Fix fstat (a bug in the fstat implementation caused problems with some text editors (e.g. nano) falsely thinking a file changed since they opened it).

ChangeLog.txt

@@ -6,6 +6,7 @@ Version 0.9.3 (unreleased)
 * You can disable the automatic update check by setting CRYFS_NO_UPDATE_CHECK=true in your environment.
 * Building CryFS from the GitHub tarball (i.e. when there is no .git directory present) works.
 * The ciphertext block size is configurable. You can use the "--blocksize-bytes" command line argument. If not specified, CryFS will ask you for a block size when creating a file system.
+* Fix fstat (a bug in the fstat implementation caused problems with some text editors (e.g. nano) falsely thinking a file changed since they opened it).
 
 Version 0.9.2
 ---------------

src/cryfs/filesystem/CryDir.cpp

@@ -41,8 +41,9 @@ unique_ref<fspp::OpenFile> CryDir::createAndOpenFile(const string &name, mode_t
   device()->callFsActionCallbacks();
   auto child = device()->CreateFileBlob();
   auto now = fsblobstore::time::now();
-  LoadBlob()->AddChildFile(name, child->key(), mode, uid, gid, now, now);
-  return make_unique_ref<CryOpenFile>(device(), std::move(child));
+  auto dirBlob = LoadBlob();
+  dirBlob->AddChildFile(name, child->key(), mode, uid, gid, now, now);
+  return make_unique_ref<CryOpenFile>(device(), cpputils::to_unique_ptr(std::move(dirBlob)), std::move(child));
 }
 
 void CryDir::createDir(const string &name, mode_t mode, uid_t uid, gid_t gid) {

src/cryfs/filesystem/CryFile.cpp

@@ -37,7 +37,7 @@ unique_ref<parallelaccessfsblobstore::FileBlobRef> CryFile::LoadBlob() const {
 unique_ref<fspp::OpenFile> CryFile::open(int flags) const {
   device()->callFsActionCallbacks();
   auto blob = LoadBlob();
-  return make_unique_ref<CryOpenFile>(device(), std::move(blob));
+  return make_unique_ref<CryOpenFile>(device(), parent(), std::move(blob));
 }
 
 void CryFile::truncate(off_t size) const {

src/cryfs/filesystem/CryNode.cpp

@@ -17,6 +17,7 @@ using cpputils::dynamic_pointer_move;
 using cpputils::unique_ref;
 using boost::optional;
 using boost::none;
+using std::shared_ptr;
 using cryfs::parallelaccessfsblobstore::FsBlobRef;
 using cryfs::parallelaccessfsblobstore::DirBlobRef;
 
@@ -28,8 +29,11 @@ namespace cryfs {
 
 CryNode::CryNode(CryDevice *device, optional<unique_ref<DirBlobRef>> parent, const Key &key)
 : _device(device),
-  _parent(std::move(parent)),
+  _parent(none),
   _key(key) {
+  if (parent != none) {
+    _parent = cpputils::to_unique_ptr(std::move(*parent));
+  }
 }
 
 CryNode::~CryNode() {
@@ -42,10 +46,15 @@ void CryNode::access(int mask) const {
   throw FuseErrnoException(ENOTSUP);
 }
 
