I have a compiled objective-C binary on iOS 8.1 which I am attempting to debug with lldb on my machine and debugserver on the handset. (No XCode involved- though I am willing to get it involved if that is the issue.)
Ida can correctly recognize the binary as objective-C and decompose objects and component messages. Because of this, I would expect commands like
platform select remote-ios
connect://ip:port
breakpoint set --name "-[Login doLoginStuff]"
to correctly function, but this method is called in code without breaking in lldb.
Is there the need for some type of target call to hint to the debugger what the remote architecture or SDK target is?
Without the symbols I don't believe lldb can map -[Login doLoginStuff] to a memory address. If it cant find the name it fails silently as far as I remember.
Related
This is the umpteenth time I've tried to create an AUv3 plugin, all with various amounts of success (no complete joy, ever :/ )
It works in the app, but auval fails with
Bad Max Frames - Render should fail
ERROR: AudioUnitRender should have returned an error for too many frames but returned noErr
Current OS: 10.13.5
XCode: 9.4
created an AUv3 MacOS Instrument by creating a Cocoa Objective C app
added an AudioUnit app extension
added a Cocoa framework
etc. Details supplied if needed. (I made notes about my steps since I've never completely succeeded previously.) It is essentially the same as the Demo MacOS AUv3 instrument but I started the project from scratch. The only swift code is in SimplePlayEngine.swift. The rest is Objective C, Objective C++, and straight-up C++.
The only web search hit I found on this problem is add arg to prepareInputBufferList but there are two problems with this link:
Applying the change doesn't fix my problem
The demo AUv3 instrument builds and passes auval validation on my system with no modification.
I don't know if this is related but I find that NO breakpoint I set in the audiounit or related files (BufferedAudioBus.hpp) is ever hit. Since the audiounit functions in the app I must assume that the code is getting executed but something about the way it was built is wrong. (NSLog messages don't get printed either ... ??? (yes I know that when realtime rendering, printing to the console is a bad idea)).
I diffed between my AU source and the demo AU and the only changes are name changes. The "Build Phases" are comparable.
I know this is a pretty non-specific question, but I've run out of ideas. Does anyone have any ideas where to look to resolve the "Bad Max Frames" auval failure?
I am doing iOS game development using the cocos2d framework, and I tremendously envy the ability for Eclipse Java programmers to hot swap their code while they are debugging their application (i.e. change out variable values within a method and have the program live update as if you had a REPL without having to recompile).
This seems like something that would be absolutely tremendously helpful when it came to iOS development, where my development environment is (obviously) Xcode and the language I am programming in is Objective C. I have googled around but havent been able to find anything - so I thought I would ask the community.
Does anyone know if there a way to Hot Swap code in Xcode while programming in Objective C?
Thanks in advance
There is a great plugin which allow changing code in live, working APP. It is called InjectionPlugin.
As FAQ says:
How does it work? The Objective-C runtime allows you to load a new version of a class into an application using a bundle even if there is already an implementation linked into the application. Swizzling is used as the bundle is loaded to switch the existing class to use the methods of the new implementation. This can be done repeatedly and works for OSX and iOS applications and on iOS devices.
I made some small video which shows how to install and use this plugin
http://nomtek.com/developers/how-to-install-and-use-injection-plugin-for-xcode/
Hope it helps!
Not possible with the current tools.
Keep in mind that iOS applications are signed -- if you change a single byte you'd have resign the whole thing. One could imagine making it work using runtime's support for dynamically adding and removing methods. But that'd surely require adding some extra stuff to support it on the device, and that's something that malware could easily take advantage of. So it's probably not a feature you'll be likely to see anytime soon.
By the way, Xcode versions 1.x-3.x did have a "Fix and Continue" feature. You could edit as you were debugging, use the Fix and Continue command, and continue running the updated code. I believe it was removed at some point, perhaps due to some combination of: requiring that your project be configured to use "zero link" and perhaps some other things; being less than completely reliable; probably not supporting iOS; the switch to llvm; other changes in Xcode 4. Maybe it'll come back someday -- if you want it back, file a bug -- but again, I think supporting it on iOS would be a challenge.
