Database Develop

[Q] how to hook an overloaded method

I want to develop a permission manage program.
but how can i hook the method startActivity?
it has
startActivity(Intent)
startActivity(Intent,Bundle)
startActivityForResult(Intent,int)
startActivityFromChild(Activity,Intent)
.....
and other overload method.
which one should i hook?
if I hook all the methods,when startAcitivyt(Intent) is called, and all the methods are called too.
but if I only hook startActivity(Intent), when the startAcivity(Intent,Bundle) is called,i will not catch it.
please help me.thanks.

Look at the source code, startActivity(Intent) will call startActivity(Intent, Bundle) so you only need to hook the latter. This may vary between different Android versions so you'll also want to check that.
In general you can also define a hook then use that for multiple methods. For example:
Code:
ZC_MethodHook hook = new XC_MethodHook(...);
findAndHookMethod (someClass, "someMethod", Argument.class, AnotherArgument.class, hook);
"someMethod", Argument.class, hook);

GermainZ said:
Look at the source code, startActivity(Intent) will call startActivity(Intent, Bundle) so you only need to hook the latter. This may vary between different Android versions so you'll also want to check that.
In general you can also define a hook then use that for multiple methods. For example:
Code:
ZC_MethodHook hook = new XC_MethodHook(...);
findAndHookMethod (someClass, "someMethod", Argument.class, AnotherArgument.class, hook);
"someMethod", Argument.class, hook);
Click to expand...
Click to collapse
but there is a problem.
if the two methods are:
void methodA(){
//some code ..
methodA(0);
}
void methodA(int a){
//...
}
if i hook methodA(int) and prevent it from running. when methodA() is called, the "some code" will execute,but then stop.

tonyzzp said:
but there is a problem.
if the two methods are:
void methodA(){
//some code ..
methodA(0);
}
void methodA(int a){
//...
}
if i hook methodA(int) and prevent it from running. when methodA() is called, the "some code" will execute,but then stop.
Click to expand...
Click to collapse
This isn't the case for startActivity - again, look at the source code.
I'm not sure what you're asking here, to be honest. Of course, you *can* hook both methods (or even all of them using hookAllMethods, but be careful about argument when you do that), but in startActivity's case that seems unnecessary.

[Q] Can Xposed hook native methods?

Letts assume there is a method
public static native boolean doSomething(params...);
which gets called by regular Java code.
Can Xposed hook it?

EDIT: I'm wrong, see rovo's answer.

Yes, native methods can be hooked. However, in case this is for an app's code, it has to be done after System.loadLibrary(), otherwise the latter overwrites the hook. Ideally, the framework should take care of this itself, but it's not straight-forward and the has been vey little need for this.

rovo89 said:
Yes, native methods can be hooked. However, in case this is for an app's code, it has to be done after System.loadLibrary(), otherwise the latter overwrites the hook. Ideally, the framework should take care of this itself, but it's not straight-forward and the has been vey little need for this.
Click to expand...
Click to collapse
I've always assumed this wasn't the case. Just to clarify, Xposed is able to hook native functions, but not (native) C/C++ code/libraries? I've read more than once it can't so I'm a bit confused. Thanks for the correction.

GermainZ said:
Just to clarify, Xposed is able to hook native functions, but not (native) C/C++ code/libraries?
Click to expand...
Click to collapse
Correct. Only JNI functions can be hooked, i.e. those which are declared in and called by Java code.

How to do it "after System.loadLibrary()"?

How you go about hooking such methods? I am trying to hook some API methods, mainly the ones declared in the "Connectivity" class one such example is "isTetheringSupported" however I am struggling to do so as when I hook the method directly, the hook is never executed as I believe it is being called via the java.lang.reflect.Method invoke method, and when I try and hook that method I get the following error "java.lang.NoSuchMethodError: java.lang.reflect.Method#invoke()#exact"

hwhh_1 said:
How you go about hooking such methods? I am trying to hook some API methods, mainly the ones declared in the "Connectivity" class one such example is "isTetheringSupported" however I am struggling to do so as when I hook the method directly, the hook is never executed as I believe it is being called via the java.lang.reflect.Method invoke method, and when I try and hook that method I get the following error "java.lang.NoSuchMethodError: java.lang.reflect.Method#invoke()#exact"
Click to expand...
Click to collapse
Are you talking about EdXposed? If so it should be noted that hook not working for a particular method can also be a result of art compiler optimizations. E.g. if the method is simple and not called from many places, compiler will include body of such method directly into methods that call that method. It's called inlining. So while you can see method at source code level, during runtime it's empty and never called as original body became part of another method. To overcome this you have to find a different strategy, e.g. hook such methods that are less likely to become inlined.

