Hi there, i'm new to developing Android Apps, so i have some questions.
1. I know that always have a chance of breaking security on computer world
2. Whats the most secure method to generate a UniqueID? because my app needs to work on china tablets, original tablets, cellphones, hacked phones, etc. I need this for verification of paid things (wait, xda will have a free version ;o)
3. There is any way to encript the program without affecting the performance too much? I'm new to java and comming from C++, so there is any compaction, encrypt, etc? Because if anybody knows the NEW IDA will come with android support.
4. There is any HTML parser on java? Because i need to fetch a html page with httpclient and after i need to parse it to get content... the contect is dynamic (html table with N rows), so i need a parser... or there is any other way?
5. I know how to make a tabed interface, but how is the best way to know the app state? Like it:
App Start -> User Already Logged (Save on SQLite?) ?
Yes = Display app interface and unlock config menu (here is the tabed interface)
No = Display login interface and lock config menu (here is just a relative layout with login bnts)
Thanks in advance.
1: Number one is not a question.
2: Do you mean most secure possible, or most secure practical? Those concerns should be addressed. Most secure would be to have a courier bring the user one-time-pads for every session, but that's not very practical. That said, what is the nature of your ID? Depending on what you are using it for, I would think a few randomly generated bits from some user entered entropy (like touchpad event timing) should suffice.
3: Again, what is the nature of your need for encryption? Do you want to keep it from being decompiled and analysed? If so, you're pretty much out of luck as there is always a way for a dedicated hacker to disassemble the code that does the decryption unless you use some sort of challenge-handshaking algorithm to load the keys at runtime for every session from some secure source but that requires connectivity and user interaction which necessarily complicates the process.
4: The XML parsers available as part of the Android SDK do a pretty good job of parsing HTML if it is clean compliant HTM> See, i.e. the Sax classes:
http://developer.android.com/reference/org/xml/sax/package-summary.html
5: You can use the API included preference classes to save state between sessions:
http://developer.android.com/reference/android/preference/package-summary.html
Note: for general application cryptography information, you still can't beat the venerated Applied Cryptography by Bruce Schneier.
Thanks for the answers.
I just wanna know how the most used programs like rom manager, power amp, titanium backup and whatsapp protect their paid versions, and how they validate it.
Another question that leaves on it is that some programs have a dedicated paid version, and some have just a key that you download and unlock the free version, how they did it? They just check if key is installed assuming that it was downloaded from market?
My uses is just for two reasons:
1.) protect my app as possible from newbie crackers
2.) transmit user information with a secure method to my server. Its important because my app will be used on open networks.
As for UniqueID generating, i just wanna a "unique world global super id" for each user of my app, and it will be installed on cellphones, tablets without phone, tv with android, and all of this.
Also, what to do if html is not well formated?
Related
Hi,
I asked this question over on another mobile phone forum and a user directed me here, so here goes:
Is it necessary for apps developed for Windows Mobile 5 and 6 (PPC) to be "signed" in any way in order to be installed and run? Similar to the way newer Symbian OS apps must be signed? Or can they just be developed and flat-out installed without any hassle or complication, the same way apps for regular desktop Windows PC's can be?
As a programmer/developer and also a Symbian user, I absolutely HATE the need for signing or certifying anything for it to be able to run. If it's not necessary on a laptop or desktop, it shouldn't be necessary on a phone. I am considering switching over from Symbian to WM6, but ONLY if the platform is completely free of the need for anything resembling certificates and signing.
At the very least, is there the option for the end WM6/5 user to easily change a setting within the OS so as to allow the full installation of non-signed apps? I'd settle for that. With Symbian, both developers and users are completely imprisoned by certificates and cannot do anything without the permission of the OS fascists.
Thanks for any help on this..
on WM5 default, when you try and uninstall something unsigned, you just have to tap the "yes" button to run the application, after that it remembers it for that app.
so basically for my setup (wm5/wm6) i can run anything, signed or unsigned. And there is a fix somewhere to disable the notification warning
hope that helps
and
come to the light side
Pocket PC's for the win
Thanks for your reply.. it's certainly encouraging to hear that WM5/6 is not restricted by the absolute necessity for signed certificates like Symbian is. As a programmer I completely refuse to bother developing software for a platform that handcuffs both developer and end user so mercilessly. If I can write programs in Visual Basic that will comple to an EXE and run hassle-free on any Windows PC, I don't see why I should have any less freedom when writing programs for a mobile device.
SymbianSigned and its locked OS is a deal-breaker for me. In looking through this forum though, it seems that there are in fact some components of WM that absolutely must be signed to be installed? Like skins for example? Are there any other components that fall into that category?
