Add option to make file uploads use move_copy_to instead of persist_to

This is to support scenarios where the attachments and sends folder are to be stored on a separate device from the tmp_folder (i.e. fuse-mounted S3 storage), due to having the tmp_dir on the same device being undesirable.

Example being fuse-mounted S3 storage with the reasoning that because S3 basically requires a copy+delete operations to rename files, it's inefficient to rename files on device, if it's even allowed.

src/api/core/ciphers.rs

@@ -998,7 +998,11 @@ async fn save_attachment(
         attachment.save(&conn).await.expect("Error saving attachment");
     }
 
+    if CONFIG.uploads_use_copy() {
+        data.data.move_copy_to(file_path).await?;
+    } else {
         data.data.persist_to(file_path).await?;
+    }
 
     nt.send_cipher_update(UpdateType::CipherUpdate, &cipher, &cipher.update_users_revision(&conn).await).await;
 

src/api/core/sends.rs

@@ -225,7 +225,12 @@ async fn post_send_file(data: Form<UploadData<'_>>, headers: Headers, conn: DbCo
     let folder_path = tokio::fs::canonicalize(&CONFIG.sends_folder()).await?.join(&send.uuid);
     let file_path = folder_path.join(&file_id);
     tokio::fs::create_dir_all(&folder_path).await?;
+
+    if CONFIG.uploads_use_copy() {
+        data.move_copy_to(&file_path).await?;
+    } else {
         data.persist_to(&file_path).await?;
+    }
 
     let mut data_value: Value = serde_json::from_str(&send.data)?;
     if let Some(o) = data_value.as_object_mut() {

src/config.rs

@@ -343,6 +343,8 @@ make_config! {
         rsa_key_filename:       String, false,  auto,   |c| format!("{}/{}", c.data_folder, "rsa_key");
         /// Web vault folder
         web_vault_folder:       String, false,  def,    "web-vault/".to_string();
+        /// Uploading files uses move_copy_to instead of persist_to to support cross-device scenarios where having tmp_folder on the same drive is undesirable. i.e. fuse-mounted S3.
+        uploads_use_copy:       bool,   false,  def,     false;
     },
     ws {
         /// Enable websocket notifications