Modify build system to properly handle unreal version upgrades

build.py

@@ -51,6 +51,20 @@ def read_if_exists(fn):
     try: return Path(fn).read_text()
     except: return ""
 
+#
+# Fix a chmod bug in the Zipfile module.
+#
+
+class JZipFile(zipfile.ZipFile):
+    def _extract_member(self, member, targetpath, pwd):
+        if not isinstance(member, zipfile.ZipInfo):
+            member = self.getinfo(member)
+        targetpath = super()._extract_member(member, targetpath, pwd)
+        attr = member.external_attr >> 16
+        if attr != 0:
+            os.chmod(targetpath, attr)
+        return targetpath
+
 #
 # A JSON preprocessor.
 #
@@ -191,20 +205,26 @@ def unzip_unreal_engine_and_apply_patch():
     """
     Unzip the unreal engine source, then apply a patch.
     """
-    if not Path(UNREALENGINE).is_dir():
-        zipfn = f"{INTEGRATION}/UnrealEngine.zip";
-        with zipfile.ZipFile(zipfn, 'r') as z:
-            version = z.namelist()[0].split('/')[0]
-        if not fnmatch.fnmatch(version, 'UnrealEngine-*-release'):
-            sys.exit("UnrealEngine.zip does not contain UnrealEngine-*-release")
-        unrealversion = os.path.join(INTEGRATION, version)
+    zips = list(Path(INTEGRATION).glob("UnrealEngine-*-release.zip"))
+    if len(zips) == 0:
+        sys.exit("Cannot find UnrealEngine-*-release.zip")
+    if len(zips) > 1:
+        sys.exit("Found multiple files matching UnrealEngine-*-release.zip")
+    print("Unreal version: ", zips[0].stem)
+    zipfn = os.path.join(INTEGRATION, zips[0].name)
+    extracted = os.path.join(INTEGRATION, zips[0].stem)
+    touchfile = os.path.join(UNREALENGINE, zips[0].stem)
+    if not Path(touchfile).is_file():
+        print("Removing old version of unreal engine source...")
         shutil.rmtree(UNREALENGINE, ignore_errors=True)
-        shutil.rmtree(unrealversion, ignore_errors=True)
-        print("Unzipping UnrealEngine.zip...")
-        shell(INTEGRATION, "unzip -q UnrealEngine.zip")
+        shutil.rmtree(extracted, ignore_errors=True)
+        print(f"Unzipping {zipfn}...")
+        with JZipFile(zipfn) as zf:
+            zf.extractall(INTEGRATION)
         patchfile = f"{INTEGRATION}/EnginePatches/EnginePatch"
-        shell(unrealversion, f"patch -p1 < {patchfile}")
-        Path(unrealversion).rename(UNREALENGINE)
+        shell(extracted, f"patch -p1 < {patchfile}")
+        Path(extracted).rename(UNREALENGINE)
+        Path(touchfile).touch()
 
 
 def generate_buildconfiguration_xml():