fix: Properly load/save DB and stop creating dummy users

src/db/filesystem.rs

@@ -1,5 +1,4 @@
 use camino::{Utf8Path, Utf8PathBuf};
-use serde::{Deserialize, Serialize};
 use serde_json::Error as JsonError;
 
 use std::fmt;
@@ -35,7 +34,7 @@ impl fmt::Display for FilesystemDatabaseError {
 
 impl std::error::Error for FilesystemDatabaseError {}
 
-#[derive(Clone, Debug, Default, Deserialize, Serialize)]
+#[derive(Clone, Debug, Default)]
 pub struct FilesystemDatabase {
     // TODO: Once we have common validation steps in place across DB backends, we can reduce cloning.
     //       For now, we clone the DB on every write operation, and update it when saving to disk
@@ -59,10 +58,14 @@ impl FilesystemDatabase {
                 path: path.to_path_buf(),
             };
 
-            db.save().await?;
+            tracing::info!("Initializing empty database in file {path}. Checking permissions...");
+            db.save_self().await?;
+            tracing::info!("Database successfully created");
+
             return Ok(Database::new(db));
         }
 
+        tracing::info!("Loading database from file {path}");
         let s = tokio::fs::read(path)
             .await
             .map_err(|e| Box::new(FilesystemDatabaseError::ReadFileIO(path.to_path_buf(), e)))?;
@@ -74,13 +77,29 @@ impl FilesystemDatabase {
         }))
     }
 
-    pub async fn save(&mut self) -> Result<(), BoxedError> {
-        let s = serde_json::to_string(&self)
+    /// Attempts to save a new state of the DB, effectively switching to the new state
+    /// only if the save is successful.
+    pub async fn save(&mut self, new_db: MemoryDatabase) -> Result<(), BoxedError> {
+        self.save_inner(&new_db).await?;
+        self.inner = new_db;
+        Ok(())
+    }
+
+    /// Saves an in-memory DB to disk. Cannot be used directly to observe exclusive access.
+    async fn save_inner(&self, inner: &MemoryDatabase) -> Result<(), BoxedError> {
+        let s = serde_json::to_string(inner)
             .map_err(|e| Box::new(FilesystemDatabaseError::WriteFileJson(self.path.clone(), e)))?;
         Ok(tokio::fs::write(&self.path, &s)
             .await
             .map_err(|e| Box::new(FilesystemDatabaseError::WriteFileIO(self.path.clone(), e)))?)
     }
+
+    /// Save the database without switching to a new state.
+    ///
+    /// Used when initializing the DB, to check for permissions.
+    pub async fn save_self(&mut self) -> Result<(), BoxedError> {
+        self.save_inner(&self.inner).await
+    }
 }
 
 #[async_trait::async_trait]
@@ -95,9 +114,7 @@ impl DatabaseInterface for FilesystemDatabase {
             return Ok(Err(e));
         }
 
-        self.save().await?;
-        self.inner = new_db;
-
+        self.save(new_db).await?;
         Ok(Ok(()))
     }
 
@@ -119,9 +136,7 @@ impl DatabaseInterface for FilesystemDatabase {
             return Ok(Err(e));
         }
 
-        self.save().await?;
-        self.inner = new_db;
-
+        self.save(new_db).await?;
         Ok(Ok(()))
     }
 
@@ -136,9 +151,7 @@ impl DatabaseInterface for FilesystemDatabase {
             return Ok(Err(e));
         }
 
-        self.save().await?;
-        self.inner = new_db;
-
+        self.save(new_db).await?;
         Ok(Ok(()))
     }