X-Git-Url: https://code.grnet.gr/git/ganeti-local/blobdiff_plain/88076fd142267b9439989a4ac8c5fc4c00fe07ad..905108aba23c253f17ad1a4f2bf4883b8108bda5:/lib/qlang.py diff --git a/lib/qlang.py b/lib/qlang.py index 2a7f755..db0a59d 100644 --- a/lib/qlang.py +++ b/lib/qlang.py @@ -1,7 +1,7 @@ # # -# Copyright (C) 2010 Google Inc. +# Copyright (C) 2010, 2011 Google Inc. # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by @@ -19,83 +19,306 @@ # 02110-1301, USA. -"""Module for a simple query language""" +"""Module for a simple query language + +A query filter is always a list. The first item in the list is the operator +(e.g. C{[OP_AND, ...]}), while the other items depend on the operator. For +logic operators (e.g. L{OP_AND}, L{OP_OR}), they are subfilters whose results +are combined. Unary operators take exactly one other item (e.g. a subfilter for +L{OP_NOT} and a field name for L{OP_TRUE}). Binary operators take exactly two +operands, usually a field name and a value to compare against. Filters are +converted to callable functions by L{query._CompileFilter}. + +""" + +import re +import string # pylint: disable-msg=W0402 +import logging + +import pyparsing as pyp from ganeti import errors +from ganeti import netutils +from ganeti import utils +from ganeti import compat -# Logic operators +# Logic operators with one or more operands, each of which is a filter on its +# own OP_OR = "|" OP_AND = "&" -# Unary operators +# Unary operators with exactly one operand OP_NOT = "!" +OP_TRUE = "?" -# Binary operators +# Binary operators with exactly two operands, the field name and an +# operator-specific value OP_EQUAL = "=" OP_NOT_EQUAL = "!=" -OP_GLOB = "=*" OP_REGEXP = "=~" OP_CONTAINS = "=[]" -def ReadSimpleFilter(namefield, filter_): - """Function extracting wanted names from restricted filter. +#: Characters used for detecting user-written filters (see L{_CheckFilter}) +FILTER_DETECTION_CHARS = frozenset("()=/!~'\"\\" + string.whitespace) + +#: Characters used to detect globbing filters (see L{_CheckGlobbing}) +GLOB_DETECTION_CHARS = frozenset("*?") - This should only be used until proper filtering is implemented. The filter - must either be empty or of the format C{["|", ["=", field, "name1"], ["=", - field, "name2"], ...]}. + +def MakeSimpleFilter(namefield, values): + """Builds simple a filter. + + @param namefield: Name of field containing item name + @param values: List of names """ - if filter_ is None: - return [] + if values: + return [OP_OR] + [[OP_EQUAL, namefield, i] for i in values] - if not isinstance(filter_, list): - raise errors.ParameterError("Filter should be list") + return None - if not filter_ or filter_[0] != OP_OR: - raise errors.ParameterError("Filter should start with OR operator") - if len(filter_) < 2: - raise errors.ParameterError("Invalid filter, OR operator should have" - " operands") +def _ConvertLogicOp(op): + """Creates parsing action function for logic operator. - result = [] + @type op: string + @param op: Operator for data structure, e.g. L{OP_AND} - for idx, item in enumerate(filter_[1:]): - if not isinstance(item, list): - raise errors.ParameterError("Invalid OR operator, operand %s not a" - " list" % idx) + """ + def fn(toks): + """Converts parser tokens to query operator structure. - if len(item) != 3 or item[0] != OP_EQUAL: - raise errors.ParameterError("Invalid OR operator, operand %s is not an" - " equality filter" % idx) + @rtype: list + @return: Query operator structure, e.g. C{[OP_AND, ["=", "foo", "bar"]]} - (_, name, value) = item + """ + operands = toks[0] - if not isinstance(value, basestring): - raise errors.ParameterError("Operand %s for OR should compare against a" - " string" % idx) + if len(operands) == 1: + return operands[0] - if name != namefield: - raise errors.ParameterError("Operand %s for OR should filter field '%s'," - " not '%s'" % (idx, namefield, name)) + # Build query operator structure + return [[op] + operands.asList()] - result.append(value) + return fn - return result +_KNOWN_REGEXP_DELIM = "/#^|" +_KNOWN_REGEXP_FLAGS = frozenset("si") -def MakeSimpleFilter(namefield, values): - """Builds a filter for use with L{ReadSimpleFilter}. - @param namefield: Name of field containing item name - @param values: List of names +def _ConvertRegexpValue(_, loc, toks): + """Regular expression value for condition. """ - if values: - return [OP_OR] + [[OP_EQUAL, namefield, i] for i in values] + (regexp, flags) = toks[0] - return None + # Ensure only whitelisted flags are used + unknown_flags = (frozenset(flags) - _KNOWN_REGEXP_FLAGS) + if unknown_flags: + raise pyp.ParseFatalException("Unknown regular expression flags: '%s'" % + "".join(unknown_flags), loc) + + if flags: + re_flags = "(?