Prevent symbolic link loops in import completion

etiennerichart · web-flow · commit b2111bda87aa · 2020-07-22T09:24:30.000-07:00
Use os.path.realpath while crawling the filesystem for import completion make sure that we are not in a loop. Resolves #806
diff --git a/bpython/importcompletion.py b/bpython/importcompletion.py
@@ -48,6 +48,9 @@
 
 # The cached list of all known modules
 modules = set()
+# List of stored paths to compare against so that real paths are not repeated
+# handles symlinks not mount points
+paths = set()
 fully_loaded = False
 
 
@@ -190,9 +193,12 @@ def find_modules(path):
             continue
         else:
             if is_package:
-                for subname in find_modules(pathname):
-                    if subname != "__init__":
-                        yield "%s.%s" % (name, subname)
+                path_real = os.path.realpath(pathname)
+                if path_real not in paths:
+                    paths.add(path_real)
+                    for subname in find_modules(pathname):
+                        if subname != "__init__":
+                            yield "%s.%s" % (name, subname)
             yield name
 
 
diff --git a/bpython/test/test_import_not_cyclical.py b/bpython/test/test_import_not_cyclical.py
@@ -0,0 +1,92 @@
+from bpython.test import unittest
+from bpython.importcompletion import find_modules
+import os, sys, tempfile
+
+
+@unittest.skipIf(sys.version_info[0] <= 2, "Test doesn't work in python 2.")
+class TestAvoidSymbolicLinks(unittest.TestCase):
+    def setUp(self):
+        with tempfile.TemporaryDirectory() as import_test_folder:
+            os.mkdir(os.path.join(import_test_folder, "Level0"))
+            os.mkdir(os.path.join(import_test_folder, "Right"))
+            os.mkdir(os.path.join(import_test_folder, "Left"))
+
+            current_path = os.path.join(import_test_folder, "Level0")
+            with open(
+                os.path.join(current_path, "__init__.py"), "x"
+            ) as init_file:
+                pass
+
+            current_path = os.path.join(current_path, "Level1")
+            os.mkdir(current_path)
+            with open(
+                os.path.join(current_path, "__init__.py"), "x"
+            ) as init_file:
+                pass
+
+            current_path = os.path.join(current_path, "Level2")
+            os.mkdir(current_path)
+            with open(
+                os.path.join(current_path, "__init__.py"), "x"
+            ) as init_file:
+                pass
+
+            os.symlink(
+                os.path.join(import_test_folder, "Level0/Level1"),
+                os.path.join(current_path, "Level3"),
+                True,
+            )
+
+            current_path = os.path.join(import_test_folder, "Right")
+            with open(
+                os.path.join(current_path, "__init__.py"), "x"
+            ) as init_file:
+                pass
+
+            os.symlink(
+                os.path.join(import_test_folder, "Left"),
+                os.path.join(current_path, "toLeft"),
+                True,
+            )
+
+            current_path = os.path.join(import_test_folder, "Left")
+            with open(
+                os.path.join(current_path, "__init__.py"), "x"
+            ) as init_file:
+                pass
+
+            os.symlink(
+                os.path.join(import_test_folder, "Right"),
+                os.path.join(current_path, "toRight"),
+                True,
+            )
+
+            self.foo = list(find_modules(os.path.abspath(import_test_folder)))
+            self.filepaths = [
+                "Left.toRight.toLeft",
+                "Left.toRight",
+                "Left",
+                "Level0.Level1.Level2.Level3",
+                "Level0.Level1.Level2",
+                "Level0.Level1",
+                "Level0",
+                "Right",
+                "Right.toLeft",
+                "Right.toLeft.toRight",
+            ]
+
+    def test_simple_symbolic_link_loop(self):
+        for thing in self.foo:
+            self.assertTrue(thing in self.filepaths)
+            if thing == "Left.toRight.toLeft":
+                self.filepaths.remove("Right.toLeft")
+                self.filepaths.remove("Right.toLeft.toRight")
+            if thing == "Right.toLeft.toRight":
+                self.filepaths.remove("Left.toRight.toLeft")
+                self.filepaths.remove("Left.toRight")
+            self.filepaths.remove(thing)
+        self.assertFalse(self.filepaths)
+
+
+if __name__ == "__main__":
+    unittest.main()
