[Q] Android technical introduction - Android Q&A, Help & Troubleshooting

Hi. I'm about to get my first Android phone, and would naturally like to know more about the OS. I would describe myself as intimately familiar with ordinary GNU/Linux systems, but let's face it, Android is hardly your ordinary such creature. Moreover, there seems to be very few technical introductions to Android around; those I've found tend to be idiotic user's guides (not technical at all) or focused on software development (interesting, but not what I'm looking for right now).
Things I wonder about with Android include:
There's an unusual libc, right? Is the GNU userland around, though?
The file system directory structure. It's hardly LSB-compliant, eh?
The package system. Everything I've come across is centered around the SDK, and hides many of the details of what goes on here. Sub-questions: Is it only "apps" (gah, I hate the word, I'm sorry) that use the package manager, or is everything covered by it, as in a normal Linux system?
The boot loader. Experience with other ARM/non-x86-systems indicate this is a world very different from GRUB, and also a highly varied one.
How do shared libraries fit into the Android ecosystem? Some places I get the impression everything is static. Is that really true?
What's this non-X display system? How do you configure it, etc.?
What's the init system like?
As far as I've understood, the actual phone software (is "baseband" the right terminology?) tends to be proprietary and separate from the OS. How does it fit into all of this? Does the OS execute code at some mysterious memory location? Is some special-purpose hardware run? Is it just a standard process? Is it in kernel-space?
I'm not looking to get these questions answered here. Rather, I'm asking: Are there any documents or books around that try to fill the role of bringing an experienced Linux user with decent development background and technical knowledge into Android?

Related

[Q] Wanting to tinker with Android

I've been following threads on here for a few months, and now I think I want to try to learn more about how Android actually works. I'm familiar with IDEs and coding in general(not my strong point), so I think I could pick up some things pretty quickly. Where would you guys recommend I look for learning to code/tweak Android code*?
I kind of want to be able to say I'm running my own cooked up version of Android.
*please ignore this redundant word choice, please.
rougegoat,
There is a fork in the road right at your starting point, strangely enough. You could choose to study Android application development, or you could choose to look at ROM "development". They are almost worlds apart in both nomenclature, toolsets, and skills; and because of the breadth of skills that are needed in both domains, I have no doubt that there are people that are simultaneously geniuses in one of those areas of expertise, and a numb-skull in the other: that's how far apart they are.
The former is all about Java, Android API's, the "SDK", and an IDE such as Eclipse, and emulators and the device bridge; the latter has a distinct "Unix jock" nature to it: Android "NDK", (or CodeSourcery) toolchains, gcc, make, command-line and shell scripting, understanding dynamic linking and execution environments, and use of configuration management tools (git and repo).
When "code" comes up in the former, it's Java; in the latter, ANSI C (or any other native-compiler language, but C is most typical). In the latter case, if you are building source trees from public repositories, (say Cyanogen or AOSP) initially you won't spend any time at all with C - you'll be spending 95% of your time struggling with with the build environment(s) and trying to wrap your head around the mysteries of "git" and "repo" - and also deciphering Unix shell scripts (typically written in the "Bourne" or "Bash" shell dialect) when things go wrong or are poorly documented. And yes, they will go wrong; effectively diagnosing what happened when things go wrong requires solid Unix/Linux skills.
Your question as posed suggests that you are more interested in the OS/ROM side of things than App development; if that is the case I would suggest you:
-brush up or learn from scratch basic Unix/Linux skill sets (they map over to Android almost 1-to-1).
-If you are a Windows user, download VirtualBox, and create a VM with Ubuntu (8.0.4 or 10x); use developer.android.com as a reference for dependencies and setup. Make sure the virtual disk is plenty big: at least 30-40 Gb. Don't attempt to set up a native development enviroment in Windows/cygwin. ( Windows is a great place for the Android SDK and Android App development, but decidedly not for native code development for Android "ROMs"** ).
-Install both the CodeSourcery and the Android "NDK" (Native Development Kit) in your Linux VM, and try and build a smallish, but multi-file C source-code project that uses Makefiles using both of those toolchains. (Sounds easy, right? Wait till you try anything involving the standard I/O library with the NDK).
-Get your simple project code to run correctly on a real phone device.
- Then, download and build an HTC kernel from their (standalone) source tree - try and do it with both toolchains (CodeSourcery and Android NDK) - simply for the experience of setting up the environments correctly.
- Then, learn the basics of dealing with repo, download an Android source tree and compile it - using both toolchains (CodeSourcery and Android NDK)
- After succeeding with the above, try pulling code from someone else's "git" repository and merging it into an Android build tree - and getting it to build correctly.
The above looks like a pretty short list - but it represents many, many hours of effort. Good luck.
bftb0
** There might be folks that take issue with that statement about ROM-building and Windows. They might tell you, "just download so-and-so's kitchen, and start building ROMs", it works fine under Windows." There's nothing wrong with that, especially because it can be satisfying seeing something of your creation actually running on a phone in a short period of time - but you probably won't learn very much, and when things go wrong, you'll be stumped about how to go about fixing things. The difference between a "chef" and a "developer" is that the former merely assembles together pre-built executable programs and libraries - whereas the latter understands not only how to go about building those things when the sources are available, but also has the opportunity to change them.
Lucky for me that I'm a Slackware guy. I'd much rather learn the system then just have a pretty GUI that does it all for me. That's half the fun of it.
Thanks for the advice, I'll have to try that whole bit out and see where it gets me. A weekend project awaits!

[Q] Wine-like iOS emulation?

Hello All,
My question is whether the reverse-engineering of iOS's API is being looked at as an option any time soon. I would be interested in something similar to Wine (Wine Is Not an Emulator), which is a reverse engineering of the Win32API and allows you to run Windows .exe files natively in Linux or Mac OS. I am aware of iEmu (and it's unfortunate suspension).
However, my interest is not in getting iOS itself running on my phone, but instead I would like to run the apps themselves. I'm pretty sure there isn't currently a project on this. If there is, can you inform me of it?
If there is not, I would like to discuss the difficulty of implementing this. I could definitely be an aid in starting a project of ths nature.