C3C076 said:
Are you talking about EdXposed? If so it should be noted that hook not working for a particular method can also be a result of art compiler optimizations. E.g. if the method is simple and not called from many places, compiler will include body of such method directly into methods that call that method. It's called inlining. So while you can see method at source code level, during runtime it's empty and never called as original body became part of another method. To overcome this you have to find a different strategy, e.g. hook such methods that are less likely to become inlined.
Click to expand...
Click to collapse
In order to see if it inlined, there is a setting in EDXPOSED to deoptimize boot image.

[Q] Hook existing DialogInterface.OnDismiss

I have a dialog that I am trying to get when its closed. I am able to get the object of the dialog itself and add my own setOnDismissListener but that overwrites the default one causing problems.
What I'm doing now is re-copying the code from the original DialogInterface.OnDismissListener into my own OnDismissListener.
However, because I'm lazy, how, if possible, could I hook the existing OnDismissListener without hooking the DialogInterface class?

elesbb said:
I have a dialog that I am trying to get when its closed. I am able to get the object of the dialog itself and add my own setOnDismissListener but that overwrites the default one causing problems.
What I'm doing now is re-copying the code from the original DialogInterface.OnDismissListener into my own OnDismissListener.
However, because I'm lazy, how, if possible, could I hook the existing OnDismissListener without hooking the DialogInterface class?
Click to expand...
Click to collapse
Can't you hook the existing OnDismissListener? Or do you want to avoid that because it's in an anonymous class?
I think the closest to what you want to do is hook DialogInterface when that dialog is shown, and unhook it when it's hidden. You'll still need to check the package in your hook, but only when necessary.

GermainZ said:
Can't you hook the existing OnDismissListener? Or do you want to avoid that because it's in an anonymous class?
I think the closest to what you want to do is hook DialogInterface when that dialog is shown, and unhook it when it's hidden. You'll still need to check the package in your hook, but only when necessary.
Click to expand...
Click to collapse
Well, DIalogInterface.OnDismissListener is an interface which I believe xposed cannot hook.
I really think I am looking for something that doesn't exist because I am being lazy
What I think I can do though is hook the "Dialog" class then hook the "setOnDismissListener" and steal the parameter that was sent to it and store it as an object in my xposed class. Then register my own onDismissListener, and execute what I need, then call the original saved method.... I think. Lol.

elesbb said:
Well, DIalogInterface.OnDismissListener is an interface which I believe xposed cannot hook.
I really think I am looking for something that doesn't exist because I am being lazy
What I think I can do though is hook the "Dialog" class then hook the "setOnDismissListener" and steal the parameter that was sent to it and store it as an object in my xposed class. Then register my own onDismissListener, and execute what I need, then call the original saved method.... I think. Lol.
Click to expand...
Click to collapse
Well it'll be an anonymous class so you could try hooking that (e.g. ClassName$1.onDismissListener or ClassName$2.onDismissListener).

GermainZ said:
Well it'll be an anonymous class so you could try hooking that (e.g. ClassName$1.onDismissListener or ClassName$2.onDismissListener).
Click to expand...
Click to collapse
Ohhh I see what you mean. Yeah I could hook that, I thought you meant the general DialogInterface.OnDismissListener. Doh. I'm dumb

GermainZ said:
Well it'll be an anonymous class so you could try hooking that (e.g. ClassName$1.onDismissListener or ClassName$2.onDismissListener).
Click to expand...
Click to collapse
I remember now why this wouldn't work. The anonymous class is named differently in each device depending on OS version. (IE Sense, TouchWiz, AOSP)
So I think what I have now is to hooke each anonymous class then try to hook the "onDismiss" method and have a catch to catch any errors. Then if it catches an exception, go to the next anonymous class and try again then repeat until it hooks.

