1 files changed, 184 insertions, 0 deletions
diff --git a/Lib/rexec.py b/Lib/rexec.py
new file mode 100644
index 0000000..0e6ba20
--- /dev/null
+++ b/Lib/rexec.py
@@ -0,0 +1,184 @@
+# Implement restricted execution of Python code
+
+import __builtin__
+import new
+import os
+import sys
+import types
+
+def trace(fmt, *args):
+	if 0:
+		sys.stderr.write(fmt % args + '\n')
+
+def copydict(src, dst, exceptions = [], only = None):
+	if only is None:
+		for key in src.keys():
+			if key not in exceptions:
+				dst[key] = src[key]
+	else:
+		for key in only:
+			dst[key] = src[key]
+
+def copymodule(src, dst, exceptions = [], only = None):
+	copydict(src.__dict__, dst.__dict__, exceptions, only)
+
+safe_path = ['/ufs/guido/lib/python']
+safe_modules = ['array', 'math', 'regex', 'strop', 'time']
+unsafe_builtin_names = ['open', 'reload', '__import__',
+			'eval', 'execfile', 'dir', 'vars',
+			'raw_input', 'input']
+safe_posix_names = ['error', 'fstat', 'listdir', 'lstat', 'readlink', 'stat',
+		    'times', 'uname', 'getpid', 'getppid', 'getcwd',
+		    'getuid', 'getgid', 'geteuid', 'getegid']
+
+safe_sys = new.module('sys')
+safe_sys.modules = {}
+safe_sys.modules['sys'] = safe_sys
+safe_sys.path = safe_path[:]
+safe_sys.argv = ['-']
+safe_sys.builtin_module_names = safe_modules[:] + ['posix']
+safe_sys.builtin_module_names.sort()
+safe_sys.copyright = sys.copyright
+safe_sys.version = sys.version + ' [restricted mode]'
+safe_sys.exit = sys.exit
+
+def new_module(name):
+	safe_sys.modules[name] = m = new.module(name)
+	return m
+
+safe_builtin = new_module('__builtin__')
+copymodule(__builtin__, safe_builtin, unsafe_builtin_names)
+
+safe_main = new_module('__main__')
+
+safe_posix = new_module('posix')
+import posix
+copymodule(posix, safe_posix, None, safe_posix_names)
+safe_posix.environ = {}
+copydict(posix.environ, safe_posix.environ)
+
+safe_types = new_module('types')
+copymodule(types, safe_types)
+
+def safe_import(name):
+	if safe_sys.modules.has_key(name):
+		return safe_sys.modules[name]
+	if name in safe_modules:
+		temp = {}
+		exec "import "+name in temp
+		m = new_module(name)
+		copymodule(temp[name], m)
+		return m
+	for dirname in safe_path:
+		filename = os.path.join(dirname, name + '.py')
+		try:
+			f = open(filename, 'r')
+			f.close()
+		except IOError:
+			continue
+		m = new_module(name)
+		rexecfile(filename, m.__dict__)
+		return m
+	raise ImportError, name
+safe_builtin.__import__ = safe_import
+
+def safe_open(file, mode = 'r'):
+	if type(file) != types.StringType or type(mode) != types.StringType:
+		raise TypeError, 'open argument(s) must be string(s)'
+	if mode not in ('r', 'rb'):
+		raise IOError, 'open for writing not allowed'
+	if '/' in file:
+		raise IOError, 'open pathname not allowed'
+	return open(file, mode)
+safe_builtin.open = safe_open
+
+def safe_dir(object = safe_main):
+	keys = object.__dict__.keys()
+	keys.sort()
+	return keys
+safe_builtin.dir = safe_dir
+
+def safe_vars(object = safe_main):
+	keys = safe_dir(object)
+	dict = {}
+	copydict(object.__dict__, dict, None, keys)
+	return dict
+safe_builtin.vars = safe_vars
+
+
+def exterior():
+	"""Return env of caller's caller, as triple: (name, locals, globals).
+
+	Name will be None if env is __main__, and locals will be None if same
+	as globals, ie local env is global env."""
+
+	import sys, __main__
+
+	bogus = 'bogus'			# A locally usable exception
+	try: raise bogus		# Force an exception
+	except bogus:
+		at = sys.exc_traceback.tb_frame.f_back # The external frame.
+		if at.f_back: at = at.f_back # And further, if any.
+		where, globals, locals = at.f_code, at.f_globals, at.f_locals
+		if locals == globals:	# Exterior is global?
+			locals = None
+		if where:
+			where = where.co_name
+		return (where, locals, globals)
+
+
+def rexec(str, globals = None, locals = None):
+	trace('rexec(%s, ...)', `str`)
+	if globals is None:
+		globals = locals = exterior()[2]
+	elif locals is None:
+		locals = globals
+	globals['__builtins__'] = safe_builtin.__dict__
+	safe_sys.stdout = sys.stdout
+	safe_sys.stderr = sys.stderr
+	exec str in globals, locals
+
+def rexecfile(file, globals = None, locals = None):
+	trace('rexecfile(%s, ...)', `file`)
+	if globals is None:
+		globals = locals = exterior()[2]
+	elif locals is None:
+		locals = globals
+	globals['__builtins__'] = safe_builtin.__dict__
+	safe_sys.stdout = sys.stdout
+	safe_sys.stderr = sys.stderr
+	return execfile(file, globals, locals)
+
+def reval(str, globals = None, locals = None):
+	trace('reval(%s, ...)', `str`)
+	if globals is None:
+		globals = locals = exterior()[2]
+	elif locals is None:
+		locals = globals
+	globals['__builtins__'] = safe_builtin.__dict__
+	safe_sys.stdout = sys.stdout
+	safe_sys.stderr = sys.stderr
+	return eval(str, globals, locals)
+safe_builtin.eval = reval
+
+
+def test():
+	import traceback
+	g = {}
+	while 1:
+		try:
+			s = raw_input('--> ')
+		except EOFError:
+			break
+		try:
+			try:
+				c = compile(s, '', 'eval')
+			except:
+				rexec(s, g)
+			else:
+				print reval(c, g)
+		except:
+			traceback.print_exc()
+
+if __name__ == '__main__':
+	test()