[libcxx] [test] Allow C:\System Volume Information to be missing

If running in a Windows Container, there is no such directory at all.

If running from within bash on Windows Server, the directory seems to
be fully accessible. (The mechanics of this isn't fully understood, and
it doesn't seem to happen on desktop versions.)

If the directory isn't available with the expected behaviour, mark those
individual tests as unsupported. (The test as a whole is considered to
pass, but the unsupported test is mentioned in a test summary printed on
stdout.)

Differential Revision: https://reviews.llvm.org/D98960

Author: mstorsjo

libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.cons/path.pass.cpp

@@ -8,8 +8,6 @@
 
 // UNSUPPORTED: c++03
 
-// XFAIL: LIBCXX-WINDOWS-FIXME
-
 // <filesystem>
 
 // class directory_entry
@@ -155,7 +153,8 @@ TEST_CASE(path_ctor_cannot_resolve) {
   // reading directories; test using a special inaccessible directory
   // instead.
   const path dir = GetWindowsInaccessibleDir();
-  TEST_REQUIRE(!dir.empty());
+  if (dir.empty())
+    TEST_UNSUPPORTED();
   const path file = dir / "file";
   {
     std::error_code ec = GetTestEC();

libcxx/test/std/input.output/filesystems/class.directory_iterator/directory_iterator.members/ctor.pass.cpp

@@ -8,8 +8,6 @@
 
 // UNSUPPORTED: c++03
 
-// XFAIL: LIBCXX-WINDOWS-FIXME
-
 // <filesystem>
 
 // class directory_iterator
@@ -94,7 +92,8 @@ TEST_CASE(access_denied_test_case)
     // reading directories; test using a special inaccessible directory
     // instead.
     const path testDir = GetWindowsInaccessibleDir();
-    TEST_REQUIRE(!testDir.empty());
+    if (testDir.empty())
+        TEST_UNSUPPORTED();
 #else
     scoped_test_env env;
     path const testDir = env.make_env_path("dir1");

libcxx/test/std/input.output/filesystems/class.rec.dir.itr/rec.dir.itr.members/ctor.pass.cpp

@@ -8,8 +8,6 @@
 
 // UNSUPPORTED: c++03
 
-// XFAIL: LIBCXX-WINDOWS-FIXME
-
 // <filesystem>
 
 // class directory_iterator
@@ -95,7 +93,8 @@ TEST_CASE(access_denied_test_case)
     // reading directories; test using a special inaccessible directory
     // instead.
     const path testDir = GetWindowsInaccessibleDir();
-    TEST_REQUIRE(!testDir.empty());
+    if (testDir.empty())
+        TEST_UNSUPPORTED();
 #else
     scoped_test_env env;
     path const testDir = env.make_env_path("dir1");

libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.exists/exists.pass.cpp

@@ -8,8 +8,6 @@
 
 // UNSUPPORTED: c++03
 
-// XFAIL: LIBCXX-WINDOWS-FIXME
-
 // <filesystem>
 
 // bool exists(file_status s) noexcept
@@ -91,7 +89,8 @@ TEST_CASE(test_exists_fails)
     // reading directories; test using a special inaccessible directory
     // instead.
     const path p = GetWindowsInaccessibleDir();
-    TEST_REQUIRE(!p.empty());
+    if (p.empty())
+        TEST_UNSUPPORTED();
 #else
     scoped_test_env env;
     const path dir = env.create_dir("dir");

libcxx/test/support/filesystem_test_helper.h

@@ -678,22 +678,28 @@ inline fs::path GetWindowsInaccessibleDir() {
   const fs::path dir("C:\\System Volume Information");
   std::error_code ec;
   const fs::path root("C:\\");
-  fs::directory_iterator it(root, ec);
-  if (ec)
-    return fs::path();
-  const fs::directory_iterator endIt{};
-  while (it != endIt) {
-    const fs::directory_entry &ent = *it;
-    if (ent == dir) {
-      // Basic sanity checks on the directory_entry
-      if (!ent.exists())
-        return fs::path();
-      if (!ent.is_directory())
-        return fs::path();
-      return ent;
+  for (const auto &ent : fs::directory_iterator(root, ec)) {
+    if (ent != dir)
+      continue;
+    // Basic sanity checks on the directory_entry
+    if (!ent.exists() || !ent.is_directory()) {
+      fprintf(stderr, "The expected inaccessible directory \"%s\" was found "
+                      "but doesn't behave as expected, skipping tests "
+                      "regarding it\n", dir.string().c_str());
+      return fs::path();
     }
-    ++it;
+    // Check that it indeed is inaccessible as expected
+    (void)fs::exists(ent, ec);
+    if (!ec) {
+      fprintf(stderr, "The expected inaccessible directory \"%s\" was found "
+                      "but seems to be accessible, skipping tests "
+                      "regarding it\n", dir.string().c_str());
+      return fs::path();
+    }
+    return ent;
   }
+  fprintf(stderr, "No inaccessible directory \"%s\" found, skipping tests "
+                  "regarding it\n", dir.string().c_str());
   return fs::path();
 }