If you're just talking about changing variable values then you can achieve that surreptitiously via lldb (or, presumably) gdb. Supposing you had:
- (void)uselessMethod
{
NSString *localString = #"I'm some local text";
NSLog(#"%#", localString);
}
And put a breakpoint on the NSLog, at that point you could ask lldb to evaluate a reassignment of localString as a means of performing it. E.g.
po localString = #"Hat"
If you then allow program execution to continue, you should find that the reassignment has stuck. Similarly you can call any method or perform any other sort of assignment.
I've just tested this against Xcode 4.3.2.
You can hot swap a variable value in Xcode by:
expression <variable> = <value>;.
By having a break point in the place where you wanna change the value and doing the command in Xcode console.
Example:
// Messages From Console
(lldb) expression graphFlag = #"X"; // Update variable value
(__NSCFConstantString *) $0 = 0x36f95718 #"X" // Xcode prints the updated value
(lldb) expression graphFlag; // Printing value through expression command
(__NSCFConstantString *) $1 = 0x36f95718 #"X" // Hot Swapped variable value
I compile a DLL with mingw 4.5.0 and use it as a Game Maker 8.0 extension. Game Maker dynamically loads the dll. Everything appears to work (the dll functions are called and provide correct return values), but when I close Game Maker a dialog pops up: "Microsoft Visual C++ Runtime Library", "This application has requested the Runtime to terminate in an unusual way." After that, the process continues to linger in the background for a few seconds and then disappears.
This also happens when none of the functions of the dll are actually called. There is no DllMain, and all static/global variables are basic data types or std::string (it actually also happens when I remove the std::strings).
The dll statically links with zlib and libpng. The problem seems to vanish when I pass -static to the linker which (I assume) also links the runtime statically. However, this considerably inflates the size of my DLL, and it is at best a workaround until I understand what is going on.
Any ideas on what might be the cause?
Update: Actually, it seems that the problem only happens when two extensons are loaded in Game Maker: One with a dll linked with -static, and the other without. Linking both without -static makes the problem disappear. However, I still don't understand the problem, because the dlls never directly interact or share data structures.
Update 2: I recently found out that this might be related to strange behavior of Game Maker itself. It seems that global variables aren't initialized correctly when the DLL is loaded, which might cause a crash on unloading if global objects try to free memory they don't own. That would mean the -static was just a random factor that changed the value of the uninitialized memory the globals were associated with.
Update 3: Modified the above to include the info that this is about Game Maker extensions, since this is likely relevant as per Update 2.
It's just a guess. Try to look into something like the "static initialization order fiasco" that is described here. It may be that your problem is more related to the destructors (since it happens on close).
My application is experiencing cashes in production.
The crash dump indicates a SIGSEGV has occurred in GCTaskThread
It uses JNI, so there might be some source for memory corruption, although I can't be sure.
How can I debug this problem - I though of doing -XX:OnError... but i am not sure what will help me debug this.
Also, can some of you give a concrete example on how JNI code can crash GC with SIGSEGV
EDIT:
OS:SUSE Linux Enterprise Server 10 (x86_64)
vm_info: Java HotSpot(TM) 64-Bit Server VM (11.0-b15) for linux-amd64 JRE (1.6.0_10-b33), built on Sep 26 2008 01:10:29 by "java_re" with gcc 3.2.2 (SuSE Linux)
EDIT:
The issue stop occurring after we disable the hyper threading, any thoughts?
Errors in JNI code can occur in several ways:
The program crashes during execution of a native method (most common).
The program crashes some time after returning from the native method, often during GC (not so common).
Bad JNI code causes deadlocks shortly after returning from a native method (occasional).
If you think that you have a problem with the interaction between user-written native code and the JVM (that is, a JNI problem), you can run diagnostics that help you check the JNI transitions. to invoke these diagnostics; specify the -Xcheck:jni option when you start up the JVM.
The -Xcheck:jni option activates a set of wrapper functions around the JNI functions. The wrapper functions perform checks on the incoming parameters. These checks include:
Whether the call and the call that initialized JNI are on the same thread.
Whether the object parameters are valid objects.
Whether local or global references refer to valid objects.
Whether the type of a field matches the Get<Type>Field or Set<Type>Field call.