+shared_ptr<const DirBlobRef> CryNode::parent() const {
+  ASSERT(_parent != none, "We are the root directory and can't get the parent of the root directory");
+  return *_parent;
+}
+
 void CryNode::rename(const bf::path &to) {
   device()->callFsActionCallbacks();
   if (_parent == none) {
-    //We are the base direcory.
+    //We are the root direcory.
     //TODO What should we do?
     throw FuseErrnoException(EIO);
   }
@@ -70,7 +79,7 @@ void CryNode::rename(const bf::path &to) {
 void CryNode::utimens(timespec lastAccessTime, timespec lastModificationTime) {
   device()->callFsActionCallbacks();
   if (_parent == none) {
-    //We are the base direcory.
+    //We are the root direcory.
     //TODO What should we do?
     throw FuseErrnoException(EIO);
   }
@@ -80,7 +89,7 @@ void CryNode::utimens(timespec lastAccessTime, timespec lastModificationTime) {
 void CryNode::removeNode() {
   //TODO Instead of all these if-else and having _parent being an optional, we could also introduce a CryRootDir which inherits from fspp::Dir.
   if (_parent == none) {
-    //We are the base direcory.
+    //We are the root direcory.
     //TODO What should we do?
     throw FuseErrnoException(EIO);
   }
@@ -103,7 +112,7 @@ unique_ref<FsBlobRef> CryNode::LoadBlob() const {
 void CryNode::stat(struct ::stat *result) const {
   device()->callFsActionCallbacks();
   if(_parent == none) {
-    //We are the base directory.
+    //We are the root directory.
 	//TODO What should we do?
     result->st_uid = getuid();
     result->st_gid = getgid();
@@ -130,7 +139,7 @@ void CryNode::stat(struct ::stat *result) const {
 void CryNode::chmod(mode_t mode) {
   device()->callFsActionCallbacks();
   if (_parent == none) {
-    //We are the base direcory.
+    //We are the root direcory.
 	//TODO What should we do?
 	throw FuseErrnoException(EIO);
   }
@@ -140,7 +149,7 @@ void CryNode::chmod(mode_t mode) {
 void CryNode::chown(uid_t uid, gid_t gid) {
   device()->callFsActionCallbacks();
   if (_parent == none) {
-	//We are the base direcory.
+	//We are the root direcory.
 	//TODO What should we do?
 	throw FuseErrnoException(EIO);
   }

src/cryfs/filesystem/CryNode.h

@@ -27,6 +27,7 @@ protected:
   CryDevice *device();
   const CryDevice *device() const;
   cpputils::unique_ref<parallelaccessfsblobstore::FsBlobRef> LoadBlob() const;
+  std::shared_ptr<const parallelaccessfsblobstore::DirBlobRef> parent() const;
 
   virtual fspp::Dir::EntryType getType() const = 0;
 
@@ -34,7 +35,7 @@ protected:
 
 private:
   CryDevice *_device;
-  boost::optional<cpputils::unique_ref<parallelaccessfsblobstore::DirBlobRef>> _parent;
+  boost::optional<std::shared_ptr<parallelaccessfsblobstore::DirBlobRef>> _parent;
   blockstore::Key _key;
 
   DISALLOW_COPY_AND_ASSIGN(CryNode);

src/cryfs/filesystem/CryOpenFile.cpp

@@ -8,8 +8,10 @@
 
 namespace bf = boost::filesystem;
 
+using std::shared_ptr;
 using cpputils::unique_ref;
 using cryfs::parallelaccessfsblobstore::FileBlobRef;
+using cryfs::parallelaccessfsblobstore::DirBlobRef;
 
 //TODO Get rid of this in favor of a exception hierarchy
 using fspp::fuse::CHECK_RETVAL;
@@ -17,8 +19,8 @@ using fspp::fuse::FuseErrnoException;
 
 namespace cryfs {
 
-CryOpenFile::CryOpenFile(const CryDevice *device, unique_ref<FileBlobRef> fileBlob)
-: _device(device), _fileBlob(std::move(fileBlob)) {
+CryOpenFile::CryOpenFile(const CryDevice *device, shared_ptr<const DirBlobRef> parent, unique_ref<FileBlobRef> fileBlob)
+: _device(device), _parent(parent), _fileBlob(std::move(fileBlob)) {
 }
 
 CryOpenFile::~CryOpenFile() {
@@ -32,9 +34,8 @@ void CryOpenFile::flush() {
 
 void CryOpenFile::stat(struct ::stat *result) const {
   _device->callFsActionCallbacks();
-  result->st_mode = S_IFREG | S_IRUSR | S_IXUSR | S_IWUSR;
+  _parent->statChildExceptSize(_fileBlob->key(), result);
   result->st_size = _fileBlob->size();
-  return;
 }
 
 void CryOpenFile::truncate(off_t size) const {

src/cryfs/filesystem/CryOpenFile.h

@@ -4,13 +4,14 @@
 
 #include <fspp/fs_interface/OpenFile.h>
 #include "parallelaccessfsblobstore/FileBlobRef.h"
+#include "parallelaccessfsblobstore/DirBlobRef.h"
 
