Make it easier to extend zipfile code

Feature or enhancement

Proposal:

This is follow up from https://github.com/python/cpython/issues/53416

Even if stdlib will never support WinZIP AES encrpyption, it would be useful to allow for downstream project to implement it.

There is pyzipper based on a fork but the code is now very different to what we have in stdlib.

it would help if the stdlib zipfile code is written to allow dependency injection

A very simple proof of concept downstream code is here that can only read AES ZIP files is here

https://github.com/chevah/zipfile-aes

It is using a patch for stdblib that looks like this

--- lib/python3.12/zipfile/__init__.py        2025-07-17 11:19:59.376677338 +0100
+++ src/dev_tools/zipfile_init.py       2025-07-17 11:21:50.797894299 +0100
@@ -1286,6 +1286,9 @@
 
     """
 
+    _ZipInfo = ZipInfo
+    _ZipExtFile = ZipExtFile
+
     fp = None                   # Set here since __del__ checks it
     _windows_illegal_name_trans_table = None
 
@@ -1456,7 +1459,7 @@
                 # Historical ZIP filename encoding
                 filename = filename.decode(self.metadata_encoding or 'cp437')
             # Create ZipInfo instance to store file information
-            x = ZipInfo(filename)
+            x = self._ZipInfo(filename)
             x.extra = fp.read(centdir[_CD_EXTRA_FIELD_LENGTH])
             x.comment = fp.read(centdir[_CD_COMMENT_LENGTH])
             x.header_offset = centdir[_CD_LOCAL_HEADER_OFFSET]
@@ -1592,11 +1595,11 @@
                 "Attempt to use ZIP archive that was already closed")
 
         # Make sure we have an info object
-        if isinstance(name, ZipInfo):
+        if isinstance(name, self._ZipInfo):
             # 'name' is already an info object
             zinfo = name
         elif mode == 'w':
-            zinfo = ZipInfo(name)
+            zinfo = self._ZipInfo(name)
             zinfo.compress_type = self.compression
             zinfo._compresslevel = self.compresslevel
         else:
@@ -1664,7 +1667,7 @@
             else:
                 pwd = None
 
-            return ZipExtFile(zef_file, mode, zinfo, pwd, True)
+            return self._ZipExtFile(zef_file, mode, zinfo, pwd, True)
         except:
             zef_file.close()
             raise
@@ -1762,7 +1765,7 @@
         """Extract the ZipInfo object 'member' to a physical
            file on the path targetpath.
         """
-        if not isinstance(member, ZipInfo):
+        if not isinstance(member, self._ZipInfo):
             member = self.getinfo(member)
 
         # build the destination pathname, replacing
@@ -1838,7 +1841,7 @@
                 "Can't write to ZIP archive while an open writing handle exists"
             )
 
-        zinfo = ZipInfo.from_file(filename, arcname,
+        zinfo = self._ZipInfo.from_file(filename, arcname,
                                   strict_timestamps=self._strict_timestamps)
 
         if zinfo.is_dir():
@@ -1868,8 +1871,8 @@
         the name of the file in the archive."""
         if isinstance(data, str):
             data = data.encode("utf-8")
-        if not isinstance(zinfo_or_arcname, ZipInfo):
-            zinfo = ZipInfo(filename=zinfo_or_arcname,
+        if not isinstance(zinfo_or_arcname, self._ZipInfo):
+            zinfo = self._ZipInfo(filename=zinfo_or_arcname,
                             date_time=time.localtime(time.time())[:6])
             zinfo.compress_type = self.compression
             zinfo._compresslevel = self.compresslevel
@@ -1910,7 +1913,7 @@
             directory_name = zinfo_or_directory_name
             if not directory_name.endswith("/"):
                 directory_name += "/"
-            zinfo = ZipInfo(directory_name)
+            zinfo = self._ZipInfo(directory_name)
             zinfo.compress_size = 0
             zinfo.CRC = 0
             zinfo.external_attr = ((0o40000 | mode) & 0xFFFF) << 16

Would you consider such a patch ?

Thanks

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

https://github.com/python/cpython/issues/53416

https://github.com/python/cpython/issues/81719

PR at https://github.com/python/cpython/pull/14957

Bắt đầu với lib/python3.12/zipfile/init.py, đặc biệt là ZipFile, ZipInfo và ZipExtFile, sau đó xem xét các issue 53416 và 81719 cùng PR 14957 để tham khảo các thảo luận thiết kế trước đây. Được xem là hoàn tất khi các dự án downstream có thể mở rộng triển khai zipfile cho các tính năng như hỗ trợ AES mà không phải duy trì một fork, và cơ chế mở rộng được chấp nhận đã được xác thực dựa trên hành vi liên quan.