sonic-yang-mgmt: helpers to prevent dependents from calling into libyang

src/sonic-yang-mgmt/sonic_yang.py

@@ -197,6 +197,22 @@ def _load_data_model(self, yang_dir, yang_files, data_files, output=None):
 
         return (self.ctx, self.root)
 
+    """
+    load_module_str_name(): load a module based on the provided string and return
+                            the loaded module name.  This is needed by
+                            sonic-utilities to prevent direct dependency on
+                            libyang.
+    input: yang_module_str yang-formatted module
+    returns: module name on success, exception on failure
+    """
+    def load_module_str_name(self, yang_module_str):
+        try:
+            module = self.ctx.parse_module_mem(yang_module_str, ly.LYS_IN_YANG)
+        except Exception as e:
+            self.fail(e)
+
+        return module.name()
+
     """
     print_data_mem():  print the data tree
     input:  option:  "JSON" or "XML"
@@ -229,7 +245,7 @@ def _get_module_tree(self, module_name, format):
         try:
             module = self.ctx.get_module(str(module_name))
         except Exception as e:
-            self.sysLog(msg="Cound not get module: " + str(module_name), debug=syslog.LOG_ERR, doPrint=True)
+            self.sysLog(msg="Could not get module: " + str(module_name), debug=syslog.LOG_ERR, doPrint=True)
             self.fail(e)
         else:
             if (module is not None):
@@ -364,7 +380,7 @@ def _find_schema_node(self, schema_xpath):
              return None
         else:
              for schema_node in schema_set.schema():
-                 if schema_xapth == schema_node.path():
+                 if schema_xpath == schema_node.path():
                      return schema_node
              return None
     """
@@ -517,7 +533,7 @@ def find_schema_must_count(self, schema_xpath, match_ancestors: bool=False):
         try:
             schema_node = self._find_schema_node(schema_xpath)
         except Exception as e:
-            self.sysLog(msg="Cound not find the schema node from xpath: " + str(schema_xpath), debug=syslog.LOG_ERR, doPrint=True)
+            self.sysLog(msg="Could not find the schema node from xpath: " + str(schema_xpath), debug=syslog.LOG_ERR, doPrint=True)
             self.fail(e)
             return 0
 
@@ -582,10 +598,28 @@ def find_schema_dependencies(self, schema_xpath, match_ancestors: bool=False):
             return result
 
         ref_list = []
+        if schema_xpath is None or len(schema_xpath) == 0 or schema_xpath == "/":
+            if not match_ancestors:
+                return ref_list
+
+            # Iterate across all modules, can't use "/"
+            for module in self.ctx.get_module_iter():
+                if module.data() is None:
+                    continue
+
+                module_list = []
+                try:
+                    module_list = self.find_schema_dependencies(module.data().path(), match_ancestors=match_ancestors)
+                except Exception as e:
+                    self.sysLog(msg=f"Exception while finding schema dependencies for module {module.name()}: {str(e)}", debug=syslog.LOG_ERR, doPrint=True)
+
+                ref_list.extend(module_list)
+            return ref_list
+
         try:
             schema_node = self._find_schema_node(schema_xpath)
         except Exception as e:
-            self.sysLog(msg="Cound not find the schema node from xpath: " + str(schema_xpath), debug=syslog.LOG_ERR, doPrint=True)
+            self.sysLog(msg=f"Could not find the schema node from xpath: {str(schema_xpath)}: {str(e)}", debug=syslog.LOG_ERR, doPrint=True)
             self.fail(e)
             return ref_list
 
@@ -632,36 +666,80 @@ def __find_schema_dependencies_only(self, schema_node):
         return ref_list
 