Here are some things about iOS's apps I am unfamiliar with (I am aware that this specific section of the post may be more fit for the iOS forum):
Does the Obj-C code compiled for iOS resemble native ARM code (the iPhone chips are ARM to the best of my knowledge), like how C++ would be compiled, or does it resemble something more like C# or Java, compiled into bytecode that is executed by a library?
Compared to the size of the .NET framework or Win32API, how big is the iOS library?
Has a successful program been created that can run Obj-C code?
Would this have to be worked from the ground up (figuring out how Obj-C compiles in the first place), or has there been some effort already mounted similar to this?
I am aware of the extreme difficulty in implementing this. However, I'm sure this was thought while planning Wine or Mono. I'm not even suggesting this be made, but I'm simply asking on your opinion on the general difficulty (can it be done).
Thank you,
- κυριακος
kupiakos42 said:
Hello All,
My question is whether the reverse-engineering of iOS's API is being looked at as an option any time soon. I would be interested in something similar to Wine (Wine Is Not an Emulator), which is a reverse engineering of the Win32API and allows you to run Windows .exe files natively in Linux or Mac OS. I am aware of iEmu (and it's unfortunate suspension).
However, my interest is not in getting iOS itself running on my phone, but instead I would like to run the apps themselves. I'm pretty sure there isn't currently a project on this. If there is, can you inform me of it?
If there is not, I would like to discuss the difficulty of implementing this. I could definitely be an aid in starting a project of ths nature.
Here are some things about iOS's apps I am unfamiliar with (I am aware that this specific section of the post may be more fit for the iOS forum):
Does the Obj-C code compiled for iOS resemble native ARM code (the iPhone chips are ARM to the best of my knowledge), like how C++ would be compiled, or does it resemble something more like C# or Java, compiled into bytecode that is executed by a library?
Compared to the size of the .NET framework or Win32API, how big is the iOS library?
Has a successful program been created that can run Obj-C code?
Would this have to be worked from the ground up (figuring out how Obj-C compiles in the first place), or has there been some effort already mounted similar to this?
I am aware of the extreme difficulty in implementing this. However, I'm sure this was thought while planning Wine or Mono. I'm not even suggesting this be made, but I'm simply asking on your opinion on the general difficulty (can it be done).
Thank you,
- κυριακος
Click to expand...
Click to collapse
Hey and welcome to the forum's I would like to know this as well but I do not know any project and any that gets started and gains popularity gets chased down by Apple's legal team quite quickly. I have my doubts that this could happen (I would be glad if someone could prove me wrong) because iOS and its apps work on 12 devices and Android has hundreds of devices, most with different hardware. Windows apps are built for variable hardware, likewise with Linux and now Mac OS X. Sorry but as much of a pessimist as I seem I do not think it's possible but I'd love to be proven wrong. (Can someone at least make a frigging Windows Mobile runtime)

[Q] Tablet ubuntu able to run edubuntu (kde etc)?

Hi all
Does anyone know if I can run kde-based software on the developer alpha of Ubuntu for tablets yet please? Not expecting reliability, just want to do some child user testing of the edubuntu suite on tablets.
Thanks
Chris
Currently you can't and probably neither in the near futur 'cause you need an X Server for that.
And there is no X server on ubuntu touch.
Huge thanks, that is really useful
Hempe said:
Currently you can't and probably neither in the near futur 'cause you need an X Server for that.
And there is no X server on ubuntu touch.
Click to expand...
Click to collapse
After some research on your reply I've a couple questions. Does it mean the Unity interface doesn't need X-server? Or are they just using a temporary workaround until X-server is implemented?
And does this apply to both Ubuntu for Android, and Ubuntu for tablets?
Huge thanks
Having done some further research I've made my decision - thanks hugely for providing the missing link in my knowledge. What follows is my best interpretation of the rumours.
Currently in place of X-server is SurfaceFlinger, ("because X-server uses 30 yr old code" - Canonical). Canonical publicly dabbled with using Wayland until mid-Feb, then decided to create their own revamped display server from scratch, called Mir, which they seem to have been working on since mid last year, and are trying to get GPU vendors to support, written to run across all devices and to meet the needs of the Unity interface, and written in Qt/QML which is what they want native apps written in.
Bottom line for me, is that the technology is still right up there in the clouds and nowhere near decided enough to base my business strategy on. Also, Ubuntu for tablets seems a pretty thin version of Ubuntu anyway, so Edubuntu was never an option and I'm unlikely to be able to leverage much from Ubuntu's Open Source libraries anyway.
Like others, (see the comment on jonobacon.org below), I find it frustrating that the wealth of code written for Ubuntu is no longer usable, but I reckon this is probably necessary to squeeze the most out of every single CPU cycle and milliamp. Ubuntu for tablet is dead in the water if it kills the battery and performs worse than the established competitors.
Therefore all indications are I need to write for Android, keeping my options as open as possible to migrate. So it is now Titanium/UnityIDE versus HTML5, particularly assessing relative performance.
http://www.omgubuntu.co.uk/2013/03/canonical-announce-custom-display-server-mir-not-wayland-not-x
http://www.jonobacon.org/2013/02/21/five-ubuntu-touch-facts/ -- not the article but the comment starting "In that case, wouldn't it be better to port existing apps instead of...."
http://www.omgubuntu.co.uk/2013/02/canonical-working-on-new-display-server
http://www.phoronix.com/scan.php?page=news_item&px=MTMwOTM
Just to clarify.
1. There are plans to make a X-Mir compatibility layer that will allow you to run programs that require an X-Server to work with mir.
2. Not all is lost at the moment it just looks that way.
Only Graphical Userinterfaces are affected. Your commandline tools and libraries don't need to be changed.
3. If you are looking for platform to write apps for, well there is worke being done to let you run your QML apps (intended for ubuntu touch) on android.
So if you choose to make QML apps they can be or will be able to run on linux, mac, windows and android
Wow, huge thanks, I missed that.
Does this mean EVERYTHING Ubuntu without a GUI will work? I want to run a NodeJS server. How likely is it that it will work perfectly now? How likely is it that it will work perfectly in the (nominally October 2013) release? (Sorry, just give me a keyword and I'll go off and do my research.)