 namespace cryfs {
 class CryDevice;
 
 class CryOpenFile final: public fspp::OpenFile {
 public:
-  explicit CryOpenFile(const CryDevice *device, cpputils::unique_ref<parallelaccessfsblobstore::FileBlobRef> fileBlob);
+  explicit CryOpenFile(const CryDevice *device, std::shared_ptr<const parallelaccessfsblobstore::DirBlobRef> parent, cpputils::unique_ref<parallelaccessfsblobstore::FileBlobRef> fileBlob);
   ~CryOpenFile();
 
   void stat(struct ::stat *result) const override;
@@ -23,6 +24,7 @@ public:
 
 private:
   const CryDevice *_device;
+  std::shared_ptr<const parallelaccessfsblobstore::DirBlobRef> _parent;
   cpputils::unique_ref<parallelaccessfsblobstore::FileBlobRef> _fileBlob;
 
   DISALLOW_COPY_AND_ASSIGN(CryOpenFile);

src/cryfs/filesystem/cachingfsblobstore/DirBlobRef.h

@@ -47,6 +47,10 @@ public:
         return _base->statChild(key, result);
     }
 
+    void statChildExceptSize(const blockstore::Key &key, struct ::stat *result) const {
+        return _base->statChildExceptSize(key, result);
+    }
+
     void chmodChild(const blockstore::Key &key, mode_t mode) {
         return _base->chmodChild(key, mode);
     }

src/cryfs/filesystem/fsblobstore/DirBlob.cpp

@@ -112,13 +112,16 @@ off_t DirBlob::lstat_size() const {
 }
 
 void DirBlob::statChild(const Key &key, struct ::stat *result) const {
+  statChildExceptSize(key, result);
+  result->st_size = _getLstatSize(key);
+}
+
+void DirBlob::statChildExceptSize(const Key &key, struct ::stat *result) const {
   auto childOpt = GetChild(key);
   if (childOpt == boost::none) {
     throw fspp::fuse::FuseErrnoException(ENOENT);
   }
   const auto &child = *childOpt;
-  //TODO Loading the blob for only getting the size of the file/symlink is not very performant.
-  //     Furthermore, this is the only reason why DirBlob needs a pointer to _fsBlobStore, which is ugly
   result->st_mode = child.mode();
   result->st_uid = child.uid();
   result->st_gid = child.gid();
@@ -133,7 +136,6 @@ void DirBlob::statChild(const Key &key, struct ::stat *result) const {
   result->st_mtim = child.lastModificationTime();
   result->st_ctim = child.lastMetadataChangeTime();
 #endif
-  result->st_size = _getLstatSize(key);
   //TODO Move ceilDivision to general utils which can be used by cryfs as well
   result->st_blocks = blobstore::onblocks::utils::ceilDivision(result->st_size, (off_t)512);
   result->st_blksize = _fsBlobStore->blocksizeBytes();

src/cryfs/filesystem/fsblobstore/DirBlob.h

@@ -52,6 +52,8 @@ namespace cryfs {
 
             void statChild(const blockstore::Key &key, struct ::stat *result) const;
 
+            void statChildExceptSize(const blockstore::Key &key, struct ::stat *result) const;
+
             void chmodChild(const blockstore::Key &key, mode_t mode);
 
             void chownChild(const blockstore::Key &key, uid_t uid, gid_t gid);

src/cryfs/filesystem/parallelaccessfsblobstore/DirBlobRef.h

@@ -43,6 +43,10 @@ public:
         return _base->statChild(key, result);
     }
 
+    void statChildExceptSize(const blockstore::Key &key, struct ::stat *result) const {
+        return _base->statChildExceptSize(key, result);
+    }
+
     void chmodChild(const blockstore::Key &key, mode_t mode) {
         return _base->chmodChild(key, mode);
     }

src/fspp/fstest/testutils/FileTest.h

@@ -25,8 +25,7 @@ public:
 	  file.stat(&st1);
 	  callback(st1);
 	  file.open(O_RDONLY)->stat(&st2);
-      //TODO Enable this line
-	  //callback(st2);
+	  callback(st2);
   }
 
   void EXPECT_SIZE(uint64_t expectedSize, const fspp::File &file) {