     """
-    find_data_dependencies():   find the data dependencies from data xpath
-    input:    data_xpath - xpath of data node. (Public)
-    returns:  - list of xpath
-              - Exception if error
+    find_data_dependencies(): find the data dependencies from data xpath  (Public)
+    input:    data_xpath - xpath to search.  If it references an exact data node
+                           only the references to that data node will be returned.
+                           If a path contains multiple data nodes, then all references
+                           to all child nodes will be returned.  If set to None (or "" or "/"),
+                           will return all references, globally.
     """
     def find_data_dependencies(self, data_xpath):
         ref_list = []
-        node = self.root
-        try:
-            data_node = self._find_data_node(data_xpath)
-        except Exception as e:
-            self.sysLog(msg="find_data_dependencies(): Failed to find data node from xpath: {}".format(data_xapth), debug=syslog.LOG_ERR, doPrint=True)
-            return ref_list
+        required_value = None
+        base_dnode = None
+        search_xpath = None
+
+        if data_xpath is None or len(data_xpath) == 0 or data_xpath == "/":
+            data_xpath = None
+            search_xpath = "/"
+
+        if data_xpath is not None:
+            dnode_list = []
+            try:
+                dnode_list = list(self.root.find_path(data_xpath).data())
+            except Exception as e:
+                # We don't care the reason for the failure, this is caught in 
+                # the next statement.
+                pass
+
+            if len(dnode_list) == 0:
+                self.sysLog(msg="find_data_dependencies(): Failed to find data node from xpath: {}".format(data_xpath), debug=syslog.LOG_ERR, doPrint=True)
+                return ref_list
+
+            base_dnode = dnode_list[0]
+            if base_dnode.schema() is None:
+                return ref_list
+
+            search_xpath = base_dnode.schema().path()
+
+            # If exactly 1 node and it's a data node, we need to match the value.
+            if len(dnode_list) == 1:
+                try:
+                    required_value = self._find_data_node_value(data_xpath)
+                except Exception as e:
+                    # Might not be a data node, ignore
+                    pass
+
+        # Get a list of all schema leafrefs pointing to this node (or these data nodes).
+        lreflist = []
 
         try:
-            value = str(self._find_data_node_value(data_xpath))
-
-            backlinks = self.find_schema_dependencies(data_node.schema().path(), False)
-            if backlinks is not None and len(backlinks) > 0:
-                for link in backlinks:
-                     node_set = node.find_path(link)
-                     for data_set in node_set.data():
-                          data_set.schema()
-                          casted = data_set.subtype()
-                          if value == casted.value_str():
-                              ref_list.append(data_set.path())
+            match_ancestors = True
+            if required_value is not None:
+                match_ancestors = False
+
+            lreflist = self.find_schema_dependencies(search_xpath, match_ancestors=match_ancestors)
+            if lreflist is None:
+                raise Exception("no schema backlinks found")
         except Exception as e:
-            self.sysLog(msg='Failed to find node or dependencies for {}'.format(data_xpath), debug=syslog.LOG_ERR, doPrint=True)
-            raise SonicYangException("Failed to find node or dependencies for \
-                {}\n{}".format(data_xpath, str(e)))
+            self.sysLog(msg='Failed to find node or dependencies for {}: {}'.format(data_xpath, str(e)), debug=syslog.LOG_ERR, doPrint=True)
+            lreflist = []
+            # Exception not expected by existing tests if backlinks not found, so don't raise.
+            # raise SonicYangException("Failed to find node or dependencies for {}\n{}".format(data_xpath, str(e)))
+
+        # For all found data nodes, emit the path to the data node.  If we need to
+        # restrict to a value, do so.
+        for lref in lreflist:
+            try:
+                data_set = self.root.find_path(lref).data()
+                for dnode in data_set:
+                    if required_value is None or (
+                        dnode.subtype() is not None and dnode.subtype().value_str() == required_value
+                    ):
+                        ref_list.append(dnode.path())
+            except Exception as e:
+                # Possible no data paths matched, ignore
+                pass
 
