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From 1c961f8bf67a798d51d88195f89d035012a681d4 Mon Sep 17 00:00:00 2001
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From: Michal Sekletar <msekleta@redhat.com>
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Date: Thu, 27 Feb 2014 17:56:16 +0100
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Subject: [PATCH] core: introduce new stop protocol for unit scopes
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By specifiy a Controller property when creating the scope a client can
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specify a bus name that will be notified with a RequestStop bus signal
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when the scope has been asked to shut down, instead of sending SIGTERM
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to the scope processes themselves.
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https://bugzilla.redhat.com/show_bug.cgi?id=1032695
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Based-on: 2d4a39e759c4ab846ad8a546abeddd40bc8d736e
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---
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 src/core/dbus-scope.c    | 55 ++++++++++++++++++++++++++++++++++++++++++++++++
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 src/core/dbus-scope.h    |  2 ++
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 src/core/scope.c         | 20 +++++++++++++++---
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 src/core/scope.h         |  2 ++
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 src/run/run.c            |  8 +++++++
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 src/shared/dbus-common.c | 42 ++++++++++++++++++++++++++++++++++++
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 src/shared/dbus-common.h |  2 ++
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 7 files changed, 128 insertions(+), 3 deletions(-)
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diff --git a/src/core/dbus-scope.c b/src/core/dbus-scope.c
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index 783a969..b576f76 100644
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--- a/src/core/dbus-scope.c
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+++ b/src/core/dbus-scope.c
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@@ -31,10 +31,12 @@
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 #define BUS_SCOPE_INTERFACE                                             \
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         " <interface name=\"org.freedesktop.systemd1.Scope\">\n"        \
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         BUS_UNIT_CGROUP_INTERFACE                                       \
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+        "  <property name=\"Controller\" type=\"s\" access=\"read\"/>\n"\
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         "  <property name=\"TimeoutStopUSec\" type=\"t\" access=\"read\"/>\n" \
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         BUS_KILL_CONTEXT_INTERFACE                                      \
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         BUS_CGROUP_CONTEXT_INTERFACE                                    \
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         "  <property name=\"Result\" type=\"s\" access=\"read\"/>\n"    \
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+        "  <signal name=\"RequestStop\"/>\n"                            \
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         " </interface>\n"
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 #define INTROSPECTION                                                   \
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@@ -56,6 +58,7 @@ const char bus_scope_interface[] _introspect_("Scope") = BUS_SCOPE_INTERFACE;
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 static DEFINE_BUS_PROPERTY_APPEND_ENUM(bus_scope_append_scope_result, scope_result, ScopeResult);
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 static const BusProperty bus_scope_properties[] = {
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+        { "Controller",             bus_property_append_string,    "s", offsetof(Scope, controller)        },
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         { "TimeoutStopUSec",        bus_property_append_usec,      "t", offsetof(Scope, timeout_stop_usec) },
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         { "Result",                 bus_scope_append_scope_result, "s", offsetof(Scope, result)            },
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         {}
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@@ -127,6 +130,31 @@ static int bus_scope_set_transient_property(
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                 return 1;
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+        } else if (streq(name, "Controller")) {
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+                const char *controller;
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+
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+                if (dbus_message_iter_get_arg_type(i) != DBUS_TYPE_STRING)
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+                        return -EINVAL;
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+
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+                dbus_message_iter_get_basic(i, &controller);
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+
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+                if (!isempty(controller) && !bus_service_name_is_valid(controller))
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+                        return -EINVAL;
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+
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+                if (mode != UNIT_CHECK) {
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+                        char *c = NULL;
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+
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+                        if (!isempty(controller)) {
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+                                c = strdup(controller);
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+                                if (!c)
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+                                        return -ENOMEM;
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+                        }
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+
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+                        free(s->controller);
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+                        s->controller = c;
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+                }
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+
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+                return 1;
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         } else if (streq(name, "TimeoutStopUSec")) {
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                 if (dbus_message_iter_get_arg_type(i) != DBUS_TYPE_UINT64)
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@@ -187,3 +215,30 @@ int bus_scope_commit_properties(Unit *u) {
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         unit_realize_cgroup(u);
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         return 0;
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 }
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+
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+int bus_scope_send_request_stop(Scope *s) {
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+        _cleanup_dbus_message_unref_ DBusMessage *m = NULL;
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+        _cleanup_free_ char *p = NULL;
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+        int r;
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+
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+        assert(s);
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+
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+        if (!s->controller)
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+                return 0;
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+
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+        p = unit_dbus_path(UNIT(s));
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+        if (!p)
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+                return -ENOMEM;
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+
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+        m = dbus_message_new_signal(p,
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+                                    "org.freedesktop.systemd1.Scope",
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+                                    "RequestStop");
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+        if (!m)
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+                return 0;
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+
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+        r = dbus_message_set_destination(m, s->controller);
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+        if (!r)
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+                return 0;
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+
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+        return dbus_connection_send(UNIT(s)->manager->api_bus, m, NULL);
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+}
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diff --git a/src/core/dbus-scope.h b/src/core/dbus-scope.h
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index e6836f1..34720f2 100644
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--- a/src/core/dbus-scope.h
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+++ b/src/core/dbus-scope.h
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@@ -30,4 +30,6 @@ DBusHandlerResult bus_scope_message_handler(Unit *u, DBusConnection *c, DBusMess
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 int bus_scope_set_property(Unit *u, const char *name, DBusMessageIter *i, UnitSetPropertiesMode mode, DBusError *error);
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 int bus_scope_commit_properties(Unit *u);
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+int bus_scope_send_request_stop(Scope *s);
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+
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 extern const char bus_scope_interface[];
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diff --git a/src/core/scope.c b/src/core/scope.c
