Develop Reference

Debugging a native application with GDB on Android

I have a native C++ app which is supposed to run on an Android device. The application crashes at the startup, most likely when calling a function from a linked library. I am trying to debug it with gdb, but I can't succeed.
I am starting gdbserver on the Android device on some arbitrarily picked port (2000):
shell#msm8996: gdbserver :2000 my_app
Process my_app created; pid = 3420
Listening on port 2000
Now I am trying to attach to this process on my Host system (Windows 7) with gdb that was provided in Android-NDK.
C:\> gdb
(gdb) attach 3420
Can't attach to process.
(gdb) target remote :2000
:2000: The system tried to join a drive to a directory on a joined drive.
What is the problem?
EDIT:
Prior to running gdb I forwarded the port 2000 using adb:
adb forward tcp:2000 tcp:2000
This at least helped me to establish some communication, but:
(gdb) target remote :2000
Remote debugging using :2000
warning: Architecture rejected target-supplied description
Remote 'g' packet reply is too long: 00000000000000000000000000000...
On the device side:
Listening on port 2000
Remote debugging from host 127.0.0.1
readchar: Got EOF
Remote side has terminated connection. GDBserver will reopen the connection.
Listening on port 2000

You are most probably using different architecture / version of gdb. When you start the gdb, it displays a line like (I am showing what my GDB shows):
This GDB was configured as "--host=x86_64-linux-gnu
--target=arm-Linux-android"
Check if this matches with your phone's architecture.
Downloading the correct GDB version may solve your problem.

Android remote gdb output is painfully slow

I am debugging C++ library for Android with GDB (gdbserver + gdb on host), and I've noticed that gdb output is very very slow.
E.g. application has about 15 threads, and when I type thread apply all bt it takes 15-20 seconds to output all stacktraces to terminal/file. All output is about 200 lines of text, it should not be that slow!
Moreover, on my host machine (64-bit Ubuntu) the same thing takes no more than 0.1-0.2 seconds!
I suspected that terminal output on host may be the cause of slowdown, but it is not the case. Even with the following settings it takes the same amount of time:
set width 0
set height 0
set pagination 0
set logging redirect on
set logging overwrite on
set logging file prof.txt
set logging on
I am not completely sure what is the main cause of slowdown, it is either slow stack unwinding on Android or slow transfer of data via gdb<-->gdbserver connection. But I am suspecting the latter, because when gdb outputs data the adb process consumes a lot of CPU time.
My question is: how do I make the gdb output to file faster?
Please help, if anyone knows how to achieve one of the following:
Set some gdb/adb options to make the data transfer faster
make gdbserver save data to local file (on Android device) instead of sending it to remote gdb client
Build gdb client for target device and debug on the device
EDIT:
It worth mentioning that I am using adb forward to establish tcp connection between gdb and gdbserver:
adb push $NDK_ROOT/prebuilt/android-arm/gdbserver/gdbserver /data/local/tmp
adb shell chmod 777 /data/local/tmp/gdbserver
adb shell /data/local/tmp/gdbserver :5039 --attach $1 &
adb forward tcp:5039 tcp:5039

Port of adb tool to run on Android device failing to bind TCP port 5037

I want to use adb to install apps to my Android-based TV from an Android phone rather than a computer.
So I decide to read adb source code, port the adb code and compile it to a library file (libadb.so) and then invoke it by JNI from within an Android app.
When I test this apk on my telephone, the adb server fails with can not bind 'tcp:5037' port.
I thought the failure to open that port might be a conflict with the existing implementation of ADB which might be using it, so I removed that. It didn't work. I tried to change to other ports, such as 4097,or 6066. It still didn't work. I have no further ideas how to solve this problem.

Android enforces its Internet Permission via a modification to the Linux Kernel which checks that a process is a member of an associated unix group before allowing it to open sockets in the AF_INET domain.
Such membership is inherited, so native code executed, either as a JNI library or by invoking a distinct executable, will only be able to perform network operations if it is either run as a privileged user automatically having this membership (such as adb's "shell" account, or as root on an engineering build) or run under the identify of an application package having the Internet permission in its manifest.
There may be a number of additional challenges with your goal (and it is unclear why the stock adb client on the device is not workable for you), but the immediate solution to your present problem is to run your customized adb tool from an application with Internet permission.

