sequencer (rebase -i): allow continuing with staged changes

When an interactive rebase is interrupted, the user may stage changes
before continuing, and we need to commit those changes in that case.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

sequencer.c

@@ -1587,6 +1587,39 @@ static int continue_single_pick(void)
 	return run_command_v_opt(argv, RUN_GIT_CMD);
 }
 
+static int commit_staged_changes(struct replay_opts *opts)
+{
+	int amend = 0;
+
+	if (has_unstaged_changes(1))
+		return error(_("Cannot rebase: You have unstaged changes."));
+	if (!has_uncommitted_changes(0))
+		return 0;
+
+	if (file_exists(git_path_rebase_amend())) {
+		struct strbuf rev = STRBUF_INIT;
+		unsigned char head[20], to_amend[20];
+
+		if (get_sha1("HEAD", head))
+			return error("Cannot amend non-existing commit");
+		if (strbuf_read_file(&rev, git_path_rebase_amend(), 41) <= 0)
+			return error("Invalid file: %s",
+				git_path_rebase_amend());
+		if (get_sha1_hex(rev.buf, to_amend))
+			return error("Invalid contents: %s",
+				git_path_rebase_amend());
+		if (hashcmp(head, to_amend))
+			return error("\nYou have uncommitted changes in your "
+				"working tree. Please, commit them\nfirst and "
+				"then run 'git rebase --continue' again.");
+
+		strbuf_release(&rev);
+		amend = 1;
+	}
+
+	return sequencer_commit(git_path_rebase_msg(), opts, 1, 1, amend);
+}
+
 int sequencer_continue(struct replay_opts *opts)
 {
 	struct todo_list todo_list = TODO_LIST_INIT;
@@ -1595,7 +1628,11 @@ int sequencer_continue(struct replay_opts *opts)
 	if (read_and_refresh_cache(opts))
 		return -1;
 
-	if (!file_exists(get_todo_path(opts)))
+	if (IS_REBASE_I()) {
+		if (commit_staged_changes(opts))
+			return -1;
+	}
+	else if (!file_exists(get_todo_path(opts)))
 		return continue_single_pick();
 	if (read_populate_opts(opts) ||
 			read_populate_todo(&todo_list, opts))
@@ -1608,10 +1645,11 @@ int sequencer_continue(struct replay_opts *opts)
 		if (ret)
 			return ret;
 	}
-	if (index_differs_from("HEAD", 0))
-		return error_dirty_index(opts);
-	if (opts->action <= REPLAY_REVERT)
+	if (opts->action != REPLAY_INTERACTIVE_REBASE) {
+		if (index_differs_from("HEAD", 0))
+			return error_dirty_index(opts);
 		todo_list.current++;
+	}
 	res = pick_commits(&todo_list, opts);
 	todo_list_release(&todo_list);
 	return res;