If a migration was interrupted, continue on next mount

src/cryfs/config/CryConfig.cpp

@@ -32,6 +32,7 @@ CryConfig::CryConfig()
 , _exclusiveClientId(none)
 #ifndef CRYFS_NO_COMPATIBILITY
 , _hasVersionNumbers(true)
+, _hasParentPointers(true)
 #endif
 {
 }
@@ -53,6 +54,7 @@ CryConfig CryConfig::load(const Data &data) {
   cfg._exclusiveClientId = pt.get_optional<uint32_t>("cryfs.exclusiveClientId");
 #ifndef CRYFS_NO_COMPATIBILITY
   cfg._hasVersionNumbers = pt.get<bool>("cryfs.migrations.hasVersionNumbers", false);
+  cfg._hasParentPointers = pt.get<bool>("cryfs.migrations.hasParentPointers", false);
 #endif
 
   optional<string> filesystemIdOpt = pt.get_optional<string>("cryfs.filesystemId");
@@ -81,6 +83,7 @@ Data CryConfig::save() const {
   }
 #ifndef CRYFS_NO_COMPATIBILITY
   pt.put<bool>("cryfs.migrations.hasVersionNumbers", _hasVersionNumbers);
+  pt.put<bool>("cryfs.migrations.hasParentPointers", _hasParentPointers);
 #endif
 
   stringstream stream;
@@ -172,6 +175,14 @@ bool CryConfig::HasVersionNumbers() const {
 void CryConfig::SetHasVersionNumbers(bool value) {
   _hasVersionNumbers = value;
 }
+
+bool CryConfig::HasParentPointers() const {
+  return _hasParentPointers;
+}
+
+void CryConfig::SetHasParentPointers(bool value) {
+  _hasParentPointers = value;
+}
 #endif
 
 }

src/cryfs/config/CryConfig.h

@@ -56,6 +56,11 @@ public:
   // Version numbers cannot be disabled, but the file system will be migrated to version numbers automatically.
   bool HasVersionNumbers() const;
   void SetHasVersionNumbers(bool value);
+
+  // This is a trigger to recognize old file systems that didn't have version numbers.
+  // Version numbers cannot be disabled, but the file system will be migrated to version numbers automatically.
+  bool HasParentPointers() const;
+  void SetHasParentPointers(bool value);
 #endif
 
   static CryConfig load(const cpputils::Data &data);
@@ -73,6 +78,7 @@ private:
   boost::optional<uint32_t> _exclusiveClientId;
 #ifndef CRYFS_NO_COMPATIBILITY
   bool _hasVersionNumbers;
+  bool _hasParentPointers;
 #endif
 
   CryConfig &operator=(const CryConfig &rhs) = delete;

src/cryfs/filesystem/CryDevice.cpp

@@ -80,7 +80,14 @@ unique_ref<fsblobstore::FsBlobStore> CryDevice::MigrateOrCreateFsBlobStore(uniqu
   if ("" == rootBlobId) {
     return make_unique_ref<FsBlobStore>(std::move(blobStore));
   }
-  return FsBlobStore::migrateIfNeeded(std::move(blobStore), BlockId::FromString(rootBlobId));
+  if (!configFile->config()->HasParentPointers()) {
+    auto result = FsBlobStore::migrateIfNeeded(std::move(blobStore), BlockId::FromString(rootBlobId));
+    // Don't migrate again if it was successful
+    configFile->config()->SetHasParentPointers(true);
+    configFile->save();
+    return result;
+  }
+  return make_unique_ref<FsBlobStore>(std::move(blobStore));
 }
 #endif
 
@@ -106,6 +113,7 @@ unique_ref<BlockStore2> CryDevice::CreateIntegrityEncryptedBlockStore(unique_ref
   if (!configFile->config()->HasVersionNumbers()) {
     IntegrityBlockStore2::migrateFromBlockstoreWithoutVersionNumbers(encryptedBlockStore.get(), integrityFilePath, myClientId);
     configFile->config()->SetBlocksizeBytes(configFile->config()->BlocksizeBytes() + IntegrityBlockStore2::HEADER_LENGTH - blockstore::BlockId::BINARY_LENGTH); // Minus BlockId size because EncryptedBlockStore doesn't store the BlockId anymore (that was moved to IntegrityBlockStore)
+    // Don't migrate again if it was successful
     configFile->config()->SetHasVersionNumbers(true);
     configFile->save();
   }

src/cryfs/filesystem/fsblobstore/FsBlobStore.cpp

@@ -2,6 +2,7 @@
 #include "FileBlob.h"
 #include "DirBlob.h"
 #include "SymlinkBlob.h"
+#include <cryfs/config/CryConfigFile.h>
 
 using cpputils::unique_ref;
 using cpputils::make_unique_ref;

src/cryfs/filesystem/fsblobstore/FsBlobView.cpp

@@ -10,7 +10,11 @@ namespace cryfs {
     void FsBlobView::migrate(blobstore::Blob *blob, const blockstore::BlockId &parentId) {
         constexpr unsigned int OLD_HEADER_SIZE = sizeof(FORMAT_VERSION_HEADER) + sizeof(uint8_t);
 
-        ASSERT(FsBlobView::getFormatVersionHeader(*blob) == 0, "Block already migrated");
+        if(FsBlobView::getFormatVersionHeader(*blob) != 0) {
+          // blob already migrated
+          return;
+        }
+
         // Resize blob and move data back
         cpputils::Data data = blob->readAll();
         blob->resize(blob->size() + blockstore::BlockId::BINARY_LENGTH);