Is Canonical planning to get X-Mir into the next ~Oct release?
My other query was whether QML on Android would perform as well. For others interested, it looks like it works directly with the Android SurfaceFlinger, bypassing the Dalvik VM, so performance should compare with native Java code.
Huge thanks once again
Chris
Sources:
http://www.youtube.com/watch?v=TEkubKZaUt8
http://victorpalau.net/2013/01/25/ubuntu-qml-todo-android-vs-ubuntu/

[Q] Native C++ Access To Native Linux API Or Not?

This is my first post to XDA.
I have been asking this question about various OS's in various forums, for past 18 months, and each time I ask it, the person who answers it spends a few iterations with me bending-over-backwards trying to avoid telling me what I want to know. I hope that this does not happen here.
I have a native C++ application. It currently runs on Linux desktop. It does many things that native C++ applications do, including sending raw Ethernet frames (mesh networking).
Obviously, if one of my customers tries to install this application on his/her Android device, there will be problems, and it won't work.
I am aware that a human being has the ability to root his/her phone.
I am aware that a human being has the ability to root his/her phone.
I am aware that a human being has the ability to root his/her phone.
Please do not send me a reply saying, "But your customer has the ability to root his/her phone!" :cyclops:
What I would like, is a smartphone, that is running Linux, that allows my customer to install a 100% Native C++ application, >>>WITHOUT<<< having to go through the process of rooting his/her phone. Ideally, the barrier-to-installation would be roughly equivalent to what s/he would experience on a desktop computer.
I am not concerned about the presence of X or any particular GUI subsystem, but I will definitely need access to all the normal system-level Linux primitives (multi-threading, asynchronous I/O, etc.)
Please do not send me a reply saying, You can ssh into the phone and install the app that way."
I would like to know if Ubuntu on smartphone allows a relatively naive user to install a 100% native C++ application that interfaces with the system-level primitives of Linux.
And finally, please note that I am not interested in finding a work-around to an engineering problem that I am having. I am trying to determine the maximum permissible degree of nativity of Ubuntu Touch applications when the application is to be installed by a naive user.
If Ubuntu touch does allow such native applications to be installed, I would be interested in getting an idea of the steps that a customer would take.
UT apps can be uploaded as a click app to the UbuntuOne store and then can be installed as easy as any Android app. You should be able to "sideload" click apps, but I never tried.
UT apps - that are not a web app - are written in native C++ using QT5/QML for UI.
UT apps are restricted by apparmour profiles, but that should not keep them from using multithreading or asynchronous I/O. You would have to test, if your specific requirements work.
There is only one way to answer all your questions: give it a try!
Sent from my TF300T using Tapatalk
f69m said:
UT apps can be uploaded as a click app to the UbuntuOne store and then can be installed as easy as any Android app. You should be able to "sideload" click apps, but I never tried.
UT apps - that are not a web app - are written in native C++ using QT5/QML for UI.
UT apps are restricted by apparmour profiles, but that should not keep them from using multithreading or asynchronous I/O. You would have to test, if your specific requirements work.
There is only one way to answer all your questions: give it a try!
Sent from my TF300T using Tapatalk
Click to expand...
Click to collapse
:good:
Yes, you would need to change the packaging system from debian archives to click packages but that shouldn't be too difficult. If you run into problems with the Ubuntu SDK in connection with C++, have a look at this bug report and the mentioned fixes: https://bugs.launchpad.net/ubuntu/+source/qtcreator/+bug/1215913
f69m said:
UT apps can be uploaded as a click app to the UbuntuOne store and then can be installed as easy as any Android app. You should be able to "sideload" click apps, but I never tried.
Click to expand...
Click to collapse
Any idea at all what the user would see when trying to sideload a click app. [I am trying to set my expectations before diving in.] Would the user download package to a directory, then click on it, or?
UT apps are restricted by apparmour profiles, but that should not keep them from using multithreading or asynchronous I/O. You would have to test, if your specific requirements work.
There is only one way to answer all your questions: give it a try!
Click to expand...
Click to collapse
OK, apparmour seems to be the focal point. I would be really interested (if any knows), how restrictive apparmour will be with a newly-purchased UT phone, and what control a naive user of that phone will have in allowing native C++ applications to run. I would check this myself, but I cannot do any significant coding (porting) until mid-March.
In particular, my app works with WiFi, and will need to interact with stock WiFi drivers (mac80211/etc.). I would like to know what I, and the user, can expect when s/he:
acquires my app from my web site
does something to install it (what would s/he do at this step?)
attempts to execute it (will apparmour block access to mac80211-like drivers)
RareHare said:
Any idea at all what the user would see when trying to sideload a click app. [I am trying to set my expectations before diving in.] Would the user download package to a directory, then click on it, or?
OK, apparmour seems to be the focal point. I would be really interested (if any knows), how restrictive apparmour will be with a newly-purchased UT phone, and what control a naive user of that phone will have in allowing native C++ applications to run. I would check this myself, but I cannot do any significant coding (porting) until mid-March.
In particular, my app works with WiFi, and will need to interact with stock WiFi drivers (mac80211/etc.). I would like to know what I, and the user, can expect when s/he:
acquires my app from my web site
does something to install it (what would s/he do at this step?)
attempts to execute it (will apparmour block access to mac80211-like drivers)
Click to expand...
Click to collapse
Applications should be installed from the Ubuntu app store. If you've just got the click package, you currently need to use the command line to install it:
Code:
sudo install <path to package>
sudo register --user=phablet <package name> <package version>
I hope that this will change though. (It's name is "click" package. )
RareHare said:
Any idea at all what the user would see when trying to sideload a click app. [I am trying to set my expectations before diving in.] Would the user download package to a directory, then click on it, or?
Click to expand...
Click to collapse
nikwen said:
Applications should be installed from the Ubuntu app store. If you've just got the click package, you currently need to use the command line to install it:
Click to expand...
Click to collapse
Technically it should be possible to install a click package just by clicking on a web link, if the web site serves a specific mime type, but this is not implemented.
