GingerCal 1.1: apksigner v1 signing so Android 2.3 installs it; add Pangolin VPS setup notes

tools/zipalign.py

@@ -1,6 +1,8 @@
 #!/usr/bin/env python3
-"""Minimal zipalign: stored entries start on 4-byte boundaries. Keeps v1 (JAR) signatures valid,
-since those cover file contents, not the zip layout. usage: zipalign.py in.apk out.apk"""
+"""Minimal zipalign: uncompressed entries start on 4-byte boundaries (like the SDK's
+`zipalign 4`). Safe after v1 (JAR) signing, which covers entry contents, not zip layout.
+usage: zipalign.py in.apk out.apk"""
+import struct
 import sys
 import zipfile
 
@@ -16,9 +18,11 @@ with zipfile.ZipFile(src) as zin, open(dst, "wb") as f:
                 header_end = f.tell() + 30 + len(info.filename.encode("utf-8"))
                 out.extra = b"\0" * ((4 - header_end % 4) % 4)
             zout.writestr(out, data)
-with zipfile.ZipFile(dst) as z:
+
+with open(dst, "rb") as raw, zipfile.ZipFile(dst) as z:
     for info in z.infolist():
         if info.compress_type == zipfile.ZIP_STORED:
-            start = info.header_offset + 30 + len(info.filename.encode("utf-8")) + len(info.extra)
-            assert start % 4 == 0, info.filename
+            raw.seek(info.header_offset + 26)
+            n, m = struct.unpack("<HH", raw.read(4))
+            assert (info.header_offset + 30 + n + m) % 4 == 0, info.filename
 print("aligned", dst)