How an Android native executable accept external socket connections?

I am working on developing an Android native executable service which is launched by init(I register it in init.rc) when system boots up. This native executable creates a socket listening on 0.0.0.0:4615 and is supposed to accept connections from outside.
OS is Android K; it runs on a development kit which has Ethernet interface for plugging it onto a Lan.
I have done the test running the same native executable in adb shell as root. It works fine - an external socket client on my Windows machine can connect to the native executable and send/recv message successfully. When I have it launched by init, it listens to 0.0.0.0:4615 successfully, but the external socket client cannot connect to it - connection refused.
The snippet I added in init.rc is:
service msger-daemon /system/bin/msgerd
class main
When "ps" to check the user of msgerd, we found it was root.
Please help, thanks!

Solved by adding a SE policy file under $TOP/external/sepolicy, the content of that file is:
# File types must be defined for file_contexts.
type msgerd, domain;
type msgerd_exec, exec_type, file_type;
init_daemon_domain(msgerd)
permissive msgerd;
# Add msgerd to various domains
net_domain(msgerd)
allow msgerd self:capability { net_admin net_raw };
If anyone would like to review and advice, welcome!

Getting "Launch error: Failed to connect to remote VM. Connection timed out" when trying to debug my app on my device in android

I tried all the possible options given on net and on this site, but none of them worked.
I am getting:
Launch error: Failed to connect to remote VM. Connection timed out.
when I am trying to debug my application on my mobile device.
the application runs properly with out any issue when I am running normally
I have used at lease these links by now:
How to resolve "Waiting for Debugger" message?
Eclipse issue - Launch error: Failed to connect to remote VM. Connection timed out
Eclipse Error: "Failed to connect to remote VM"
Launch error: Failed to connect to remote VM
https://forums.oracle.com/forums/thread.jspa?threadID=653343
None of the above seem to work.

Go to Window -> Preferences -> General -> Network Connections, and check if there is any proxy set here, change the 'Active Provider' to be 'Direct' and try again.

I dont know why, but this works for me:
First Run(or Debug) your application in an emulator and then Debug the application on the device (without closing the emulator).
let me know if this works for you.

I've been having the same frustrating problem. I finally found something that is working for me: making sure localhosts is being resolved correctly (and really explicitly).
Test to see if it works when your development machine is not connected to the net (no WiFi, no network cables). If it does work under those conditions, then it may be that you need to make sure that addresses are resolving to localhost properly. The messages that DDMS and adb.exe use for debugging and communicating to the VM must properly resolve to localhost on your machine. (Yes, it's odd that other commands using DDMS & adb work just fine but debugging doesn't. Seems that something in DDMS or adb needs to be standardized so they all work under the same conditions.)
If you need to make sure that things are resolving to localhost properly:
1) Make sure that this line is in your /Windows/System32/drivers/etc/hosts [windows] (or etc/hosts [*nix] file:
127.0.0.1 localhost
(you can have any amount of whitespace between "127.0.0.1" and "localhost")
2) If that doesn't work, then you may need to also add your PC's IPv4 address to the hosts file, and resolve it to localhost. (You can find out the IPv4 address for your machine with the ipconfig command.) If, for example, your machine's IPv4 address is 192.168.1.100 then you'd add the line
192.168.1.100 localhost
to your hosts file. (You can add it below the "127.0.0.1 localhost" line in the file.)
I had (1) in my hosts file but it still wasn't working (unless my PC wasn't connected to the net). I tried (2) on a bit of a guess, and that worked for me.
BTW: You can verify that adb (and your emulator if you're running one) is listening on ports by using the netstat -b command. (Note that on Win7 you need admin privileges for the -b option. I open a command window using "Run as Administrator.")

May seem like an obvious answer but make sure you don't have two emulators running - 5554; 5556; ... The debugger has difficulty setting the port when it doesn't know which one to connect to.