systemctl: drop useless DBus calls from 'systemctl show foo.service'

systemctl called LoadUnit, GetUnit, GetAll in this order to get the properties.

It is useless to load units explicitly, because it won't ensure anything. The
unit may be freed immediately by the garbage collector.

It is unnecessary to call GetUnit, because systemctl can easily translate the
unit name to DBus path by itself.

GetAll will load the unit if necessary.

1 files changed, 80 insertions, 130 deletions

diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index 0034c55384..92c79d038f 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -2955,18 +2955,70 @@ finish:
         return r;
 }
 
-static int show(DBusConnection *bus, char **args) {
+static int show_one_by_pid(const char *verb, DBusConnection *bus, uint32_t pid, bool *new_line) {
         DBusMessage *m = NULL, *reply = NULL;
-        int r, ret = 0;
+        const char *path = NULL;
         DBusError error;
+        int r;
+
+        dbus_error_init(&error);
+
+        m = dbus_message_new_method_call(
+                              "org.freedesktop.systemd1",
+                              "/org/freedesktop/systemd1",
+                              "org.freedesktop.systemd1.Manager",
+                              "GetUnitByPID");
+        if (!m) {
+                log_error("Could not allocate message.");
+                r = -ENOMEM;
+                goto finish;
+        }
+
+        if (!dbus_message_append_args(m,
+                                      DBUS_TYPE_UINT32, &pid,
+                                      DBUS_TYPE_INVALID)) {
+                log_error("Could not append arguments to message.");
+                r = -ENOMEM;
+                goto finish;
+        }
+
+        reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error);
+        if (!reply) {
+                log_error("Failed to issue method call: %s", bus_error_message(&error));
+                r = -EIO;
+                goto finish;
+        }
+
+        if (!dbus_message_get_args(reply, &error,
+                                   DBUS_TYPE_OBJECT_PATH, &path,
+                                   DBUS_TYPE_INVALID)) {
+                log_error("Failed to parse reply: %s", bus_error_message(&error));
+                r = -EIO;
+                goto finish;
+        }
+
+        r = show_one(verb, bus, path, false, new_line);
+
+finish:
+        if (m)
+                dbus_message_unref(m);
+
+        if (reply)
+                dbus_message_unref(reply);
+
+        dbus_error_free(&error);
+
+        return r;
+}
+
+static int show(DBusConnection *bus, char **args) {
+        int r, ret = 0;
         bool show_properties, new_line = false;
         char **name;
 
         assert(bus);
         assert(args);
 
-        dbus_error_init(&error);
-
         show_properties = !streq(args[0], "status");
 
         if (show_properties)
@@ -2976,157 +3028,55 @@ static int show(DBusConnection *bus, char **args) {
                 /* If not argument is specified inspect the manager
                  * itself */
 
-                ret = show_one(args[0], bus, "/org/freedesktop/systemd1", show_properties, &new_line);
-                goto finish;
+                return show_one(args[0], bus, "/org/freedesktop/systemd1", show_properties, &new_line);
         }
 
         STRV_FOREACH(name, args+1) {
-                const char *path = NULL;
                 uint32_t id;
 
                 if (safe_atou32(*name, &id) < 0) {
 
                         /* Interpret as unit name */
 
-                        if (!(m = dbus_message_new_method_call(
-                                              "org.freedesktop.systemd1",
-                                              "/org/freedesktop/systemd1",
-                                              "org.freedesktop.systemd1.Manager",
-                                              "LoadUnit"))) {
-                                log_error("Could not allocate message.");
-                                ret = -ENOMEM;
-                                goto finish;
-                        }
-
-                        if (!dbus_message_append_args(m,
-                                                      DBUS_TYPE_STRING, name,
-                                                      DBUS_TYPE_INVALID)) {
-                                log_error("Could not append arguments to message.");
-                                ret = -ENOMEM;
-                                goto finish;
-                        }
-
-                        if (!(reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error))) {
-
-                                if (!dbus_error_has_name(&error, DBUS_ERROR_ACCESS_DENIED)) {
-                                        log_error("Failed to issue method call: %s", bus_error_message(&error));
-                                        ret = -EIO;
-                                        goto finish;
-                                }
-
-                                dbus_error_free(&error);
-
-                                dbus_message_unref(m);
-                                if (!(m = dbus_message_new_method_call(
-                                                      "org.freedesktop.systemd1",
-                                                      "/org/freedesktop/systemd1",
-                                                      "org.freedesktop.systemd1.Manager",
-                                                      "GetUnit"))) {
-                                        log_error("Could not allocate message.");
-                                        ret = -ENOMEM;
-                                        goto finish;
-                                }
+                        char *e, *p;
+                        e = bus_path_escape(*name);
+                        if (!e)
+                                return -ENOMEM;
+                        p = strappend("/org/freedesktop/systemd1/unit/", e);
+                        free(e);
+                        if (!p)
+                                return -ENOMEM;
 
