read-cache: check for leading symlinks when refreshing index

Don't add paths with leading symlinks to the index while refreshing; we
only track those symlinks themselves.  We already ignore them while
preloading (see read_index_preload.c).

Reported-by: Nikolay Avdeev <avdeev@math.vsu.ru>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

read-cache.c

@@ -1044,6 +1044,14 @@ static struct cache_entry *refresh_cache_ent(struct index_state *istate,
 		return ce;
 	}
 
+	if (has_symlink_leading_path(ce->name, ce_namelen(ce))) {
+		if (ignore_missing)
+			return ce;
+		if (err)
+			*err = ENOENT;
+		return NULL;
+	}
+
 	if (lstat(ce->name, &st) < 0) {
 		if (ignore_missing && errno == ENOENT)
 			return ce;

t/t7515-status-symlinks.sh

@@ -0,0 +1,43 @@
+#!/bin/sh
+
+test_description='git status and symlinks'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	echo .gitignore >.gitignore &&
+	echo actual >>.gitignore &&
+	echo expect >>.gitignore &&
+	mkdir dir &&
+	echo x >dir/file1 &&
+	echo y >dir/file2 &&
+	git add dir &&
+	git commit -m initial &&
+	git tag initial
+'
+
+test_expect_success SYMLINKS 'symlink to a directory' '
+	test_when_finished "rm symlink" &&
+	ln -s dir symlink &&
+	echo "?? symlink" >expect &&
+	git status --porcelain >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success SYMLINKS 'symlink replacing a directory' '
+	test_when_finished "rm -rf copy && git reset --hard initial" &&
+	mkdir copy &&
+	cp dir/file1 copy/file1 &&
+	echo "changed in copy" >copy/file2 &&
+	git add copy &&
+	git commit -m second &&
+	rm -rf copy &&
+	ln -s dir copy &&
+	echo " D copy/file1" >expect &&
+	echo " D copy/file2" >>expect &&
+	echo "?? copy" >>expect &&
+	git status --porcelain >actual &&
+	test_cmp expect actual
+'
+
+test_done