[PATCH] Fix directory_iterator handling of DT_UNKNOWN

[Jonathan Wakely]

We need to handle DT_UNKNOWN earlier, not only during directory
recursion, so that the cached file_type value in the directory_entry
won't be used.

        * src/c++17/fs_dir.cc (_Dir::advance(bool, error_code&)): Handle
        d_type == DT_UNKNOWN immediately.
        (_Dir::should_recurse(bool, error_code&)): Remove file_type::unknown
        handling here.
        * testsuite/27_io/filesystem/iterators/caching.cc: New test.

Tested powerpc64le-linux, committed to trunk.


commit df4389dfe37019b8ff26fca36bb3754e7e493ab9
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Fri Apr 5 17:43:20 2019 +0100

    Fix directory_iterator handling of DT_UNKNOWN
    
    We need to handle DT_UNKNOWN earlier, not only during directory
    recursion, so that the cached file_type value in the directory_entry
    won't be used.
    
            * src/c++17/fs_dir.cc (_Dir::advance(bool, error_code&)): Handle
            d_type == DT_UNKNOWN immediately.
            (_Dir::should_recurse(bool, error_code&)): Remove file_type::unknown
            handling here.
            * testsuite/27_io/filesystem/iterators/caching.cc: New test.

diff --git a/libstdc++-v3/src/c++17/fs_dir.cc b/libstdc++-v3/src/c++17/fs_dir.cc
index 8e6755ead85..629c4ebf78f 100644
--- a/libstdc++-v3/src/c++17/fs_dir.cc
+++ b/libstdc++-v3/src/c++17/fs_dir.cc
@@ -62,7 +62,13 @@ struct fs::_Dir : _Dir_base
       {
        auto name = path;
        name /= entp->d_name;
-       entry = fs::directory_entry{std::move(name), get_file_type(*entp)};
+       file_type type = file_type::none;
+#ifdef _GLIBCXX_HAVE_STRUCT_DIRENT_D_TYPE
+       // Even if the OS supports dirent::d_type the filesystem might not:
+       if (entp->d_type != DT_UNKNOWN)
+         type = get_file_type(*entp);
+#endif
+       entry = fs::directory_entry{std::move(name), type};
        return true;
       }
     else if (!ec)
@@ -90,7 +96,7 @@ struct fs::_Dir : _Dir_base
   bool should_recurse(bool follow_symlink, error_code& ec) const
   {
     file_type type = entry._M_type;
-    if (type == file_type::none || type == file_type::unknown)
+    if (type == file_type::none)
     {
       type = entry.symlink_status(ec).type();
       if (ec)
diff --git a/libstdc++-v3/testsuite/27_io/filesystem/iterators/caching.cc 
b/libstdc++-v3/testsuite/27_io/filesystem/iterators/caching.cc
new file mode 100644
index 00000000000..e95e514149e
--- /dev/null
+++ b/libstdc++-v3/testsuite/27_io/filesystem/iterators/caching.cc
@@ -0,0 +1,75 @@
+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+// { dg-do run { target c++17 } }
+
+#include <filesystem>
+#include <testsuite_fs.h>
+#include <testsuite_hooks.h>
+
+namespace fs = std::filesystem;
+
+__gnu_test::scoped_file
+create_dir(fs::path dir = __gnu_test::nonexistent_path())
+{
+  fs::create_directory(dir);
+  return { dir, __gnu_test::scoped_file::adopt_file };
+}
+
+void
+test01()
+{
+  auto testdir = create_dir();
+  __gnu_test::scoped_file file1(testdir.path/"file1");
+  __gnu_test::scoped_file file2(testdir.path/"file2");
+
+  fs::directory_iterator it(testdir.path);
+  VERIFY( it->is_regular_file() );
+  ++it;
+  VERIFY( it->is_regular_file() );
+  ++it;
+  VERIFY( it == fs::directory_iterator{} );
+}
+
+void
+test02()
+{
+  auto testdir = create_dir();
+  const auto sub1 = create_dir(testdir.path/"sub1");
+  __gnu_test::scoped_file file1(sub1.path / "file");
+  const auto sub2 = create_dir(testdir.path/"sub2");
+  __gnu_test::scoped_file file2(sub2.path / "file");
+
+  fs::recursive_directory_iterator it(testdir.path);
+  VERIFY( it->is_directory() );
+  ++it;
+  VERIFY( it->is_regular_file() );
+  ++it;
+  VERIFY( it->is_directory() );
+  ++it;
+  VERIFY( it->is_regular_file() );
+  ++it;
+  VERIFY( it == fs::recursive_directory_iterator{} );
+}
+
+int
+main()
+{
+  test01();
+  test02();
+}