Implement migration for old filesystems that don't have parent pointers.

src/cryfs/filesystem/CryDevice.cpp

@@ -54,19 +54,27 @@ namespace bf = boost::filesystem;
 namespace cryfs {
 
 CryDevice::CryDevice(CryConfigFile configFile, unique_ref<BlockStore> blockStore, uint32_t myClientId)
-: _fsBlobStore(
+: _fsBlobStore(CreateFsBlobStore(std::move(blockStore), &configFile, myClientId)),
-      make_unique_ref<ParallelAccessFsBlobStore>(
-        make_unique_ref<CachingFsBlobStore>(
-          make_unique_ref<FsBlobStore>(
-            CreateBlobStore(std::move(blockStore), &configFile, myClientId)
-          )
-        )
-      )
-    ),
   _rootKey(GetOrCreateRootKey(&configFile)),
   _onFsAction() {
 }
 
+unique_ref<parallelaccessfsblobstore::ParallelAccessFsBlobStore> CryDevice::CreateFsBlobStore(unique_ref<BlockStore> blockStore, CryConfigFile *configFile, uint32_t myClientId) {
+  auto blobStore = CreateBlobStore(std::move(blockStore), configFile, myClientId);
+
+#ifndef CRYFS_NO_COMPATIBILITY
+  auto fsBlobStore = FsBlobStore::migrateIfNeeded(std::move(blobStore), Key::FromString(configFile->config()->RootBlob()));
+#else
+  auto fsBlobStore = make_unique_ref<FsBlobStore>(std::move(blobStore));
+#endif
+
+  return make_unique_ref<ParallelAccessFsBlobStore>(
+    make_unique_ref<CachingFsBlobStore>(
+      std::move(fsBlobStore)
+    )
+  );
+}
+
 unique_ref<blobstore::BlobStore> CryDevice::CreateBlobStore(unique_ref<BlockStore> blockStore, CryConfigFile *configFile, uint32_t myClientId) {
   auto versionCountingEncryptedBlockStore = CreateVersionCountingEncryptedBlockStore(std::move(blockStore), configFile, myClientId);
   // Create versionCountingEncryptedBlockStore not in the same line as BlobStoreOnBlocks, because it can modify BlocksizeBytes

src/cryfs/filesystem/CryDevice.h

@@ -49,6 +49,7 @@ private:
 
   blockstore::Key GetOrCreateRootKey(CryConfigFile *config);
   blockstore::Key CreateRootBlobAndReturnKey();
+  static cpputils::unique_ref<parallelaccessfsblobstore::ParallelAccessFsBlobStore> CreateFsBlobStore(cpputils::unique_ref<blockstore::BlockStore> blockStore, CryConfigFile *configFile, uint32_t myClientId);
   static cpputils::unique_ref<blobstore::BlobStore> CreateBlobStore(cpputils::unique_ref<blockstore::BlockStore> blockStore, CryConfigFile *configFile, uint32_t myClientId);
   static cpputils::unique_ref<blockstore::BlockStore> CreateVersionCountingEncryptedBlockStore(cpputils::unique_ref<blockstore::BlockStore> blockStore, CryConfigFile *configFile, uint32_t myClientId);
   static cpputils::unique_ref<blockstore::BlockStore> CreateEncryptedBlockStore(const CryConfig &config, cpputils::unique_ref<blockstore::BlockStore> baseBlockStore);

src/cryfs/filesystem/fsblobstore/FsBlobStore.cpp

@@ -10,6 +10,7 @@ using blobstore::BlobStore;
 using blockstore::Key;
 using boost::none;
 using std::function;
+using std::vector;
 
 namespace cryfs {
 namespace fsblobstore {
@@ -31,5 +32,38 @@ boost::optional<unique_ref<FsBlob>> FsBlobStore::load(const blockstore::Key &key
     }
 }
 
+#ifndef CRYFS_NO_COMPATIBILITY
+    unique_ref<FsBlobStore> FsBlobStore::migrateIfNeeded(unique_ref<BlobStore> blobStore, const blockstore::Key &rootKey) {
+        auto rootBlob = blobStore->load(rootKey);
+        ASSERT(rootBlob != none, "Could not load root blob");
+        uint16_t format = FsBlobView::getFormatVersionHeader(**rootBlob);
+
+        auto fsBlobStore = make_unique_ref<FsBlobStore>(std::move(blobStore));
+        if (format == 0) {
+            // migration needed
+            std::cout << "Migrating file system for conflict resolution features. Please don't interrupt this process. This can take a while..." << std::flush;
+            fsBlobStore->_migrate(std::move(*rootBlob), blockstore::Key::Null());
+            std::cout << "done" << std::endl;
+        }
+        return fsBlobStore;
+    }
+
+    void FsBlobStore::_migrate(unique_ref<blobstore::Blob> node, const blockstore::Key &parentKey) {
+        FsBlobView::migrate(node.get(), parentKey);
+        if (FsBlobView::blobType(*node) == FsBlobView::BlobType::DIR) {
+            DirBlob dir(this, std::move(node), _getLstatSize());
+            vector<fspp::Dir::Entry> children;
+            dir.AppendChildrenTo(&children);
+            for (const auto &child : children) {
+                auto childEntry = dir.GetChild(child.name);
+                ASSERT(childEntry != none, "Couldn't load child, although it was returned as a child in the lsit.");
+                auto childBlob = _baseBlobStore->load(childEntry->key());
+                ASSERT(childBlob != none, "Couldn't load child blob");
+                _migrate(std::move(*childBlob), dir.key());
+            }
+        }
+    }
+#endif
+
 }
 }