Still hoping to get a defnitive answer on what components of WM require mandatory signing and which ones are totally non-restrictive optional. So far my understanding is that under no circumstances do any applications ever have to be signed in order to be installed and run, no matter what kind of advanced access and functions they involve. Correct? Whereas fully integrated keyboard skins do need to be signed, for some reason. Correct?
Any other categories not covered above that do or don't require signing?
Thanks!
As far as I know the worse case scenario for signing is that you must also install your own cert. All that happens when you do this is again a warning.
As for the merits of the whole signing thing. Although I agree symbian goes too far, I think some kind of signing procedure, that is more robust should be required for windows mobile.
My preferred solution would be to have restricted functions that on install warn the user of exactly what capabilities the SW has, and allows the user to allow or restrict certain capabilities.
Simply an I trust this or that is useless as everyone ends up trusting everything as you have little choice. But given that it is easy to write SW using the RIL functions that completely unknown to the user can call expensive pay lines, download ridiculous amounts of data over gprs, or even send me personal information from your device, some security should definitely be required.
The truth is because of the ability to make expensive phone calls directly to people who will have direct financial benefit, I would argue security for a phone is at least if not more important than on the PC.
my 2 cents
WM5/WM6 editions for touch-screen devices generally come with "relaxed" security which means that third party apps don't have to be signed to execute once somebody answers yes to a first-time warning dialog box. ROM cookers here generally relax this requirement even more by setting a registry value HKLM\Security\Policies\Policies\0000101A to a 1. This disables the first-time warning message also.
However, services and device drivers generally need to be signed because they are executed before these relaxed settings take effect. Application developers generally can work around this too by starting the service/device driver themselves with a little program placed in \windows\startup
WM6/WM5 editions for devices without touch-screens generally have a higher security setting that disallows execution of any application unless it is signed.
Hi all,
I'm new to Android development, kind of a Java noob, but not to programming in general. I'm not looking for code examples, just theory or a basic 'how this is done' in Java/Android. I also hope this will become useful information for other developers heading down this path.
I've had some success creating my first Android app - I apologize for not going into details about the specifics of the app, as I plan to eventually sell it commercially on the market - the question should, however, be applicable to any application using this flow model.
My current goal for this application is to create a 'plugin' type system ( like those used in OpenHome and other apps that allow user-generated plugin-able content / functionality ), to allow for flexibility in both my own further component development, as well as eventually creating an open interface for other developers to use to extend the application.
Currently my application is laid out as follows:
Main UI class
- entry point to the application
- starts the service class to spawn 'spinners' ( data processors )
- presents the user with an (ideally) extendable interface to the service
- binds to the service class using AIDL
Service class
- presents an AIDL interface for communication from the UI process
- creates 'spinners' of various types based on user interaction that process data
- persistent, will run in background, new Main UI instances will connect to the running service and present the currently running spinners.
- extendable via an as-yet-unimplemented plugin interface to add new types of spinners
Spinner classes
- use a generic interface with a handfull of common methods to communicate with the Service class, bubbling up data to the UI interface.
- processes user defined data streams, outputs to a buffer/sink suppled by the Service
Assumptions I can make are:
- the plugin (Spinner) class will always implement / override a group of methods to present to the Service class; ie 'putData()', 'getStatus()', 'start()' and 'exit()'
- the plugin class should always return data to the Service class via a supplied/shared buffer ( short array, for example )
Where I'm stuck at the moment is exactly how to implement extendable classes without those classes being a part of the current code base package. More simply, how do I interface with these classes without knowing their names, methods, etc?
As mentioned, I'm new to Java so I may just be overlooking an already implemented class that handles this interaction. If that is the case, I'd be happy for anyone to tell me to shut up and read the docs, if you can point me at the proper docs
What I really don't want to do is create a 'plugin language' for these external bits, as I feel this could hamper development of fast/functional plugins vs. those written as native Java classes. This would also expose potential security issues, as I'd need to create a public interface to the Service class for these applications to link to. I'd prefer if execution of the plugins remained private / internal to the 'main' application.
I'm already using an AIDL interface between the UI class and the Service class - it would potentially be possible to use further AIDL interfaces into each plugin, but from my romp-through-the-park implementing the UI -> Server communication in this way, I find it cumbersome and difficult to pass any kind of complex data sets/controls. And I'm still unsure how the Service class would actually implement these without inheriting the interface directly.