[Q][Development] XSharedPreferences issue, no entries

For my Xposed Module Play Store Chagenlog an update was released yesterday, this added a GUI as wel as some options. There have been quite a few reports about settings preferences not being applied. After some debugging, I found out that this XSharedPreferences simply doesn't have any entries and thus always returns the default values. I'm 100% sure the options are set (the preferences screen shows them correct and you can see them in the .xml) and the right file is being loaded. There are no errors in the Xposed Log or in the logcat.
I've found a workaround (only tested by me), unchecking and re-checking an option and then the preferences are read correctly. All my modules (actually most of all Xposed Modules) use this way to load an user's preferences, I have absolutely no clue what's causing this behaviour.
The source code is on GitHub, links to relevant files:
PlayStoreChangelog.java
SettingsActivity.java
SettingsFragment.java
settings.xml
For debugging purposes, I've added a snippet to dump the preferences beneath initializing XSharedPreferences. This says it loads the right file, the file exists but it contains no entries (size 0). So when trying to get values (getString, getBoolean etc), it only returns the default values.
Java:
sharedPreferences = new XSharedPreferences(BuildConfig.APPLICATION_ID);
XposedBridge.log(LOG_TAG + sharedPreferences.getFile().getAbsolutePath() + " exists: " + sharedPreferences.getFile().exists());
XposedBridge.log(LOG_TAG + " ---PREFS: " + sharedPreferences.getAll().size() + "---");
Map<String, ?> sortedKeys = new TreeMap<String, Object>(sharedPreferences.getAll());
for (Map.Entry<String, ?> entry : sortedKeys.entrySet()) {
XposedBridge.log(LOG_TAG + entry.getKey() + "=" + entry.getValue().toString());
}
Summary
The app uses a PreferenceFragment to set the preferences and XSharedPreferences to load them. The changes are written to the .xml file and shown in the GUI. The XSharedPreferences instance remains empty and does not contain any entries, thus it always returns the default value. I don't get why it doesn't work, I don't even get why the 'workaround' does work.
I'd really appreciate any help, I'm stuck on this one. No idea what causes it and whether it's a but in my code or something else.
I hope I gave enough information. Thanks in advance.

I'm really stuck on this one, I haven't got a clue what causes this. Maybe @rovo89, @MohammadAG, @GermainZ or @defim, you guys are the most experienced Xposed developers out here. Thanks in advance!

Could something like `sharedPreferences.makeWorldReadable();` (probably needs to be in initZygote) solve your issue? I can't personally think of any reason this might happen except a permission issue.
(Also make sure you're using the latest Xposed Bridge API. I remember there were some commits related to XSharedPreferences, although I can't remember what they were exactly and can't check right now.)

Permission problem sounds reasonable. PSC has for its xml file only set 660, so world readable is mission. After changing it by command line Play Store starts as expected. But i've to say that i use in no app the makeWorldReadable(), Xposed should do it by itself: http://forum.xda-developers.com/showpost.php?p=41976845&postcount=1586 But I also dont use settings fragment, which could cause it...

GermainZ said:
Could something like `sharedPreferences.makeWorldReadable();` (probably needs to be in initZygote) solve your issue? I can't personally think of any reason this might happen except a permission issue.
(Also make sure you're using the latest Xposed Bridge API. I remember there were some commits related to XSharedPreferences, although I can't remember what they were exactly and can't check right now.)
Click to expand...
Click to collapse
defim said:
Permission problem sounds reasonable. PSC has for its xml file only set 660, so world readable is mission. After changing it by command line Play Store starts as expected. But i've to say that i use in no app the makeWorldReadable(), Xposed should do it by itself: http://forum.xda-developers.com/showpost.php?p=41976845&postcount=1586 But I also dont use settings fragment, which could cause it...
Click to expand...
Click to collapse
First of al, both thanks you for your response, it's highly appreciated.
I've been testing with permissions, it indeed looks like a permission problem, because makeWorldReadable() solved it. I use the following line the SettingsFragment to make it World Readable, which has always worked, even though Context.MODE_WORLD_READABLE is officially deprecated because if security reasons:
Java:
getPreferenceManager().setSharedPreferencesMode(Context.MODE_WORLD_READABLE);
It creates a file with 660 permissions, with makeWorldReadable in initZygote it sets it to 664. This is my initZygote:
Java:
@Override
public void initZygote(StartupParam startupParam) throws Throwable {
sharedPreferences = new XSharedPreferences(BuildConfig.APPLICATION_ID);
XposedBridge.log(LOG_TAG + "Readable before: " + sharedPreferences.getFile().canRead());
sharedPreferences.makeWorldReadable();
XposedBridge.log(LOG_TAG + "Readable after: " + sharedPreferences.getFile().canRead());
}
The weird thing is, both readable before and after return true, which indicates it has the permission to read the file before makeWorldReadable(). But... it doesn't work without it
In the end, I created a snippet in SettingsFragment to solve it where the problem arises, instead of makeWorldReadable():
Code:
File sharedPrefsDir = new File(getActivity().getFilesDir(), "../shared_prefs");
File sharedPrefsFile = new File(sharedPrefsDir, getPreferenceManager().getSharedPreferencesName() + ".xml");
if (sharedPrefsFile.exists()) {
sharedPrefsFile.setReadable(true, false);
}
This still needs setSharedPreferencesMode(Context.MODE_WORLD_READABLE), otherwise the permissions will be reset to 660 when a preference changes, now they stay 664. So basically al it does it make it readable for others in addition to the setSharedPreferenceMode().
Thanks again for your replies, it really helped. I still think it's weird, especially since File.canRead() returns true, while it obviously can't read it. I hope it'll help others in the future.