Not sure about Canonical's policy on that, they might not like the idea. Otherwise they might implement it or at least accept a patch from a community developer.
RareHare said:
OK, apparmour seems to be the focal point. I would be really interested (if any knows), how restrictive apparmour will be with a newly-purchased UT phone, and what control a naive user of that phone will have in allowing native C++ applications to run. I would check this myself, but I cannot do any significant coding (porting) until mid-March.
Click to expand...
Click to collapse
Sorry, have not looked myself into the apparmour profiles too closely and don't have the time to do that right now.
However you can download a recent UT rootfs using the link below and have a look at the profiles yourself:
https://system-image.ubuntu.com/pool/ubuntu-cd4246419c888397c0d8debbd9f945219f40fc670220b7ac86753dc79eb73707.tar.xz
RareHare said:
In particular, my app works with WiFi, and will need to interact with stock WiFi drivers (mac80211/etc.).
Click to expand...
Click to collapse
I don't think this is possible with any current or future off-the-shelf phone. Any OS will provide an abstract API for WLAN and require root to talk to the drivers directly.
As you say requiring your customers to root the phone is not an option, this seems to leave only one way out: you need to split off the low-level code of your app into a generic and secure API and submit it to Ubuntu Touch. If it is accepted, your app can use the new API.
f69m said:
Technically it should be possible to install a click package just by clicking on a web link, if the web site serves a specific mime type, but this is not implemented.
Not sure about Canonical's policy on that, they might not like the idea. Otherwise they might implement it or at least accept a patch from a community developer.
Click to expand...
Click to collapse
Of course, it would technically be possible. Recently, I read a Google Plus post on that topic. Here's the link. (The interesting part is in the comments. Read all of them. )
They said that they'll offer those options in the future.
f69m said:
Technically it should be possible to install a click package just by clicking on a web link, if the web site serves a specific mime type, but this is not implemented.
Not sure about Canonical's policy on that, they might not like the idea. Otherwise they might implement it or at least accept a patch from a community developer.[
Sorry, have not looked myself into the apparmour profiles too closely and don't have the time to do that right now.
Click to expand...
Click to collapse
I am in the same situation myself - I do not have enough time to experiment with apparmour, so I'm asking Ubuntu so that I do not have to search/guess.:victory:
I don't think this is possible with any current or future off-the-shelf phone.
Click to expand...
Click to collapse
So it would seem.
Any OS will provide an abstract API for WLAN and require root to talk to the drivers directly.
As you say requiring your customers to root the phone is not an option, this seems to leave only one way out: you need to split off the low-level code of your app into a generic and secure API and submit it to Ubuntu Touch. If it is accepted, your app can use the new API.
Click to expand...
Click to collapse
Well, the low-level code, in my case, is the WiFi drivers. Also, I cannot imagine submitting a new API to Ubuntu Touch every-time a new model for accessing system-level primitives arrive. That would essentially loop Canonical into all of our engineering processes.
Your last comment actually is the crux of the issue. It points to a policy question, not a technical one, and one for which the answer is yes or no. I would imagine that, at this point, Canonical already knows the answer...
Principle:
There are numerous situations where it is good for a native application to not be sand-boxed, but have the same access to the Linux subsystems as a user would have on Ubuntu Desktop. There are situations where the owner of the phone would be sophisticated and comfortable enough that s/he can decide for himself/herself whether an application should be allowed root access to the phone. A fellow engineer called this the "welded-hood" principle:
Do people prefer buying cars that have the hoods welded-shut?
Many people might, but there are a significant number who would prefer not. As it turns out, an automobile can dangerous if the person opens the hood and starts working on things that s/he should not be touching (no pun intended). In the case of the fuel and braking system, it can even be lethal. But in the end, it was decided that, since we are all liberated adults, it is better to allow the customer freedom-of-choice.
What we have, right now, is a situation where the "hoods" on all mobile devices are essentially welded shut. I think that is unfortunate, because there is a huge latent demand for mobile devices that "still have their hoods", but if the user chooses to open the hood, with they key word here being easily, that would be his/her prerogative.
By the default, the system should be sand-boxed, but the user should have a facility that allows him/her access to install some native, system-level applications, easily, just as a user is allowed to tap-off her break fluid or bleed the fuel-line if she so desires, even though there are many warnings about what could happen if the application is installed. The "open-the-hood" operation would come with warnings that the user can choose to ignore, with resulting consequences.
Question:
Will Ubuntu Touch allow the owner of an Ubuntu Touch phone to side-load a native C++ application that interfaces with the various existing WiFi drivers in Linux, if the user decides for himself/herself, that it is OK for the application to interface with such drivers?
I have a feeling that the answer is no, but I am asking here to make sure.
RareHare said:
I am in the same situation myself - I do not have enough time to experiment with apparmour, so I'm asking Ubuntu so that I do not have to search/guess.:victory:
So it would seem.
Well, the low-level code, in my case, is the WiFi drivers. Also, I cannot imagine submitting a new API to Ubuntu Touch every-time a new model for accessing system-level primitives arrive. That would essentially loop Canonical into all of our engineering processes.
Your last comment actually is the crux of the issue. It points to a policy question, not a technical one, and one for which the answer is yes or no. I would imagine that, at this point, Canonical already knows the answer...
Principle:
There are numerous situations where it is good for a native application to not be sand-boxed, but have the same access to the Linux subsystems as a user would have on Ubuntu Desktop. There are situations where the owner of the phone would be sophisticated and comfortable enough that s/he can decide for himself/herself whether an application should be allowed root access to the phone. A fellow engineer called this the "welded-hood" principle:
Do people prefer buying cars that have the hoods welded-shut?
Many people might, but there are a significant number who would prefer not. As it turns out, an automobile can dangerous if the person opens the hood and starts working on things that s/he should not be touching (no pun intended). In the case of the fuel and braking system, it can even be lethal. But in the end, it was decided that, since we are all liberated adults, it is better to allow the customer freedom-of-choice.
What we have, right now, is a situation where the "hoods" on all mobile devices are essentially welded shut. I think that is unfortunate, because there is a huge latent demand for mobile devices that "still have their hoods", but if the user chooses to open the hood, with they key word here being easily, that would be his/her prerogative.
