extmod/vfs_posix: Do not filter '..*' in ilistdir when filtering '..'.

When iterating over os.ilistdir(), the special directories '.' and '..'
are filtered from the results.  But the code inadvertently also filtered
any file/directory which happened to match '..*'.  This change fixes the
filter.

Fixes issue #11032.

Signed-off-by: Jeremy Rand <jeremy@rand-family.com>

extmod/vfs_posix.c

@@ -192,7 +192,7 @@ STATIC mp_obj_t vfs_posix_ilistdir_it_iternext(mp_obj_t self_in) {
         MP_THREAD_GIL_ENTER();
         const char *fn = dirent->d_name;
 
-        if (fn[0] == '.' && (fn[1] == 0 || fn[1] == '.')) {
+        if (fn[0] == '.' && (fn[1] == 0 || (fn[1] == '.' && fn[2] == 0))) {
             // skip . and ..
             continue;
         }

tests/extmod/vfs_posix_ilistdir_filter.py

@@ -0,0 +1,47 @@
+# Test ilistdir filter of . and .. for VfsPosix.
+
+try:
+    import os
+
+    os.VfsPosix
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
+
+
+def test(testdir):
+    vfs = os.VfsPosix(testdir)
+
+    dirs = [".a", "..a", "...a", "a.b", "a..b"]
+
+    for dir in dirs:
+        vfs.mkdir(dir)
+
+    dirs = []
+    for entry in vfs.ilistdir("/"):
+        dirs.append(entry[0])
+    dirs.sort()
+
+    print(dirs)
+
+
+# We need an empty directory for testing.
+# Skip the test if it already exists.
+temp_dir = "vfs_posix_ilistdir_filter_test_dir"
+try:
+    os.stat(temp_dir)
+    print("SKIP")
+    raise SystemExit
+except OSError:
+    pass
+
+os.mkdir(temp_dir)
+
+try:
+    test(temp_dir)
+finally:
+    # Remove tempdir.
+    for td in os.listdir(temp_dir):
+        os.rmdir("/".join((temp_dir, td)))
+
+    os.rmdir(temp_dir)

tests/extmod/vfs_posix_ilistdir_filter.py.exp

@@ -0,0 +1 @@
+['...a', '..a', '.a', 'a..b', 'a.b']