Adding the file access times makes CryFS 0.9 incompatible with earlier versions. This commit adds a warning telling the user when they try to mount an old file system.

ChangeLog.txt

@@ -1,5 +1,6 @@
 Version 0.9.0 (unreleased)
 ---------------
+  (warning) file systems created with earlier CryFS versions are incompatible with this release
 * Fully support file access times
 
 Version 0.8.6 (unreleased)

src/config/CryConfig.cpp

@@ -15,11 +15,11 @@ using cpputils::Data;
 namespace cryfs {
 
 CryConfig::CryConfig()
-: _rootBlob(""), _encKey(""), _cipher("") {
+: _rootBlob(""), _encKey(""), _cipher(""), _version("") {
 }
 
 CryConfig::CryConfig(CryConfig &&rhs)
-: _rootBlob(std::move(rhs._rootBlob)), _encKey(std::move(rhs._encKey)), _cipher(std::move(rhs._cipher)) {
+: _rootBlob(std::move(rhs._rootBlob)), _encKey(std::move(rhs._encKey)), _cipher(std::move(rhs._cipher)), _version(std::move(rhs._version)) {
 }
 
 CryConfig CryConfig::load(const Data &data) {
@@ -32,6 +32,7 @@ CryConfig CryConfig::load(const Data &data) {
   cfg._rootBlob = pt.get("cryfs.rootblob", "");
   cfg._encKey = pt.get("cryfs.key", "");
   cfg._cipher = pt.get("cryfs.cipher", "");
+  cfg._version = pt.get("cryfs.version", "0.8"); // CryFS 0.8 didn't specify this field, so if the field doesn't exist, it's 0.8.
   return cfg;
 }
 
@@ -41,6 +42,7 @@ Data CryConfig::save() const {
   pt.put("cryfs.rootblob", _rootBlob);
   pt.put("cryfs.key", _encKey);
   pt.put("cryfs.cipher", _cipher);
+  pt.put("cryfs.version", _version);
 
   stringstream stream;
   write_json(stream, pt);
@@ -71,4 +73,12 @@ void CryConfig::SetCipher(const std::string &value) {
   _cipher = value;
 }
 
+const std::string &CryConfig::Version() const {
+  return _version;
+}
+
+void CryConfig::SetVersion(const std::string &value) {
+  _version = value;
+}
+
 }

src/config/CryConfig.h

@@ -24,6 +24,9 @@ public:
   const std::string &Cipher() const;
   void SetCipher(const std::string &value);
 
+  const std::string &Version() const;
+  void SetVersion(const std::string &value);
+
   static CryConfig load(const cpputils::Data &data);
   cpputils::Data save() const;
 
@@ -31,6 +34,7 @@ private:
   std::string _rootBlob;
   std::string _encKey;
   std::string _cipher;
+  std::string _version;
 
   DISALLOW_COPY_AND_ASSIGN(CryConfig);
 };

src/config/CryConfigCreator.cpp

@@ -1,5 +1,6 @@
 #include "CryConfigCreator.h"
 #include "CryCipher.h"
+#include <gitversion/version.h>
 
 using cpputils::Console;
 using cpputils::unique_ref;
@@ -21,6 +22,7 @@ namespace cryfs {
         config.SetCipher(_generateCipher(cipherFromCommandLine));
         config.SetEncryptionKey(_generateEncKey(config.Cipher()));
         config.SetRootBlob(_generateRootBlobKey());
+        config.SetVersion(version::VERSION_STRING);
         return config;
     }
 

src/config/CryConfigLoader.cpp

@@ -3,6 +3,8 @@
 #include <boost/filesystem.hpp>
 #include <messmer/cpp-utils/random/Random.h>
 #include <messmer/cpp-utils/logging/logging.h>
+#include <boost/algorithm/string/predicate.hpp>
+#include <gitversion/version.h>
 
 namespace bf = boost::filesystem;
 using cpputils::unique_ref;
@@ -37,12 +39,24 @@ optional<CryConfigFile> CryConfigLoader::_loadConfig(const bf::path &filename) {
     return none;
   }
   std::cout << "done" << std::endl;
-  if (_cipherFromCommandLine != none && config->config()->Cipher() != *_cipherFromCommandLine) {
-    throw std::runtime_error("Filesystem uses "+config->config()->Cipher()+" cipher and not "+*_cipherFromCommandLine+" as specified.");
-  }
+  _checkVersion(*config->config());
+  _checkCipher(*config->config());
   return std::move(*config);
 }
 
+void CryConfigLoader::_checkVersion(const CryConfig &config) {
+  const string allowedVersionPrefix = string() + version::VERSION_COMPONENTS[0] + "." + version::VERSION_COMPONENTS[1] + ".";
+  if (!boost::starts_with(config.Version(), allowedVersionPrefix)) {
+    throw std::runtime_error(string() + "This filesystem was created with CryFS " + config.Version() + " and is incompatible. Please create a new one with your version of CryFS and migrate your data.");
+  }
+}
+
+void CryConfigLoader::_checkCipher(const CryConfig &config) const {
+  if (_cipherFromCommandLine != none && config.Cipher() != *_cipherFromCommandLine) {
+    throw std::runtime_error(string() + "Filesystem uses " + config.Cipher() + " cipher and not " + *_cipherFromCommandLine + " as specified.");
+  }
+}
+
 optional<CryConfigFile> CryConfigLoader::loadOrCreate(const bf::path &filename) {
   if (bf::exists(filename)) {
     return _loadConfig(filename);

src/config/CryConfigLoader.h

@@ -21,6 +21,8 @@ public:
 private:
     boost::optional<CryConfigFile> _loadConfig(const boost::filesystem::path &filename);
     CryConfigFile _createConfig(const boost::filesystem::path &filename);
+    static void _checkVersion(const CryConfig &config);
+    void _checkCipher(const CryConfig &config) const;
 
     CryConfigCreator _creator;
     cpputils::SCryptSettings _scryptSettings;