GH-115060: Speed up `pathlib.Path.glob()` by omitting initial `stat()` (#117831)

Since 6258844c, paths that might not exist can be fed into pathlib's
globbing implementation, which will call `os.scandir()` / `os.lstat()` only
when strictly necessary. This allows us to drop an initial `self.is_dir()`
call, which saves a `stat()`.

Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>

4 files changed, 12 insertions, 6 deletions

diff --git a/Lib/pathlib/__init__.py b/Lib/pathlib/__init__.py
index 66eb08a..a4721fb 100644
--- a/Lib/pathlib/__init__.py
+++ b/Lib/pathlib/__init__.py
@@ -607,11 +607,9 @@ class Path(_abc.PathBase, PurePath):
         if raw[-1] in (self.parser.sep, self.parser.altsep):
             # GH-65238: pathlib doesn't preserve trailing slash. Add it back.
             parts.append('')
-        if not self.is_dir():
-            return iter([])
         select = self._glob_selector(parts[::-1], case_sensitive, recurse_symlinks)
         root = str(self)
-        paths = select(root, exists=True)
+        paths = select(root)
 
         # Normalize results
         if root == '.':
diff --git a/Lib/pathlib/_abc.py b/Lib/pathlib/_abc.py
index b51ad6f..05698d5 100644
--- a/Lib/pathlib/_abc.py
+++ b/Lib/pathlib/_abc.py
@@ -705,10 +705,8 @@ class PathBase(PurePathBase):
         anchor, parts = pattern._stack
         if anchor:
             raise NotImplementedError("Non-relative patterns are unsupported")
-        if not self.is_dir():
-            return iter([])
         select = self._glob_selector(parts, case_sensitive, recurse_symlinks)
-        return select(self, exists=True)
+        return select(self)
 
     def rglob(self, pattern, *, case_sensitive=None, recurse_symlinks=True):
         """Recursively yield all existing files (of any kind, including
diff --git a/Lib/test/test_pathlib/test_pathlib.py b/Lib/test/test_pathlib/test_pathlib.py
index 651d666..5fd1a41 100644
--- a/Lib/test/test_pathlib/test_pathlib.py
+++ b/Lib/test/test_pathlib/test_pathlib.py
@@ -1263,6 +1263,13 @@ class PathTest(test_pathlib_abc.DummyPathTest, PurePathTest):
             self.assertEqual(
                 set(P('.').glob('**/*/*')), {P("dirD/fileD")})
 
+    def test_glob_inaccessible(self):
+        P = self.cls
+        p = P(self.base, "mydir1", "mydir2")
+        p.mkdir(parents=True)
+        p.parent.chmod(0)
+        self.assertEqual(set(p.glob('*')), set())
+
     def test_rglob_pathlike(self):
         P = self.cls
         p = P(self.base, "dirC")
diff --git a/Lib/test/test_pathlib/test_pathlib_abc.py b/Lib/test/test_pathlib/test_pathlib_abc.py
index 6656b03..aadecbc 100644
--- a/Lib/test/test_pathlib/test_pathlib_abc.py
+++ b/Lib/test/test_pathlib/test_pathlib_abc.py
@@ -8,6 +8,7 @@ import unittest
 from pathlib._abc import UnsupportedOperation, ParserBase, PurePathBase, PathBase
 import posixpath
 
+from test.support import is_wasi
 from test.support.os_helper import TESTFN
 
 
@@ -1920,6 +1921,8 @@ class DummyPathTest(DummyPurePathTest):
                   }
         self.assertEqual(given, {p / x for x in expect})
 
+    # See https://github.com/WebAssembly/wasi-filesystem/issues/26
+    @unittest.skipIf(is_wasi, "WASI resolution of '..' parts doesn't match POSIX")
     def test_glob_dotdot(self):
         # ".." is not special in globs.
         P = self.cls