Whether static and nonstatic field IDs are valid.
Whether strings are valid and non-null.
Whether array elements are non-null.
The types on array elements.
Pls read the following links
http://publib.boulder.ibm.com/infocenter/javasdk/v5r0/index.jsp?topic=/com.ibm.java.doc.diagnostics.50/html/jni_debug.html
http://www.oracle.com/technetwork/java/javase/clopts-139448.html#gbmtq
Use valgrind. This sounds like a memory corruption. The output will be verbose but try to isolate the report to the JNI library if its possible.
Since the faulty thread seems to be GCTaskThread, did you try enabling verbose:gc and analyzing the output (preferably using a graphical tool like samurai, etc.)? Are you able to isolate a specific lib after examining the hs_err file?
Also, can you please provide more information on what causes the issue and if it is easily reproducible?
I'd like to know if there is a way to mix C# and Obj-C code in one project. Specifically, I'd like to use Cocos2D for my UI in Obj-C and call some MonoTouch C#-Library that does some computations and get some values back. Is there a way to do this? Or maybe the other way around, i. e. building in MonoTouch and calling Cocos2D-functions?
Thanks.
The setup that you describe is possible, but the pipeline is not as smooth as it is when you do your entire project in MonoTouch. This is in fact how we bootstrapped MonoTouch: we took an existing Objective-C sample and we then replaced the bits one by one with managed code.
We dropped those samples as they bitrot.
But you can still get this done, use the mtouch's --xcode command line option to generate a sample program for you, and then copy the bits that you want from the generated template.m into your main.m. Customize the components that you want, and just start the XCode project from there.
During your development cycle, you will continue to use mtouch --xcode
Re: unknown (google):
We actually did this as described.
See this page for a quick start, but the last code segment on that page is wrong, because it's omitting the "--xcode"-parameter.
http://monotouch.net/Documentation/XCode
What you have to do to embed your Mono-EXE/DLL into an Objective-C program is to compile your source with SharpDevelop, then run mtouch with these parameters:
/Developer/MonoTouch/usr/bin/mtouch --linksdkonly --xcode=output_dir MyMonoAssembly.exe
This only works with the full version of MonoTouch. The trial does not allow to use the "--xcode"-argument . The "--linksdkonly"-argument is needed if you want mtouch to keep unreferenced classes in the compiled output, otherwise it strips unused code.
Then mtouch compiles your assembly into native ARM-code (file extension .s) and also generates a XCode template which loads the Mono-Runtime and your code inside the XCode/ObjC-program. You can now use this template right away and include your Obj-C-code or extract the runtime loading code from the "main.m"-file and insert it into your existing XCode-project. If you use an existing project you also have to copy all .exe/.dll/.s files from the xcode-output-dir that mtouch made.
Now you have your Mono-Runtime and assembly loaded in an XCode-project. To communicate with your assembly, you have to use the Mono-Embedding-API (not part of MonoTouch, but Mono). These are C-style API calls. For a good introduction see this page.
Also the Mono-Embedding-API documentation might be helpful.
What you have to do now in your Obj-C-code is to make Embedding-API calls. These steps might involve: Get the application domain, get the assembly, get the image of the assembly, locate the class you want to use, instantiate an object from that class, find methods in class, call methods on object, encapsulate method arguments in C-arrays and pass them to the method-call, get and extract method return values.
There are examples for this on the embedding-api-doc-page above.
You just have to be careful with memory consumption of your library, as the mono runtime takes some memory as well.
So this is the way from Obj-C to C#. If you want to make calls from C#/Mono into your Obj-C-program, you have to use the MonoTouch-bindings, which are described here.
You could also use pure C-method calls from the embedding/P/Invoke-API.
Hope this gets you started.
Over the weekend it emerged that someone has been porting Cocos2D to .NET, so you could also do the whole work on .NET:
http://github.com/city41/CocosNet
Cocos2D started as a Python project, that later got ported to Objective-C, and now there is an active effort to bring it to C#. It is not finished, but the author is accepting patches and might be a better way forward.
Calling Objective-C from MonoTouch definitely looks possible. See the Objective-C selector examples
What library are you calling? Perhaps there's an Objective-C equivalent.