I'm trying to update a software system to JDK-11 using modules, and everything was going just fine right up until I slammed head-on into the aforementioned issue.
I have a legacy signed JAR that I need to incorporate for interaction with legacy systems. There's no way to update the JAR and no way to get a new version. The JAR must be signed in order to be usable (the whole "trusted code" deal and whatnot). The problem is that the JAR contains classes in the unnamed (root) package. Yeah. Stupid. Bad practice. Blablabla. It's still there, and I still need to use it.
I've not found any documentation or answers anywhere that would remotely suggest that what I need is possible. In fact, the opposite is true: everyone is adamant that in the "new"(ish) module system, no class may reside in the unnamed package.
Needless to say I'm unable to both modify the contents of the JAR, or get at the sources to render a new one - that's without even considering the issue of the signature...
That said: I refuse to believe the folks at Oracle would leave such a glaring oversight with regards to legacy code. As we all know, a lot of the time we have no choice but to use it for legitimate reasons, and we can't do anything to fix/update/refactor/etc... I would have hoped there was a mechanism added to the module system to support this, albeit for extreme cases only, etc...etc...
Disclaimer: I do fully understand why this isn't meant to be supported. What I'm having a hard time with is the lack of a workaround...
Thanks!
I've already tried:
creating a facade module that transitively adds the offending module (obviously no dice, same problem)
unpacking-and-repacking the module while temporarily disabling signature validation in a test env (fails because the class is apparently referenced within many other, properly-organized classes)
finding an updated module (no luck here, either)
beheading a chicken and roasting it over a pentagram while invoking the aid of ancient pagan gods (tasty, but didn't fix it)
curling up in a ball under my desk and weeping until execution succeeds (that's where I'm typing this from)...
Related
So, there is this cool package I've found but it leaves a lot to be desired. Since it made more sense to modify it, rather than build a new one myself, I changed the code in the corresponding source directory (C:\Users[my username].julia\v0.4[package name]\src). I made sure to modify not just the base.jl file, but also the [name of package].jl one so that there are no issues with dependencies or the new functions I added. I tried running the package several times to ensure that Julia doesn't spit out any errors or exceptions (the original package had some deprecated stuff, which I also remedied). Still, I fail to use the additional functionality of the package that I augmented. Any help would be greatly appreciated.
I'm using Julia ver 0.4.2, on a Windows 7 machine. As an IDE I use Notepad++. Thanks
I'm not exactly sure what you tried, but here's a guess as to what's going on: if you've already loaded the package in your julia session, edits to the source files won't take effect unless you explicitly reload the package. There are some good workflow tips here, and more explanation of the module system here.
However, for a newbie the easiest thing might be to quit julia and restart.
As far as making changes to a package, as Gnumic commented, your best approach is to make a branch and commit your changes there. Once you become convinced your changes represent an improvement, consider sharing your changes with the rest of the world.
I just finished skating around that infamous "cannot load main class start" thing, and I got blindsided with a sea of errors:
A friend suggests it might have something to do with com.google, but ultimately can't help me.
I haven't made a single alteration to any of the code so far. Eclipse just started up not being able to run and stayed that way. I think there's a way to fix it but it would require making acute changes at the sight of every single error; work that could be wiped by a cleanup if I'm proved wrong.
Anyone have a clue what the issue is? Thank you for the trouble.
UPDATE: Adding guava as a library relieved the error involving com.google, but threw in a handful of others. This one class file contains 3 of the most common unresolved types I've seen scattered throughout: Logger/LogManagaer, PropertyMap, and CrashReport
Your general problems revolve around not having dependencies in the build path. Eclipse's error messages are pretty clear about this; e.g. if a package name is underlined in red and can't be found, then that means it can't be found, and the obvious solution is to add the library that provides it, so that it can be found.
In virtually all cases here, a Google search for the missing packages and classes will lead you to the packages that contain it.
For each unresolved dependency, find the library, add it to the build path, then move on.
