[needs-restarting] add -s to list services (RhBug:1772939)

= changelog =
msg:           [needs-restarting] add -s to list services (RhBug:1772939)
type:          bugfix
resolves:      https://bugzilla.redhat.com/show_bug.cgi?id=1772939

Closes: #395
Approved by: kontura

dnf-plugins-core.spec

@@ -99,8 +99,10 @@ Summary:        Core Plugins for DNF
 %{?python_provide:%python_provide python2-%{name}}
 BuildRequires:  python2-dnf >= %{dnf_lowest_compatible}
 %if 0%{?rhel} && 0%{?rhel} <= 7
+BuildRequires:  dbus-python
 BuildRequires:  python-nose
 %else
+BuildRequires:  python2-dbus
 BuildRequires:  python2-nose
 %endif
 BuildRequires:  python2-devel
@@ -110,8 +112,10 @@ Requires:       python2-distro
 Requires:       python2-dnf >= %{dnf_lowest_compatible}
 Requires:       python2-hawkey >= %{hawkey_version}
 %if 0%{?rhel} && 0%{?rhel} <= 7
+Requires:       dbus-python
 Requires:       python-dateutil
 %else
+Requires:       python2-dbus
 Requires:       python2-dateutil
 %endif
 Provides:       python2-dnf-plugins-extras-debug = %{version}-%{release}
@@ -140,12 +144,14 @@ Additionally provides generate_completion_cache passive plugin.
 %package -n python3-%{name}
 Summary:    Core Plugins for DNF
 %{?python_provide:%python_provide python3-%{name}}
+BuildRequires:  python3-dbus
 BuildRequires:  python3-devel
 BuildRequires:  python3-dnf >= %{dnf_lowest_compatible}
 BuildRequires:  python3-nose
 %if 0%{?fedora}
 Requires:       python3-distro
 %endif
+Requires:       python3-dbus
 Requires:       python3-dnf >= %{dnf_lowest_compatible}
 Requires:       python3-hawkey >= %{hawkey_version}
 Requires:       python3-dateutil

doc/needs_restarting.rst

@@ -48,3 +48,6 @@ All general DNF options are accepted, see `Options` in :manpage:`dnf(8)` for det
 ``-r, --reboothint``
 
     Only report whether a reboot is required (exit code 1) or not (exit code 0).
+
+``-s, --services``
+    Only list the affected systemd services.

plugins/needs_restarting.py

@@ -29,6 +29,7 @@
 
 import dnf
 import dnf.cli
+import dbus
 import functools
 import os
 import re
@@ -126,6 +127,30 @@ def print_cmd(pid):
     print('%d : %s' % (pid, command))
 
 
+def get_service_dbus(pid):
+    bus = dbus.SystemBus()
+    systemd_manager_object = bus.get_object(
+        'org.freedesktop.systemd1',
+        '/org/freedesktop/systemd1'
+    )
+    systemd_manager_interface = dbus.Interface(
+        systemd_manager_object,
+        'org.freedesktop.systemd1.Manager'
+    )
+    service_proxy = bus.get_object(
+        'org.freedesktop.systemd1',
+        systemd_manager_interface.GetUnitByPID(pid)
+    )
+    service_properties = dbus.Interface(
+        service_proxy, dbus_interface="org.freedesktop.DBus.Properties")
+    name = service_properties.Get(
+        "org.freedesktop.systemd1.Unit",
+        'Id'
+    )
+    if name.endswith(".service"):
+        return name
+    return
+
 def smap2opened_file(pid, line):
     slash = line.find('/')
     if slash < 0:
@@ -205,6 +230,8 @@ def set_argparser(parser):
         parser.add_argument('-r', '--reboothint', action='store_true',
                             help=_("only report whether a reboot is required "
                                    "(exit code 1) or not (exit code 0)"))
+        parser.add_argument('-s', '--services', action='store_true',
+                            help=_("only report affected systemd services"))
 
     def configure(self):
         demands = self.cli.demands
@@ -251,5 +278,11 @@ def run(self):
             if pkg.installtime > process_start(ofile.pid):
                 stale_pids.add(ofile.pid)
 
+        if self.opts.services:
+            names = set([get_service_dbus(pid) for pid in sorted(stale_pids)])
+            for name in names:
+                if name is not None:
+                    print(name)
+            return 0
         for pid in sorted(stale_pids):
             print_cmd(pid)