Fix for tmpdir when loading multiple mission files

This change makes sure that each mission file, when loaded, it extracts
resources to unique temp dir rather than a shared one, which would lead
to resource overwriting when working with multiple loaded missions. I
worked with two missions, and each had "briefing.png" attached. When I
saved them I noticed that one was overwriting the other.

I guess accessing map_resource.files["DEFAULT"].values() directly might
not be desired and if you want, I can remove it. I think if m.tmpdir is
good, then a validation that m1.tmpdir != m2.tmpdir should be enough.

NOTE that get_file_path works only when .miz is loaded. It does not work
properly (even before this patch) for missions generated by pydcs, where
resources are added, e.g:

m = dcs.Mission(terrain=dcs.terrain.Caucasus()) res_key =
m.add_picture_blue("tests/images/blue") calling
m.map_resource.get_file_path(res_key) would returns
"'cs/dcs/tests/images/blue.png'". But that's a separate problem to
solve.

With this patch the get_file_path() throws an exception, which is IMHO
better than silently working wrong.

tmpdir is optional since I didn't see the need of creating a new tmp
folder every time a new Mission() object is created.

dcs/mission.py

@@ -106,6 +106,7 @@ def __init__(self, terrain: Optional[Terrain] = None) -> None:
         self.current_group_id = 0
         self.current_dict_id = 0
         self.filename: Optional[str] = None
+        self.tmpdir: Optional[str] = None
 
         self.translation = Translation(self)
         self.map_resource = MapResource(self)
@@ -235,6 +236,7 @@ def load_file(self, filename: str, bypass_triggers: bool = False) -> List[Status
         self.current_unit_id = 0
         self.current_group_id = 0
         self.current_dict_id = 0
+        self.tmpdir = tempfile.mkdtemp()
         status = []
 
         def loaddict(fname: str, mizfile: zipfile.ZipFile, reserved_files: List[str]) -> Dict[str, Any]:
@@ -2128,14 +2130,13 @@ def __init__(self, mission: Mission):
 
     def load_from_dict(self, _dict, zipf: zipfile.ZipFile, lang='DEFAULT'):
         _dict = _dict["mapResource"]
-
         for key in _dict:
             filename = _dict[key]
             filepath = 'l10n/{lang}/{fn}'.format(lang=lang, fn=filename)
             self.added_paths.append(filepath)
 
             try:
-                extractedpath = zipf.extract(filepath, tempfile.gettempdir())
+                extractedpath = zipf.extract(filepath, self.mission.tmpdir)
                 self.add_resource_file(extractedpath, lang, key)
             except KeyError as ke:
                 print(ke, file=sys.stderr)
@@ -2146,7 +2147,7 @@ def load_binary_files(self, zipf: zipfile.ZipFile, reserved_files: List[str]):
                 continue
 
             try:
-                extractedpath = zipf.extract(filepath, tempfile.gettempdir())
+                extractedpath = zipf.extract(filepath, self.mission.tmpdir)
                 self.binary_files.append({
                     "path": os.path.abspath(extractedpath),
                     "respath": filepath,
@@ -2188,7 +2189,10 @@ def get_file_path(self, resource_key: ResourceKey, lang: str = 'DEFAULT'):
         :param lang:
         :return:
         """
-        return self.files[lang][resource_key.key][len(tempfile.gettempdir()) + len('/l10n//') + len(lang):]
+        if self.mission.tmpdir is None:
+            raise RuntimeError("get_file_path() only works for loaded missions.")
+
+        return self.files[lang][resource_key.key][len(self.mission.tmpdir) + len('/l10n//') + len(lang):]
 
     def store(self, zipf: zipfile.ZipFile, lang='DEFAULT'):
         d = {}

tests/test_mission.py

@@ -1245,6 +1245,35 @@ def test_action_a_out_picture_u(self) -> None:
 
         self.assertEqual(m_action, m2.triggerrules.triggers[0].actions[5])
 
+    def test_resource_name_conflict_in_two_missions(self) -> None:
+        m1_filename = "missions/saved.m1.miz"
+        m1 = dcs.Mission(terrain=dcs.terrain.Caucasus())
+        m1_img_path = 'tests/images/m1/briefing.png'
+        m1.add_picture_blue(m1_img_path)
+        m1.save(m1_filename)
+
+        m2_filename = "missions/saved.m2.miz"
+        m2 = dcs.Mission(terrain=dcs.terrain.Caucasus())
+        m2_img_path = 'tests/images/m2/briefing.png'
+        m2.add_picture_blue(m2_img_path)
+        m2.save(m2_filename)
+
+        # verify that when a mission file is loaded
+        # it creates a unique temp folders for it's
+        # resources. If that's not true m2, which is loaded
+        # last, would overwrite resources from m1, and if m1
+        # is safed after m2 is loaded, it's resources
+        # would not have the right content.
+
+        m1 = dcs.Mission()
+        m1.load_file(m1_filename)
+        m2 = dcs.Mission()
+        m2.load_file(m2_filename)
+
+        self.assertNotEqual(m1.tmpdir, m2.tmpdir)
+        self.assertNotEqual(list(m1.map_resource.files["DEFAULT"].values()),
+                            list(m2.map_resource.files["DEFAULT"].values()))
+
     def test_empty_mission_with_coalitions(self) -> None:
         m = dcs.mission.Mission()
         m_filename = "tests/missions/countries-without-units-on-the-map.miz"