3eff81fbf7
We need a proper lexer to be able to understand YouTube's code, which contains /* inside of strings. For now it's sufficient to just disable comment support altogether. Fixes #4976, fixes #4979, fixes #4980, fixes #4981, fixes #4982. Closes #4977.
259 lines
8.6 KiB
Python
259 lines
8.6 KiB
Python
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.truediv),
|
|
('*', 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_$0-9]*'
|
|
|
|
|
|
class JSInterpreter(object):
|
|
def __init__(self, code, objects=None):
|
|
if objects is None:
|
|
objects = {}
|
|
self.code = code
|
|
self._functions = {}
|
|
self._objects = objects
|
|
|
|
def interpret_statement(self, stmt, local_vars, allow_recursion=100):
|
|
if allow_recursion < 0:
|
|
raise ExtractorError('Recursion limit reached')
|
|
|
|
should_abort = False
|
|
stmt = stmt.lstrip()
|
|
stmt_m = re.match(r'var\s', stmt)
|
|
if stmt_m:
|
|
expr = stmt[len(stmt_m.group(0)):]
|
|
else:
|
|
return_m = re.match(r'return(?:\s+|$)', 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 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>.*)$''' % (_NAME_RE, re.escape(op)), expr)
|
|
if not m:
|
|
continue
|
|
right_val = self.interpret_expression(
|
|
m.group('expr'), local_vars, allow_recursion - 1)
|
|
|
|
if m.groupdict().get('index'):
|
|
lvar = local_vars[m.group('out')]
|
|
idx = self.interpret_expression(
|
|
m.group('index'), local_vars, allow_recursion)
|
|
assert isinstance(idx, int)
|
|
cur = lvar[idx]
|
|
val = opfunc(cur, right_val)
|
|
lvar[idx] = val
|
|
return val
|
|
else:
|
|
cur = local_vars.get(m.group('out'))
|
|
val = opfunc(cur, right_val)
|
|
local_vars[m.group('out')] = val
|
|
return val
|
|
|
|
if expr.isdigit():
|
|
return int(expr)
|
|
|
|
var_m = re.match(
|
|
r'(?!if|return|true|false)(?P<name>%s)$' % _NAME_RE,
|
|
expr)
|
|
if var_m:
|
|
return local_vars[var_m.group('name')]
|
|
|
|
try:
|
|
return json.loads(expr)
|
|
except ValueError:
|
|
pass
|
|
|
|
m = re.match(
|
|
r'(?P<var>%s)\.(?P<member>[^(]+)(?:\(+(?P<args>[^()]*)\))?$' % _NAME_RE,
|
|
expr)
|
|
if m:
|
|
variable = m.group('var')
|
|
member = m.group('member')
|
|
arg_str = m.group('args')
|
|
|
|
if variable in local_vars:
|
|
obj = local_vars[variable]
|
|
else:
|
|
if variable not in self._objects:
|
|
self._objects[variable] = self.extract_object(variable)
|
|
obj = self._objects[variable]
|
|
|
|
if arg_str is None:
|
|
# Member access
|
|
if member == 'length':
|
|
return len(obj)
|
|
return obj[member]
|
|
|
|
assert expr.endswith(')')
|
|
# Function call
|
|
if arg_str == '':
|
|
argvals = tuple()
|
|
else:
|
|
argvals = tuple([
|
|
self.interpret_expression(v, local_vars, allow_recursion)
|
|
for v in arg_str.split(',')])
|
|
|
|
if member == 'split':
|
|
assert argvals == ('',)
|
|
return list(obj)
|
|
if member == 'join':
|
|
assert len(argvals) == 1
|
|
return argvals[0].join(obj)
|
|
if member == 'reverse':
|
|
assert len(argvals) == 0
|
|
obj.reverse()
|
|
return obj
|
|
if member == 'slice':
|
|
assert len(argvals) == 1
|
|
return obj[argvals[0]:]
|
|
if member == 'splice':
|
|
assert isinstance(obj, list)
|
|
index, howMany = argvals
|
|
res = []
|
|
for i in range(index, min(index + howMany, len(obj))):
|
|
res.append(obj.pop(index))
|
|
return res
|
|
|
|
return obj[member](argvals)
|
|
|
|
m = re.match(
|
|
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]
|
|
|
|
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>%s)\((?P<args>[a-zA-Z0-9_$,]+)\)$' % _NAME_RE, expr)
|
|
if m:
|
|
fname = m.group('func')
|
|
argvals = tuple([
|
|
int(v) if v.isdigit() else local_vars[v]
|
|
for v in m.group('args').split(',')])
|
|
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):
|
|
obj = {}
|
|
obj_m = re.search(
|
|
(r'(?:var\s+)?%s\s*=\s*\{' % re.escape(objname)) +
|
|
r'\s*(?P<fields>([a-zA-Z$0-9]+\s*:\s*function\(.*?\)\s*\{.*?\})*)' +
|
|
r'\}\s*;',
|
|
self.code)
|
|
fields = obj_m.group('fields')
|
|
# Currently, it only supports function definitions
|
|
fields_m = re.finditer(
|
|
r'(?P<key>[a-zA-Z$0-9]+)\s*:\s*function'
|
|
r'\((?P<args>[a-z,]+)\){(?P<code>[^}]+)}',
|
|
fields)
|
|
for f in fields_m:
|
|
argnames = f.group('args').split(',')
|
|
obj[f.group('key')] = self.build_function(argnames, f.group('code'))
|
|
|
|
return obj
|
|
|
|
def extract_function(self, funcname):
|
|
func_m = re.search(
|
|
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)
|
|
argnames = func_m.group('args').split(',')
|
|
|
|
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, abort = self.interpret_statement(stmt, local_vars)
|
|
if abort:
|
|
break
|
|
return res
|
|
return resf
|