jython-users

[Jython-users] "Bad magic number" error

[Andrew K. <aku...@me...>]

I'm trying to build an applet with Jython 2.0 (it worked fine with
1.0something), and am getting a mysterious error from the resulting
JAR file.

Java Traceback:
	at org.python.core.Py.JavaError(Py.java:238)
	at org.python.core.Py.findClassEx(Py.java:620)
        ...
	at java.lang.Thread.run(Thread.java:484)
Traceback (innermost last):
  File "/home/akuchlin/src/mems/proto3/instrument/client/awt/MicroscopeApplet.py", line 0, in main
  File "/home/akuchlin/src/mems/proto3/instrument/client/awt/PyClient.py", line 0, in main
  File "/usr/local/jython-2.0/Lib/string.py", line 0, in main
java.lang.ClassFormatError: strop (Bad magic number)

(Full traceback below, in case that information is useful.)
Inspecting the JAR file finds that strop.class isn't in it, but
string.py should surely get an ImportError and continue running.  The
same error occurs with both the Sun and IBM JVMs. Has anyone seen this
before?  Anyone got a clue about its cause?

--amk

Java Traceback:

	at org.python.core.Py.JavaError(Py.java:238)
	at org.python.core.Py.findClassEx(Py.java:620)
	at org.python.core.SysPackageManager.findClass(SysPackageManager.java:91)
	at org.python.core.PackageManager.findClass(PackageManager.java:19)
	at org.python.core.SysPackageManager.findClass(SysPackageManager.java:83)
	at org.python.core.PyJavaPackage.__findattr__(PyJavaPackage.java:128)
	at org.python.core.PackageManager.lookupName(PackageManager.java:96)
	at org.python.core.imp.load(imp.java:361)
	at org.python.core.imp.load(imp.java:376)
	at org.python.core.imp.importName(imp.java:447)
	at org.python.core.imp.importName(imp.java:509)
	at org.python.core.ImportFunction.load(__builtin__.java:967)
	at org.python.core.ImportFunction.__call__(__builtin__.java:961)
	at org.python.core.PyObject.__call__(PyObject.java:250)
	at org.python.core.__builtin__.__import__(__builtin__.java:921)
	at org.python.core.imp.importFromAs(imp.java:566)
	at string$_PyInner.main$27(string.java:724)
	at string$_PyInner.call_function(string.java:228)
	at org.python.core.PyTableCode.call(PyTableCode.java:155)
	at org.python.core.imp.createFromCode(imp.java:157)
	at org.python.core.imp.createFromClass(imp.java:178)
	at org.python.core.imp.loadPrecompiled(imp.java:246)
	at org.python.core.imp.loadFromPath(imp.java:257)
	at org.python.core.imp.loadFromPath(imp.java:252)
	at org.python.core.imp.load(imp.java:357)
	at org.python.core.imp.load(imp.java:376)
	at org.python.core.imp.importName(imp.java:447)
	at org.python.core.imp.importName(imp.java:509)
	at org.python.core.ImportFunction.load(__builtin__.java:967)
	at org.python.core.ImportFunction.__call__(__builtin__.java:961)
	at org.python.core.PyObject.__call__(PyObject.java:250)
	at org.python.core.__builtin__.__import__(__builtin__.java:921)
	at org.python.core.imp.importOne(imp.java:518)
	at PyClient$_PyInner.main$20(PyClient.java:736)
	at PyClient$_PyInner.call_function(PyClient.java:246)
	at org.python.core.PyTableCode.call(PyTableCode.java:155)
	at org.python.core.imp.createFromCode(imp.java:157)
	at org.python.core.imp.createFromClass(imp.java:178)
	at org.python.core.imp.loadPrecompiled(imp.java:246)
	at org.python.core.imp.loadFromPath(imp.java:257)
	at org.python.core.imp.loadFromPath(imp.java:252)
	at org.python.core.imp.load(imp.java:357)
	at org.python.core.imp.load(imp.java:376)
	at org.python.core.imp.importName(imp.java:447)
	at org.python.core.imp.importName(imp.java:509)
	at org.python.core.ImportFunction.load(__builtin__.java:967)
	at org.python.core.ImportFunction.__call__(__builtin__.java:961)
	at org.python.core.PyObject.__call__(PyObject.java:250)
	at org.python.core.__builtin__.__import__(__builtin__.java:921)
	at org.python.core.imp.importOne(imp.java:518)
	at MicroscopeApplet$_PyInner.main$6(MicroscopeApplet.java:111)
	at MicroscopeApplet$_PyInner.call_function(MicroscopeApplet.java:62)
	at org.python.core.PyTableCode.call(PyTableCode.java:155)
	at org.python.core.imp.createFromCode(imp.java:157)
	at org.python.core.Py.initProxy(Py.java:731)
	at MicroscopeApplet.<init>(MicroscopeApplet.java:247)
	at java.lang.Class.newInstance0(Native Method)
	at java.lang.Class.newInstance(Class.java:237)
	at sun.applet.AppletPanel.createApplet(AppletPanel.java:579)
	at sun.plugin.AppletViewer.createApplet(AppletViewer.java:1178)
	at sun.applet.AppletPanel.runLoader(AppletPanel.java:515)
	at sun.applet.AppletPanel.run(AppletPanel.java:293)
	at sun.plugin.navig.motif.MotifAppletViewer.maf_run(MotifAppletViewer.java:127)
	at sun.plugin.navig.motif.MotifAppletViewer.run(MotifAppletViewer.java:123)
	at java.lang.Thread.run(Thread.java:484)
Traceback (innermost last):
  File "/home/akuchlin/src/mems/proto3/instrument/client/awt/MicroscopeApplet.py", line 0, in main
  File "/home/akuchlin/src/mems/proto3/instrument/client/awt/PyClient.py", line 0, in main
  File "/usr/local/jython-2.0/Lib/string.py", line 0, in main
java.lang.ClassFormatError: strop (Bad magic number)

