Bug 1752630 - Use UNIX permissions in packaged omnijars and XPIs. r=glandium

This unifies the ZIP permissions in omnijars and internal XPIs
produced by the packager directly and those repacked by l10n
single-repacks.

Differential Revision: https://phabricator.services.mozilla.com/D137340

python/mozbuild/mozpack/mozjar.py

@@ -611,8 +611,9 @@ class JarWriter(object):
         respectively, to JAR_DEFLATE and JAR_STORED.
         When the data should be compressed, it is only really compressed if
         the compressed size is smaller than the uncompressed size.
-        The mode option gives the unix permissions that should be stored
-        for the jar entry.
+        The mode option gives the unix permissions that should be stored for the
+        jar entry, which defaults to 0o100644 (regular file, u+rw, g+r, o+r) if
+        not specified.
         If a duplicated member is found skip_duplicates will prevent raising
         an exception if set to True.
         The given data may be a buffer, a file-like instance, a Deflater or a
@@ -646,11 +647,16 @@ class JarWriter(object):
         # Fill a central directory entry for this new member.
         entry = JarCdirEntry()
         entry["creator_version"] = 20
-        if mode is not None:
-            # Set creator host system (upper byte of creator_version)
-            # to 3 (Unix) so mode is honored when there is one.
-            entry["creator_version"] |= 3 << 8
-            entry["external_attr"] = (mode & 0xFFFF) << 16
+        if mode is None:
+            # If no mode is given, default to u+rw, g+r, o+r.
+            mode = 0o000644
+        if not mode & 0o777000:
+            # If no file type is given, default to regular file.
+            mode |= 0o100000
+        # Set creator host system (upper byte of creator_version) to 3 (Unix) so
+        # mode is honored when there is one.
+        entry["creator_version"] |= 3 << 8
+        entry["external_attr"] = (mode & 0xFFFF) << 16
         if deflater.compressed:
             entry["min_version"] = 20  # Version 2.0 supports deflated streams
             entry["general_flag"] = 2  # Max compression