Add project files.

env/Lib/site-packages/pip/utils/filesystem.py

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+import os
+import os.path
+
+from pip.compat import get_path_uid
+
+
+def check_path_owner(path):
+    # If we don't have a way to check the effective uid of this process, then
+    # we'll just assume that we own the directory.
+    if not hasattr(os, "geteuid"):
+        return True
+
+    previous = None
+    while path != previous:
+        if os.path.lexists(path):
+            # Check if path is writable by current user.
+            if os.geteuid() == 0:
+                # Special handling for root user in order to handle properly
+                # cases where users use sudo without -H flag.
+                try:
+                    path_uid = get_path_uid(path)
+                except OSError:
+                    return False
+                return path_uid == 0
+            else:
+                return os.access(path, os.W_OK)
+        else:
+            previous, path = path, os.path.dirname(path)