Develop Reference

Android Gdb gcore "command not implemented for this target"

I am using gdb for dumping core file for an android process. I am running gdbserver on the device on tcp port and gdb client on the desktop. When i do gcore on client i get the below error.
Does any one know why i'm getting this error , any help much appreciated.
(gdb) gcore
Command not implemented for this target.
The reason i'm doing this to dump process memory and extract Classes.dex file from the memory using core file. I've tried doing this using /proc/pid/mem and proc/pid/maps and dump memory but that has too many mapped regions , i couldn't find the area where the Classes.dex file is. Any other alternate approach is also welcome. Thanks for your help.

First of all, you can only dump odex from memory (because dex compiled to odex for execute). But its not a big deal to convert odex to dex using baksmali-smali.
To find odex in memory you can use gdb for checking magic number for every begin-address of mapped memory(proc/pid/maps - first column):
gdb --batch --pid "pid_task" -ex x/s "mem_start"
So, when returned value equal to "dey\n036", you can dump this memory region via gdb.
Try to begin checking memory addresses from the end of file "proc/pid/maps", it will be much faster.
PS Sorry for my english, but hope it will help.

#Chris Stratton, the memory mapped classes.dex file will be different from the dex file inside apk on disk, for example in cases of packed dex files, some part of dex will be deobfuscated, question is to dump the memory mapped classes.dex file by getting the process memory.

You can use GameGuardian for this. Need root.
Memory editor tab - menu - memory dump - input 0-0 as range and folder - press ok - wait for toast Dump end.
Go to selected folder - open maps file - search needed odex in regions - remember start address of region - open GameGuardian - menu - memory dump - input remembered address in both field as range - press ok - wait for toast Dump end.
Now you have in your folder .bin file with dumped odex file.
Also you can find address in drop down list in GameGuardian UI. Press drop down icon on right with dump range field.
Here some video examples how to do this:
How to dump odex file from memory on Android -
GameGuardian

LogCat error: Error opening trace file: No such file or directory (2) [duplicate]

I am getting the above error:
error opening trace file: No such file or directory (2)
when I run my android application on the emulator. Can someone tell me what could be the possible reason for this?
I am using android-sdk-20 and below lines are added to AndroidManifest.xml
<uses-sdk android:minSdkVersion="14" android:targetSdkVersion="15" />
I have also added the line:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
since I thought that there may be some issue with writing to the sd card.

It happens because you have not installed the minSdkVersion or targetSdkVersion in you’re computer. I've tested it right now.
For example, if you have those lines in your Manifest.xml:
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
And you have installed only the API17 in your computer, it will report you an error. If you want to test it, try installing the other API version (in this case, API 8).
Even so, it's not an important error. It doesn't mean that your app is wrong.
Sorry about my expression. English is not my language.
Bye!

I think this is the problem
A little background
Traceview is a graphical viewer for execution logs that you create by using the Debug class to log tracing information in your code. Traceview can help you debug your application and profile its performance. Enabling it creates a .trace file in the sdcard root folder which can then be extracted by ADB and processed by traceview bat file for processing. It also can get added by the DDMS.
It is a system used internally by the logger. In general unless you are using traceview to extract the trace file this error shouldnt bother you. You should look at error/logs directly related to your application
How do I enable it:
There are two ways to generate trace logs:
Include the Debug class in your code and call its methods such as startMethodTracing() and stopMethodTracing(), to start and stop
logging of trace information to disk. This option is very precise
because you can specify exactly where to start and stop logging trace
data in your code.
Use the method profiling feature of DDMS to generate trace logs. This option is less precise because you do not modify code, but rather
specify when to start and stop logging with DDMS. Although you have
less control on exactly where logging starts and stops, this option is
useful if you don't have access to the application's code, or if you
do not need precise log timing.
But the following restrictions exist for the above
If you are using the Debug class, your application must have
permission to write to external storage (WRITE_EXTERNAL_STORAGE).
If you are using DDMS: Android 2.1 and earlier devices must have an SD
card present and your application must have permission to write to the
SD card. Android 2.2 and later devices do not need an SD card. The
trace log files are streamed directly to your development machine.
So in essence the traceFile access requires two things
1.) Permission to write a trace log file i.e. WRITE_EXTERNAL_STORAGE and READ_EXTERNAL_STORAGE for good measure
2.) An emulator with an SDCard attached with sufficient space. The doc doesnt say if this is only for DDMS but also for debug, so I am assuming this is also true for debugging via the application.
What do I do with this error:
Now the error is essentially a fall out of either not having the sdcard path to create a tracefile or not having permission to access it. This is an old thread, but the dev behind the bounty, check if are meeting the two prerequisites. You can then go search for the .trace file in the sdcard folder in your emulator. If it exists it shouldn't be giving you this problem, if it doesnt try creating it by adding the startMethodTracing to your app.
I'm not sure why it automatically looks for this file when the logger kicks in. I think when an error/log event occurs , the logger internally tries to write to trace file and does not find it, in which case it throws the error.Having scoured through the docs, I don't find too many references to why this is automatically on.
But in general this doesn't affect you directly, you should check direct application logs/errors.
Also as an aside Android 2.2 and later devices do not need an SD card for DDMS trace logging. The trace log files are streamed directly to your development machine.
Additional information on Traceview:
Copying Trace Files to a Host Machine
After your application has run
and the system has created your trace files .trace on
a device or emulator, you must copy those files to your development
computer. You can use adb pull to copy the files. Here's an example
that shows how to copy an example file, calc.trace, from the default
location on the emulator to the /tmp directory on the emulator host
machine:
adb pull /sdcard/calc.trace /tmp Viewing Trace Files in Traceview To
run Traceview and view the trace files, enter traceview
. For example, to run Traceview on the example files
copied in the previous section, use:
traceview /tmp/calc Note: If you are trying to view the trace logs of
an application that is built with ProGuard enabled (release mode
build), some method and member names might be obfuscated. You can use
the Proguard mapping.txt file to figure out the original unobfuscated
names. For more information on this file, see the Proguard
documentation.
I think any other answer regarding positioning of oncreate statements or removing uses-sdk are not related, but this is Android and I could be wrong. Would be useful to redirect this question to an android engineer or post it as a bug
More in the docs