I also suggest consulting the documentation that comes with the source code you are attempting to compile, which often simply lists the dependencies, thus saving you the trouble of hunting them down as you go.
While we could do the internet searches for you and hash this out one step at a time, it's both better and faster for you to do it yourself. Better because if you're messing around with Minecraft source, having at least a basic knowledge of how your tools work is going to help you (I also suggest some of the material at http://docs.oracle.com/javase/tutorial/). Faster because the turnaround time of typing package names into the Google search box is a heck of a lot faster than constantly updating your question here and waiting for replies.
It looks like you are missing the Google Collections package, which now is called Guava.
Download the jar file, and add it as a library.
this is my first post, and it covers something which I've been trying to get working on and off for about a year now.
Essentially it boils down to the following: I have a copy of newlib which I'm trying to get working on an LPC2388 (an ARM7TDMI from NXP). This is on a linux box using arm-elf-gcc
The question I have is that I've been looking at a lot of the tutorials talking about porting newlib, and they all talk about the stubs (like exit, open, read/write, sbrk), and I have a pretty good idea of how to implement all of these functions. But where should I put them?
I have the newlib distribution from sources.redhat.com/pub/newlib/newlib-1.18.0.tar.gz and after poking around I found "syscalls.c" (in newlib-1.18.0/newlib/libc/sys/arm) which contains all of the stubs which I have to update, but they're all filled in with rather finished looking code (which does NOT seem to work without the crt0.S, which itself does not work with my chip).
Should I just be wiping out those functions myself, and re-writing them? Or should I write them somewhere else. Should I make a whole new folder in newlib/libc/sys with the name of my "architecture" and change the target to match?
I'm also curious if there's proper etiquette on distribution of something like this after releasing it as an open source project. I currently have a script which downloads binutils, arm-elf-gcc, newlib, and gdb, and compiles them. If I am modifying files which are in the newlib directory, should I hand a patch which my script auto-applies? Or should I add the modified newlib to the repository?
Thanks for bothering to read! Following this is a more detailed breakdown of what I'm doing.
For those who want/need more info about my setup:
I'm building a ARM videogame console based loosely on the Uzebox project ( http://belogic.com/uzebox/ ).
I've been doing all sorts of things pulling from a lot of different resources as I try and figure it out. You can read about the start of my adventures here (sparkfun forums, no one responds as I figure it out on my own): forum.sparkfun.com/viewtopic.php?f=11&t=22072
I followed all of this by reading through the Stackoverflow questions about porting newlib and saw a few of the different tutorials (like wiki.osdev.org/Porting_Newlib ) but they also suffer from telling me to implements stubs without mentioning where, who, what, when, or how!
But where should I put them?
You can put them where you like, so long as they exist in the final link. You might incorporate them in the libc library itself, or you might keep that generic, and have the syscalls as a separate target specific object file or library.
You may need to create your own target specific crt0.s and assemble and link it for your target.
A good tutorial by Miro Samek of Quantum Leaps on getting GNU/ARM development up and running is available here. The examples are based on an Atmel AT91 part so you will need to know a little about your NXP device to adapt the start-up code.
A ready made Newlib porting layer for LPC2xxx was available here, but the links ot teh files appear to be broken. The same porting layer is used in Martin Thomas' WinARM project. This is a Windows port of GNU ARM GCC, but the examples included in it are target specific not host specific.
You should only need to modify the porting layer on Newlib, and since it is target and application specific, you need not (in fact probably should not) submit your code to the project.
When I was using newlib that is exactly what I did, blew away crt0.s, syscalls.c and libcfunc.c. My personal preference was to link in the replacement for crt0.s and syscalls.c (rolled the few functions in libcfunc into the syscalls.c replacement) based on the embedded application.
I never had an interest in pushing any of that work back into the distro, so cannot help you there.