-                                if (!dbus_message_append_args(m,
-                                                              DBUS_TYPE_STRING, name,
-                                                              DBUS_TYPE_INVALID)) {
-                                        log_error("Could not append arguments to message.");
-                                        ret = -ENOMEM;
-                                        goto finish;
-                                }
+                        r = show_one(args[0], bus, p, show_properties, &new_line);
+                        free(p);
 
-                                if (!(reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error))) {
-                                        log_error("Failed to issue method call: %s", bus_error_message(&error));
-
-                                        if (dbus_error_has_name(&error, BUS_ERROR_NO_SUCH_UNIT))
-                                                ret = 4; /* According to LSB: "program or service status is unknown" */
-                                        else
-                                                ret = -EIO;
-                                        goto finish;
-                                }
-                        }
+                        if (r != 0)
+                                ret = r;
 
                 } else if (show_properties) {
 
                         /* Interpret as job id */
 
-                        if (!(m = dbus_message_new_method_call(
-                                              "org.freedesktop.systemd1",
-                                              "/org/freedesktop/systemd1",
-                                              "org.freedesktop.systemd1.Manager",
-                                              "GetJob"))) {
-                                log_error("Could not allocate message.");
-                                ret = -ENOMEM;
-                                goto finish;
-                        }
+                        char *p;
+                        if (asprintf(&p, "/org/freedesktop/systemd1/job/%u", id) < 0)
+                                return -ENOMEM;
 
-                        if (!dbus_message_append_args(m,
-                                                      DBUS_TYPE_UINT32, &id,
-                                                      DBUS_TYPE_INVALID)) {
-                                log_error("Could not append arguments to message.");
-                                ret = -ENOMEM;
-                                goto finish;
-                        }
+                        r = show_one(args[0], bus, p, show_properties, &new_line);
+                        free(p);
+
+                        if (r != 0)
+                                ret = r;
 
-                        if (!(reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error))) {
-                                log_error("Failed to issue method call: %s", bus_error_message(&error));
-                                ret = -EIO;
-                                goto finish;
-                        }
                 } else {
 
                         /* Interpret as PID */
 
-                        if (!(m = dbus_message_new_method_call(
-                                              "org.freedesktop.systemd1",
-                                              "/org/freedesktop/systemd1",
-                                              "org.freedesktop.systemd1.Manager",
-                                              "GetUnitByPID"))) {
-                                log_error("Could not allocate message.");
-                                ret = -ENOMEM;
-                                goto finish;
-                        }
-
-                        if (!dbus_message_append_args(m,
-                                                      DBUS_TYPE_UINT32, &id,
-                                                      DBUS_TYPE_INVALID)) {
-                                log_error("Could not append arguments to message.");
-                                ret = -ENOMEM;
-                                goto finish;
-                        }
-
-                        if (!(reply = dbus_connection_send_with_reply_and_block(bus, m, -1, &error))) {
-                                log_error("Failed to issue method call: %s", bus_error_message(&error));
-                                ret = -EIO;
-                                goto finish;
-                        }
+                        r = show_one_by_pid(args[0], bus, id, &new_line);
+                        if (r != 0)
+                                ret = r;
                 }
-
-                if (!dbus_message_get_args(reply, &error,
-                                           DBUS_TYPE_OBJECT_PATH, &path,
-                                           DBUS_TYPE_INVALID)) {
-                        log_error("Failed to parse reply: %s", bus_error_message(&error));
-                        ret = -EIO;
-                        goto finish;
-                }
-
-                if ((r = show_one(args[0], bus, path, show_properties, &new_line)) != 0)
-                        ret = r;
-
-                dbus_message_unref(m);
-                dbus_message_unref(reply);
-                m = reply = NULL;
         }
 
-finish:
-        if (m)
-                dbus_message_unref(m);
-
-        if (reply)
-                dbus_message_unref(reply);
-
-        dbus_error_free(&error);
-
         return ret;
 }