jython-dev

[Jython-dev] jythonc breaks "import random"

[Chris M. <ch...@bo...>]

My program works fine in jython, but I can't use jythonc to create an 
applet.

I narrowed the problem down to this line of python code:

    import random

The stack trace given when I try to run the applet is as follows (it's 
longer than that, but I'm trying to keep the message short).

 Java Traceback:

        at org.python.core.Py.JavaError(Py.java)
        at org.python.core.BytecodeLoader.makeCode(BytecodeLoader.java)
        at org.python.core.Py.compile_flags(Py.java)
        at org.python.core.Py.compile_flags(Py.java)
        at org.python.core.Py.compile_flags(Py.java)
        at org.python.core.__builtin__.eval(__builtin__.java)
        at org.python.core.__builtin__.eval(__builtin__.java)
        at java.lang.reflect.Method.invoke(Native Method)
        at 
org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java)
        at 
org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java)
        at org.python.core.PyObject.__call__(PyObject.java)
        at random$_PyInner._verify$1(random.java:377)
        at random$_PyInner.call_function(random.java:310)
        at org.python.core.PyTableCode.call(PyTableCode.java)
        at org.python.core.PyTableCode.call(PyTableCode.java)
        at org.python.core.PyFunction.__call__(PyFunction.java)
        at random$_PyInner.main$31(random.java:1029)
        at random$_PyInner.call_function(random.java:370)
        at org.python.core.PyTableCode.call(PyTableCode.java)
        at org.python.core.PyCode.call(PyCode.java)

    <snip>

So, it appears that the _verify method in the random module is doing an 
eval!  That's all well and good, but I don't have org.python.core.parser 
anywhere in my jar file.  Oops.

It turns out that adding that file doesn't help.  If I use the --all 
flag, I get this:
Java Traceback:

        at org.python.core.Py.JavaError(Py.java)
        at org.python.core.BytecodeLoader.makeCode(BytecodeLoader.java)
        at org.python.core.Py.compile_flags(Py.java)
        at org.python.core.Py.compile_flags(Py.java)
        at org.python.core.Py.compile_flags(Py.java)
        at org.python.core.__builtin__.eval(__builtin__.java)
        at org.python.core.__builtin__.eval(__builtin__.java)
        at java.lang.reflect.Method.invoke(Native Method)
        at 
org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java)
        at 
org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java)
        at org.python.core.PyObject.__call__(PyObject.java)
        at random$_PyInner._verify$1(random.java:377)

....

  File "/usr/local/jython-2.1a3/Lib/random.py", line 0, in main
  File "/usr/local/jython-2.1a3/Lib/random.py", line 0, in _verify
java.security.AccessControlException: access denied 
(java.lang.RuntimePermission createClassLoader)
        at 
java.security.AccessControlContext.checkPermission(AccessControlContext.java:272)
        at 
java.security.AccessController.checkPermission(AccessController.java:399)
        at 
java.lang.SecurityManager.checkPermission(SecurityManager.java:545)
        at 
java.lang.SecurityManager.checkCreateClassLoader(SecurityManager.java:610)   

        at java.lang.ClassLoader.<init>(ClassLoader.java:234)
        at org.python.core.BytecodeLoader1.<init>(BytecodeLoader1.java)
        at org.python.core.BytecodeLoader.makeLoader(BytecodeLoader.java)
        at org.python.core.BytecodeLoader.makeClass(BytecodeLoader.java)
        at org.python.core.BytecodeLoader.makeCode(BytecodeLoader.java)
        at org.python.core.Py.compile_flags(Py.java)
        at org.python.core.Py.compile_flags(Py.java)
        at org.python.core.Py.compile_flags(Py.java)

etc, etc.

So, I tried not importing random at all, but rather doing a simple eval:

print eval("1 + 1")

Again, I am required to use --all (which kind of makes sense), and 
again, I get an AccessControlException just like above.

Does this mean that I can't use eval or any module that uses eval in my 
applets?

C

Re: [Jython-dev] jythonc breaks "import random"

[<bc...@wo...>]

[Chris Monson]

>My program works fine in jython, but I can't use jythonc to create an 
>applet.
>
>I narrowed the problem down to this line of python code:
>
>    import random
>
>The stack trace given when I try to run the applet is as follows (it's 
>longer than that, but I'm trying to keep the message short).
>
> Java Traceback:
>
>        at org.python.core.__builtin__.eval(__builtin__.java)
>...
>        at random$_PyInner._verify$1(random.java:377)
>
>    <snip>
>
>So, it appears that the _verify method in the random module is doing an 
>eval!

