"""Configuration backend for storing settings in a simple plain text format""" __all__ = ["FileParserError", "FileBuilderError", "FileBackend"] import errno import os import re import platform import random from collections import deque from application.system import makedirs, openfile, unlink from zope.interface import implements from sipsimple.configuration.backend import IConfigurationBackend, ConfigurationBackendError class FileParserError(ConfigurationBackendError): """Error raised when the configuration file cannot be parsed.""" class FileBuilderError(ConfigurationBackendError): """Error raised when the configuration data cannot be saved.""" class GroupState(object): """ Internal class used for keeping track of the containing groups while parsing. """ def __init__(self, indentation): self.indentation = indentation self.data = {} class Line(object): """Internal representation of lines in a configuration file""" def __init__(self, indentation, name, separator, value): self.indentation = indentation self.name = name self.separator = separator self.value = value def __repr__(self): return "%s(%r, %r, %r, %r)" % (self.__class__.__name__, self.indentation, self.name, self.separator, self.value) class FileBackend(object): """ Implementation of a configuration backend that stores data in a simple plain text format. """ implements(IConfigurationBackend) escape_characters_re = re.compile(ur"""[,"'=: #\\\t\x0b\x0c\n\r]""") def __init__(self, filename, encoding='utf-8'): """ Initialize the configuration backend with the specified file. The file is not read at this time, but rather each time the load method is called. """ self.filename = filename self.encoding = encoding def load(self): """ Read the file configured with this backend and parse it, returning a dictionary conforming to the IConfigurationBackend specification. """ try: file = open(self.filename) except IOError, e: if e.errno == errno.ENOENT: return {} else: raise ConfigurationBackendError("failed to read configuration file: %s" % str(e)) state_stack = deque() state_stack.appendleft(GroupState(-1)) for lineno, line in enumerate(file, 1): line = self._parse_line(line, lineno) if not line.name: continue # find the container for this declaration while state_stack[0].indentation >= line.indentation: state_stack.popleft() if line.separator == u':': new_group_state = GroupState(line.indentation) state_stack[0].data[line.name] = new_group_state.data state_stack.appendleft(new_group_state) elif line.separator == u'=': state_stack[0].data[line.name] = line.value return state_stack[-1].data def save(self, data): """ Given a dictionary conforming to the IConfigurationBackend specification, write the data to the file configured with this backend in a format suitable to be read back using load(). """ lines = self._build_group(data, 0) config_directory = os.path.dirname(self.filename) tmp_filename = '%s.%d.%08X' % (self.filename, os.getpid(), random.getrandbits(32)) try: if config_directory: makedirs(config_directory) file = openfile(tmp_filename, 'wb', permissions=0600) file.write((os.linesep.join(lines)+os.linesep).encode(self.encoding)) file.close() if platform.system() == 'Windows': # os.rename does not work on Windows if the destination file already exists. # It seems there is no atomic way to do this on Windows. unlink(self.filename) os.rename(tmp_filename, self.filename) except (IOError, OSError), e: raise ConfigurationBackendError("failed to write configuration file: %s" % str(e)) def _parse_line(self, line, lineno): def advance_to_next_token(line): counter = 0 while line and line[0].isspace(): line.popleft() counter += 1 if line and line[0] == u'#': line.clear() return counter def token_iterator(line, delimiter=''): quote_char = None while line: if quote_char is None and line[0] in delimiter: break char = line.popleft() if char in u"'\"": if quote_char is None: quote_char = char continue elif quote_char == char: quote_char = None continue else: yield char elif char == u'\\': if not line: raise FileParserError("unexpected `\\' at end of line %d" % lineno) char = line.popleft() if char == 'n': yield u'\n' elif char == 'r': yield u'\r' else: yield char elif quote_char is None and char == u'#': line.clear() break elif quote_char is None and char.isspace(): break else: yield char if quote_char is not None: raise FileParserError("missing ending quote at line %d" % lineno) line = deque(line.rstrip().decode(self.encoding)) indentation = advance_to_next_token(line) if not line: return Line(indentation, None, None, None) name = u''.join(token_iterator(line, delimiter=u':=')) advance_to_next_token(line) if not line or line[0] not in u':=': raise FileParserError("expected one of `:' or `=' at line %d" % lineno) if not name: raise FileParserError("missing setting/section name at line %d" % lineno) separator = line.popleft() advance_to_next_token(line) if not line: return Line(indentation, name, separator, None) elif separator == u':': raise FileParserError("unexpected characters after `:' at line %d" % lineno) value = None value_list = None while line: value = u''.join(token_iterator(line, delimiter=u',')) advance_to_next_token(line) if line: if line[0] == u',': line.popleft() advance_to_next_token(line) if value_list is None: value_list = [] else: raise FileParserError("unexpected characters after value at line %d" % lineno) if value_list is not None: value_list.append(value) value = value_list if value_list is not None else value return Line(indentation, name, separator, value) def _build_group(self, group, indentation): setting_lines = [] group_lines = [] indent_spaces = u' '*4*indentation for name, data in sorted(group.iteritems()): if data is None: setting_lines.append(u'%s%s =' % (indent_spaces, self._escape(name))) elif type(data) is dict: group_lines.append(u'%s%s:' % (indent_spaces, self._escape(name))) group_lines.extend(self._build_group(data, indentation+1)) group_lines.append(u'') elif type(data) is list: list_value = u', '.join(self._escape(item) for item in data) if len(data) == 1: list_value += u',' setting_lines.append(u'%s%s = %s' % (indent_spaces, self._escape(name), list_value)) elif type(data) is unicode: setting_lines.append(u'%s%s = %s' % (indent_spaces, self._escape(name), self._escape(data))) else: raise FileBuilderError("expected unicode, dict or list object, got %s" % type(data).__name__) return setting_lines + group_lines def _escape(self, value): if value == u'': return u'""' elif self.escape_characters_re.search(value): return u'"%s"' % value.replace(u'\\', u'\\\\').replace(u'"', u'\\"').replace(u'\n', u'\\n').replace(u'\r', u'\\r') else: return value