src/cryfs/filesystem/fsblobstore/FsBlobStore.h

@@ -27,8 +27,16 @@ namespace cryfs {
 
             uint64_t virtualBlocksizeBytes() const;
 
+#ifndef CRYFS_NO_COMPATIBILITY
+            static cpputils::unique_ref<FsBlobStore> migrateIfNeeded(cpputils::unique_ref<blobstore::BlobStore> blobStore, const blockstore::Key &rootKey);
+#endif
+
         private:
 
+#ifndef CRYFS_NO_COMPATIBILITY
+            void _migrate(cpputils::unique_ref<blobstore::Blob> node, const blockstore::Key &parentKey);
+#endif
+
             std::function<off_t(const blockstore::Key &)> _getLstatSize();
 
             cpputils::unique_ref<blobstore::BlobStore> _baseBlobStore;

src/cryfs/filesystem/fsblobstore/FsBlobView.cpp

@@ -1,6 +1,24 @@
 #include "FsBlobView.h"
 
+using cpputils::Data;
+
 namespace cryfs {
     constexpr uint16_t FsBlobView::FORMAT_VERSION_HEADER;
     constexpr unsigned int FsBlobView::HEADER_SIZE;
+
+#ifndef CRYFS_NO_COMPATIBILITY
+    void FsBlobView::migrate(blobstore::Blob *blob, const blockstore::Key &parentKey) {
+        constexpr unsigned int OLD_HEADER_SIZE = sizeof(FORMAT_VERSION_HEADER) + sizeof(uint8_t);
+
+        ASSERT(FsBlobView::getFormatVersionHeader(*blob) == 0, "Block already migrated");
+        // Resize blob and move data back
+        cpputils::Data data = blob->readAll();
+        blob->resize(blob->size() + blockstore::Key::BINARY_LENGTH);
+        blob->write(data.dataOffset(OLD_HEADER_SIZE), HEADER_SIZE, data.size() - OLD_HEADER_SIZE);
+        // Write parent pointer
+        blob->write(parentKey.data(), sizeof(FORMAT_VERSION_HEADER) + sizeof(uint8_t), blockstore::Key::BINARY_LENGTH);
+        // Update format version number
+        blob->write(&FORMAT_VERSION_HEADER, 0, sizeof(FORMAT_VERSION_HEADER));
+    }
+#endif
 }

src/cryfs/filesystem/fsblobstore/FsBlobView.h

@@ -89,14 +89,23 @@ namespace cryfs {
             return std::move(_baseBlob);
         }
 
+        static uint16_t getFormatVersionHeader(const blobstore::Blob &blob) {
+            static_assert(sizeof(uint16_t) == sizeof(FORMAT_VERSION_HEADER), "Wrong type used to read format version header");
+            uint16_t actualFormatVersion;
+            blob.read(&actualFormatVersion, 0, sizeof(FORMAT_VERSION_HEADER));
+            return actualFormatVersion;
+        }
+
+#ifndef CRYFS_NO_COMPATIBILITY
+        static void migrate(blobstore::Blob *blob, const blockstore::Key &parentKey);
+#endif
+
     private:
         static constexpr uint16_t FORMAT_VERSION_HEADER = 1;
         static constexpr unsigned int HEADER_SIZE = sizeof(FORMAT_VERSION_HEADER) + sizeof(uint8_t) + blockstore::Key::BINARY_LENGTH;
 
         static void _checkHeader(const blobstore::Blob &blob) {
-            static_assert(sizeof(uint16_t) == sizeof(FORMAT_VERSION_HEADER), "Wrong type used to read format version header");
+            uint16_t actualFormatVersion = getFormatVersionHeader(blob);
-            uint16_t actualFormatVersion;
-            blob.read(&actualFormatVersion, 0, sizeof(FORMAT_VERSION_HEADER));
             if (FORMAT_VERSION_HEADER != actualFormatVersion) {
                 throw std::runtime_error("This file system entity has the wrong format. Was it created with a newer version of CryFS?");
             }