->name, strerror(-r));
@@ -244,21 +244,22 @@ finish:
 }
 
 int user_load(User *u) {
-        int r;
-        char *display = NULL;
+        _cleanup_free_ char *display = NULL, *realtime = NULL, *monotonic = NULL;
         Session *s = NULL;
+        int r;
 
         assert(u);
 
         r = parse_env_file(u->state_file, NEWLINE,
-                           "CGROUP", &u->cgroup_path,
-                           "RUNTIME", &u->runtime_path,
-                           "SERVICE", &u->service,
-                           "DISPLAY", &display,
+                           "CGROUP",    &u->cgroup_path,
+                           "RUNTIME",   &u->runtime_path,
+                           "SERVICE",   &u->service,
+                           "DISPLAY",   &display,
+                           "SLICE",     &u->slice,
+                           "REALTIME",  &realtime,
+                           "MONOTONIC", &monotonic,
                            NULL);
         if (r < 0) {
-                free(display);
-
                 if (r == -ENOENT)
                         return 0;
 
@@ -266,14 +267,24 @@ int user_load(User *u) {
                 return r;
         }
 
-        if (display) {
+        if (display)
                 s = hashmap_get(u->manager->sessions, display);
-                free(display);
-        }
 
         if (s && s->display && display_is_local(s->display))
                 u->display = s;
 
+        if (realtime) {
+                unsigned long long l;
+                if (sscanf(realtime, "%llu", &l) > 0)
+                        u->timestamp.realtime = l;
+        }
+
+        if (monotonic) {
+                unsigned long long l;
+                if (sscanf(monotonic, "%llu", &l) > 0)
+                        u->timestamp.monotonic = l;
+        }
+
         return r;
 }
 
@@ -309,13 +320,18 @@ static int user_mkdir_runtime_path(User *u) {
 
 static int user_create_cgroup(User *u) {
         char **k;
-        char *p;
         int r;
 
         assert(u);
 
+        if (!u->slice) {
+                u->slice = strdup(SPECIAL_USER_SLICE);
+                if (!u->slice)
+                        return log_oom();
+        }
+
         if (!u->cgroup_path) {
-                _cleanup_free_ char *name = NULL, *escaped = NULL;
+                _cleanup_free_ char *name = NULL, *escaped = NULL, *slice = NULL;
 
                 if (asprintf(&name, "%lu.user", (unsigned long) u->uid) < 0)
                         return log_oom();
@@ -324,30 +340,29 @@ static int user_create_cgroup(User *u) {
                 if (!escaped)
                         return log_oom();
 
-                p = strjoin(u->manager->cgroup_path, "/", escaped, NULL);
-                if (!p)
+                r = cg_slice_to_path(u->slice, &slice);
+                if (r < 0)
+                        return r;
+
+                u->cgroup_path = strjoin(u->manager->cgroup_root, "/", slice, "/", escaped, NULL);
+                if (!u->cgroup_path)
                         return log_oom();
-        } else
-                p = u->cgroup_path;
+        }
 
-        r = cg_create(SYSTEMD_CGROUP_CONTROLLER, p, NULL);
+        r = cg_create(SYSTEMD_CGROUP_CONTROLLER, u->cgroup_path, NULL);
         if (r < 0) {
-                log_error("Failed to create cgroup "SYSTEMD_CGROUP_CONTROLLER":%s: %s", p, strerror(-r));
-                free(p);
-                u->cgroup_path = NULL;
+                log_error("Failed to create cgroup "SYSTEMD_CGROUP_CONTROLLER":%s: %s", u->cgroup_path, strerror(-r));
                 return r;
         }
 
-        u->cgroup_path = p;
-
         STRV_FOREACH(k, u->manager->controllers) {
 
                 if (strv_contains(u->manager->reset_controllers, *k))
                         continue;
 
-                r = cg_create(*k, p, NULL);
+                r = cg_create(*k, u->cgroup_path, NULL);
                 if (r < 0)
-                        log_warning("Failed to create cgroup %s:%s: %s", *k, p, strerror(-r));
+                        log_warning("Failed to create cgroup %s:%s: %s", *k, u->cgroup_path, strerror(-r));
         }
 
         r = hashmap_put(u->manager->user_cgroups, u->cgroup_path, u);
@@ -390,7 +405,8 @@ int user_start(User *u) {
         if (r < 0)
                 return r;
 
-        dual_timestamp_get(&u->timestamp);
+        if (!dual_timestamp_is_set(&u->timestamp))
+                dual_timestamp_get(&u->timestamp);
 
         u->started = true;
 
@@ -633,8 +649,8 @@ UserState user_get_state(User *u) {
 }
 
 int user_kill(User *u, int signo) {
-        int r = 0, q;
-        Set *pid_set = NULL;
+        _cleanup_set_free_ Set *pid_set = NULL;
+        int r;
 
         assert(u);
 
@@ -645,15 +661,11 @@ int user_kill(User *u, int signo) {
         if (!pid_set)
                 return -ENOMEM;
 
-        q = cg_kill_recursive(SYSTEMD_CGROUP_CONTROLLER, u->cgroup_path, signo, false, true, false, pid_set);
-        if (q < 0)
-                if (q != -EAGAIN && q != -ESRCH && q != -ENOENT)
-                        r = q;
-
-        if (pid_set)
-                set_free(pid_set);
+        r = cg_kill_recursive(SYSTEMD_CGROUP_CONTROLLER, u->cgroup_path, signo, false, true, false, pid_set);
+        if (r < 0 && (r != -EAGAIN && r != -ESRCH && r != -ENOENT))
+                return r;
 
-        return r;
+        return 0;
 }
 
 static const char* const user_state_table[_USER_STATE_MAX] = {