I think I use the deprecated SettingsActivity for this reason. I can override getSharedPreferences so it always returns a world readable file, this avoids the permissions resetting when a preference changes.
Sent from my HTC One_M8 using Tapatalk

MohammadAG said:
I think I use the deprecated SettingsActivity for this reason. I can override getSharedPreferences so it always returns a world readable file, this avoids the permissions resetting when a preference changes.
Sent from my HTC One_M8 using Tapatalk
Click to expand...
Click to collapse
Thanks for your response, just checked out one of your modules, saw you were using getPreferenceManager().setSharedPreferencesMode(MODE_WORLD_READABLE); too. (and indeed SettingsActivity). This has always been sufficient for me using PreferenceFragment. To be sure it's world readable I now manually set the permissions on onPause as a workaround. Still weird because it has always worked flawless for me.

P1nGu1n_ said:
Thanks for your response, just checked out one of your modules, saw you were using getPreferenceManager().setSharedPreferencesMode(MODE_WORLD_READABLE); too. (and indeed SettingsActivity). This has always been sufficient for me using PreferenceFragment. To be sure it's world readable I now manually set the permissions on onPause as a workaround. Still weird because it has always worked flawless for me.
Click to expand...
Click to collapse
Yeah, I also override getSharedPreferences in PreferenceActivity, that allows it to stay world readable.
Sent from my HTC One_M8 using Tapatalk

Sam code works for me in XInstaller. Try check it out, it is open source.

Be aware that using XSharedPreferences will probably lead to problems on Lollipop caused by more stringent SELinux rules.

M66B said:
Be aware that using XSharedPreferences will probably lead to problems on Lollipop caused by more stringent SELinux rules.
Click to expand...
Click to collapse
Good point, but it's too early to say. I'll wait for Xposed to be compatible (hope it will), than I'll look into what changes it'll require. That's something almost every Xposed developer will face ;p
Sent from my phone, please forgive any tpyos.

Yes, I think also Xposed should then handle with LOL XResources properly

Breaking XSharedPreferences means that *almost* every module is not going to work on Lollipop.

I also migrated my project to use PreferenceFragment and getPreferenceManager().setSharedPreferencesMode(Context.MODE_WORLD_READABLE) pretty much does nothing. After I change any setting, prefs file lose "world available" mode.

I checked out P1ngu1n_'s implementation using PreferenceFragment, but it still doesn't work for me. Do any of you have an idea why?
Here is my source
The only difference I can see is that I don't have an xml file for the preferences and that I'm adding the keys in the fragment.
I even checked the permissions and they seem to be fine.

asdfasdfvful said:
I checked out P1ngu1n_'s implementation using PreferenceFragment, but it still doesn't work for me. Do any of you have an idea why?
Here is my source
The only difference I can see is that I don't have an xml file for the preferences and that I'm adding the keys in the fragment.
I even checked the permissions and they seem to be fine.
Click to expand...
Click to collapse
If the permissions seem to be fine, than what doesn't work?

P1nGu1n_ said:
If the permissions seem to be fine, than what doesn't work?
Click to expand...
Click to collapse
That's what confuses me. I have the xml file under shared_prefs and it definitely has values. However, xposed won't read it unless I open the app itself.
Sent from my Nexus 5 using Tapatalk

[Q] Is Java native function unhookable?

I have used NDK development techs to create a simple Android App that connects remote server using socket.
The JNI method name is "public native static void doConnect(String ip,int port,String imei);"
While my attempt to hook it results in "java.lang.NoSuchMethodError"
Is Xposed not able to hook JNI functions?
PS: If there is a function hooked, how can I get the parameters it received?

XDAchushu10 said:
I have used NDK development techs to create a simple Android App that connects remote server using socket.
The JNI method name is "public native static void doConnect(String ip,int port,String imei);"
While my attempt to hook it results in "java.lang.NoSuchMethodError"
Is Xposed not able to hook JNI functions?
PS: If there is a function hooked, how can I get the parameters it received?
Click to expand...
Click to collapse
I've read this post: http://forum.xda-developers.com/xposed/creating-nfc-module-nosuchmethoderror-t2811440
The problem is that I didn't list the paramters in "findAndHookMethod".
And that's it! It's been solved.