gh-117084: Fix ZIP file extraction for directory entry names with backslashes on Windows (GH-117129)

1 files changed, 9 insertions, 1 deletions

diff --git a/Lib/zipfile/__init__.py b/Lib/zipfile/__init__.py
index cc08f60..b330ece 100644
--- a/Lib/zipfile/__init__.py
+++ b/Lib/zipfile/__init__.py
@@ -605,7 +605,15 @@ class ZipInfo:
 
     def is_dir(self):
         """Return True if this archive member is a directory."""
-        return self.filename.endswith('/')
+        if self.filename.endswith('/'):
+            return True
+        # The ZIP format specification requires to use forward slashes
+        # as the directory separator, but in practice some ZIP files
+        # created on Windows can use backward slashes.  For compatibility
+        # with the extraction code which already handles this:
+        if os.path.altsep:
+            return self.filename.endswith((os.path.sep, os.path.altsep))
+        return False
 
 
 # ZIP encryption uses the CRC32 one-byte primitive for scrambling some