By the default, the system should be sand-boxed, but the user should have a facility that allows him/her access to install some native, system-level applications, easily, just as a user is allowed to tap-off her break fluid or bleed the fuel-line if she so desires, even though there are many warnings about what could happen if the application is installed. The "open-the-hood" operation would come with warnings that the user can choose to ignore, with resulting consequences.
Question:
Will Ubuntu Touch allow the owner of an Ubuntu Touch phone to side-load a native C++ application that interfaces with the various existing WiFi drivers in Linux, if the user decides for himself/herself, that it is OK for the application to interface with such drivers?
I have a feeling that the answer is no, but I am asking here to make sure.
Click to expand...
Click to collapse
Well, your comparison is not quite correct. On most phones, there is a way for an educated user to open the hood. This is usually referred to as rooting the phone. Some companies will give you a tool to unlock the bootloader and thus open the hood easily, for others it is a little harder. But any user has the freedom of choice to open the hood or leave it closed.
Now, what you are asking for is something completely different. You are asking for a closed-source "black box" app to get access to what is under the hood, without the user ever opening it. This would mean opening the door for all kinds of malware, and I sure hope this will not be allowed by Ubuntu Touch . Let an educated user open the hood and place the black box there, if he feels comfortable about it, but don't make it too easy. A user that is not willing or not able to open the hood himself should also not be required to understand the consequences of installing a black box app with root privileges.
And there is another thing to consider: Ubuntu is heading for convergence, meaning the same app runs fine on a phone, on a tablet and on a desktop. This means apps must be written against an abstract SDK and not have access to the actual hardware.
Well, I am afraid we have hit a dead end now, unless you are willing to disclose more details on the functionality of your app.
Sent from my TF300T using Tapatalk
83594455 676
And there is another thing to consider: Ubuntu is heading for convergence, meaning the same app runs fine on a phone, on a tablet and on a
desktop. This means apps must be written against an abstract SDK and not have access to the actual hardware.
Click to expand...
Click to collapse
I think my native, system-level app would not only run on all versions of Ubuntu, regardless of device, but most versions of Linux, on 100's of different hardware devices, without changes to my code. So actually, I would be accessing a standard Linux software interface.
Well, I am afraid we have hit a dead end now, unless you are willing to disclose more details on the functionality of your app.
Click to expand...
Click to collapse
Sure. I would like to send and receive raw 802.11 frames from user-space utilizing the various standard Linux 802.11 system-level API's for mesh networking. My application is entirely user-space, and would run on any stock Linux kernel. My field of work is wireless communication, so naturally, if someone were to offer me a mesh-networking packaging as an alternative, I could not use it - my goal is not to have a mesh network for mesh networking sake, but to create a mesh network using my own user-space algorithms. In other words, I really do need access to the 802.11 drivers.
You can run every system command from your app using C++: http://askubuntu.com/questions/288494/run-system-commands-from-qml-app
The sudo password is "phablet". You could also ask the user for it if it was changed. You can pass it like this:
Code:
echo phablet | sudo -S <my command>
That might help you.
You could also ask in the IRC channel for Ubuntu app development (search the internet and you'll find it). Some Canonical people as well as some awesome community members will surely answer your questions. (But tell us the result, please.)
nikwen said:
You can run every system command from your app using C++: http://askubuntu.com/questions/288494/run-system-commands-from-qml-app
The sudo password is "phablet". You could also ask the user for it if it was changed. You can pass it like this:
Code:
echo phablet | sudo -S <my command>
That might help you.
Click to expand...
Click to collapse
That works for the development images and community ports, but I am afraid if you buy a pre-configured UT phone (once they are available), sudo will not work. At least I would be surprised if a company would give full warranty for a device with working sudo.
Sent from my TF300T using Tapatalk
---------- Post added at 11:14 PM ---------- Previous post was at 11:02 PM ----------
RareHare said:
I think my native, system-level app would not only run on all versions of Ubuntu, regardless of device, but most versions of Linux, on 100's of different hardware devices, without changes to my code. So actually, I would be accessing a standard Linux software interface.
Sure. I would like to send and receive raw 802.11 frames from user-space utilizing the various standard Linux 802.11 system-level API's for mesh networking. My application is entirely user-space, and would run on any stock Linux kernel. My field of work is wireless communication, so naturally, if someone were to offer me a mesh-networking packaging as an alternative, I could not use it - my goal is not to have a mesh network for mesh networking sake, but to create a mesh network using my own user-space algorithms. In other words, I really do need access to the 802.11 drivers.
Click to expand...
Click to collapse
Hmm, never really used the user-space network link interface, but I believe it would be possible to grant the required capabilities to a click application.
You would have to figure out, exactly what capabilities your process needs to run this as a non-root user. Then the right place to ask for supporting this would be the Ubuntu Phone mailing list.
Just a Tip: You should present a very strong use case to get this kind of capabilities. The benefits of using your user-space algorithms should be plain, even to someone just scanning over your email.
Sent from my TF300T using Tapatalk
f69m said:
That works for the development images and community ports, but I am afraid if you buy a pre-configured UT phone (once they are available), sudo will not work. At least I would be surprised if a company would give full warranty for a device with working sudo.
Click to expand...
Click to collapse
When nikwen made the suggestion, I was happy for maybe 2-3 seconds, but then caught myself, because I suspected this.
[Notice how I am saving myself enormous amounts of time and frustration by avoiding downloading the SDK, opening my compiler tool-chain, and experimenting., and discovering all the things that you are telling me as we go along (especially about apparmour). Yes, I am very proud of myself for saving myself so much time by asking questions here. :angel:]
So my question still stands:
Under the assumption that my customers (doctors, scientists, etc.) are mature/sophisticated/responsible/whatever enough to know that the application that they are about to install on their smartphone (mine) is potentially very dangerous, but they are still interested in installing my app, and that they are uninterested in going through the manual process of rooting their phone or engaging in any other type of significant manual reconfiguration, what are my options?
Can Ubuntu Phone to be the OS-of-choice for this situation, or am I out-of-luck?