You are on the right path though, crt0.S and syscalls.c are where you want to work to customize for your target. Personally I was interested in a C library (and printf) and would primarily neuter all of the functions to return 0 or 1 or whatever it took to get the function to just work and not get in the way of linking, periodically making the file I/O functions operate on linked in data in rom/ram. Basically without replacing or modifying any other files in newlib I had a fair amount of success, so you are on the right path.
I mean, can I use the com.sun.org.apache (all subpackages) classes as I use they from org.apache (in any Apache lib)?
Will the OpenJDK maintain this package up to date with apache updates?
And the JDK7 will maintain this package?
Where can I find information about that?
It is a very bad idea to use it. Once upon a time, Sun took a copy of Xerces, chock full of bugs. They made some changes. Perhaps they subtracted some bugs. We know that there are many very serious bugs that they did not subtract.
And they renamed it to com.sun.... for one reason: to tell you not to use it. At any time, in any point release, in any patch, they can change those classes incompatibly or remove them.
Further, these classes may not be in IBM's copy of the JRE, or Apple's, or (haha) Microsoft's, or JRocket.
If you want Xerces, use Xerces. To find information about this, read the Xerces-j mailing list archive for many stern warnings from the Xerces developers about the version forked by Sun.
The fact that the classes are formally 'public' means nothing except that Sun needed to be able to new them from some other package.
Err I wouldn't, just based on the fact that they're internal classes and there is a risk of them changing over time. Use the org.apache classes instead.
No idea about the intentions with keeping them up to date, maybe try posting a message on the openjdk forum:
http://mail.openjdk.java.net/mailman/listinfo
My understanding is that this is a fork of the apache code. At one point they were the same, but no more. So you can't count on the same bug fixes being present in both versions.
If documentation for this package says that it is public, then it's OK to use.
Otherwise they can pool a floor underneath you when they decide not to support it in the future.
Usually, you should not rely on anything other than java and javax in JDK.
This is what I'm doing:
extract contents of my JRE's rt.jar
extract src.zip of my JDK (same version)
Now, if I copy Runtime.java from the extracted src folder and compile it using javac.exe without any modifications and then put it in the extracted rt folder to finally put everything back in a jar file using jar.exe, everything works as expected. The JRE runs fine.
However, if I make the slightest change to Runtime.java and compile it and put it in rt.jar, the JRE crashes whenever I attempt to start it. This is an example of a slight change that causes the silent crash:
/** Don't let anyone else instantiate this class */
private Runtime() {
System.out.println("This is a test.");
}
Instead of:
/** Don't let anyone else instantiate this class */
private Runtime() {}
Could anyone tell me why this is causing my JRE to crash?
Thanks in advance.
It's possible that System.out has not been initialised at the time that the Runtime() constructor runs. Usually console output is not considered a "slight" change, but at the wrong time it can invoke way too much stuff that may not be set up at all yet.
You're doing this all wrong. You can't distribute that modified JRE for a start, so it is only useful inside your organization . Install a SecurityManager and don't grant your codebase any of the RuntimePermissions you're trying to protect against.
#Tom - I advise you NOT to try to do this:
You cannot distribute the modified rt.jar file without violating the Sun binary license.
Even if you did, you would not be allowed to call it Java.
As you are finding, there are lots of complications that arise when you make changes, particularly when those changes might interfere with the JVM's behind the scenes initialization. And when things blow up during initialization, the JVM often cannot report the problem in an intelligible way.
If you do succeed in making the modified rt.jar work for one JRE, there is no guarantee that the same hacks will work for a different version.
Nobody in their right mind would knowingly use a modified JVM (especially one modified by a third-party) in a production app.
EDIT : judging from your other questions, I guess you are trying to reverse engineer or modify some third party Java application with a custom launcher. If you provided more information on what you were really trying to do, we might be able to suggest the right way to do it ... rather than using "desperate measures" such as modifying the JRE.
That's pretty strange, as I did the same trick with many classes in rt.jar in past.
Can you provide us with the crashed process output?