Test cases use a fake home directory for their configuration, so they don't clutter the actual home directory.

src/cpp-utils/system/homedir.cpp

@@ -4,10 +4,26 @@
 
 namespace bf = boost::filesystem;
 using std::string;
+using cpputils::unique_ref;
+using cpputils::make_unique_ref;
 
 namespace cpputils {
     namespace system {
-        bf::path home_directory() {
+
+        HomeDirectory::HomeDirectory()
+                :_home_directory(_get_home_directory()) {
+        }
+
+        HomeDirectory &HomeDirectory::singleton() {
+            static HomeDirectory _singleton;
+            return _singleton;
+        }
+
+        const bf::path &HomeDirectory::get() {
+            return singleton()._home_directory;
+        }
+
+        bf::path HomeDirectory::_get_home_directory() {
             struct passwd* pwd = getpwuid(getuid());
             string homedir;
             if (pwd) {
@@ -21,5 +37,15 @@ namespace cpputils {
             }
             return homedir;
         }
+
+        FakeHomeDirectoryRAII::FakeHomeDirectoryRAII(const boost::filesystem::path &fakeHomeDirectory)
+                :_oldHomeDirectory(HomeDirectory::singleton()._home_directory) {
+            HomeDirectory::singleton()._home_directory = fakeHomeDirectory;
+        }
+
+        FakeHomeDirectoryRAII::~FakeHomeDirectoryRAII() {
+            // Reset to old (non-fake) value
+            HomeDirectory::singleton()._home_directory = _oldHomeDirectory;
+        }
     }
-}
+}

src/cpp-utils/system/homedir.h

@@ -3,11 +3,41 @@
 #define MESSMER_CPPUTILS_SYSTEM_GETTOTALMEMORY_H
 
 #include <boost/filesystem/path.hpp>
+#include "../macros.h"
+#include <cpp-utils/pointer/unique_ref.h>
 
 namespace cpputils {
     namespace system {
 
-        boost::filesystem::path home_directory();
+        class FakeHomeDirectoryRAII;
+
+        class HomeDirectory final {
+        public:
+            static const boost::filesystem::path &get();
+
+        private:
+            boost::filesystem::path _home_directory;
+
+            HomeDirectory();
+            static HomeDirectory &singleton();
+            boost::filesystem::path _get_home_directory();
+
+            friend class FakeHomeDirectoryRAII;
+
+            DISALLOW_COPY_AND_ASSIGN(HomeDirectory);
+        };
+
+
+        class FakeHomeDirectoryRAII final {
+        public:
+            FakeHomeDirectoryRAII(const boost::filesystem::path &fakeHomeDirectory);
+            ~FakeHomeDirectoryRAII();
+
+        private:
+            boost::filesystem::path _oldHomeDirectory;
+
+            DISALLOW_COPY_AND_ASSIGN(FakeHomeDirectoryRAII);
+        };
 
     }
 }

src/cryfs/filesystem/CryDevice.cpp

@@ -76,7 +76,7 @@ Key CryDevice::CreateRootBlobAndReturnKey() {
 }
 
 bf::path CryDevice::_integrityFilePath(const CryConfig::FilesystemID &filesystemId) {
-  bf::path app_dir = cpputils::system::home_directory() / ".cryfs";
+  bf::path app_dir = cpputils::system::HomeDirectory::get() / ".cryfs";
   _createDirIfNotExists(app_dir);
   bf::path filesystems_dir = app_dir / "filesystems";
   _createDirIfNotExists(filesystems_dir);

test/cryfs/filesystem/CryFsTest.cpp

@@ -9,6 +9,8 @@
 #include <cryfs/filesystem/CryOpenFile.h>
 #include "../testutils/MockConsole.h"
 #include <cryfs/config/CryConfigLoader.h>
+#include <cpp-utils/system/homedir.h>
+#include "../testutils/TestWithFakeHomeDirectory.h"
 
 //TODO (whole project) Make constructors explicit when implicit construction not needed
 
@@ -24,13 +26,14 @@ using cpputils::Console;
 using cpputils::Random;
 using cpputils::SCrypt;
 using cpputils::Data;
+using cpputils::system::FakeHomeDirectoryRAII;
 using blockstore::ondisk::OnDiskBlockStore;
 using boost::none;
 
 namespace bf = boost::filesystem;
 using namespace cryfs;
 
-class CryFsTest: public Test, public TestWithMockConsole {
+class CryFsTest: public Test, public TestWithMockConsole, public TestWithFakeHomeDirectory {
 public:
   CryFsTest(): rootdir(), config(false) {
   }

test/cryfs/filesystem/FileSystemTest.cpp

@@ -5,6 +5,7 @@
 #include <cryfs/filesystem/CryDevice.h>
 #include <cryfs/config/CryConfigLoader.h>
 #include "../testutils/MockConsole.h"
+#include "../testutils/TestWithFakeHomeDirectory.h"
 
 using cpputils::unique_ref;
 using cpputils::make_unique_ref;
@@ -19,7 +20,7 @@ using blockstore::testfake::FakeBlockStore;
 
 using namespace cryfs;
 
-class CryFsTestFixture: public FileSystemTestFixture, public TestWithMockConsole {
+class CryFsTestFixture: public FileSystemTestFixture, public TestWithMockConsole, public TestWithFakeHomeDirectory {
 public:
   CryFsTestFixture()
   // Don't create config tempfile yet

test/cryfs/filesystem/testutils/CryTestBase.h

@@ -5,8 +5,9 @@
 #include <blockstore/implementations/testfake/FakeBlockStore.h>
 #include <cpp-utils/tempfile/TempFile.h>
 #include <cpp-utils/crypto/kdf/Scrypt.h>
+#include "../../testutils/TestWithFakeHomeDirectory.h"
 
-class CryTestBase {
+class CryTestBase : public TestWithFakeHomeDirectory {
 public:
     CryTestBase(): _configFile(false), _device(nullptr) {
         auto fakeBlockStore = cpputils::make_unique_ref<blockstore::testfake::FakeBlockStore>();

test/cryfs/testutils/TestWithFakeHomeDirectory.h

@@ -0,0 +1,19 @@
+#pragma once
+#ifndef MESSMER_CRYFS_TEST_TESTUTILS_TESTWITHFAKEHOMEDIRECTORY_H
+#define MESSMER_CRYFS_TEST_TESTUTILS_TESTWITHFAKEHOMEDIRECTORY_H
+
+#include <cpp-utils/tempfile/TempDir.h>
+#include <cpp-utils/system/homedir.h>
+
+class TestWithFakeHomeDirectory {
+public:
+    TestWithFakeHomeDirectory()
+        :homedir(), fakeHomeDirRAII(homedir.path()) {
+    }
+
+private:
+    cpputils::TempDir homedir;
+    cpputils::system::FakeHomeDirectoryRAII fakeHomeDirRAII;
+};
+
+#endif