Shorten path on image build if needed (Windows with no long path supp…

…ort)

src/virtualenv/seed/embed/via_app_data/pip_install/base.py

@@ -51,13 +51,28 @@ def build_image(self):
         # 1. first extract the wheel
         logging.debug("build install image for %s to %s", self._wheel.name, self._image_dir)
         with zipfile.ZipFile(str(self._wheel)) as zip_ref:
+            self._shorten_path_if_needed(zip_ref)
             zip_ref.extractall(str(self._image_dir))
             self._extracted = True
         # 2. now add additional files not present in the distribution
         new_files = self._generate_new_files()
         # 3. finally fix the records file
         self._fix_records(new_files)
 
+    def _shorten_path_if_needed(self, zip_ref):
+        if os.name == "nt":
+            to_folder = str(self._image_dir)
+            # https://docs.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation
+            zip_max_len = max(len(i) for i in zip_ref.namelist())
+            path_len = zip_max_len + len(to_folder)
+            if path_len > 260:
+                self._image_dir.mkdir(exist_ok=True)  # to get a short path must exist
+
+                from virtualenv.util.path import get_short_path_name
+
+                to_folder = get_short_path_name(to_folder)
+                self._image_dir = Path(to_folder)
+
     def _records_text(self, files):
         record_data = "\n".join(
             "{},,".format(os.path.relpath(ensure_text(str(rec)), ensure_text(str(self._image_dir)))) for rec in files

src/virtualenv/util/path/__init__.py

@@ -3,6 +3,7 @@
 from ._pathlib import Path
 from ._permission import make_exe, set_tree
 from ._sync import copy, copytree, ensure_dir, safe_delete, symlink
+from ._win import get_short_path_name
 
 __all__ = (
     "ensure_dir",
@@ -13,4 +14,5 @@
     "make_exe",
     "set_tree",
     "safe_delete",
+    "get_short_path_name",
 )

src/virtualenv/util/path/_win.py

@@ -0,0 +1,19 @@
+def get_short_path_name(long_name):
+    """
+    Gets the short path name of a given long path.
+    http://stackoverflow.com/a/23598461/200291
+    """
+    import ctypes
+    from ctypes import wintypes
+
+    _GetShortPathNameW = ctypes.windll.kernel32.GetShortPathNameW
+    _GetShortPathNameW.argtypes = [wintypes.LPCWSTR, wintypes.LPWSTR, wintypes.DWORD]
+    _GetShortPathNameW.restype = wintypes.DWORD
+    output_buf_size = 0
+    while True:
+        output_buf = ctypes.create_unicode_buffer(output_buf_size)
+        needed = _GetShortPathNameW(long_name, output_buf, output_buf_size)
+        if output_buf_size >= needed:
+            return output_buf.value
+        else:
+            output_buf_size = needed

tests/conftest.py

@@ -335,9 +335,6 @@ def current_fastest(current_creators):
 @pytest.fixture(scope="session")
 def session_app_data(tmp_path_factory):
     temp_folder = tmp_path_factory.mktemp("session-app-data")
-    # check long path support
-    test_long_path_support = temp_folder / ("a" * (270 - len(str(temp_folder))))
-    test_long_path_support.write_text("a")
     app_data = AppDataDiskFolder(folder=str(temp_folder))
     with change_env_var(str("VIRTUALENV_OVERRIDE_APP_DATA"), str(app_data.lock.path)):
         yield app_data