Try removing the uses-sdk part form AndroidManifest.xml file. it worked for me!
Don't use the Android Virtual Device with too low configuration. Let it be medium.

Write all your code below this 2 lines:-
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
It worked for me without re-installing again.

I didn't want to reinstall everything because I have so many SDK versions installed and my development environment is set up just right. Getting it set up again takes way too long.
What worked for me was deleting, then re-creating the Android Virtual Device, being certain to put in a value for SD Card Size (I used 200 MiB).
Additional information:
while the above does fix the problem temporarily, it is recurring. I just tried my application within Android Studio and saw this in the output log which I did not notice before in Eclipse:
"/Applications/Android Studio.app/sdk/tools/emulator" -avd AVD_for_Nexus_S_by_Google -netspeed full -netdelay none
WARNING: Data partition already in use. Changes will not persist!
WARNING: SD Card image already in use: /Users/[user]/.android/avd/AVD_for_Nexus_S_by_Google.avd/sdcard.img
ko:Snapshot storage already in use: /Users/[user]/.android/avd/AVD_for_Nexus_S_by_Google.avd/snapshots.img
I suspect that changes to the log are not saving to the SD Card, so when LogCat tries to access the logs, they aren't there, causing the error message. The act of deleting the AVD and re-creating it removes the files, and the next launch is a fresh launch, allowing LogCat to access the virtual SD Card.

You will not have access to your real sd card in emulator. You will have to follow the steps in this tutorial to direct your emulator to a directory on your development environment acting as your SD card.

Actually, the problem is that either /sys/kernel/debug is not mounted, or that the running kernel has no ftrace tracers compiled in so that /sys/kernel/debug/tracing is unavailable. This is the code throwing the error (platform_frameworks_native/libs/utils/Trace.cpp):
void Tracer::init() {
Mutex::Autolock lock(sMutex);
if (!sIsReady) {
add_sysprop_change_callback(changeCallback, 0);
const char* const traceFileName =
"/sys/kernel/debug/tracing/trace_marker";
sTraceFD = open(traceFileName, O_WRONLY);
if (sTraceFD == -1) {
ALOGE("error opening trace file: %s (%d)", strerror(errno), errno);
sEnabledTags = 0; // no tracing can occur
} else {
loadSystemProperty();
}
android_atomic_release_store(1, &sIsReady);
}
}
The log message could definitely be a bit more informative.

Error opening trace file: No such file or directory (2) in logcat [duplicate]

I am getting the above error:
error opening trace file: No such file or directory (2)
when I run my android application on the emulator. Can someone tell me what could be the possible reason for this?
I am using android-sdk-20 and below lines are added to AndroidManifest.xml
<uses-sdk android:minSdkVersion="14" android:targetSdkVersion="15" />
I have also added the line:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
since I thought that there may be some issue with writing to the sd card.