I've poked around Intents in Android, but I'm having trouble wrapping my head around them/what they're for - it seems it might be possible to inherit the plugins that define themselves as sinks for my applications specific Intent type, but I'm lost in the details of how this works exactly, or if it would even be a viable path for what I'm trying to do. Can new Intents even be introduced into Android?
I apologize for the long-winded explanation of what boils down to a simple question:
How can I implement a 'plugin' interface in my application to allow myself and other developers to extend my app through their own classes?
I've been a Java developer for 10 years or so.
From what I understand the "Android" way, would be intents. I'm still working on wrapping my brain around them too.
However, the "Java" way would be to define an interface (or several) for the plug-in(s) to implement. Then use reflection to identify classes in the classpath that implement that interface.
There are some advanced techniques using custom class-loaders, but researching reflection should get you started; if you choose to go that route.
Thanks for the quick response, I'll take a look at the reflection implementation.
Intents do seem to be the 'way to go' for inter-application communication in Android the more I read about it though - if I can figure out how to pull in plugins which specify my applications 'Intent' dynamically. Intents seem to work really well for spawning a 'dumb instance' of an application - like the browser when clicking a link in another app - when your application doesn't want to deal with that data locally.
Seems a bit more difficult to wrap them around a bi-directional interface between the service and the external plugin application. If anyone's got experience with this kind of thing I'd definitely appreciate prodding in the right direction. Documentation on Intents is confusing at best.
Question for you Android SDK wizzes out there.
I was wondering if anyone can explain from a high level how Android SDK or any SDK works. I know android runs off java, but was hoping how an SDK helps you design an app.
Also, is there an Android App editor out there? (Similar to an HTML editor to help you make websites). basically I am looking for a way to make a simple android app without needing to know too much java.
Thanks,
You could check out Google Inventor.
It's really easiest just to answer your questions with links:
SDK
http://en.wikipedia.org/wiki/Software_development_kit
App editor for non-coders:
http://appinventor.googlelabs.com/about/
Android SDK:
http://developer.android.com/sdk/index.html
What is in it:
http://developer.android.com/sdk/installing.html
Eclipse, the IDE most people use to develop Java Android apps:
http://www.eclipse.org/screenshots/
Thanks guys!
Does anyone know what good books on java you would recommend for someone just starting out to program android apps?
In addition, can someone point me in the direction of what specific skills i need (after learning java) I would need in order to program something similar to what I am about to describe:
Make a plugin for an android game (that a friend has developed, so I have the game source code) that can read in-game achievements and display a different advertisement depending on what in-game achievement is reached. So i'm not really programming an app, but a backend program...if that makes sense which would connect to a server to obtain the display advertising corresponding to the in-game acheivement.
Using angry birds as an example:
- if i hit level 5 - display an ad from Bestbuy
- if i hit level 10 - display an ad from futureshop
Thanks again!
Here are some basic Java tutorials;
http://download.oracle.com/javase/tutorial/
A lot of android information and examples here;
http://developer.android.com/guide/topics/ui/index.html
Check out Admob or doubleclick for serving ads;
http://developer.admob.com/wiki/Android
http://code.google.com/mobile/afma_ads/docs/android/doubleclick/
I don't think you can do what you're asking as a plug-in, (don't think there really is a plug-in equivalent in android, unless it's maybe a jar file or a service. Then you're getting way beyond what a novice programmer would be capable of). But I'm a rookie myself. So maybe someone else can tell you better.
________________________________
http://ron-droid.blogspot.com
misc86 said:
Thanks guys!
Does anyone know what good books on java you would recommend for someone just starting out to program android apps?
In addition, can someone point me in the direction of what specific skills i need (after learning java) I would need in order to program something similar to what I am about to describe:
Make a plugin for an android game (that a friend has developed, so I have the game source code) that can read in-game achievements and display a different advertisement depending on what in-game achievement is reached. So i'm not really programming an app, but a backend program...if that makes sense which would connect to a server to obtain the display advertising corresponding to the in-game acheivement.
Using angry birds as an example:
- if i hit level 5 - display an ad from Bestbuy
- if i hit level 10 - display an ad from futureshop
Thanks again!
Click to expand...
Click to collapse
You would have to get an ad partnership with Bestbuy and Futureshop to do that, ad "plug ins" are just random ads that pop up, so when you add Admob to an app Admob decides what ad will appear.
misc86 said:
Make a plugin for an android game (that a friend has developed, so I have the game source code) that can read in-game achievements and display a different advertisement depending on what in-game achievement is reached. So i'm not really programming an app, but a backend program...if that makes sense which would connect to a server to obtain the display advertising corresponding to the in-game acheivement.
