diff options
Diffstat (limited to 'youtube_dl/jsinterp.py')
| -rw-r--r-- | youtube_dl/jsinterp.py | 172 |
1 files changed, 126 insertions, 46 deletions
diff --git a/youtube_dl/jsinterp.py b/youtube_dl/jsinterp.py index b4617fbad..49364786b 100644 --- a/youtube_dl/jsinterp.py +++ b/youtube_dl/jsinterp.py @@ -1,59 +1,122 @@ from __future__ import unicode_literals import json +import operator import re from .utils import ( ExtractorError, ) +_OPERATORS = [ + ('|', operator.or_), + ('^', operator.xor), + ('&', operator.and_), + ('>>', operator.rshift), + ('<<', operator.lshift), + ('-', operator.sub), + ('+', operator.add), + ('%', operator.mod), + ('/', operator.div), + ('*', operator.mul), +] +_ASSIGN_OPERATORS = [(op + '=', opfunc) for op, opfunc in _OPERATORS] +_ASSIGN_OPERATORS.append(('=', lambda cur, right: right)) + +_NAME_RE = r'[a-zA-Z_$][a-zA-Z_$0-9]*' + class JSInterpreter(object): - def __init__(self, code): - self.code = code + def __init__(self, code, objects=None): + if objects is None: + objects = {} + self.code = self._remove_comments(code) self._functions = {} - self._objects = {} + self._objects = objects + + def _remove_comments(self, code): + return re.sub(r'(?s)/\*.*?\*/', '', code) - def interpret_statement(self, stmt, local_vars, allow_recursion=20): + def interpret_statement(self, stmt, local_vars, allow_recursion=100): if allow_recursion < 0: raise ExtractorError('Recursion limit reached') - if stmt.startswith('var '): - stmt = stmt[len('var '):] - ass_m = re.match(r'^(?P<out>[a-z]+)(?:\[(?P<index>[^\]]+)\])?' + - r'=(?P<expr>.*)$', stmt) - if ass_m: - if ass_m.groupdict().get('index'): - def assign(val): - lvar = local_vars[ass_m.group('out')] - idx = self.interpret_expression( - ass_m.group('index'), local_vars, allow_recursion) - assert isinstance(idx, int) - lvar[idx] = val - return val - expr = ass_m.group('expr') - else: - def assign(val): - local_vars[ass_m.group('out')] = val - return val - expr = ass_m.group('expr') - elif stmt.startswith('return '): - assign = lambda v: v - expr = stmt[len('return '):] + should_abort = False + stmt = stmt.lstrip() + stmt_m = re.match(r'var\s', stmt) + if stmt_m: + expr = stmt[len(stmt_m.group(0)):] else: - # Try interpreting it as an expression - expr = stmt - assign = lambda v: v + return_m = re.match(r'return(?:\s+|$)', stmt) + if return_m: + expr = stmt[len(return_m.group(0)):] + should_abort = True + else: + # Try interpreting it as an expression + expr = stmt v = self.interpret_expression(expr, local_vars, allow_recursion) - return assign(v) + return v, should_abort def interpret_expression(self, expr, local_vars, allow_recursion): + expr = expr.strip() + + if expr == '': # Empty expression + return None + + if expr.startswith('('): + parens_count = 0 + for m in re.finditer(r'[()]', expr): + if m.group(0) == '(': + parens_count += 1 + else: + parens_count -= 1 + if parens_count == 0: + sub_expr = expr[1:m.start()] + sub_result = self.interpret_expression( + sub_expr, local_vars, allow_recursion) + remaining_expr = expr[m.end():].strip() + if not remaining_expr: + return sub_result + else: + expr = json.dumps(sub_result) + remaining_expr + break + else: + raise ExtractorError('Premature end of parens in %r' % expr) + + for op, opfunc in _ASSIGN_OPERATORS: + m = re.match(r'''(?x) + (?P<out>%s)(?:\[(?P<index>[^\]]+?)\])? + \s*%s + (?P<expr>.