%s)" % "".join(sorted(flags)) + else: + re_flags = "" + + re_cond = re_flags + regexp + + # Test if valid + try: + re.compile(re_cond) + except re.error, err: + raise pyp.ParseFatalException("Invalid regular expression (%s)" % err, loc) + + return [re_cond] + + +def BuildFilterParser(): + """Builds a parser for query filter strings. + + @rtype: pyparsing.ParserElement + + """ + field_name = pyp.Word(pyp.alphas, pyp.alphanums + "_/.") + + # Integer + num_sign = pyp.Word("-+", exact=1) + number = pyp.Combine(pyp.Optional(num_sign) + pyp.Word(pyp.nums)) + number.setParseAction(lambda toks: int(toks[0])) + + quoted_string = pyp.quotedString.copy().setParseAction(pyp.removeQuotes) + + # Right-hand-side value + rval = (number | quoted_string) + + # Boolean condition + bool_cond = field_name.copy() + bool_cond.setParseAction(lambda (fname, ): [[OP_TRUE, fname]]) + + # Simple binary conditions + binopstbl = { + "==": OP_EQUAL, + "!=": OP_NOT_EQUAL, + } + + binary_cond = (field_name + pyp.oneOf(binopstbl.keys()) + rval) + binary_cond.setParseAction(lambda (lhs, op, rhs): [[binopstbl[op], lhs, rhs]]) + + # "in" condition + in_cond = (rval + pyp.Suppress("in") + field_name) + in_cond.setParseAction(lambda (value, field): [[OP_CONTAINS, field, value]]) + + # "not in" condition + not_in_cond = (rval + pyp.Suppress("not") + pyp.Suppress("in") + field_name) + not_in_cond.setParseAction(lambda (value, field): [[OP_NOT, [OP_CONTAINS, + field, value]]]) + + # Regular expression, e.g. m/foobar/i + regexp_val = pyp.Group(pyp.Optional("m").suppress() + + pyp.MatchFirst([pyp.QuotedString(i, escChar="\\") + for i in _KNOWN_REGEXP_DELIM]) + + pyp.Optional(pyp.Word(pyp.alphas), default="")) + regexp_val.setParseAction(_ConvertRegexpValue) + regexp_cond = (field_name + pyp.Suppress("=~") + regexp_val) + regexp_cond.setParseAction(lambda (field, value): [[OP_REGEXP, field, value]]) + + not_regexp_cond = (field_name + pyp.Suppress("!~") + regexp_val) + not_regexp_cond.setParseAction(lambda (field, value): + [[OP_NOT, [OP_REGEXP, field, value]]]) + + # Globbing, e.g. name =* "*.site" + glob_cond = (field_name + pyp.Suppress("=*") + quoted_string) + glob_cond.setParseAction(lambda (field, value): + [[OP_REGEXP, field, + utils.DnsNameGlobPattern(value)]]) + + not_glob_cond = (field_name + pyp.Suppress("!*") + quoted_string) + not_glob_cond.setParseAction(lambda (field, value): + [[OP_NOT, [OP_REGEXP, field, + utils.DnsNameGlobPattern(value)]]]) + + # All possible conditions + condition = (binary_cond ^ bool_cond ^ + in_cond ^ not_in_cond ^ + regexp_cond ^ not_regexp_cond ^ + glob_cond ^ not_glob_cond) + + # Associativity operators + filter_expr = pyp.operatorPrecedence(condition, [ + (pyp.Keyword("not").suppress(), 1, pyp.opAssoc.RIGHT, + lambda toks: [[OP_NOT, toks[0][0]]]), + (pyp.Keyword("and").suppress(), 2, pyp.opAssoc.LEFT, + _ConvertLogicOp(OP_AND)), + (pyp.Keyword("or").suppress(), 2, pyp.opAssoc.LEFT, + _ConvertLogicOp(OP_OR)), + ]) + + parser = pyp.StringStart() + filter_expr + pyp.StringEnd() + parser.parseWithTabs() + + # Originally C{parser.validate} was called here, but there seems to be some + # issue causing it to fail whenever the "not" operator is included above. + + return parser + + +def ParseFilter(text, parser=None): + """Parses a query filter. + + @type text: string + @param text: Query filter + @type parser: pyparsing.ParserElement + @param parser: Pyparsing object + @rtype: list + + """ + logging.debug("Parsing as query filter: %s", text) + + if parser is None: + parser = BuildFilterParser() + + try: + return parser.parseString(text)[0] + except pyp.ParseBaseException, err: + raise errors.QueryFilterParseError("Failed to parse query filter" + " '%s': %s" % (text, err), err) + + +def _IsHostname(text): + """Checks if a string could be a hostname. + + @rtype: bool + + """ + try: + netutils.Hostname.GetNormalizedName(text) + except errors.OpPrereqError: + return False + else: + return True + + +def _CheckFilter(text): + """CHecks if a string could be a filter. + + @rtype: bool + + """ + return bool(frozenset(text) & FILTER_DETECTION_CHARS) + + +def _CheckGlobbing(text): + """Checks if a string could be a globbing pattern. + + @rtype: bool + + """ + return bool(frozenset(text) & GLOB_DETECTION_CHARS) + + +def _MakeFilterPart(namefield, text): + """Generates filter for one argument. + + """ + if _CheckGlobbing(text): + return [OP_REGEXP, namefield, utils.DnsNameGlobPattern(text)] + else: + return [OP_EQUAL, namefield, text] + + +def MakeFilter(args, force_filter): + """Try to make a filter from arguments to a command. + + If the name could be a filter it is parsed as such. If it's just a globbing + pattern, e.g. "*.site", such a filter is constructed. As a last resort the + names are treated just as a plain name filter. + + @type args: list of string + @param args: Arguments to command + @type force_filter: bool + @param force_filter: Whether to force treatment as a full-fledged filter + @rtype: list + @return: Query filter + + """ + if (force_filter or + (args and len(args) == 1 and _CheckFilter(args[0]))): + try: + (filter_text, ) = args + except (TypeError, ValueError): + raise errors.OpPrereqError("Exactly one argument must be given as a" + " filter") + + result = ParseFilter(filter_text) + elif args: + result = [OP_OR] + map(compat.partial(_MakeFilterPart, "name"), args) + else: + result = None + + return result