Click to expand...
Click to collapse
it wouldn't be a plugin per se, but it would depend on how your friend calls the ad code. i'm not familiar with admob codes and so on, but you should be querying a php/asp file from a server and passing a level argument, which is then parsed, and relevant ad code returned in exchange. i'm not sure if android can accept 3rdparty js like this, but i'd assume it can.
call to ads: http://somedomain.com/friends-game/ads.php?level=12
ads.php
Code:
<?php
$adcodes = array();
$adcodes[] = "....."; // adcode for first levels, e.g. 1-4
$adcodes[] = "....."; // adcode for first levels, e.g. 5-9
//... etc
// check level is valid number, greater than 0, and less than max amount of levels
if (ctype_digit($_GET['level']) && $_GET['level'] > 0 && $_GET['level'] < 100){
// return the correct ad code -
print $adcodes[floor($_GET['level'] / 5)];
}
exit;
with my mid-morning pre-coffee head on, that'll probably accomplish what you want
you could add extra to it, by passing a "clientid" arg to the script call for your "purposes"
I am using a phone that has a Windows 6.5 operating system on it.
I wish to disable all the features on my phone other than GPRS connectivity,Wifi connectivity and Camera features.i.e.I shouldnt be able to make or receive calls,text anyone,play games,or use any other default feature.
Either it must be completely disabled or i should be able to give so kind of password protection to these features.
Please help me at the earliest,i require it for a project completion,and i am not able to figure it out as how this can be done.
Thank You in advance
i dont know whether this is the right place to post as i am a new user,so i am extremely sorry if i have made a mistake.
You should get a SIM card that only supports data access for your project. This will prevent any circuit switched (i.e. voice) features and linked services like SMS. There are also options to activate call barring features for a normal SIM (so you can steer what is allowed or not) - but his is then again part of the SIM card subscription (and can be used on any phone likewise).
There are no default options which could cripple your device in such way as you have asked for.
How to make changes in security policy of Windows Mobile 6.5 Professional?
i was browsing through the net and i found this matter:
4102
Unsigned Applications Policy
SECPOLICY_UNSIGNEDAPPS
This setting indicates whether unsigned applications are allowed to run on Windows Mobile devices. If a signed application does not have a matching root certificate in the Privileged Execution Trust Authorities or the Unprivileged Execution Trust Authorities certificate store, the application is unsigned.
You should always use SECPOLICY_UNSIGNEDCABS together with SECPOLICY_UNSIGNEDAPPS policy. This means that when you block unsigned applications from running, you should also block unsigned cab files from getting installed on the device.
Default value is 1 for Windows Mobile.
The following list shows the possible values:
0 indicates that unsigned applications are not allowed to run on the device.
1 indicates that unsigned applications are allowed to run on the device.
Any value other than 1 is treated as 0.
The required role to modify this policy is SECROLE_MANAGER.
i think this will help me as i can make the applications that i dont need as unsigned applications and then make it 0 which will serve my purpose...but i have no clue how to make these changes in my mobile..
Can u please help me with this???
the solution that is given wont work for me because if anyone changes the sim then the settings i require will change and thus the solution is not full proof. i also dont know i will get any sim dat only offers data transfer.
thank you for the quick reply and i am expecting the same in future too!!
Thanks in advance
Regards,
Sneha
Let me write you this last reply to your query, please do not expect any further from my side.
This forum deals with understanding restrictions and enabling previously hidden or restricted functions mainly - learning from each other's experience.
The subforum you have chosen (chef central) deals with understanding how the Operating System is constructed from packages and how these can be recombined to new (cooked) ROMs.
There is no intention to cripple the existing functions of the operating system itself or to restrict the Radio part of it in any way.
You may think that the snippet you took from a MSDN page delivers something you could use for your purpose (which you have not outlined) without understanding the security concept of Windows Mobile. This is quite complex and often (for simplicity) simply disabled completely on several levels - so no security either for whatever you want to do.
The existing packages of the OS do not have separate components that you could omit to disable your desired functions.
Even if so, these core packages of the OS are usually delivered as modules (another special concept of Windows CE/Mobile) that do not need any security or signing - so they run anyway without restrictions.
So finally good luck with whatever you want to do, but I believe that you cannot achieve this with a crippled Windows Mobile - at least not fool proof.
Hello Sneha,
Welcome to the forums.
Unsigned Applications Policy is totally different then what you are looking for. More info here. When enabled, you will be allowed to install or run unsigned aka untrusted apps.
But the inside apps or features are already signed so you cannot stop them from running by enabling or disabling Unsigned Applications Policy.
