Don't attempt to load symlinks as morphologies

This was noticed because our definitions.git had a dangling symlink,
so it failed to construct the temporary build branch.

We shouldn't process symlinks as morphologies either, since either we
make symlinked morphologies a first-class behaviour, and validate that
the link points inside the repository, which is a lot of work for
something we don't and probably won't need; or we can just assume that
we deal with the morphology this is linked to correctly anyway.

3 files changed, 48 insertions, 1 deletions

diff --git a/morphlib/gitdir.py b/morphlib/gitdir.py
index 8f6d69d7..5b0693cb 100644
--- a/morphlib/gitdir.py
+++ b/morphlib/gitdir.py
@@ -515,6 +515,16 @@ class GitDirectory(object):
         tree = self.resolve_ref_to_tree(ref)
         return self.get_file_from_ref(tree, filename)
 
+    def is_symlink(self, filename, ref=None):
+        if ref is None and self.is_bare():
+            raise NoWorkingTreeError(self)
+        if ref is None:
+            filepath = os.path.join(self.dirname, filename.lstrip('/'))
+            return os.path.islink(filepath)
+        tree_entry = self._runcmd(['git', 'ls-tree', ref, filename])
+        file_mode = tree_entry.split(' ', 1)[0]
+        return file_mode == '120000'
+
     @property
     def HEAD(self):
         output = self._runcmd(['git', 'rev-parse', '--abbrev-ref', 'HEAD'])
diff --git a/morphlib/gitdir_tests.py b/morphlib/gitdir_tests.py
index 14b2a57a..b3b4a8ab 100644
--- a/morphlib/gitdir_tests.py
+++ b/morphlib/gitdir_tests.py
@@ -216,6 +216,43 @@ class GitDirectoryContentsTests(unittest.TestCase):
         self.assertEqual(gd.describe(), 'example')
 
 
+class GitDirectoryFileTypeTests(unittest.TestCase):
+
+    def setUp(self):
+        self.tempdir = tempfile.mkdtemp()
+        self.dirname = os.path.join(self.tempdir, 'foo')
+        os.mkdir(self.dirname)
+        gd = morphlib.gitdir.init(self.dirname)
+        with open(os.path.join(self.dirname, 'file'), "w") as f:
+            f.write('dummy morphology text')
+        os.symlink('file', os.path.join(self.dirname, 'link'))
+        os.symlink('no file', os.path.join(self.dirname, 'broken'))
+        gd._runcmd(['git', 'add', '.'])
+        gd._runcmd(['git', 'commit', '-m', 'Initial commit'])
+        self.mirror = os.path.join(self.tempdir, 'mirror')
+        gd._runcmd(['git', 'clone', '--mirror', self.dirname, self.mirror])
+
+    def tearDown(self):
+        shutil.rmtree(self.tempdir)
+
+    def test_working_tree_symlinks(self):
+        gd = morphlib.gitdir.GitDirectory(self.dirname)
+        self.assertTrue(gd.is_symlink('link'))
+        self.assertTrue(gd.is_symlink('broken'))
+        self.assertFalse(gd.is_symlink('file'))
+
+    def test_bare_symlinks(self):
+        gd = morphlib.gitdir.GitDirectory(self.mirror)
+        self.assertTrue(gd.is_symlink('link', 'HEAD'))
+        self.assertTrue(gd.is_symlink('broken', 'HEAD'))
+        self.assertFalse(gd.is_symlink('file', 'HEAD'))
+
+    def test_is_symlink_raises_no_ref_no_work_tree(self):
+        gd = morphlib.gitdir.GitDirectory(self.mirror)
+        self.assertRaises(morphlib.gitdir.NoWorkingTreeError,
+                          gd.is_symlink, 'file')
+
+
 class GitDirectoryRefTwiddlingTests(unittest.TestCase):
 
     def setUp(self):
diff --git a/morphlib/sysbranchdir.py b/morphlib/sysbranchdir.py
index 8546d726..d82390c7 100644
--- a/morphlib/sysbranchdir.py
+++ b/morphlib/sysbranchdir.py
@@ -175,7 +175,7 @@ class SystemBranchDirectory(object):
     def load_all_morphologies(self, loader): # pragma: no cover
         gd_name = self.get_git_directory_name(self.root_repository_url)
         gd = morphlib.gitdir.GitDirectory(gd_name)
-        for filename in gd.list_files():
+        for filename in (f for f in gd.list_files() if not gd.is_symlink(f)):
             text = gd.read_file(filename)
             try:
                 m = loader.load_from_string(text, filename=filename)