It happens because you have not installed the minSdkVersion or targetSdkVersion in you’re computer. I've tested it right now.
For example, if you have those lines in your Manifest.xml:
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
And you have installed only the API17 in your computer, it will report you an error. If you want to test it, try installing the other API version (in this case, API 8).
Even so, it's not an important error. It doesn't mean that your app is wrong.
Sorry about my expression. English is not my language.
Bye!

I think this is the problem
A little background
Traceview is a graphical viewer for execution logs that you create by using the Debug class to log tracing information in your code. Traceview can help you debug your application and profile its performance. Enabling it creates a .trace file in the sdcard root folder which can then be extracted by ADB and processed by traceview bat file for processing. It also can get added by the DDMS.
It is a system used internally by the logger. In general unless you are using traceview to extract the trace file this error shouldnt bother you. You should look at error/logs directly related to your application
How do I enable it:
There are two ways to generate trace logs:
Include the Debug class in your code and call its methods such as startMethodTracing() and stopMethodTracing(), to start and stop
logging of trace information to disk. This option is very precise
because you can specify exactly where to start and stop logging trace
data in your code.
Use the method profiling feature of DDMS to generate trace logs. This option is less precise because you do not modify code, but rather
specify when to start and stop logging with DDMS. Although you have
less control on exactly where logging starts and stops, this option is
useful if you don't have access to the application's code, or if you
do not need precise log timing.
But the following restrictions exist for the above
If you are using the Debug class, your application must have
permission to write to external storage (WRITE_EXTERNAL_STORAGE).
If you are using DDMS: Android 2.1 and earlier devices must have an SD
card present and your application must have permission to write to the
SD card. Android 2.2 and later devices do not need an SD card. The
trace log files are streamed directly to your development machine.
So in essence the traceFile access requires two things
1.) Permission to write a trace log file i.e. WRITE_EXTERNAL_STORAGE and READ_EXTERNAL_STORAGE for good measure
2.) An emulator with an SDCard attached with sufficient space. The doc doesnt say if this is only for DDMS but also for debug, so I am assuming this is also true for debugging via the application.
What do I do with this error:
Now the error is essentially a fall out of either not having the sdcard path to create a tracefile or not having permission to access it. This is an old thread, but the dev behind the bounty, check if are meeting the two prerequisites. You can then go search for the .trace file in the sdcard folder in your emulator. If it exists it shouldn't be giving you this problem, if it doesnt try creating it by adding the startMethodTracing to your app.
I'm not sure why it automatically looks for this file when the logger kicks in. I think when an error/log event occurs , the logger internally tries to write to trace file and does not find it, in which case it throws the error.Having scoured through the docs, I don't find too many references to why this is automatically on.
But in general this doesn't affect you directly, you should check direct application logs/errors.
Also as an aside Android 2.2 and later devices do not need an SD card for DDMS trace logging. The trace log files are streamed directly to your development machine.
Additional information on Traceview:
Copying Trace Files to a Host Machine
After your application has run
and the system has created your trace files .trace on
a device or emulator, you must copy those files to your development
computer. You can use adb pull to copy the files. Here's an example
that shows how to copy an example file, calc.trace, from the default
location on the emulator to the /tmp directory on the emulator host
machine:
adb pull /sdcard/calc.trace /tmp Viewing Trace Files in Traceview To
run Traceview and view the trace files, enter traceview
. For example, to run Traceview on the example files
copied in the previous section, use:
traceview /tmp/calc Note: If you are trying to view the trace logs of
an application that is built with ProGuard enabled (release mode
build), some method and member names might be obfuscated. You can use
the Proguard mapping.txt file to figure out the original unobfuscated
names. For more information on this file, see the Proguard
documentation.
I think any other answer regarding positioning of oncreate statements or removing uses-sdk are not related, but this is Android and I could be wrong. Would be useful to redirect this question to an android engineer or post it as a bug
More in the docs

Try removing the uses-sdk part form AndroidManifest.xml file. it worked for me!
Don't use the Android Virtual Device with too low configuration. Let it be medium.

Write all your code below this 2 lines:-
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
It worked for me without re-installing again.

I didn't want to reinstall everything because I have so many SDK versions installed and my development environment is set up just right. Getting it set up again takes way too long.
What worked for me was deleting, then re-creating the Android Virtual Device, being certain to put in a value for SD Card Size (I used 200 MiB).
Additional information:
while the above does fix the problem temporarily, it is recurring. I just tried my application within Android Studio and saw this in the output log which I did not notice before in Eclipse:
"/Applications/Android Studio.app/sdk/tools/emulator" -avd AVD_for_Nexus_S_by_Google -netspeed full -netdelay none
WARNING: Data partition already in use. Changes will not persist!
WARNING: SD Card image already in use: /Users/[user]/.android/avd/AVD_for_Nexus_S_by_Google.avd/sdcard.img
ko:Snapshot storage already in use: /Users/[user]/.android/avd/AVD_for_Nexus_S_by_Google.avd/snapshots.img
I suspect that changes to the log are not saving to the SD Card, so when LogCat tries to access the logs, they aren't there, causing the error message. The act of deleting the AVD and re-creating it removes the files, and the next launch is a fresh launch, allowing LogCat to access the virtual SD Card.