The really thing you need is to make a custom ROM, remove all the unnecessary things and flash it to your device(s). That means you should change/modify the built in OS (in a simple word) but you cannot do within the device
However, its not a day, week or even a month task. It takes many months to learn things and then you can finally do it. I'm 99% sure that all of your needs can be fully filled but :
1. Takes many months to learn.
2. You need to get the stock ROM, Modify and flash to the device.
BTW; which device you really have?
Thanks...
Best Regards
Closed environment is something that should be done in bsp: kernel to be precise. Also it is possible via custom certmod.dll.
BUT. Little problems:
1) no bsp sources unless you're OEM
2) no certmod.dll sources.
Please look at the initial request on the restriction of radio features. This is handled in the radio layer and this cannot be cut in pieces. So there are no components to sign/restrict/omit for that query.
Cooking can do a lot, but it does not go inside one component.
Cutting all other things may be feasible - but not for radio relevant parts imho.
tobbbie said:
Please look at the initial request on the restriction of radio features. This is handled in the radio layer and this cannot be cut in pieces. So there are no components to sign/restrict/omit for that query.
Cooking can do a lot, but it does not go inside one component.
Cutting all other things may be feasible - but not for radio relevant parts imho.
Click to expand...
Click to collapse
Of courses its a lot of work but its possible. Within the OS functions. Radio thing is just for input and output but the way its handled is under OS itself. Am I right or wrong? Think of removing packages depending to what you don't want.
i.e to disable messaging, Remove all things which are related to it. I'm sure you know it.
Though its a plenty of work and have to be expert so not messing around things.
ultrashot is right but if we had the source, every thing would have been different and even easy.
Radio is special and never dealt with in cooking. The Radio lower layers are treated with code in a dedicated partition (GSM) and accessed via an interface Layer (RIL = Radio Interface Layer) from the OS.
On top of that are applications like messaging or MMS - these can be cut.
I see no option to prevent e.g. only speech calls but allow data calls. On RIL level these are just different GSMBCIE elements (look up the relevent 3gpp specs). Of course you could find dirty ways to cut off e.g. the GSM speech codecs, but this would possibly not prevent to set up a call - creating cost but not having success when connected.
Tweaking these parts has not been of anyone's interest and thus "in theory" possible but hardly practically feasible.
How can i make changes on the OS?
Thanx a lot Cracing for the positive advice.I was planning to consult the OEM to make changes in the security policies.
I am working with the Synqe device .My main aim is barcode scanning and sending the data via GPRS or Wifi.and at the same time i want that all others connectivities and applications are to be deactivated.
Moreover i wish to restrict the usage of GPRS strictly for my application.
As u mentioned that i will have to make changes in the OS,will the OEM be able to do that for me or should i consult a good Mobile OS developer?
sneha6689 said:
Thanx a lot Cracing for the positive advice.I was planning to consult the OEM to make changes in the security policies.
I am working with the Synqe device .My main aim is barcode scanning and sending the data via GPRS or Wifi.and at the same time i want that all others connectivities and applications are to be deactivated.
Moreover i wish to restrict the usage of GPRS strictly for my application.
As u mentioned that i will have to make changes in the OS,will the OEM be able to do that for me or should i consult a good Mobile OS developer?
Click to expand...
Click to collapse
I see
Going with OEM should be better idea. They have the sources to do anything. Its not so easy for 3rd party Mobile OS developers (i.e here ). Need things and takes long enough to R&D and finish the project.
Hope you will find a good solution for your project soon.
Thanks...
Best Regards
Hi guys, could you tell me how to open file for writing in the phone app LocalStorage for the non-unlocked handset (regular app for store)?
Code below doesn't work
Code:
FILE *tmp;
auto tmpPath = Windows::Storage::ApplicationData::Current->LocalFolder->Path + "\\tmp.txt";
auto tmpErr = _wfopen_s(&tmp, tmpPath->Data(), L"w");
Any suggestions?
Try looking though msdn articles. I found it somewhere in there. But I have forgotten it now.
Sent from Board Express on my Nokia Lumia 1020. Best phone ever!!
Note to noobs: DON'T PM ME WITH QUESTIONS. POST IN THE FORUMS. THAT'S WHAT THEY ARE HERE FOR!
@wcomhelp, please keep your rtfm advices for yourself, OK? I'm not a noob and of course I've searched msdn, google, codeplex, github etc. and so on before posting here. If you don't know how, much better be silent (like others who read this post but have no idea what I'm talking about)
I've tried a few possible methods including ugly "MS-way" with task & lambda syntax (see below) but nothing worked as it should be (code below works if no file exist and fails if file already exist - CreationCollisionOption::ReplaceExisting options is not worked/not implemented/buggy/billgates_knows_only ).
