FileSystem: Add a test for deleting directories with symlinks

tests/ctest/common/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_pcsx2_test(common_test
 	byteswap_tests.cpp
+	filesystem_tests.cpp
 	path_tests.cpp
 	string_util_tests.cpp
 )

tests/ctest/common/filesystem_tests.cpp

@@ -0,0 +1,60 @@
+// SPDX-FileCopyrightText: 2002-2024 PCSX2 Dev Team
+// SPDX-License-Identifier: GPL-3.0+
+
+#include "common/FileSystem.h"
+#include "common/Path.h"
+#include <gtest/gtest.h>
+
+#ifdef __linux__
+
+#include <unistd.h>
+
+static std::optional<std::string> create_test_directory()
+{
+	for (u16 i = 0; i < UINT16_MAX; i++)
+	{
+		std::string path = std::string("/tmp/pcsx2_filesystem_test_") + std::to_string(i);
+		if (!FileSystem::DirectoryExists(path.c_str()))
+		{
+			if (!FileSystem::CreateDirectoryPath(path.c_str(), false))
+				break;
+
+			return path;
+		}
+	}
+
+	return std::nullopt;
+}
+
+TEST(FileSystem, RecursiveDeleteDirectoryDontFollowSymbolicLinks)
+{
+	// Find a suitable location to write some test files.
+	std::optional<std::string> test_dir = create_test_directory();
+	ASSERT_TRUE(test_dir.has_value());
+
+	// Create a target directory containing a file that shouldn't be deleted.
+	std::string target_dir = Path::Combine(*test_dir, "target_dir");
+	ASSERT_TRUE(FileSystem::CreateDirectoryPath(target_dir.c_str(), false));
+	std::string file_path = Path::Combine(target_dir, "file.txt");
+	ASSERT_TRUE(FileSystem::WriteStringToFile(file_path.c_str(), "Lorem ipsum!"));
+
+	// Create a directory containing a symlink to the target directory.
+	std::string dir_to_delete = Path::Combine(*test_dir, "dir_to_delete");
+	ASSERT_TRUE(FileSystem::CreateDirectoryPath(dir_to_delete.c_str(), false));
+	std::string symlink_path = Path::Combine(dir_to_delete, "link");
+	ASSERT_EQ(symlink(target_dir.c_str(), symlink_path.c_str()), 0);
+
+	// Delete the directory containing the symlink.
+	ASSERT_TRUE(dir_to_delete.starts_with("/tmp/"));
+	ASSERT_TRUE(FileSystem::RecursiveDeleteDirectory(dir_to_delete.c_str()));
+
+	// Make sure the target file didn't get deleted.
+	ASSERT_TRUE(FileSystem::FileExists(file_path.c_str()));
+
+	// Clean up.
+	ASSERT_TRUE(FileSystem::DeleteFilePath(file_path.c_str()));
+	ASSERT_TRUE(FileSystem::DeleteDirectory(target_dir.c_str()));
+	ASSERT_TRUE(FileSystem::DeleteDirectory(test_dir->c_str()));
+}
+
+#endif