Merge branch 'mr/rerere-crash-fix'

When .git/rr-cache/ rerere database gets corrupted or rerere is fed to
work on a file with conflicted hunks resolved incompletely, the rerere
machinery got confused and segfaulted, which has been corrected.

* mr/rerere-crash-fix:
  rerere: fix crashes due to unmatched opening conflict markers

Author: gitster

rerere.c

@@ -219,6 +219,11 @@ static void read_rr(struct repository *r, struct string_list *rr)
 		buf.buf[hexsz] = '\0';
 		id = new_rerere_id_hex(buf.buf);
 		id->variant = variant;
+		/*
+		 * make sure id->collection->status has enough space
+		 * for the variant we are interested in
+		 */
+		fit_variant(id->collection, variant);
 		string_list_insert(rr, path)->util = id;
 	}
 	strbuf_release(&buf);

t/t4200-rerere.sh

@@ -671,4 +671,67 @@ test_expect_success 'test simple stage 1 handling' '
 	)
 '
 
+test_expect_success 'rerere does not crash with missing preimage' '
+	git config rerere.enabled true &&
+
+	echo bar >test &&
+	git add test &&
+	git commit -m "one" &&
+	git branch rerere_no_crash &&
+
+	echo foo >>test &&
+	git add test &&
+	git commit -m "two" &&
+
+	git checkout rerere_no_crash &&
+	echo "bar" >>test &&
+	git add test &&
+	git commit -m "three" &&
+
+	test_must_fail git rebase main &&
+	rm .git/rr-cache/*/preimage &&
+	git rebase --abort
+'
+
+test_expect_success 'rerere does not crash with unmatched conflict marker' '
+	git config rerere.enabled true &&
+
+	echo bar >test &&
+	git add test &&
+	git commit -m "one" &&
+	git branch rerere_no_preimage &&
+
+	cat >test <<-EOF &&
+	test
+	bar
+	foobar
+	EOF
+	git add test &&
+	git commit -m "two" &&
+
+	git checkout rerere_no_preimage &&
+	echo "bar" >>test &&
+	git add test &&
+	git commit -m "three" &&
+
+	cat >test <<-EOF &&
+	foobar
+	bar
+	bar
+	EOF
+	git add test &&
+	git commit -m "four" &&
+
+	test_must_fail git rebase main &&
+	cat >test <<-EOF &&
+	test
+	bar
+	<<<<<<< HEAD
+	foobar
+	bar
+	EOF
+	git add test &&
+	test_must_fail git rebase --continue
+'
+
 test_done