pull --rebase: exit early when the working directory is dirty

Re-implement the behavior introduced by f9189cf (pull --rebase: exit
early when the working directory is dirty, 2008-05-21).

Signed-off-by: Paul Tan <pyokagan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/pull.c

@@ -14,6 +14,8 @@
 #include "remote.h"
 #include "dir.h"
 #include "refs.h"
+#include "revision.h"
+#include "lockfile.h"
 
 enum rebase_type {
 	REBASE_INVALID = -1,
@@ -295,6 +297,73 @@ static enum rebase_type config_get_rebase(void)
 	return REBASE_FALSE;
 }
 
+/**
+ * Returns 1 if there are unstaged changes, 0 otherwise.
+ */
+static int has_unstaged_changes(const char *prefix)
+{
+	struct rev_info rev_info;
+	int result;
+
+	init_revisions(&rev_info, prefix);
+	DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
+	DIFF_OPT_SET(&rev_info.diffopt, QUICK);
+	diff_setup_done(&rev_info.diffopt);
+	result = run_diff_files(&rev_info, 0);
+	return diff_result_code(&rev_info.diffopt, result);
+}
+
+/**
+ * Returns 1 if there are uncommitted changes, 0 otherwise.
+ */
+static int has_uncommitted_changes(const char *prefix)
+{
+	struct rev_info rev_info;
+	int result;
+
+	if (is_cache_unborn())
+		return 0;
+
+	init_revisions(&rev_info, prefix);
+	DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
+	DIFF_OPT_SET(&rev_info.diffopt, QUICK);
+	add_head_to_pending(&rev_info);
+	diff_setup_done(&rev_info.diffopt);
+	result = run_diff_index(&rev_info, 1);
+	return diff_result_code(&rev_info.diffopt, result);
+}
+
+/**
+ * If the work tree has unstaged or uncommitted changes, dies with the
+ * appropriate message.
+ */
+static void die_on_unclean_work_tree(const char *prefix)
+{
+	struct lock_file *lock_file = xcalloc(1, sizeof(*lock_file));
+	int do_die = 0;
+
+	hold_locked_index(lock_file, 0);
+	refresh_cache(REFRESH_QUIET);
+	update_index_if_able(&the_index, lock_file);
+	rollback_lock_file(lock_file);
+
+	if (has_unstaged_changes(prefix)) {
+		error(_("Cannot pull with rebase: You have unstaged changes."));
+		do_die = 1;
+	}
+
+	if (has_uncommitted_changes(prefix)) {
+		if (do_die)
+			error(_("Additionally, your index contains uncommitted changes."));
+		else
+			error(_("Cannot pull with rebase: Your index contains uncommitted changes."));
+		do_die = 1;
+	}
+
+	if (do_die)
+		exit(1);
+}
+
 /**
  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
  * into merge_heads.
@@ -751,9 +820,15 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
 	if (get_sha1("HEAD", orig_head))
 		hashclr(orig_head);
 
-	if (opt_rebase)
+	if (opt_rebase) {
+		if (is_null_sha1(orig_head) && !is_cache_unborn())
+			die(_("Updating an unborn branch with changes added to the index."));
+
+		die_on_unclean_work_tree(prefix);
+
 		if (get_rebase_fork_point(rebase_fork_point, repo, *refspecs))
 			hashclr(rebase_fork_point);
+	}
 
 	if (run_fetch(repo, refspecs))
 		return 1;