Code:
auto folder = Windows::Storage::ApplicationData::Current->LocalFolder;
Concurrency::task<Windows::Storage::StorageFile^> createFileOp(
folder->CreateFileAsync(CONFIG_FILE_NAME, Windows::Storage::CreationCollisionOption::ReplaceExisting));
createFileOp.then([=](Windows::Storage::StorageFile^ file)
{
return file->OpenAsync(Windows::Storage::FileAccessMode::ReadWrite);
})
.then([=](Windows::Storage::Streams::IRandomAccessStream^ stream)
{
auto outputStream = stream->GetOutputStreamAt(0);
auto dataWriter = ref new Windows::Storage::Streams::DataWriter(outputStream);
// data save code skipped
return dataWriter->StoreAsync();
})
.wait();
BTW, I've used workaround, to save ported C++ app data to the LocalSettings instead of text file (as it was in original code).
"Doesn't work" doesn't give us a lot to go on, troubleshooting-wise. Can you tell us what error you get?
Only thing I see in the code that looks a little weird is that the
Code:
"\\tmp.txt"
part isn't explicitly a wide-character string, but I'd expect string concatenation to take care of that.
Also, out of curiosity, why libc functions instead of Win32? Obviously, the code you're writing here isn't intended for much portability...
@GoodDayToDie, there is no error code at all - standard POSIX functions returns NULL FILE, the ::GetLastError() also return 0.
I'm porting old C-style app to WinRT platform and don't care about portability (but the first post code - just a simplified example, nothing more).
POSIX (libc) functions works pretty well for reading only but not for writing - that's the problem...
As I said before, I resolved my issue by workaround but still curious why the POSIX calls fails for file writing in the app storage.
buuuuuuuuuuuuuuuuh
No need for lambdas
https://paoloseverini.wordpress.com/2014/04/22/async-await-in-c/
You may also want to rethink your strategy
You can't create files at arbitrary locations, so your method is kinda redundant. All the locations you are allowed to create and read files to/from are available through KnowFolders and ApplicationData classes. These return StorageFolders which in turn can create files with CreateFileAsync (used for both creating and opening existing files) and get files with GetFilesAsync ( I recommend against this one though) and similar methods.
@mcosmin222, could you please re-read my posts one more time? I'm not trying to create files at "arbitrary locations"; I wanna create/write simple text file at the app's local storage (which one should be available for reading/writing). And the problem not in the lambdas or task usage (yes, it looks ugly but it works as it supposed to be).
Could you provide a working example instead of words? And I'll be glad to say you "thanks a lot"; can't say now...
sensboston said:
@mcosmin222, could you please re-read my posts one more time? I'm not trying to create files at "arbitrary locations"; I wanna create/write simple text file at the app's local storage (which one should be available for reading/writing). And the main problem not in the task (async execution).
Could you provide a working example instead of words? And I'll be glad to say you "thanks a lot"; can't say now...
Click to expand...
Click to collapse
Sure, just gimmie a few hours till I can get near a compiler that is capable of doing that
Of course, no rush at all, take your time. It's not a showstopper for me now (actually, my workaround with AppSettings is more preferable way - at least for universal app and roaming settings) but the issue still has an "academic interest" and maybe will be useful in the next projects for porting old C/C++ code to WinRT.
sensboston said:
Of course, no rush at all, take your time. It's not a showstopper for me now (actually, my workaround with AppSettings is more preferable way - at least for universal app and roaming settings) but the issue still has an "academic interest" and maybe will be useful in the next projects for porting old C/C++ code to WinRT.
Click to expand...
Click to collapse
hi
in vs 2015
#include <pplawait.h>
Something of the like should work
Code:
WriteSomeFile() __resumable
{
auto local = ApplicationData::Current->LocalFolder;
auto file = __await local->CreateFileAsync("some file", CreationCollisionOption::eek:penIfExists);
__await FileIO::WriteTextAsync(file, "this is some text");
}
However, as of right now, in VS 2015 RC, you have a host of limitations when dealing with this, but I do not believe this will be of any issue to you.
