mirror of https://github.com/searxng/searxng.git
112 lines
2.8 KiB
Python
112 lines
2.8 KiB
Python
# SPDX-License-Identifier: AGPL-3.0-or-later
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"""Calculate mathematical expressions using ack#eval
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"""
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import ast
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import operator
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from multiprocessing import Process, Queue
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from flask_babel import gettext
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from searx.plugins import logger
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name = "Basic Calculator"
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description = gettext("Calculate mathematical expressions via the search bar")
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default_on = True
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preference_section = 'general'
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plugin_id = 'calculator'
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logger = logger.getChild(plugin_id)
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operators = {
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ast.Add: operator.add,
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ast.Sub: operator.sub,
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ast.Mult: operator.mul,
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ast.Div: operator.truediv,
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ast.Pow: operator.pow,
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ast.BitXor: operator.xor,
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ast.USub: operator.neg,
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}
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def _eval_expr(expr):
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"""
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>>> _eval_expr('2^6')
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4
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>>> _eval_expr('2**6')
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64
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>>> _eval_expr('1 + 2*3**(4^5) / (6 + -7)')
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-5.0
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"""
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return _eval(ast.parse(expr, mode='eval').body)
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def _eval(node):
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if isinstance(node, ast.Constant) and isinstance(node.value, int):
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return node.value
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if isinstance(node, ast.BinOp):
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return operators[type(node.op)](_eval(node.left), _eval(node.right))
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if isinstance(node, ast.UnaryOp):
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return operators[type(node.op)](_eval(node.operand))
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raise TypeError(node)
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def timeout_func(timeout, func, *args, **kwargs):
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def handler(q: Queue, func, args, **kwargs): # pylint:disable=invalid-name
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try:
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q.put(func(*args, **kwargs))
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except:
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q.put(None)
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raise
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que = Queue()
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p = Process(target=handler, args=(que, func, args), kwargs=kwargs)
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p.start()
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p.join(timeout=timeout)
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ret_val = None
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if not p.is_alive():
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ret_val = que.get()
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else:
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logger.debug("terminate function after timeout is exceeded")
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p.terminate()
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p.join()
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p.close()
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return ret_val
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def post_search(_request, search):
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# only show the result of the expression on the first page
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if search.search_query.pageno > 1:
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return True
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query = search.search_query.query
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# in order to avoid DoS attacks with long expressions, ignore long expressions
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if len(query) > 100:
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return True
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# replace commonly used math operators with their proper Python operator
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query = query.replace("x", "*").replace(":", "/")
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# only numbers and math operators are accepted
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if any(str.isalpha(c) for c in query):
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return True
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# in python, powers are calculated via **
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query_py_formatted = query.replace("^", "**")
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# Prevent the runtime from being longer than 50 ms
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result = timeout_func(0.05, _eval_expr, query_py_formatted)
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if result is None:
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return True
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result = str(result)
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if result != query:
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search.result_container.answers['calculate'] = {'answer': f"{query} = {result}"}
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return True
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