RareHare said:
Under the assumption that my customers (doctors, scientists, etc.) are mature/sophisticated/responsible/whatever enough to know that the application that they are about to install on their smartphone (mine) is potentially very dangerous, but they are still interested in installing my app, and that they are uninterested in going through the manual process of rooting their phone or engaging in any other type of significant manual reconfiguration, what are my options?
Can Ubuntu Phone to be the OS-of-choice for this situation, or am I out-of-luck?
Click to expand...
Click to collapse
Maybe my second answer and your post crossed? But anyhow, here are the steps you can take:
1) Figure out the minimum set of capabilities your process needs to run as a non-root user.
2) Write an email to the Ubuntu Phone mailing list, describing the required capabilities and a convincing use case that motivates the engineers to have a hard look into it.
Honestly, I think the chances are slim, given the kind of capabilities you probably need. But Ubuntu Touch is probably your best bet of all the OSs out there.
EDIT: Mind that Ubuntu Touch uses a read-only rootfs, with only some config files being writable (via bind mount) and apt/dpkg is not supported. Your app must be running as a click package as a non-root user, but I believe it is technically possible to elevate an app process with certain capabilities. It would be your job to convince Canonical to make the policy decision to support it and to make the effort of implementing it.
EDIT2 (you see, I am giving it some thought): Not sure, how your business plan looks like or if your app makes this approach feasible, but another option could be to open-source your basic algorithms and try to have them included into Ubuntu Touch. Then cash in on an app to make the features easily accessible.
f69m said:
That works for the development images and community ports, but I am afraid if you buy a pre-configured UT phone (once they are available), sudo will not work. At least I would be surprised if a company would give full warranty for a device with working sudo.
Sent from my TF300T using Tapatalk
---------- Post added at 11:14 PM ---------- Previous post was at 11:02 PM ----------
Hmm, never really used the user-space network link interface, but I believe it would be possible to grant the required capabilities to a click application.
You would have to figure out, exactly what capabilities your process needs to run this as a non-root user. Then the right place to ask for supporting this would be the Ubuntu Phone mailing list.
Just a Tip: You should present a very strong use case to get this kind of capabilities. The benefits of using your user-space algorithms should be plain, even to someone just scanning over your email.
Sent from my TF300T using Tapatalk
Click to expand...
Click to collapse
Hm...it would be a bit weird for me to justify the benefits my user-space algorithms to Canonical. My app is not an open-source app. I guess I should have mentioned that first. In any case, I can say that I am "experienced" in this field, and my colleagues, at least, are experts in the field, so if the question is whether I am mistaken in thinking I need this capability, the answer is probably no.
However, you do have me intrigued regarding the granting of capability for a click application. My guess is that this would have to happen within the context of Ubuntu Store and not any other way or?
I ask because it is not yet definite that we will choose Ubuntu Phone. That is what I am determining now. I would hate to get into a situation where we have to "work with" Canonical to get access to the Linux API that we need, which is why I was suggesting putting the decision into the hands of the user. I would also like to avoid "lobbying" Canonical for a feature. It would be more efficient for us if Canonical would simply tell us whether they are going to allow it or not, to what extent, and what would be involved.
Again, what we are asking for is pretty straightforward - access to the standard Linux WiFi drivers from user-space.
There's really not much more to it. I was hoping that, based upon the assumption that we actually need this, that Canonical would be able to give us an answer.
[P.S. Yes, our posts got crossed. ]
RareHare said:
Hm...it would be a bit weird for me to justify the benefits my user-space algorithms to Canonical. My app is not an open-source app. I guess I should have mentioned that first.
Click to expand...
Click to collapse
Well, I somehow guessed it would not be open source, and probably my EDIT2 to my last post (crossed again) is not an option. But make sure to read my first EDIT, it might have helpful information.
I think the question is not, if it is a benefit to Canonical directly, but if it is a benefit to potential users of Ubuntu Touch. The API support you need might be helpful for other applications too.
RareHare said:
However, you do have me intrigued regarding the granting of capability for a click application. My guess is that this would have to happen within the context of Ubuntu Store and not any other way or?
I ask because it is not yet definite that we will choose Ubuntu Phone. That is what I am determining now. I would hate to get into a situation where we have to "work with" Canonical to get access to the Linux API that we need, which is why I was suggesting putting the decision into the hands of the user. I would also like to avoid "lobbying" Canonical for a feature. It would be more efficient for us if Canonical would simply tell us whether they are going to allow it or not, to what extent, and what would be involved.
Click to expand...
Click to collapse
Any decision taken by the user must first be implemented by Canonical, or there is no way for the user to make that decision. Unfortunately, I am not an expert on UT app development and the UT SDK, working mostly on low-level things like porting UT to my own device. But, as an example, it should be possible to have an API that creates a sub-process with elevated capabilities (there might be a more elegant solution). Still Canonical will have to implement that and to do this, they need some kind of motivation. The motivation could be a good use case that shows potential for other applications or indeed "lobbying" them directly (which probably means to send them some money).
RareHare said:
Again, what we are asking for is pretty straightforward - access to the standard Linux WiFi drivers from user-space.
There's really not much more to it. I was hoping that, based upon the assumption that we actually need this, that Canonical would be able to give us an answer.
Click to expand...
Click to collapse
I have not really used those APIs, but I assume that the kernel capabilities needed for this are usually granted to the root user only. I am pretty certain that UT will not allow you to run a process as root, but as mentioned above, it should be possible to create a subprocess with certain elevated capabilities.
f69m said:
Well, I somehow guessed it would not be open source, and probably my EDIT2 to my last post (crossed again) is not an option. But make sure to read my first EDIT, it might have helpful information.
Click to expand...
Click to collapse
OK.
f69m said:
I think the question is not, if it is a benefit to Canonical directly, but if it is a benefit to potential users of Ubuntu Touch. The API support you need might be helpful for other applications too.
Click to expand...
Click to collapse
Well, the API that I need is definitely helpful for other applications. Namely, it is helpful to any application that already uses it. And there are many such applications that use the 802.11 WiFi drivers that come with Linux.
