message: retain non-file flags when moving

The content-flags won't change, and the unread-flag can be re-calculated.

Add a unit test, and some small doc improvements.

Fixes #2831.

lib/message/mu-flags.hh

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2022-2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2022-2025 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -86,7 +86,7 @@ enum struct MessageFlagCategory {
 };
 
 /**
- * Info about invidual message flags
+ * Info about individual message flags
  *
  */
 struct MessageFlagInfo {
@@ -373,9 +373,6 @@ flags_maildir_file(Flags flags)
 	return flags;
 }
 
-
-
-
 /**
  * Return flags, where flags = new_flags but with unmutable_flag in the
  * result the same as in old_flags

lib/message/mu-message.cc

@@ -881,6 +881,14 @@ Message::update_after_move(const std::string& new_path,
 	priv_->doc.add(Field::Id::Path, new_path);
 	priv_->doc.add(Field::Id::Changed, priv_->ctime);
 
+	// note: content-flags are retained from the existing; the unread flag
+	// is implied. only file-flags are allowed for new_flags; anything else
+	// is filtered-out
+
+	new_flags = flags_maildir_file(new_flags);
+	new_flags |= flags_filter(flags(), MessageFlagCategory::Content);
+	new_flags = imply_unread(new_flags);
+
 	set_flags(new_flags);
 
 	if (const auto res = set_maildir(sanitize_maildir(new_maildir)); !res)

lib/message/mu-message.hh

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2022-2024 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2022-2025 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -292,11 +292,10 @@ public:
 	 */
 	Flags flags() const { return document().flags_value(); }
 
-
 	/**
-	 * Update the flags for this message. This is useful for flags
+	 * Update the flags for this message. This is useful for flags that can
-	 * that can only be determined after the message has been created already,
+	 * only be determined after the message has been created already, such
-	 * such as the 'personal' flag.
+	 * as the 'personal' flag.
 	 *
 	 * @param flags new flags.
 	 */
@@ -366,11 +365,14 @@ public:
 	 */
 	const Sexp& sexp() const;
 
-	/*
+	/**
-	 * And some non-const message, for updating an existing
+	 * Update the message after a move
-	 * message after a file-system move.
 	 *
-	 * @return Ok or an error.
+	 * @param new_path the new file-system path; non-file flags are ignored
+	 * @param new_maildir the new maildir
+	 * @param new_flags the new flags
+	 *
+	 * @return Ok() or some error.
 	 */
 	Result<void> update_after_move(const std::string& new_path,
 				       const std::string& new_maildir,

lib/mu-store.hh

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2024 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2017-2025 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -306,20 +306,24 @@ public:
 	};
 
 	/**
-	 * Move a message both in the filesystem and in the store. After a successful move, the
+	 * Move a message both in the filesystem and in the store.
-	 * message is updated.
+	 *
+	 * After a successful move, the message is updated. A moved message gets
+	 * a new doc-id, since the message-path is a unique-id for the message
 	 *
 	 * @param id the id for some message
 	 * @param target_mdir the target maildir (if any)
 	 * @param new_flags new flags (if any)
 	 * @param opts move options
 	 *
-	 * @return Result, either an IdPathVec with ids and paths for the moved message(s) or some
+	 * @return Result, either an IdPathVec with ids and paths for the moved
-	 * error. Note that in case of success at least one message is returned, and only with
+	 * message(s) or some error. Note that in case of success at least one
-	 * MoveOptions::DupFlags can it be more than one.
+	 * message is returned, and only with MoveOptions::DupFlags can it be
+	 * more than one.
 	 *
-	 * The first element of the IdPathVec, is the main message that got move; any subsequent
+	 * The first element of the IdPathVec, is the main message that got
-	 * (if any) are the duplicate paths, sorted by path-name.
+	 * move; any subsequent (if any) are the duplicate paths, sorted by
+	 * path-name.
 	 */
 	Result<IdPathVec> move_message(Store::Id id,
 				       Option<const std::string&> target_mdir = Nothing,

mu/mu-cmd-move.cc

@@ -1,5 +1,5 @@
 /*
-** Copyright (C) 2023 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+** Copyright (C) 2023-2025 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
 **
 ** This program is free software; you can redistribute it and/or modify it
 ** under the terms of the GNU General Public License as published by the
@@ -28,7 +28,6 @@
 
 using namespace Mu;
 
-
 Result<void>
 Mu::mu_cmd_move(Mu::Store& store, const Options& opts)
 {
@@ -50,7 +49,6 @@ Mu::mu_cmd_move(Mu::Store& store, const Options& opts)
 			   "Must have at least one of destination and flags");
 	else if (!dest.empty()) {
 		const auto mdirs{store.maildirs()};
-
 		if (!seq_some(mdirs, [&](auto &&d){ return d == dest;}))
 			return Err(Error{Error::Code::InvalidArgument,
 					"No maildir '{}' in store", dest}
@@ -259,6 +257,65 @@ test_move_real()
 	}
 }
 
+
+static void
+test_move_retain_non_file_flags()
+{
+	g_test_bug("2831");
+
+	allow_warnings();
+
+	TempDir tdir;
+	const auto dbpath{runtime_path(RuntimePath::XapianDb, tdir.path())};
+
+	auto res = run_command0({CP_PROGRAM, "-r", MU_TESTMAILDIR, tdir.path()});
+	assert_valid_command(res);
+
+	const auto testpath{join_paths(tdir.path(), "testdir")};
+	const auto src{join_paths(testpath, "cur", "multimime!2,FS")};
+
+	Store::Id id{};
+	{
+		auto store = Store::make_new(dbpath, testpath, {});
+		assert_valid_result(store);
+		const auto idopt{store->add_message(src, true)};
+		g_assert_true(!!idopt);
+		id = *idopt;
+		const auto msg{store->find_message(id)};
+		g_assert_true(!!msg);
+		g_assert_true(msg->flags() == (Flags::Seen | Flags::Flagged | Flags::HasAttachment));
+	}
+
+	// make a message 'New'
+	const auto dst{join_paths(testpath, "new", "multimime")};
+	{
+		auto res = run_command0({MU_PROGRAM, "--debug", "move", "--muhome",
+				tdir.path(), src, "--flags", "N"});
+		assert_valid_command(res);
+		assert_equal(res->standard_out, dst + '\n');
+		// double-check it really moved.
+		g_assert_true(::access(dst.c_str(), F_OK) == 0);
+		g_assert_true(::access(src.c_str(), F_OK) != 0);
+	}
+
+	// re-open db
+	{
+		const auto store = Store::make(dbpath);
+		assert_valid_result(store);
+
+		const auto newid{store->find_message_id(dst)};
+		g_assert_true(!!newid);
+
+		const auto msg{store->find_message(*newid)};
+		g_assert_true(!!msg);
+
+		// check the old flags
+		const auto flags = msg->flags();
+		assert_equal(to_string(flags), to_string(Flags::New | Flags::Unread |
+							 Flags::HasAttachment));
+	}
+}
+
 int
 main(int argc, char* argv[])
 {
@@ -266,6 +323,8 @@ main(int argc, char* argv[])
 
 	g_test_add_func("/cmd/move/dry-run", test_move_dry_run);
 	g_test_add_func("/cmd/move/real", test_move_real);
+	g_test_add_func("/cmd/move/retain-non-file-flags",
+			test_move_retain_non_file_flags);
 
 	return g_test_run();