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index 41da3b9..e75fc2b 100644
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--- a/src/core/scope.c
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+++ b/src/core/scope.c
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@@ -64,6 +64,9 @@ static void scope_done(Unit *u) {
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         cgroup_context_done(&s->cgroup_context);
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+        free(s->controller);
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+        s->controller = NULL;
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+
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         set_free(s->pids);
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         s->pids = NULL;
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@@ -198,6 +201,7 @@ static void scope_enter_dead(Scope *s, ScopeResult f) {
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 }
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 static void scope_enter_signal(Scope *s, ScopeState state, ScopeResult f) {
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+        bool skip_signal = false;
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         int r;
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         assert(s);
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@@ -205,13 +209,23 @@ static void scope_enter_signal(Scope *s, ScopeState state, ScopeResult f) {
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         if (f != SCOPE_SUCCESS)
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                 s->result = f;
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-        r = unit_kill_context(
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+        /* If we have a controller set let's ask the controller nicely
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+         * to terminate the scope, instead of us going directly into
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+         * SIGTERM beserk mode */
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+        if (state == SCOPE_STOP_SIGTERM)
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+                skip_signal = bus_scope_send_request_stop(s) > 0;
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+
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+        if (!skip_signal) {
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+                r = unit_kill_context(
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                         UNIT(s),
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                         &s->kill_context,
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                         state != SCOPE_STOP_SIGTERM,
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                         -1, -1, false);
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-        if (r < 0)
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-                goto fail;
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+
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+                if (r < 0)
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+                        goto fail;
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+        } else
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+                r = 1;
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         if (r > 0) {
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                 if (s->timeout_stop_usec > 0) {
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diff --git a/src/core/scope.h b/src/core/scope.h
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index 2a3dcb7..b4bafa7 100644
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--- a/src/core/scope.h
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+++ b/src/core/scope.h
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@@ -55,6 +55,8 @@ struct Scope {
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         usec_t timeout_stop_usec;
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+        char *controller;
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+
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         Set *pids;
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         Watch timer_watch;
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diff --git a/src/run/run.c b/src/run/run.c
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index a6abead..93e3f88 100644
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--- a/src/run/run.c
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+++ b/src/run/run.c
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@@ -315,6 +315,14 @@ static int start_transient_scope(
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         if (r < 0)
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                 return r;
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+        {
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+                const char *unique_id;
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+                sd_bus_get_unique_name(bus, &unique_id);
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+                r = sd_bus_message_append(m, "(sv)", "Controller", "s", unique_id);
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+                if (r < 0)
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+                        return r;
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+        }
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+
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         r = sd_bus_message_append(m, "(sv)", "PIDs", "au", 1, (uint32_t) getpid());
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         if (r < 0)
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                 return r;
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diff --git a/src/shared/dbus-common.c b/src/shared/dbus-common.c
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index 3ba2d87..8a68708 100644
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--- a/src/shared/dbus-common.c
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+++ b/src/shared/dbus-common.c
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@@ -1428,3 +1428,45 @@ const char *bus_message_get_sender_with_fallback(DBusMessage *m) {
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         return ":no-sender";
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 }
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+
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+bool bus_service_name_is_valid(const char *p) {
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+        const char *q;
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+        bool dot, found_dot = false, unique;
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+
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+        if (isempty(p))
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+                return false;
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+
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+        unique = p[0] == ':';
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+
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+        for (dot = true, q = unique ? p+1 : p; *q; q++)
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+                if (*q == '.') {
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+                        if (dot)
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+                                return false;
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+
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+                        found_dot = dot = true;
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+                } else {
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+                        bool good;
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+
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+                        good =
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+                                (*q >= 'a' && *q <= 'z') ||
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+                                (*q >= 'A' && *q <= 'Z') ||
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+                                ((!dot || unique) && *q >= '0' && *q <= '9') ||
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+                                *q == '_' || *q == '-';
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+
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+                        if (!good)
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+                                return false;
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+
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+                        dot = false;
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+                }
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+
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+        if (q - p > 255)
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+                return false;
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+
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+        if (dot)
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+                return false;
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+
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+        if (!found_dot)
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+                return false;
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+
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+        return true;
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+}
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diff --git a/src/shared/dbus-common.h b/src/shared/dbus-common.h
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index 9752f08..8d01d14 100644
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--- a/src/shared/dbus-common.h
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+++ b/src/shared/dbus-common.h
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@@ -242,5 +242,7 @@ const char *bus_message_get_sender_with_fallback(DBusMessage *m);
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 void bus_message_unrefp(DBusMessage **reply);
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+bool bus_service_name_is_valid(const char *p);
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+
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 #define _cleanup_dbus_message_unref_ __attribute__((cleanup(bus_message_unrefp)))
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 #define _cleanup_dbus_error_free_ __attribute__((cleanup(dbus_error_free)))