Any decision taken by the user must first be implemented by Canonical, or there is no way for the user to make that decision. Unfortunately, I am not an expert on UT app development and the UT SDK, working mostly on low-level things like porting UT to my own device. But, as an example, it should be possible to have an API that creates a sub-process with elevated capabilities (there might be a more elegant solution). Still Canonical will have to implement that and to do this, they need some kind of motivation. The motivation could be a good use case that shows potential for other applications or indeed "lobbying" them directly (which probably means to send them some money).
I have not really used those APIs, but I assume that the kernel capabilities needed for this are usually granted to the root user only. I am pretty certain that UT will not allow you to run a process as root, but as mentioned above, it should be possible to create a sub-process with certain elevated capabilities.
Click to expand...
Click to collapse
OK.
I am going to send an email to Canonical asking if they could articulate, clearly, in a manner that a Linux C/C++ software engineer can understand, their policy on native application development. Here's what it currently says on their Wiki:
Which applications do run on Ubuntu Touch?
Ubuntu Touch is primarily designed to support web apps, and native apps programmed in qml and javascript or C++. As it is a real linux, of course all non graphical applications run equally as on any other linux system. You can ssh to Ubuntu Touch and run any console based application.
X11 is not supported (so far) so all GUI standard applications will not run.​
This is slightly confusing, because it gives the impression that, with the exception of X11, the run-time environment on Ubuntu Touch is equal to the run-time environment on Ubuntu Desktop.
Obviously, that is not true. Native applications on Ubuntu Touch are sand-boxed. My customer can run a console app on Ubuntu Desktop just fine, but on Ubuntu Touch, she cannot not - I guess she could if she rooted or re-flashed her phone, but that is not practical.
I think Canonical should make it clear that native C/C++ applications on Ubuntu Touch will be sand-boxed. Then they should articulate, clearly on their web site, just how that works, at least the part that they know so far.
The reason I feel this is necessary is that there are a lot of developers who read the press releases and see the words open source native C/C++, more open than Android, etc...and they get the impression that it is basically Ubuntu Desktop for small form-factor, but that is not quite true.
Spelling-out, explicitly, Canonical's native C/C++ strategy would save such developers a lot of time and hacking trying to figure out what is feasible and what is not.
To be fair, I just received feedback from a competitor to Ubuntu Touch, giving me assurances that the competing OS will allow the user/owner of the phone to determine whether any software should have root access, etc - basically, like the desktop version of the OS. I will send them an email asking them if they could make public what they have assured me in private.
These are things that should be crystal clear to C/C++ software developers long in advance before committing to a platform. I can only imagine the time that would have been lost if I had misinterpreted what Canonical wrote above, only to find out that there is nothing practical that my customer can do to install my application as easily as they would on Ubuntu Desktop because of the sandbox that cannot be easily turned-off.
RareHare said:
I think Canonical should make it clear that native C/C++ applications on Ubuntu Touch will be sand-boxed. Then they should articulate, clearly on their web site, just how that works, at least the part that they know so far.
Click to expand...
Click to collapse
Of course I can't speak for Canonical and I might be wrong, but I would really be surprised, if it was possibly to run applications as root on an off-the-shelf Ubuntu Touch device.
RareHare said:
To be fair, I just received feedback from a competitor to Ubuntu Touch, giving me assurances that the competing OS will allow the user/owner of the phone to determine whether any software should have root access, etc - basically, like the desktop version of the OS. I will send them an email asking them if they could make public what they have assured me in private.
Click to expand...
Click to collapse
Interesting, but then it might be a difference between the "reference" implementation and what is being delivered on an out-of-the-shelf phone. I can't belive a device vendor to take the risk of allowing root access and still providing full warranty. Most likely the user will have to accept a "no warranty" waiver to get root access, if that feature is not completly disabled by the device vendor. The same kind of holds for UT, as sudo works on the development images as mentioned previously.
EDIT: Make sure the feedback you received does refer to an actual device that is/will be available for sale and not to a development platform. Marketing wording can be tricky about simple issues like that,
RareHare said:
These are things that should be crystal clear to C/C++ software developers long in advance before committing to a platform. I can only imagine the time that would have been lost if I had misinterpreted what Canonical wrote above, only to find out that there is nothing practical that my customer can do to install my application as easily as they would on Ubuntu Desktop because of the sandbox that cannot be easily turned-off.
Click to expand...
Click to collapse
Agreed, but the same holds for any other platform.
f69m said:
Of course I can't speak for Canonical and I might be wrong, but I would really be surprised, if it was possibly to run applications as root on an off-the-shelf Ubuntu Touch device.
Interesting, but then it might be a difference between the "reference" implementation and what is being delivered on an out-of-the-shelf phone. I can't belive a device vendor to take the risk of allowing root access and still providing full warranty. Most likely the user will have to accept a "no warranty" waiver to get root access, if that feature is not completly disabled by the device vendor. The same kind of holds for UT, as sudo works on the development images as mentioned previously.
Agreed, but the same holds for any other platform.
Click to expand...
Click to collapse
I was very careful in asking the UT-competitor what their policy would be with regard to the subject of this thread, and they assured me that, when they say open, they really do mean open, as in open-like-the-desktop. However, just now, I found clues on the Internet what they said might not be quite true. So I just sent a grab-me-by-the-ears-while-you-are-speaking email asking them to be clear.
However, they have committed to allowing the user to install my application. They know that my application will open a device driver, and they said that it should work fine, that they would allow the user to do it, and that they had already intended to create a feature where the user gets to decide, after a WARNING, though they are not yet certain what this feature will be called. Note that they are not doing this for me alone. They are doing it, in general. In other words, they are doing what I proposed earlier: give the user the choice of whether to "use metal chainsaw".
As far as voiding the warranty goes...honestly, I do not think that will be a problem. As you know, I can write software that will wipe my hard disk clean on Windows, right now, put it up on my web site, and anyone in the world can download that software, and the most that will happen before they install my application is that they will get a brief warning. So the model for allowing the user to do foolish things has been with us for a while, and companies are still very profitable with this model, and despite viruses (I developed anti-virus algorithm that some of you use, btw), most people are happy with the level-of-control they get with their desktop devices. When Windows Vista tried to remove some of it, even moderate users were very angry, as you know.