You will not have access to your real sd card in emulator. You will have to follow the steps in this tutorial to direct your emulator to a directory on your development environment acting as your SD card.

Actually, the problem is that either /sys/kernel/debug is not mounted, or that the running kernel has no ftrace tracers compiled in so that /sys/kernel/debug/tracing is unavailable. This is the code throwing the error (platform_frameworks_native/libs/utils/Trace.cpp):
void Tracer::init() {
Mutex::Autolock lock(sMutex);
if (!sIsReady) {
add_sysprop_change_callback(changeCallback, 0);
const char* const traceFileName =
"/sys/kernel/debug/tracing/trace_marker";
sTraceFD = open(traceFileName, O_WRONLY);
if (sTraceFD == -1) {
ALOGE("error opening trace file: %s (%d)", strerror(errno), errno);
sEnabledTags = 0; // no tracing can occur
} else {
loadSystemProperty();
}
android_atomic_release_store(1, &sIsReady);
}
}
The log message could definitely be a bit more informative.

error opening trace file: No such file or directory (2)

I am getting the above error:
error opening trace file: No such file or directory (2)
when I run my android application on the emulator. Can someone tell me what could be the possible reason for this?
I am using android-sdk-20 and below lines are added to AndroidManifest.xml
<uses-sdk android:minSdkVersion="14" android:targetSdkVersion="15" />
I have also added the line:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
since I thought that there may be some issue with writing to the sd card.

It happens because you have not installed the minSdkVersion or targetSdkVersion in you’re computer. I've tested it right now.
For example, if you have those lines in your Manifest.xml:
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
And you have installed only the API17 in your computer, it will report you an error. If you want to test it, try installing the other API version (in this case, API 8).
Even so, it's not an important error. It doesn't mean that your app is wrong.
Sorry about my expression. English is not my language.
Bye!

I think this is the problem
A little background
Traceview is a graphical viewer for execution logs that you create by using the Debug class to log tracing information in your code. Traceview can help you debug your application and profile its performance. Enabling it creates a .trace file in the sdcard root folder which can then be extracted by ADB and processed by traceview bat file for processing. It also can get added by the DDMS.
It is a system used internally by the logger. In general unless you are using traceview to extract the trace file this error shouldnt bother you. You should look at error/logs directly related to your application
How do I enable it:
There are two ways to generate trace logs:
Include the Debug class in your code and call its methods such as startMethodTracing() and stopMethodTracing(), to start and stop
logging of trace information to disk. This option is very precise
because you can specify exactly where to start and stop logging trace
data in your code.
Use the method profiling feature of DDMS to generate trace logs. This option is less precise because you do not modify code, but rather
specify when to start and stop logging with DDMS. Although you have
less control on exactly where logging starts and stops, this option is
useful if you don't have access to the application's code, or if you
do not need precise log timing.
But the following restrictions exist for the above
If you are using the Debug class, your application must have
permission to write to external storage (WRITE_EXTERNAL_STORAGE).
If you are using DDMS: Android 2.1 and earlier devices must have an SD
card present and your application must have permission to write to the
SD card. Android 2.2 and later devices do not need an SD card. The
trace log files are streamed directly to your development machine.
So in essence the traceFile access requires two things
1.) Permission to write a trace log file i.e. WRITE_EXTERNAL_STORAGE and READ_EXTERNAL_STORAGE for good measure
2.) An emulator with an SDCard attached with sufficient space. The doc doesnt say if this is only for DDMS but also for debug, so I am assuming this is also true for debugging via the application.
What do I do with this error:
Now the error is essentially a fall out of either not having the sdcard path to create a tracefile or not having permission to access it. This is an old thread, but the dev behind the bounty, check if are meeting the two prerequisites. You can then go search for the .trace file in the sdcard folder in your emulator. If it exists it shouldn't be giving you this problem, if it doesnt try creating it by adding the startMethodTracing to your app.
I'm not sure why it automatically looks for this file when the logger kicks in. I think when an error/log event occurs , the logger internally tries to write to trace file and does not find it, in which case it throws the error.Having scoured through the docs, I don't find too many references to why this is automatically on.
But in general this doesn't affect you directly, you should check direct application logs/errors.
Also as an aside Android 2.2 and later devices do not need an SD card for DDMS trace logging. The trace log files are streamed directly to your development machine.
Additional information on Traceview:
Copying Trace Files to a Host Machine
After your application has run
and the system has created your trace files .trace on
a device or emulator, you must copy those files to your development
computer. You can use adb pull to copy the files. Here's an example
that shows how to copy an example file, calc.trace, from the default
location on the emulator to the /tmp directory on the emulator host
machine:
adb pull /sdcard/calc.trace /tmp Viewing Trace Files in Traceview To
run Traceview and view the trace files, enter traceview
. For example, to run Traceview on the example files
copied in the previous section, use:
traceview /tmp/calc Note: If you are trying to view the trace logs of
an application that is built with ProGuard enabled (release mode
build), some method and member names might be obfuscated. You can use
the Proguard mapping.txt file to figure out the original unobfuscated
names. For more information on this file, see the Proguard
documentation.
I think any other answer regarding positioning of oncreate statements or removing uses-sdk are not related, but this is Android and I could be wrong. Would be useful to redirect this question to an android engineer or post it as a bug
More in the docs