         return ref_list
 

src/sonic-yang-mgmt/tests/libyang-python-tests/test_SonicYang.json

@@ -56,6 +56,52 @@
          ],
          "xpath" : "/test-port:test-port/PORT/PORT_LIST[port_name='Ethernet8']/port_name"
       },
+      {
+         "dependencies" : [
+            "/test-acl:test-acl/ACL_RULE/ACL_RULE_LIST[ACL_TABLE_NAME='PACL-V6'][RULE_NAME='Rule_20']/ACL_TABLE_NAME",
+            "/test-acl:test-acl/ACL_RULE/ACL_RULE_LIST[ACL_TABLE_NAME='PACL-test'][RULE_NAME='rule_20']/ACL_TABLE_NAME",
+            "/test-acl:test-acl/ACL_RULE/ACL_RULE_LIST[ACL_TABLE_NAME='PACL-V4'][RULE_NAME='Rule_20']/ACL_TABLE_NAME",
+            "/test-acl:test-acl/ACL_RULE/ACL_RULE_LIST[ACL_TABLE_NAME='PACL-V4'][RULE_NAME='Rule_40']/ACL_TABLE_NAME"
+         ],
+         "xpath" : "/test-acl:test-acl/ACL_TABLE"
+      },
+      {
+         "dependencies" : [
+            "/test-acl:test-acl/ACL_TABLE/ACL_TABLE_LIST[ACL_TABLE_NAME='PACL-V6']/ports[.='Ethernet8']",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet2']/port",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet3']/vlanid",
+            "/test-vlan:test-vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='555'][ip-prefix='fe80::/10']/vlanid",
+            "/test-interface:test-interface/INTERFACE/INTERFACE_LIST[interface='Ethernet8'][ip-prefix='10.1.1.64/26']/interface",
+            "/test-vlan:test-vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='2000:f500:45:6709::/64']/vlanid",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet5']/vlanid",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet1']/port",
+            "/test-acl:test-acl/ACL_TABLE/ACL_TABLE_LIST[ACL_TABLE_NAME='PACL-V4']/ports[.='Ethernet0']",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet6']/port",
+            "/test-acl:test-acl/ACL_TABLE/ACL_TABLE_LIST[ACL_TABLE_NAME='PACL-V4']/ports[.='Ethernet2']",
+            "/test-acl:test-acl/ACL_TABLE/ACL_TABLE_LIST[ACL_TABLE_NAME='PACL-V6']/ports[.='Ethernet7']",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet3']/port",
+            "/test-interface:test-interface/INTERFACE/INTERFACE_LIST[interface='Ethernet8'][ip-prefix='2000:f500:40:a749::/126']/interface",
+            "/test-acl:test-acl/ACL_RULE/ACL_RULE_LIST[ACL_TABLE_NAME='PACL-test'][RULE_NAME='rule_20']/ACL_TABLE_NAME",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet0']/port",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet5']/port",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet1']/vlanid",
+            "/test-vlan:test-vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='fe80::/10']/vlanid",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet4']/port",
+            "/test-acl:test-acl/ACL_RULE/ACL_RULE_LIST[ACL_TABLE_NAME='PACL-V4'][RULE_NAME='Rule_20']/ACL_TABLE_NAME",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet2']/vlanid",
+            "/test-acl:test-acl/ACL_TABLE/ACL_TABLE_LIST[ACL_TABLE_NAME='PACL-V6']/ports[.='Ethernet9']",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet6']/vlanid",
+            "/test-acl:test-acl/ACL_RULE/ACL_RULE_LIST[ACL_TABLE_NAME='PACL-V4'][RULE_NAME='Rule_40']/ACL_TABLE_NAME",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet0']/vlanid",
+            "/test-acl:test-acl/ACL_RULE/ACL_RULE_LIST[ACL_TABLE_NAME='PACL-V6'][RULE_NAME='Rule_20']/ACL_TABLE_NAME",
+            "/test-vlan:test-vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='111'][ip-prefix='10.1.1.64/26']/vlanid",
+            "/test-vlan:test-vlan/VLAN_MEMBER/VLAN_MEMBER_LIST[vlanid='111'][port='Ethernet4']/vlanid",
+            "/test-acl:test-acl/ACL_TABLE/ACL_TABLE_LIST[ACL_TABLE_NAME='PACL-V4']/ports[.='Ethernet1']",
+            "/test-vlan:test-vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='555'][ip-prefix='2000:f500:41:4e9::/64']/vlanid",
+            "/test-vlan:test-vlan/VLAN_INTERFACE/VLAN_INTERFACE_LIST[vlanid='555'][ip-prefix='10.1.5.64/26']/vlanid"
+         ],
+         "xpath" : "/"
+      },
       {
          "dependencies" : [],
          "xpath" : "/test-port:test-port/PORT/PORT_LIST[port_name='Ethernet8']/alias"

src/sonic-yang-mgmt/tests/libyang-python-tests/test_sonic_yang.py

@@ -88,6 +88,22 @@ def test_load_invalid_model_files(self, data, yang_s):
         with pytest.raises(Exception):
              assert self.load_yang_model_file(yang_s, yang_dir, file, module)
 
+    # test load_module_str_name on test-acl.yang
+    def test_load_module_str_name(self, data, yang_s):
+        yang_dir = data['yang_dir']
+        file = "test-acl.yang"
+
+        try:
+            with open(f'{yang_dir}/test-acl.yang', 'r') as f:
+                content = f.read()
+
+            name = yang_s.load_module_str_name(content)
+        except Exception as e:
+            print(e)
+            raise
+
+        assert name == "test-acl"
+
     #test load yang modules in directory
     def test_load_yang_model_dir(self, data, yang_s):
         yang_dir = data['yang_dir']