I think that, especially for cell-phone carriers in the USA (Verizon, AT&T, Sprint)...the reason is not so much to protect the consumer, but to make sure that the user is not able...for example...to remove the bloatware that they put on the phone. It is more about controlling the customer experience for profit than for protection or being liable for damages.
The UT-competitor has probably figured out that there is a market for a truly open mobile platform, one where the decision of what happens to the device reverts to the owner of the device. They are probably counting on all the pent-up demand of C/C++/etc. native software developers who have been trying to escape the Android/Java iOS/* Sandbox, and not only that, the developers who are able to create revolutionary innovations if they had more access to the Linux API. My guess is that, once one OEM takes this path, the others will not have any choice but to follow, because there will be a free-for-all (no pun intended) in the development market. It will be messy, perhaps, but there will no longer be any restrictions on getting the most out of the device.
It will definitely be more efficient to decouple development from deliverance.
Well, sounds good, just hope that they will find an OEM that shares their views. I think Desktop/Windows is not a relevant reference, as nobody will send their PC back to Microsoft, if it is not working. And if you want to use official MS support you are paying dearly. On the other hand support/warranty is a huge concern for phone and tablet vendors.
Again, not being able to run a process as root on a UT device is my personal opinion and I am not speaking for Canonical or their partners.
EDIT: Do the "bad" operations you mentioned work on Windows 8 phone? I suppose not.
Sent from my TF300T using Tapatalk

How can I learn how Android works?

I'm not a developer but I have knowledge about Linux and how PCs in general work. Is there any book/course that explains how android works on a deeper level? I'm not interested in apps or user UIs, I want to know the deeper levels like how partitioning works, how the OS is loaded, why some bootloaders are locked by default, what a custom recovery is or what is the first thing to load when you power on your phone/tablet (do phones have a BIOS like PCs or anything equivalent?). Thanks in advance.
I'm also interested in this, but I think the answer is it's a bunch of undocumented proprietary baseband processor junk nobody will share for the boot, then the rest is basically a Linux distro made by 1000 monkeys on 1000 typewriters copy/pasting stuff provided by their hardware vendors together, and the components of that also probably have no documentation or incorrect documentation.
Just browsing through directory structures on a rooted phone there's so much unused and inaccessible junk like config files for really old versions of android, random vendor apks that aren't configured, and firmware for other processors strewn all over, sometimes multiple copies of the same structure, that it makes no sense. It looks like a bunch of vendors gave their support libraries to manufacturers with the intent they'd delete the unused parts and copy the used parts in, but the manufacturers don't understand how to do that so they just paste the same full directory structure several different places until it starts working.
If it made any sense, some people would just learn it and rooting new phones wouldn't be hard.
dan2525 said:
I'm not a developer but I have knowledge about Linux and how PCs in general work. Is there any book/course that explains how android works on a deeper level? I'm not interested in apps or user UIs, I want to know the deeper levels like how partitioning works, how the OS is loaded, why some bootloaders are locked by default, what a custom recovery is or what is the first thing to load when you power on your phone/tablet (do phones have a BIOS like PCs or anything equivalent?). Thanks in advance.
Click to expand...
Click to collapse
The rabbit hole goes as deep as you want it to. I have plenty of information to get you started. Happy digging!
*A general overview of the android boot process, thanks to the Lineage OS developers.
*An old, but good read on reverse engineering aboot.
*And a much more recent article on reverse engineering android. It gets very detailed in this one. It also goes into the low level processes of android. Like; What loads the bootloader? That kind of stuff. I think this is what you're after. Hope it helps.
About the bios question. The short answer is, "kind of". They have a very simple and proprietary one that's not easy to access. It also does not function in the same ways that a PC bios does. It's more like a motherboard programmer. It's hard to explain. The last article goes into some of that.
Spaceminer said:
The rabbit hole goes as deep as you want it to. I have plenty of information to get you started. Happy digging!
*A general overview of the android boot process, thanks to the Lineage OS developers.
*An old, but good read on reverse engineering aboot.
*And a much more recent article on reverse engineering android. It gets very detailed in this one. It also goes into the low level processes of android. Like; What loads the bootloader? That kind of stuff. I think this is what you're after. Hope it helps.
About the bios question. The short answer is, "kind of". They have a very simple and proprietary one that's not easy to access. It also does not function in the same ways that a PC bios does. It's more like a motherboard programmer. It's hard to explain. The last article goes into some of that.
Click to expand...
Click to collapse
Do you know if there is any tool that lists all the various initscripts and settings in use on a running system? I'd like to remove Google entirely from my phone, but there are so many firmwares and initscripts all over the place that I can't even figure out which ones are actually used to run the system. Half of the settings files, properties, and commands return 0 results or 3-4 useless results when searching for them on the internet.
ZHNN said:
Do you know if there is any tool that lists all the various initscripts and settings in use on a running system? I'd like to remove Google entirely from my phone, but there are so many firmwares and initscripts all over the place that I can't even figure out which ones are actually used to run the system. Half of the settings files, properties, and commands return 0 results or 3-4 useless results when searching for them on the internet.
Click to expand...
Click to collapse
The best way to remove google entirely is to flash a custom ROM or GSI if your device supports it. You really only need to look in system/app and system/priv-app for google stuff. Some phones use stock Google apps for things like the Calendar or MMS. So, to run google-less you may need to replace some system apps as well. Just a warning, even if you already know this. Removing certain apps, even google apps, may cause problems for normal operation. Definitely make a backup before deleting anything in the system.
ZHNN said:
Do you know if there is any tool that lists all the various initscripts and settings in use on a running system? I'd like to remove Google entirely from my phone, but there are so many firmwares and initscripts all over the place that I can't even figure out which ones are actually used to run the system. Half of the settings files, properties, and commands return 0 results or 3-4 useless results when searching for them on the internet.
Click to expand...
Click to collapse
I'm no expert but have been running lineageos 14.1 for some time now. It is a version of android 7.1 in which everything google has been removed. I use it with microG which replaces google play services.
You may wish to look into it instead of re-inventing the wheel.
I use it with a firewall (AFWall +), and Xprivacylua for additional privacy.

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