fix: always set bcc_self on backup import/export

Regardless of whether chatmail relay is used or not,
bcc_self should be enabled when second device is added.
It should also be enabled again even if the user
has turned it off manually.

Author: link2xt

deltachat-rpc-client/tests/test_multidevice.py

@@ -4,6 +4,41 @@
 from deltachat_rpc_client.const import MessageState
 
 
+def test_bcc_self_delete_server_after_defaults(acfactory):
+    """Test default values for bcc_self and delete_server_after."""
+    ac = acfactory.get_online_account()
+
+    # Initially after getting online
+    # the setting bcc_self is set to 0 because there is only one device
+    # and delete_server_after is "1", meaning immediate deletion.
+    assert ac.get_config("bcc_self") == "0"
+    assert ac.get_config("delete_server_after") == "1"
+
+    # Setup a second device.
+    ac_clone = ac.clone()
+    ac_clone.bring_online()
+
+    # Second device setup
+    # enables bcc_self and changes default delete_server_after.
+    assert ac.get_config("bcc_self") == "1"
+    assert ac.get_config("delete_server_after") == "0"
+
+    assert ac_clone.get_config("bcc_self") == "1"
+    assert ac_clone.get_config("delete_server_after") == "0"
+
+    # Manually disabling bcc_self
+    # also restores the default for delete_server_after.
+    ac.set_config("bcc_self", "0")
+    assert ac.get_config("bcc_self") == "0"
+    assert ac.get_config("delete_server_after") == "1"
+
+    # Cloning the account again enables bcc_self
+    # even though it was manually disabled.
+    ac_clone = ac.clone()
+    assert ac.get_config("bcc_self") == "1"
+    assert ac.get_config("delete_server_after") == "0"
+
+
 def test_one_account_send_bcc_setting(acfactory, log, direct_imap):
     ac1, ac2 = acfactory.get_online_accounts(2)
     ac1_clone = ac1.clone()

src/imex.rs

@@ -377,7 +377,15 @@ async fn import_backup_stream_inner<R: tokio::io::AsyncRead + Unpin>(
         res = check_backup_version(context).await;
     }
     if res.is_ok() {
-        res = adjust_bcc_self(context).await;
+        // All recent backups have `bcc_self` set to "1" before export.
+        //
+        // Setting `bcc_self` to "1" on export was introduced on 2024-12-17
+        // in commit 21664125d798021be75f47d5b0d5006d338b4531
+        //
+        // We additionally try to set `bcc_self` to "1" after import here
+        // for compatibility with older backups,
+        // but eventually this code can be removed.
+        res = context.set_config(Config::BccSelf, Some("1")).await;
     }
     fs::remove_file(unpacked_database)
         .await
@@ -751,7 +759,7 @@ async fn export_database(
         .to_str()
         .with_context(|| format!("path {} is not valid unicode", dest.display()))?;
 
-    adjust_bcc_self(context).await?;
+    context.set_config(Config::BccSelf, Some("1")).await?;
     context
         .sql
         .set_raw_config_int("backup_time", timestamp)
@@ -785,18 +793,6 @@ async fn export_database(
         .await
 }
 
-/// Sets `Config::BccSelf` (and `DeleteServerAfter` to "never" in effect) if needed so that new
-/// messages are present on the server after a backup restoration or available for all devices in
-/// multi-device case. NB: Calling this after a backup import isn't reliable as we can crash in
-/// between, but this is a problem only for old backups, new backups already have `BccSelf` set if
-/// necessary.
-async fn adjust_bcc_self(context: &Context) -> Result<()> {
-    if context.is_chatmail().await? && !context.config_exists(Config::BccSelf).await? {
-        context.set_config(Config::BccSelf, Some("1")).await?;
-    }
-    Ok(())
-}
-
 async fn check_backup_version(context: &Context) -> Result<()> {
     let version = (context.sql.get_raw_config_int("backup_version").await?).unwrap_or(2);
     ensure!(