*)$''' % (_NAME_RE, re.escape(op)), expr) + if not m: + continue + right_val = self.interpret_expression( + m.group('expr'), local_vars, allow_recursion - 1) + + if m.groupdict().get('index'): + lvar = local_vars[m.group('out')] + idx = self.interpret_expression( + m.group('index'), local_vars, allow_recursion) + assert isinstance(idx, int) + cur = lvar[idx] + val = opfunc(cur, right_val) + lvar[idx] = val + return val + else: + cur = local_vars.get(m.group('out')) + val = opfunc(cur, right_val) + local_vars[m.group('out')] = val + return val + if expr.isdigit(): return int(expr) - if expr.isalpha(): - return local_vars[expr] + var_m = re.match( + r'(?!if|return|true|false)(?P<name>%s)$' % _NAME_RE, + expr) + if var_m: + return local_vars[var_m.group('name')] try: return json.loads(expr) @@ -61,7 +124,7 @@ class JSInterpreter(object): pass m = re.match( - r'^(?P<var>[$a-zA-Z0-9_]+)\.(?P<member>[^(]+)(?:\(+(?P<args>[^()]*)\))?$', + r'(?P<var>%s)\.(?P<member>[^(]+)(?:\(+(?P<args>[^()]*)\))?$' % _NAME_RE, expr) if m: variable = m.group('var') @@ -114,23 +177,31 @@ class JSInterpreter(object): return obj[member](argvals) m = re.match( - r'^(?P<in>[a-z]+)\[(?P<idx>.+)\]$', expr) + r'(?P<in>%s)\[(?P<idx>.+)\]$' % _NAME_RE, expr) if m: val = local_vars[m.group('in')] idx = self.interpret_expression( m.group('idx'), local_vars, allow_recursion - 1) return val[idx] - m = re.match(r'^(?P<a>.+?)(?P<op>[%])(?P<b>.+?)$', expr) - if m: - a = self.interpret_expression( - m.group('a'), local_vars, allow_recursion) - b = self.interpret_expression( - m.group('b'), local_vars, allow_recursion) - return a % b + for op, opfunc in _OPERATORS: + m = re.match(r'(?P<x>.+?)%s(?P<y>.+)' % re.escape(op), expr) + if not m: + continue + x, abort = self.interpret_statement( + m.group('x'), local_vars, allow_recursion - 1) + if abort: + raise ExtractorError( + 'Premature left-side return of %s in %r' % (op, expr)) + y, abort = self.interpret_statement( + m.group('y'), local_vars, allow_recursion - 1) + if abort: + raise ExtractorError( + 'Premature right-side return of %s in %r' % (op, expr)) + return opfunc(x, y) m = re.match( - r'^(?P<func>[a-zA-Z$]+)\((?P<args>[a-z0-9,]+)\)$', expr) + r'^(?P<func>%s)\((?P<args>[a-zA-Z0-9_$,]+)\)$' % _NAME_RE, expr) if m: fname = m.group('func') argvals = tuple([ @@ -139,6 +210,7 @@ class JSInterpreter(object): if fname not in self._functions: self._functions[fname] = self.extract_function(fname) return self._functions[fname](argvals) + raise ExtractorError('Unsupported JS expression %r' % expr) def extract_object(self, objname): @@ -162,9 +234,11 @@ class JSInterpreter(object): def extract_function(self, funcname): func_m = re.search( - (r'(?:function %s|[{;]%s\s*=\s*function)' % ( - re.escape(funcname), re.escape(funcname))) + - r'\((?P<args>[a-z,]+)\){(?P<code>[^}]+)}', + r'''(?x) + (?:function\s+%s|[{;]%s\s*=\s*function)\s* + \((?P<args>[^)]*)\)\s* + \{(?P<code>[^}]+)\}''' % ( + re.escape(funcname), re.escape(funcname)), self.code) if func_m is None: raise ExtractorError('Could not find JS function %r' % funcname) @@ -172,10 +246,16 @@ class JSInterpreter(object): return self.build_function(argnames, func_m.group('code')) + def call_function(self, funcname, *args): + f = self.extract_function(funcname) + return f(args) + def build_function(self, argnames, code): def resf(args): local_vars = dict(zip(argnames, args)) for stmt in code.split(';'): - res = self.interpret_statement(stmt, local_vars) + res, abort = self.interpret_statement(stmt, local_vars) + if abort: + break return res return resf |