I want to selectively block and unblock usb devices based on their serial number. We can write kernel extensions to achieve the same. But this seems complicated and risky. So I would like to know is there any easy way to achieve the same in cocoa?
"Easy Way" most probably not; though there may be an alternative method to using a kext, it likely would not be the most sensible way of tackling the issue. You could block all usb devices quite easily, but this isn't what you're asking.
I'd advise you to write a kernel extension, which isn't as hard as you may think. If you've not written one before, I recommend you read this book, which is predominantly concerned with writing kernel extensions.
No. You basically need to write a kext to do this.
Related
I am interested in writing a small utility to modify all audio output on OS X. I essentially want to apply a certain effect to the sound systemwide and/or via individual applications (similar to how Prosoft Hear operates).
Where would I start digging in order to accomplish this? Is this done through CoreAudio or are there other more direct option?
Core Audio plugins can achieve all sorts of things, those are probably your best bet. I notice you used the kext tag - it's of course possible to do this in the kernel, but that seems overkill.
Would be usefull to see how things work but not sure on the legality of it
Most Mac apps are written using Cocoa in Objective-C; which, while it is a compiled language, means that there is a fair bit of information left over that could be used by a decompiler.
I'm not sure if there are a lot of decompilers out there that leverages this information, at least I haven't heard of any.
However, there are also another option; F-Script.
F-Script can be used to attach to an executable and explore its interfaces, while not as good as source, it can give you a pretty clear idea of how the executable is built, and how it operates.
As for the legality issue:
IANAL, but as far as I know, reverse-engineering for the purposes of compatibility is legal in many jurisdictions, and I can't imagine that decompiling an executable to look at its code is illegal, unless the specific EULA specifically prohibits it.
Edit: WRT Steam specifically, it is probably NOT written in Cocoa, but C# with some manner of .NET compatibility layer; and it's probably not a good place to start if you want to learn how to make applications for Mac OS X.
By far, the best Mac OS X disassembler I've used is Hopper available here:
http://www.hopperapp.com/
It will also convert the assembly to C pseudo code as best it can. It will generate code flow diagrams with blue lines (true blue, love it) for true and red for false paths.
It's The Mac OS reverse engineering tool. There are even Youtube videos that will show you how to use it.
If it's an open-source app, yes. Otherwise it's possible through decompilation but the output will be a real pain in the ass to look at. If you just want the protocols and the interfaces of categories and classes, have a look at class-dump.
I'm not aware of a nib decompiler.
Whether decompilation is legal: ask a lawyer. This may (and probably does) differ per jurisdiction.
Is it possible to view the source of a mac app?
Realistically, no. Sure, you might be a able to use a decompiler to get a peek, but the kind of output you'll get won't be easy to read. If you're asking this question, this route probably isn't going to be helpful to you.
Specifically interested in GUI and how the steam app for mac works
It's a good bet that it works about the same way that most other applications work. It might use custom controls to look different from a typical application that mostly uses the standard Cocoa controls. But underneath, just about any GUI application written for MacOS X will use the run loops, responder chain, and view hierarchy that Cocoa provide. The main exceptions would be applications that are built mostly using an alternate framework like OpenGL or WebKit.
Figure out what, specifically, the Steam application does that you'd like to do. Take a look at the tools that Cocoa provides to see if you can figure it out yourself; if not, ask about it here.
I am trying to port my screensaver from windows to mac and one of its features was reacting on system sound output. On windows it was easy using Direct Sound, but I can't find any example of capturing sound output on mac. Is it possible even possible without writing something like kernel extension? Using flash it is also very easy — it even gives computeSpectrum method to get raw data or even fft transformed data.
All programs that I have already found use Soundflower or their own kernel extension. But I don't think that asking to install separate program or using kernel extension is a good way.
One thing you can do, considering that Soundflower is open source, is take a look at how they did it. You can't copy & paste GPL code, but you can surely study the techniques used and create your own solution (point you in the right direction).
You won't find Apple being very helpful here. Sound capturing, in this manner, can be used for all kinds of nefarious purposes. I'm not even sure if Core Audio lets you do this without hacks. In any case, you have a working implementation of what you're trying to accomplish. I'd take advantage of it.
I'm not on my Mac right now, but I'm pretty sure that Quartz Composer has a patch for just this thing. Depending on what language you're writing your screen saver in, it may be fairly easy for you to port your code into a QC patch. Well... it probably won't be easy, but it may be doable.
I'm looking at options to access DVB data on OS X. Initially I want to support the EyeTV DTT USB device, but in the long-run I'd like to support a number of popular devices. The problem I have is that there is no standard way of controlling such devices.
All the applications I know of that use them either hide the driver code within the application (for example EyeTV itself, all it's drivers are implemented totally in userspace and are not accessible to external apps), or they use the seemingly defunkt MMInputFamily driver (no source code availible any more, author gone walkabouts).
I've done some research and found that a number of the devices I want to support are supported within the Linux DVB project. Further research indicates that some years ago there was an attempt to abstract the linux implementation so that it could potentially be recompiled on other platforms. The idea being that efforts to support devices should be pooled and the best way to do that would be to make the current open source implementation work on multiple platforms: it seems in the end to have amounted to little however.
The idea of compiling linux drivers against other *nix type platforms has also been taken up elsewhere with some success. The approach the author took is detailed on the page I linked, it seems potentially viable on OS X as well.
At any rate, there seem to be a number of options, but no clear winner:
Find the source code for the MMInputFamily driver, try to get it working on OS X 10.6 and add support for the devices I require, referrencing the linux source code for pointers. Problem: the source code is nowhere to be found, nor is the author. Additionally it seems the author might perhaps have gone down another route had he fully appreciated the previous efforts to port the linux drivers to OS X.
Attempt to port the linux drivers to OS X in a manner similar to the FreeBSD project I linked. Problem: this is very low-level work and work in this layer is not recommended by Apple if it can be avoided.
Write a driver with OS X's IOKit: this is the preferred method for implementing drivers but I would have to do everything from scratch, clearly not a small job.
If I could I would really like to use the Linux source code, but I'm unsure if such a thing is really viable. Does anyone have any advice or ideas on the best way to proceed with this task?
How can I inject USB device nodes into OSX (>= 10.5) such as you might be able for debugging USB handlers / writing new USB drivers?
I'm interested in this in order to handle non-USB devices using TokenD.
From what it looks like, I would have to tackle faking USB-device insertion and then create a PC/SC ifdHandler that would handle this fake device. (If anyone knows of any other way to inject a not-necessarily-device-backed TokenD, let me know!).
I'm guessing IOKit may be involved in this solution... as that is the underlying item I need to 'trick'.
IOKit is pretty much the only thing involved, and you'll have to get a good grip on how it works before more specific answers will make any sense. If Apple's documentation doesn't do it for you, Amit Singh's book should pick up a lot of the slack, even if it is a little bit dated.