Code:
Cannot use Windows Runtime (WinRT) types in the signature of resumable function and resumable function cannot be a member function in a WinRT class. (This is fixed, but didn't make it in time for RC release)
We may give a wrong diagnostic if return statement appears in resumable function prior to seeing an await expression or yield statement. (Workaround: restructure your code so that the first return happens after yield or await)
Compiling code with resumable functions may result in compilation errors or bad codegen if compiled with /ZI flag (Edit and Continue debugging)
Parameters of a resumable function may not be visible while debugging
Please see this link for additional details
http://blogs.msdn.com/b/vcblog/archive/2015/04/29/more-about-resumable-functions-in-c.aspx
you should also note that this works with native, standard C++ types.
@mcosmin222, looks like unbuffered writing works (i.e. without streams) fine but it still not an answer for my initial question
I'm curious why the standard POSIX libc writing operations are not working on the app's local storage (but reading from files works fine). Actually, it's all about porting old C/C++ code for WinRT; of course for the new app it's not a problem but re-writing old code to FileIO should be a huge pain in the ass. What I did: I've "mechanically" changed all libc formatted outputs from file to string, and use LocalSettings class (actually it's XML file) to store that string (I'm planning also change LocalSettings to RoamingSettings, to provide settings consistency between WP & desktop app).
P.S. <pplawait.h> is not available in my VS 2015 (release pro version) so I've tested by using lambda pattern.
OK, first things first, LIBC != POSIX! The POSIX way to do this would be to call the open() function and get back an int as an "fd" (file descriptor), which is of course not implemented on Windows Phone because Windows Phone is not a POSIX platform (you might find the Windows compatibility functions _open() and _wopen(), but I doubt it). You are attempting to use the standard C library functions, which are portable but implement kind of a lowest common denominator of functionality and are generally slightly slower than native APIs because they go through a portability wrapper.
Second, sorry to be all RTFM on you but you should really Read The Manual (or manpage, or, since this is Windows, the MSDN page)! Libc APIs set errno (include errno.h) and use different error values than Windows system error codes (or HRESULT codes, or NTSTATUS codes, or...). Error reporting in C is a mess. If you were calling CreateFile(), you would check GetLastError(), but since you're calling _wfopen(), you check errno (not a function).
@GoodDayToDie, _wfopen_s returns 0 (i.e. "no error") but tmp pointer receives also 0 (NULL) Could you explain why libc file functions are working for reading (at the app installation & local data folders of course) but not for writing? Any logical ("msdn based") explanation? Or you just... don't know, heh?
sensboston said:
@GoodDayToDie, _wfopen_s returns 0 (i.e. "no error") but tmp pointer receives also 0 (NULL) Could you explain why libc file functions are working for reading (at the app installation & local data folders of course) but not for writing? Any logical ("msdn based") explanation? Or you just... don't know, heh?
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LIBC functions will most likely work just in debug mode. The moment you try to publish the app it will fail. You can do lots of crazy stuff on your developer device with basic C functions, but if you try publishing, it won't pass the marketplace verification.
Most C APIs are simply not supported, since they do not comply with the sandbox environment of the Windows Runtime.
The code I gave you is tested with VS 2015 RC. You should be able to include <pplawait.h> just fine, if you are targeting toolchains newer than November 2013.
mcosmin222 said:
The moment you try to publish the app it will fail. You can do lots of crazy stuff on your developer device with basic C functions, but if you try publishing, it won't pass the marketplace verification.
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Hmm... Are you sure or it's just your assumption? My app is still under development but (just for test!) I've made store app package for WP and it passed local store verification I also uploaded package to the store (via browser) and it also passed. I don't have time to create all tiles and fill all fields to complete beta-submission (actually, I don't know how to mark app as beta in the new dashboard) but for me it looks like app don't have any problem and will pass store certification easily. And you may be sure - it uses A LOT of libc calls 'cause originally it was written for Linux (or kind of UX system)
sensboston said:
Hmm... Are you sure or it's just your assumption? My app is still under development but (just for test!) I've made store app package for WP and it passed local store verification I also uploaded package to the store (via browser) and it also passed. I don't have time to create all tiles and fill all fields to complete beta-submission (actually, I don't know how to mark app as beta in the new dashboard) but for me it looks like app don't have any problem and will pass store certification easily. And you may be sure - it uses A LOT of libc calls 'cause originally it was written for Linux (or kind of UX system)
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Once usage reports get up to microsoft, you will be given a notice to fix the offending API (happened to be once). You are much better off using the platform specific tools: not only they are much faster, they are also much safer and you won't have problems later on.
You might get away with reading stuff (since reading is not that harmful), but you should be using the winRT APIs each time they are available.
Simply uploading your app to the marketplace just reruns the local tests in their cloud servers: once you submit the actual app (not beta, not tests) for consumers, it will be much more aggressively checked. This is because the store allows specific scenarios for distributing apps in close circles that may break the usual validation rules.