Indeed. Rather thoughless bit of code there. I suggest you edit your
copy of random.py to have an empty _verify() function:

def _verify(name, expected):
    pass

I have posted a patch to CPython and will include a version of random.py
in 2.1b1 that does not use eval().

>That's all well and good, but I don't have org.python.core.parser 
>anywhere in my jar file.  Oops.
>
>It turns out that adding that file doesn't help.  If I use the --all 
>flag, I get this:
>Java Traceback:
>
>java.security.AccessControlException: access denied 

Using --all with applets is a topic for a different post.

>So, I tried not importing random at all, but rather doing a simple eval:
>
>print eval("1 + 1")
>
>Again, I am required to use --all (which kind of makes sense), and 
>again, I get an AccessControlException just like above.
>
>Does this mean that I can't use eval or any module that uses eval in my 
>applets?

Correct, you can't use eval() or compile() in a restricted environment
such as applets.

regards,
finn

Re: [Jython-dev] jythonc breaks "import random"

[Chris M. <ch...@bo...>]

Finn Bock wrote:

>[Chris Monson]
>
>>My program works fine in jython, but I can't use jythonc to create an 
>>applet.
>>
>>I narrowed the problem down to this line of python code:
>>
>>   import random
>>
>>The stack trace given when I try to run the applet is as follows (it's 
>>longer than that, but I'm trying to keep the message short).
>>
>>Java Traceback:
>>
>>       at org.python.core.__builtin__.eval(__builtin__.java)
>>...
>>       at random$_PyInner._verify$1(random.java:377)
>>
>>   <snip>
>>
>>So, it appears that the _verify method in the random module is doing an 
>>eval!
>>
>
>Indeed. Rather thoughless bit of code there. I suggest you edit your
>copy of random.py to have an empty _verify() function:
>
>def _verify(name, expected):
>    pass
>
>I have posted a patch to CPython and will include a version of random.py
>in 2.1b1 that does not use eval().
>
Thanks.  That worked (but, you knew it would...).  I was not certain 
that I could safely change that function in my own module, so I 
appreciate the help.

>>So, I tried not importing random at all, but rather doing a simple eval:
>>
>>print eval("1 + 1")
>>
>>Again, I am required to use --all (which kind of makes sense), and 
>>again, I get an AccessControlException just like above.
>>
>>Does this mean that I can't use eval or any module that uses eval in my 
>>applets?
>>
>
>Correct, you can't use eval() or compile() in a restricted environment
>such as applets.
>
I'll make the logical leap that says I can't do an 'exec' on uncompiled 
code, as well.

I was looking at that, and noticed that Jython is building java code 
from the dynamic code in the eval, which makes sense from a performance 
standpoint, but obviously breaks the applet security manager when it 
tries to compile and dynamically load it.

Is there any talk of allowing an option that would bundle the jython 
interpreter when compiling with jythonc, so that eval's, exec's, and 
compile's can be used in applets?  I believe that embedding the 
interpreter would allow for that, though I can't be certain without 
digging  into the source a bit more.

Anyway, it's a thought.  I'll be following the list more closely now and 
really spending some time in the Jython source.  Jython is an incredibly 
cool project, and I am interested in contributing where I can.

Thanks again for your help.

C

Re: [Jython-dev] jythonc breaks "import random"

[<bc...@wo...>]

>>[...] you can't use eval() or compile() in a restricted environment
>>such as applets.

[Chris Monson]

>I'll make the logical leap that says I can't do an 'exec' on uncompiled 
>code, as well.

Right.

>I was looking at that, and noticed that Jython is building java code 
>from the dynamic code in the eval, which makes sense from a performance 
>standpoint, but obviously breaks the applet security manager when it 
>tries to compile and dynamically load it.
>
>Is there any talk of allowing an option that would bundle the jython 
>interpreter when compiling with jythonc, 

The only 'interpreter' we have is the one that gets included when you
specify the --all option.

>so that eval's, exec's, and 
>compile's can be used in applets?  I believe that embedding the 
>interpreter would allow for that, though I can't be certain without 
>digging  into the source a bit more.

We would need a whole new subsystem that included a traditional
interpreter like CPython's ceval loop. And a whole new compiler that
creates whatever bytecode the interpreter is interpreting.

Yes, we have talked about it.

In Tools/jpythonc/PythonInterpreter.py is the beginning of an
interpreter that is running directly off the parse tree. That way we
don't need yet another compiler, but the result is likely slower than
python bytecode would be. PythonInterpreter is written by JimH and it is
some way away from being usefull.

regards,
finn