main: Error out on D-Bus communication errors

The bug reporting tool in Fedora, in its infinite wisdom, considers
innocuous exceptions that occur when system daemons aren't running
to be bug report worthy.

Catch all the D-Bus communication errors, print an error message
detailing the problem and exit with a return value of 1 when they occur
instead of printing an exception.

See:
https://bugzilla.redhat.com/show_bug.cgi?id=2019536
https://bugzilla.redhat.com/show_bug.cgi?id=2020251
https://bugzilla.redhat.com/show_bug.cgi?id=2020941

meson.build

@@ -44,7 +44,7 @@ add_global_arguments(common_cflags, language: 'c')
 
 if get_option('pylint')
     pylint = find_program('pylint-3', 'pylint3', 'pylint', required: true)
-    pylint_flags = ['-d', 'C0116', '-d', 'C0114', '-d', 'W0707']
+    pylint_flags = ['-d', 'C0116', '-d', 'C0114', '-d', 'W0707', '-d', 'W0706' ]
 endif
 xmllint = find_program('xmllint', required: false)
 

src/powerprofilesctl.in

@@ -98,7 +98,7 @@ def get_proxy():
                                        '/net/hadess/PowerProfiles',
                                        'org.freedesktop.DBus.Properties', None)
     except:
-        raise SystemError
+        raise
     return proxy
 
 def _get():
@@ -117,13 +117,13 @@ def get_profiles_property(prop):
     try:
         proxy = get_proxy()
     except:
-        raise SystemError
+        raise
 
     profiles = None
     try:
         profiles = proxy.Get('(ss)', 'net.hadess.PowerProfiles', prop)
     except:
-        raise ReferenceError
+        raise
     else:
         return profiles
 
@@ -134,8 +134,7 @@ def _list():
         degraded = (reason != '')
         active = get_proxy().Get('(ss)', 'net.hadess.PowerProfiles', 'ActiveProfile')
     except:
-        print("Couldn\'t get Profiles: ", sys.exc_info()[0])
-        raise SystemError
+        raise
     else:
         index = 0
         for profile in reversed(profiles):
@@ -152,8 +151,7 @@ def _list_holds():
     try:
         holds = get_profiles_property('ActiveProfileHolds')
     except:
-        # print("Couldn\'t get ActiveProfileHolds: ", sys.exc_info()[0])
-        raise SystemError
+        raise
     else:
         index = 0
         for hold in holds:
@@ -173,7 +171,7 @@ def _launch(args, profile, appid, reason):
                                        '/net/hadess/PowerProfiles',
                                        'net.hadess.PowerProfiles', None)
     except:
-        raise SystemError
+        raise
 
     cookie = proxy.HoldProfile('(sss)', profile, reason, appid)
 
@@ -208,16 +206,32 @@ def main(): # pylint: disable=too-many-branches, disable=too-many-statements
     elif command == 'version':
         version()
     elif command == 'get':
-        _get()
+        try:
+            _get()
+        except GLib.Error as error:
+            sys.stderr.write(f'Failed to communicate with power-profiles-daemon: {format(error)}\n')
+            sys.exit(1)
     elif command == 'set':
         if len(args) != 1:
             usage_set()
             sys.exit(1)
-        _set(args[0])
+        try:
+            _set(args[0])
+        except GLib.Error as error:
+            sys.stderr.write(f'Failed to communicate with power-profiles-daemon: {format(error)}\n')
+            sys.exit(1)
     elif command == 'list':
-        _list()
+        try:
+            _list()
+        except GLib.Error as error:
+            sys.stderr.write(f'Failed to communicate with power-profiles-daemon: {format(error)}\n')
+            sys.exit(1)
     elif command == 'list-holds':
-        _list_holds()
+        try:
+            _list_holds()
+        except GLib.Error as error:
+            sys.stderr.write(f'Failed to communicate with power-profiles-daemon: {format(error)}\n')
+            sys.exit(1)
     elif command == 'launch':
         if len(args) == 0:
             sys.exit(0)
@@ -256,7 +270,11 @@ def main(): # pylint: disable=too-many-branches, disable=too-many-statements
             reason = 'Running ' + appid
         if not profile:
             profile = 'performance'
-        _launch(args, profile, appid, reason)
+        try:
+            _launch(args, profile, appid, reason)
+        except GLib.Error as error:
+            sys.stderr.write(f'Failed to communicate with power-profiles-daemon: {format(error)}\n')
+            sys.exit(1)
 
 if __name__ == '__main__':
     main()