Add bindings for libvyosconfig -- the standalone config file parsing and manipulation library.

1 files changed, 254 insertions, 0 deletions

diff --git a/python/vyos/configtree.py b/python/vyos/configtree.py
new file mode 100644
index 000000000..e0d46260f
--- /dev/null
+++ b/python/vyos/configtree.py
@@ -0,0 +1,254 @@
+# configtree -- a standalone VyOS config file manipulation library (Python bindings)
+# Copyright (C) 2018 VyOS maintainers and contributors
+#
+# This library is free software; you can redistribute it and/or modify it under the terms of
+# the GNU Lesser General Public License as published by the Free Software Foundation;
+# either version 2.1 of the License, or (at your option) any later version.
+#
+# This library 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 Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License along with this library;
+# if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 
+
+import re
+import json
+
+from ctypes import cdll, c_char_p, c_void_p, c_int
+
+
+def strip_comments(s):
+    """ Split a config string into the config section and the trailing comments """
+    INITIAL = 0
+    IN_COMMENT = 1
+
+    i = len(s) - 1
+    state = INITIAL
+
+    config_end = 0
+
+    # Find the first character of the comments section at the end,
+    # if it exists
+    while (i >= 0):
+        c = s[i]
+
+        if (state == INITIAL) and re.match(r'\s', c):
+            # Ignore whitespace
+            if (i != 0):
+                i -= 1
+            else:
+                config_end = 0
+                break
+        elif (state == INITIAL) and (c == '/'):
+            # A comment begins, or it's a stray slash
+            try:
+                if (s[i-1] == '*'):
+                    state = IN_COMMENT
+                    i -= 2
+                else:
+                    raise ValueError("Invalid syntax")
+            except:
+                raise ValueError("Invalid syntax")
+        elif (state == INITIAL) and (c == '}'):
+            # We are not inside a comment, that's the end of the last node
+            config_end = i + 1
+            break
+        elif (state == IN_COMMENT) and (c == '*'):
+            # A comment ends here
+            try:
+                if (s[i-1] == '/'):
+                    state = INITIAL
+                    i -= 2
+            except:
+                raise ValueError("Invalid syntax")
+        elif (state == IN_COMMENT) and (c != '*'):
+            # Ignore everything inside comments, including braces
+            i -= 1
+        else:
+            raise ValueError("Invalid syntax")
+
+    return (s[0:config_end], s[config_end+1:])
+
+def check_path(path):
+    # Necessary type checking
+    if not isinstance(path, list):
+        raise TypeError("Expected a list, got a {}".format(type(path)))
+    else:
+        pass
+
+
+class ConfigTreeError(Exception):
+    pass
+
+
+class ConfigTree(object):
+    def __init__(self, config_string, libpath='/usr/lib/libvyosconfig.so.0'):
+        self.__config = None
+        self.__lib = cdll.LoadLibrary(libpath)
+
+        # Import functions
+        self.__from_string = self.__lib.from_string
+        self.__from_string.argtypes = [c_char_p]
+        self.__from_string.restype = c_void_p
+
+        self.__to_string = self.__lib.to_string
+        self.__to_string.argtypes = [c_void_p]
+        self.__to_string.restype = c_char_p
+
+        self.__set_add_value = self.__lib.set_add_value
+        self.__set_add_value.argtypes = [c_void_p, c_char_p, c_char_p]
+        self.__set_add_value.restype = c_int
+
+        self.__delete_value = self.__lib.delete_value
+        self.__delete_value.argtypes = [c_void_p, c_char_p, c_char_p]
+        self.__delete_value.restype = c_int
+
+        self.__delete = self.__lib.delete_node
+        self.__delete.argtypes = [c_void_p, c_char_p]
+        self.__delete.restype = c_int
+
+        self.__set_replace_value = self.__lib.set_replace_value
+        self.__set_replace_value.argtypes = [c_void_p, c_char_p, c_char_p]
+        self.__set_replace_value.restype = c_int
+
+        self.__set_valueless = self.__lib.set_valueless
+        self.__set_valueless.argtypes = [c_void_p, c_char_p]
+        self.__set_valueless.restype = c_int
+
+        self.__exists = self.__lib.exists
+        self.__exists.argtypes = [c_void_p, c_char_p]