@mcosmin222, one more time: is it your assumptions or personal experience? I don't know how many apps you have in store (I do have a lot) but I never heard that you said. I've used C++ libraries with WP hacks in some of published apps but never had any problem with "aggressive checks". What I know: if you are using some "prohibited" calls, your app will not pass uploading to the store (uploading, not a certification).
P.S. I'll send you personally a link when I publish release Hope, you'll like it
sensboston said:
@mcosmin222, one more time: is it your assumptions or personal experience? I don't know how many apps you have in store (I do have a lot) but I never heard that you said. I've used C++ libraries with WP hacks in some of published apps but never had any problem with "aggressive checks". What I know: if you are using some "prohibited" calls, your app will not pass uploading to the store (uploading, not a certification).
P.S. I'll send you personally a link when I publish release Hope, you'll like it
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By "hacking" you mean recompiling the code to fit the windows phone toolchain? if so, then you shouldn't have to worry about too many things.
but even so, calling stuff like fopen in locations other than local storage will get your app banned. Even if it makes past the first publication, you can get noticed weeks later or even months (yes, it did happen to me personally).
In most cases, calling C APIs that can potentially break the sandbox (like opening a file in doc library with fopen) will always fail the marketplace verification, eventually. If it hasn't happened to you yet, then you may have not been using such APIs.
No, my C++ code is not accessing other than approved locations but the app has a lot of libс (and of course other C/C++ libs) calls; I'm 99.9% sure it's legitimate and will be not a source of any problem. Otherwise what is the advantages of having C++ compiler?!
As far as I know, just some of API's are prohibited but you will notice it right after local store compatibility test run...
As for "hacks" I mean usage of undocumented ShellChromeAPI calls (including loading hack).
P.S. I've found why <pplawait.h> header is missing. Initially I've created solution with the 12.0 toolset but now I can't (or don't know how to) change it to 14. However creating the new empty universal solution in VS 2015 also gives me toolset 12 by default. What is the toolset 14 for? Windows 10?
sensboston said:
No, my C++ code is not accessing other than approved locations but the app has a lot of libс (and of course other C/C++ libs) calls; I'm 99.9% sure it's legitimate and will be not a source of any problem. Otherwise what is the advantages of having C++ compiler?!
As far as I know, just some of API's are prohibited but you will notice it right after local store compatibility test run...
As for "hacks" I mean usage of undocumented ShellChromeAPI calls (including loading hack).
P.S. I've found why <pplawait.h> header is missing. Initially I've created solution with the 12.0 toolset but now I can't (or don't know how to) change it to 14. However creating the new empty universal solution in VS 2015 also gives me toolset 12 by default. What is the toolset 14 for? Windows 10?
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Click to collapse
The advantage of C++ is the obvious versatility: the standard C++ APIs will work fine for you as long as you stay inside the sandbox (this means you can't access files even in locations that are outside of sandbox but you have permission to them, such as music library). You can use most classic C/C++ libraries without issues as long as you do the interface with the runtime broker yourself. That means using windows runtime APIs instead of classic C APIs when dealing with stuff such as file access, for example. This is a pretty extensive topic and It is rather difficult to explain it all with 100% accuracy, especially when there is lots of docs running around.
You also get deterministic memory management, which is huge in specific scenarios.
Long story short
You will be fine with standard C/C++ when using
any in-memory functions supported by the compiler (you can manipulate data types, string, mutex, etc).
File IO in isolated storage only (applicationData folder)
Threads (although you are better off using threadpool or the like, it is much easier and cleaner). You can also use futures, and std::this_thread.
You will have to use winRT replacement
File system access in any other location than application data (you must use the windows::storage APIs)
sockets, internet access and the like.
any hardware related thing: music&video playerback must be interfaced through winRT (although the underlying decoders can be classic C/C++), messing around with the device sensors.
Retrieving system properties (internet connection state etc)
cross process communications
communicating with other apps
There are also win32 equivalents
mutex, threading, fileIO (isolated storage only)
Media playback with custom rendering pipeline.
Basically, winRT functions as an abstraction layer between the hardware and your code. You can use classic C++ up to the point where you need to interact with the system in any way. At that point, system interaction must be done with winRT. This way, microsoft ensures a higher degree of stability and security for devices.
check this link out for more information on the toolchains. You should be able to use this in VS 2013 as well with windows 8 (this is a compiler feature, has nothing to do with supported platform)
https://paoloseverini.wordpress.com/2014/04/22/async-await-in-c/