Implement insert and edit sessions (#7)

crates/storage/src/repository.rs

@@ -37,6 +37,10 @@ impl EntryPath {
         &self.0
     }
 
+    pub fn parent_directory(&self) -> DirectoryPath {
+        self.parent()
+    }
+
     fn parent(&self) -> DirectoryPath {
         DirectoryPath(self.0.parent().map_or_else(PathBuf::new, Path::to_path_buf))
     }
@@ -511,6 +515,20 @@ impl Repository {
         self.write_entry_with_checkpoint(path, ciphertext, |_| Ok(()))
     }
 
+    pub fn remove_entry(&self, path: &EntryPath) -> Result<EncryptedEntry, RepositoryError> {
+        let original = self.read_entry(path)?;
+        let (parent, file_name) = self.open_entry_parent(path)?;
+        parent
+            .remove_file(&file_name)
+            .map_err(|error| io_error("remove encrypted entry", &path.0, error))?;
+        sync_directory(&parent, &path.parent().0).map_err(|_| {
+            RepositoryError::DurabilityUncertain {
+                path: path.0.clone(),
+            }
+        })?;
+        Ok(original)
+    }
+
     fn write_entry_with_checkpoint<F>(
         &self,
         path: &EntryPath,