Try removing the uses-sdk part form AndroidManifest.xml file. it worked for me!
Don't use the Android Virtual Device with too low configuration. Let it be medium.

Write all your code below this 2 lines:-
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
It worked for me without re-installing again.

I didn't want to reinstall everything because I have so many SDK versions installed and my development environment is set up just right. Getting it set up again takes way too long.
What worked for me was deleting, then re-creating the Android Virtual Device, being certain to put in a value for SD Card Size (I used 200 MiB).
Additional information:
while the above does fix the problem temporarily, it is recurring. I just tried my application within Android Studio and saw this in the output log which I did not notice before in Eclipse:
"/Applications/Android Studio.app/sdk/tools/emulator" -avd AVD_for_Nexus_S_by_Google -netspeed full -netdelay none
WARNING: Data partition already in use. Changes will not persist!
WARNING: SD Card image already in use: /Users/[user]/.android/avd/AVD_for_Nexus_S_by_Google.avd/sdcard.img
ko:Snapshot storage already in use: /Users/[user]/.android/avd/AVD_for_Nexus_S_by_Google.avd/snapshots.img
I suspect that changes to the log are not saving to the SD Card, so when LogCat tries to access the logs, they aren't there, causing the error message. The act of deleting the AVD and re-creating it removes the files, and the next launch is a fresh launch, allowing LogCat to access the virtual SD Card.

You will not have access to your real sd card in emulator. You will have to follow the steps in this tutorial to direct your emulator to a directory on your development environment acting as your SD card.

Actually, the problem is that either /sys/kernel/debug is not mounted, or that the running kernel has no ftrace tracers compiled in so that /sys/kernel/debug/tracing is unavailable. This is the code throwing the error (platform_frameworks_native/libs/utils/Trace.cpp):
void Tracer::init() {
Mutex::Autolock lock(sMutex);
if (!sIsReady) {
add_sysprop_change_callback(changeCallback, 0);
const char* const traceFileName =
"/sys/kernel/debug/tracing/trace_marker";
sTraceFD = open(traceFileName, O_WRONLY);
if (sTraceFD == -1) {
ALOGE("error opening trace file: %s (%d)", strerror(errno), errno);
sEnabledTags = 0; // no tracing can occur
} else {
loadSystemProperty();
}
android_atomic_release_store(1, &sIsReady);
}
}
The log message could definitely be a bit more informative.

Create a file in /system directory

I want to create a file in the /system directory. I think that directory is "protected" and the phone must be rooted to access and create to it.
I used this simple code to create a file in /system but nothing is created:
File file = new File("/system", "test.prop");
How can i solve that problem?
Thank you for your help.

I can't tell how to implement the following steps but I think it's not too hard to find a solution on the net:
acquire root-access for your application
check if /system is mounted with option rw, if not, remount it so
hint: use the "adb shell" and check if the upper steps can lead to success
(su && remount -o remount,rw /system && touch /system/test)
On some devices there's the unlucky chance that the internal memory is in protected mode (google S-ON / S-OFF). If this is the case for you it will not be that easy like I imagined.
But even than it must be possible, since the market is installing files there. This would be the last hint, to look at the market source-code ;/

You need to call following method on file object
file.createNewFile();
On executing this following error comes because of read-only directory
11-09 19:45:15.136: E/VideoSample(4245): java.io.IOException: open failed: EROFS
(Read-only file system)
11-09 19:45:15.136: E/VideoSample(4245): at
java.io.File.createNewFile(File.java:940)