T5996: selectively escape and restore single backslashes in config (backport #3035)

python/vyos/configtree.py

@@ -20,10 +20,22 @@
 
 LIBPATH = '/usr/lib/libvyosconfig.so.0'
 
+def replace_backslash(s, search, replace):
+    """Modify quoted strings containing backslashes not of escape sequences"""
+    def replace_method(match):
+        result = match.group().replace(search, replace)
+        return result
+    p = re.compile(r'("[^"]*[\\][^"]*"\n|\'[^\']*[\\][^\']*\'\n)')
+    return p.sub(replace_method, s)
+
 def escape_backslash(string: str) -> str:
-    """Escape single backslashes in string that are not in escape sequence"""
-    p = re.compile(r'(?<!\\)[\\](?!b|f|n|r|t|\\[^bfnrt])')
-    result = p.sub(r'\\\\', string)
+    """Escape single backslashes in quoted strings"""
+    result = replace_backslash(string, '\\', '\\\\')
+    return result
+
+def unescape_backslash(string: str) -> str:
+    """Unescape backslashes in quoted strings"""
+    result = replace_backslash(string, '\\\\', '\\')
     return result
 
 def extract_version(s):
@@ -165,11 +177,14 @@ def get_version_string(self):
 
     def to_string(self, ordered_values=False):
         config_string = self.__to_string(self.__config, ordered_values).decode()
+        config_string = unescape_backslash(config_string)
         config_string = "{0}\n{1}".format(config_string, self.__version)
         return config_string
 
     def to_commands(self, op="set"):
-        return self.__to_commands(self.__config, op.encode()).decode()
+        commands = self.__to_commands(self.__config, op.encode()).decode()
+        commands = unescape_backslash(commands)
+        return commands
 
     def to_json(self):
         return self.__to_json(self.__config).decode()
@@ -362,6 +377,7 @@ def show_diff(left, right, path=[], commands=False, libpath=LIBPATH):
         msg = __get_error().decode()
         raise ConfigTreeError(msg)
 
+    res = unescape_backslash(res)
     return res
 
 def union(left, right, libpath=LIBPATH):

smoketest/scripts/cli/test_backslash_escape.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2024 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import unittest
+
+from base_vyostest_shim import VyOSUnitTestSHIM
+from vyos.configtree import ConfigTree
+
+base_path = ['interfaces', 'ethernet', 'eth0', 'description']
+
+cases_word = [r'fo\o', r'fo\\o', r'foço\o', r'foço\\o']
+# legacy CLI output quotes only if whitespace present; this is a notable
+# difference that confounds the translation legacy -> modern, hence
+# determines the regex used in function replace_backslash
+cases_phrase = [r'some fo\o', r'some fo\\o', r'some foço\o', r'some foço\\o']
+
+case_save_config = '/tmp/smoketest-case-save'
+
+class TestBackslashEscape(VyOSUnitTestSHIM.TestCase):
+    def test_backslash_escape_word(self):
+        for case in cases_word:
+            self.cli_set(base_path + [case])
+            self.cli_commit()
+            # save_config tests translation though subsystems:
+            # legacy output -> config -> configtree -> file
+            self._session.save_config(case_save_config)
+            # reload to configtree and confirm:
+            with open(case_save_config) as f:
+                config_string = f.read()
+            ct = ConfigTree(config_string)
+            res = ct.return_value(base_path)
+            self.assertEqual(case, res, msg=res)
+            print(f'description: {res}')
+            self.cli_delete(base_path)
+            self.cli_commit()
+
+    def test_backslash_escape_phrase(self):
+        for case in cases_phrase:
+            self.cli_set(base_path + [case])
+            self.cli_commit()
+            # save_config tests translation though subsystems:
+            # legacy output -> config -> configtree -> file
+            self._session.save_config(case_save_config)
+            # reload to configtree and confirm:
+            with open(case_save_config) as f:
+                config_string = f.read()
+            ct = ConfigTree(config_string)
+            res = ct.return_value(base_path)
+            self.assertEqual(case, res, msg=res)
+            print(f'description: {res}')
+            self.cli_delete(base_path)
+            self.cli_commit()
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)