Add further msgstr plural checks

Author: rtobar

babel/messages/pofile.py

@@ -292,8 +292,21 @@ def _process_keyword_line(self, lineno, line, obsolete=False) -> None:
             self.in_msgid = False
             self.in_msgstr = True
             if arg.startswith('['):
-                idx, msg = arg[1:].split(']', 1)
-                self.translations.append([int(idx), _NormalizedString(msg)])
+                arg = arg[1:]
+                if ']' not in arg:
+                    self._invalid_pofile(line, lineno, "msgstr plural doesn't include a closing bracket")
+                    # if it doesn't include ] it probablyd doesn't have a number either
+                    arg = '0]' + arg
+                idx, msg = arg.split(']', 1)
+                try:
+                    idx = int(idx)
+                except ValueError:
+                    self._invalid_pofile(line, lineno, "msgstr plural's index is not a number")
+                    idx = 0
+                if len(msg) < 2:
+                    self._invalid_pofile(line, lineno, "msgstr plural doesn't have a message")
+                    msg = '""'
+                self.translations.append([idx, _NormalizedString(msg)])
             else:
                 self.translations.append([0, _NormalizedString(arg)])
 

tests/messages/test_pofile.py

@@ -544,6 +544,34 @@ def test_abort_invalid_po_file(self):
         output = pofile.read_po(buf, locale='fr', abort_invalid=False)
         assert isinstance(output, Catalog)
 
+    def test_invalid_msgstr_plural(self):
+        # msgstr plural broken
+        invalid_1 = '''
+        msgid "A"
+        msgstr[
+        '''
+        invalid_2 = '''
+        msgid "A"
+        msgstr[] "no index"
+        '''
+        invalid_3 = '''
+        msgid "A"
+        msgstr[bah] "index is not a number"
+        '''
+        # no content
+        invalid_4 = '''
+        msgid "A"
+        msgstr[0]
+        '''
+        for incorrectly_plural in (invalid_1, invalid_2, invalid_3, invalid_4):
+            buf = StringIO(incorrectly_plural)
+            with pytest.raises(pofile.PoFileError):
+                pofile.read_po(buf, locale='fr', abort_invalid=True)
+            buf.seek(0)
+            output = pofile.read_po(buf, locale='fr', abort_invalid=False)
+            assert isinstance(output, Catalog)
+
+
     def test_invalid_pofile_with_abort_flag(self):
         parser = pofile.PoFileParser(None, abort_invalid=True)
         lineno = 10