fix_shebang: don't touch symlinks

Symlinks can point anywhere outside the parts. Also symlinks can be
broken.

By using lstat instead of stat, the symlink is not considered as a
regular file.

See merge request nexedi/slapos.recipe.cmmi!14

slapos/recipe/cmmi/__init__.py

@@ -463,7 +463,7 @@ echo %s
                 continue
             for f in os.listdir(dir_abspath):
                 f_abspath = os.path.join(dir_abspath, f)
-                st_mode = os.stat(f_abspath).st_mode
+                st_mode = os.lstat(f_abspath).st_mode
                 if not stat.S_ISREG(st_mode):
                     continue
                 with open(f_abspath, 'rb') as f:

slapos/recipe/cmmi/tests.py

@@ -8,8 +8,10 @@ import shutil
 import stat
 import tarfile
 import tempfile
-import pkg_resources
+from contextlib import contextmanager
+from io import BytesIO
 from time import sleep
+import pkg_resources
 import zc.buildout
 import zc.buildout.testing
 import zc.buildout.tests
@@ -30,6 +32,25 @@ def setUp(test):
     zc.buildout.testing.install('slapos.recipe.build', test)
     zc.buildout.testing.install_develop('slapos.recipe.cmmi', test)
 
+def tarfile_addfileobj(tarobj, name, dataobj, **kw):
+    tarinfo = tarfile.TarInfo(name)
+    dataobj.seek(0, 2)
+    tarinfo.size = dataobj.tell()
+    dataobj.seek(0)
+    for x in kw.items():
+        setattr(tarinfo, *x)
+    tarobj.addfile(tarinfo, dataobj)
+
+@contextmanager
+def fake_package(**kw):
+    with tempfile.NamedTemporaryFile(suffix=".tar") as tmp:
+        with tarfile.open(mode='w', fileobj=tmp) as tar:
+            for k, v in kw.items():
+                tarfile_addfileobj(tar, k, BytesIO(v.encode()),
+                    **{'mode':stat.S_IRWXU} if v.startswith('#!') else {})
+        tmp.flush()
+        yield tmp.name
+
 class NonInformativeTests(unittest.TestCase):
 
     def setUp(self):
@@ -103,25 +124,13 @@ class NonInformativeTests(unittest.TestCase):
             recipe.install()
 
     def test_restart_after_failure(self):
-        temp_directory = tempfile.mkdtemp(dir=self.dir, prefix="fake_package")
-
-        configure_path = os.path.join(temp_directory, 'configure')
-        self.write_file(configure_path, 'exit 0', mode=stat.S_IRWXU)
-        makefile_path = os.path.join(temp_directory, 'Makefile')
-        self.write_file(makefile_path, 'all:\n\texit -1')
-
-        os.chdir(temp_directory)
-
-        ignore, tarfile_path = tempfile.mkstemp(suffix=".tar")
-        tar = tarfile.open(tarfile_path, 'w')
-        tar.add('configure')
-        tar.add('Makefile')
-        tar.close()
+        with fake_package(
+                configure='#!/bin/sh\n',
+                Makefile='all:\n\texit -1',
+                ) as tarfile_path:
+            recipe = self.make_recipe({}, 'test', {'url': tarfile_path})
+            os.chdir(self.dir)
 
-        recipe = self.make_recipe({}, 'test', {'url': tarfile_path})
-        os.chdir(self.dir)
-
-        try:
             # expected failure
             with self.assertRaises(zc.buildout.UserError):
                 recipe.install()
@@ -129,12 +138,6 @@ class NonInformativeTests(unittest.TestCase):
             # the install should still fail, and _not_ raise an OSError
             with self.assertRaises(zc.buildout.UserError):
                 recipe.install()
-        finally:
-            try:
-                shutil.rmtree(temp_directory)
-                os.remove(tarfile_path)
-            except:
-                pass
 
     def test_environment_restored_after_building_a_part(self):
         # Make sure the test variables do not exist beforehand
@@ -345,6 +348,22 @@ class NonInformativeTests(unittest.TestCase):
         build_directory = os.path.join(self.dir, 'test_parts/test__compile__')
         self.assertTrue(os.path.exists(build_directory))
 
+    def test_bad_symlink_in_bin(self):
+        with fake_package(
+                configure="""#!/bin/sh
+echo prefix = ${@##--prefix=} > Makefile.in
+""",
+                Makefile="""include Makefile.in
+install:
+\tmkdir -p $(prefix)/bin
+\tln -sf /DUMMYFILENOTEXISTING $(prefix)/bin/badlink
+""",
+                ) as tarfile_path:
+            recipe = self.make_recipe({}, 'test', {'url': tarfile_path})
+            os.chdir(self.dir)
+            recipe.install()
+            self.assertTrue(os.path.islink('test_parts/test/bin/badlink'))
+
 def test_suite():
     sums = []
     def md5sum(m):