Re: [Jython-users] "Bad magic number" error

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

[Andrew Kuchling]

>I'm trying to build an applet with Jython 2.0 (it worked fine with
>1.0something), and am getting a mysterious error from the resulting
>JAR file.
>
>Java Traceback:
>	at org.python.core.Py.JavaError(Py.java:238)
>	at org.python.core.Py.findClassEx(Py.java:620)
>        ...
>	at java.lang.Thread.run(Thread.java:484)
>Traceback (innermost last):
>  File "/home/akuchlin/src/mems/proto3/instrument/client/awt/MicroscopeApplet.py", line 0, in main
>  File "/home/akuchlin/src/mems/proto3/instrument/client/awt/PyClient.py", line 0, in main
>  File "/usr/local/jython-2.0/Lib/string.py", line 0, in main
>java.lang.ClassFormatError: strop (Bad magic number)
>
>(Full traceback below, in case that information is useful.)
>Inspecting the JAR file finds that strop.class isn't in it, 

Are you completely sure. If I create a file called "strop.class" in my
cwd, I get the very same error:

[d:\]\jython\jython-2.0-jdk14\jython.bat -S
Jython 2.0 on java1.4.0-beta3 (JIT: null)
>>> import string
>>> ^Z


[d:\]\jython\jython-2.0-jdk14\jython.bat -S
Jython 2.0 on java1.4.0-beta3 (JIT: null)
>>> f = open("strop.class", "w")
>>> f.write("foobar")
>>> f.close()
>>> import string
Traceback (innermost last):
  File "<console>", line 1, in ?
  File "d:\jython\jython-2.0-jdk14\Lib\string.py", line 418, in ?
java.lang.ClassFormatError: strop (Bad magic number)
        at java.lang.ClassLoader.defineClass0(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:512)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:441)


>but string.py should surely get an ImportError and continue running.

Well yeah, but we have had huge problems in previous situation when we
did catch java exceptions during import and tried to turn it into a
python exception.

And this is after all a java error, and as Javasoft say:

"""An Error is a subclass of Throwable that indicates serious problems
that a reasonable application should not try to catch. Most such errors
are abnormal conditions."""

>The
>same error occurs with both the Sun and IBM JVMs. Has anyone seen this
>before?  Anyone got a clue about its cause?

Only that some old broken strop.class file is laying around somewhere on
your CLASSPATH. Maybe it is in org/python/modules where the original
strop.java was.

regards,
finn

Re: [Jython-users] "Bad magic number" error

[Andrew K. <aku...@me...>]

On Tue, Dec 18, 2001 at 01:36:21PM +0000, Finn Bock wrote:
>Are you completely sure. If I create a file called "strop.class" in my
>cwd, I get the very same error:

Pretty sure:

ute awt>jar -t <microscope.jar |grep str
string.class
string$_PyInner.class
org/python/core/PyReflectedConstructor.class
ute awt>

Hmm... the problem might be due to the bug described at
http://developer.java.sun.com/developer/bugParade/bugs/4196224.html;
the JDK doesn't find a .class file in the JAR, tries to download it
using HTTP, doesn't find it, and reports the 'bad magic number' error.
That explains why it only shows up when running as an applet.
(However, it also shows up with IBM's 1.3 JDK; oh dear...)

A workaround is to edit string.py to not try importing strop.  Maybe
string.py should only try to import strop in CPython.

--amk