+        self.__exists.restype = c_int
+
+        self.__list_nodes = self.__lib.list_nodes
+        self.__list_nodes.argtypes = [c_void_p, c_char_p]
+        self.__list_nodes.restype = c_char_p
+
+        self.__return_value = self.__lib.return_value
+        self.__return_value.argtypes = [c_void_p, c_char_p]
+        self.__return_value.restype = c_char_p
+
+        self.__return_values = self.__lib.return_values
+        self.__return_values.argtypes = [c_void_p, c_char_p]
+        self.__return_values.restype = c_char_p
+
+        self.__is_tag = self.__lib.is_tag
+        self.__is_tag.argtypes = [c_void_p, c_char_p]
+        self.__is_tag.restype = c_int
+
+        self.__set_tag = self.__lib.set_tag
+        self.__set_tag.argtypes = [c_void_p, c_char_p]
+        self.__set_tag.restype = c_int
+
+        self.__destroy = self.__lib.destroy
+        self.__destroy.argtypes = [c_void_p]
+
+        config_section, comments_section = strip_comments(config_string)
+        config = self.__from_string(config_section.encode())
+        if config is None:
+            raise ValueError("Parse error")
+        else:
+            self.__config = config
+            self.__comments = comments_section
+    def __del__(self):
+        if self.__config is not None:
+            self.__destroy(self.__config)
+
+    def __str__(self):
+        return self.to_string()
+
+    def to_string(self):
+        config_string = self.__to_string(self.__config).decode()
+        config_string = "{0}\n{1}".format(config_string, self.__comments)
+        return config_string
+
+    def set(self, path, value=None, replace=True):
+        check_path(path)
+        path_str = " ".join(map(str, path)).encode()
+
+        if value is None:
+            self.__set_valueless(self.__config, path_str)
+        else:
+            if replace:
+                self.__set_replace_value(self.__config, path_str, str(value).encode())
+            else:
+                self.__set_add_value(self.__config, path_str, str(value).encode())
+
+    def delete(self, path):
+        check_path(path)
+        path_str = " ".join(map(str, path)).encode()
+
+        self.__delete(self.__config, path_str)
+
+    def delete_value(self, path, value):
+        check_path(path)
+        path_str = " ".join(map(str, path)).encode()
+
+        self.__delete_value(self.__config, path_str, value.encode())
+
+    def exists(self, path):
+        check_path(path)
+        path_str = " ".join(map(str, path)).encode()
+
+        res = self.__exists(self.__config, path_str)
+        if (res == 0):
+            return False
+        else:
+            return True
+
+    def list_nodes(self, path):
+        check_path(path)
+        path_str = " ".join(map(str, path)).encode()
+
+        res_json = self.__list_nodes(self.__config, path_str).decode()
+        res = json.loads(res_json)
+
+        if res is None:
+            raise ConfigTreeError("Path [{}] doesn't exist".format(path_str))
+        else:
+            return res
+
+    def return_value(self, path):
+        check_path(path)
+        path_str = " ".join(map(str, path)).encode()
+
+        res_json = self.__return_value(self.__config, path_str).decode()
+        res = json.loads(res_json)
+
+        if res is None:
+            raise ConfigTreeError("Path [{}] doesn't exist".format(path_str))
+        else:
+            return res
+
+    def return_values(self, path):
+        check_path(path)
+        path_str = " ".join(map(str, path)).encode()
+
+        res_json = self.__return_values(self.__config, path_str).decode()
+        res = json.loads(res_json)
+
+        if res is None:
+            raise ConfigTreeError("Path [{}] doesn't exist".format(path_str))
+        else:
+            return res
+
+    def is_tag(self, path):
+        check_path(path)
+        path_str = " ".join(map(str, path)).encode()
+
+        res = self.__is_tag(self.__config, path_str)
+        if (res >= 1):
+            return True
+        else:
+            return False
+
+    def set_tag(self, path):
+        check_path(path)
+        path_str = " ".join(map(str, path)).encode()
+
+        res = self.__set_tag(self.__config, path_str)
+        if (res == 0):
+            return True
+        else:
+            raise ConfigTreeError("Path [{}] doesn't exist".format(path_str))
+