track custom youtube-dl distribution

1 files changed, 262 insertions, 0 deletions

diff --git a/youtube_dl/jsinterp.py b/youtube_dl/jsinterp.py
new file mode 100644
index 0000000..7bda596
--- /dev/null
+++ b/youtube_dl/jsinterp.py
@@ -0,0 +1,262 @@
+from __future__ import unicode_literals
+
+import json
+import operator
+import re
+
+from .utils import (
+    ExtractorError,
+    remove_quotes,
+)
+
+_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<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<var>%s)(?:\.(?P<member>[^(]+)|\[(?P<member2>[^]]+)\])\s*(?:\(+(?P<args>[^()]*)\))?$' % _NAME_RE,
+            expr)
+        if m:
+            variable = m.group('var')
+            member = remove_quotes(m.group('member') or m.group('member2'))
+            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)
+
+        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 len(m.group('args')) > 0 else tuple()
+            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):
+        _FUNC_NAME_RE = r'''(?:[a-zA-Z$0-9]+|"[a-zA-Z$0-9]+"|'[a-zA-Z$0-9]+')'''
+        obj = {}
+        obj_m = re.search(
+            r'''(?x)
+                (?<!this\.)%s\s*=\s*{\s*
+                    (?P<fields>(%s\s*:\s*function\s*\(.*?\)\s*{.*?}(?:,\s*)?)*)
+                }\s*;
+            ''' % (re.escape(objname), _FUNC_NAME_RE),
+            self.code)
+        fields = obj_m.group('fields')
+        # Currently, it only supports function definitions
+        fields_m = re.finditer(
+            r'''(?x)
+                (?P<key>%s)\s*:\s*function\s*\((?P<args>[a-z,]+)\){(?P<code>[^}]+)}
+            ''' % _FUNC_NAME_RE,
+            fields)
+        for f in fields_m:
+            argnames = f.group('args').split(',')
+            obj[remove_quotes(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*=\s*function|var\s+%s\s*=\s*function)\s*
+                \((?P<args>[^)]*)\)\s*
+                \{(?P<code>[^}]+)\}''' % (
+                re.escape(funcname), 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