signal exception 0 received: a data abort exception has occurred.....how to resolve?

[raj8nokiaforum]

Hi all,

I am doing simple file operations using RFile and RFsSession. Everything works fine on emulator but when i tried to do the same on device, it failed.

I tried with device debugging and found out that when control comes to RFile declaration, data abort exception occurs and control steps into file s32file.inl pointing to the following:

/** Detaches the file from this stream buffer.

The intermediate buffer's read and write marks are not changed, and the stream 
positions are not changed. This means that the contents of the file should 
not change while it is detached. 

@see Attach()
@see Reattach() */
	{iFile=RFile();}  <---- control gets stuck in here and when try to stop the debugger given kern-exec 3
inline void RFileBuf::Reattach(RFile& aFile)

Don't know what is wrong with this because it happens on a simple line which says:

RFile file;

I am first creating a file and closing it. Then i repeatedly write data to it and close again. Then i open it again and there it happens when i declare RFile object.

Any idea anyone?

Thanks

[wizard_hu_]

When accessing a member variable (iFile) fails with KERN-EXEC 3, it often means that the method is invoked on a non-existing object (like a NULL pointer, or some totally random thing). Non-virtual methods are always present in the memory, the problems start when they try accessing something from the object.
"RFile file;" creates a local variable, it does not need the object to exist.
Note that "iFile=RFile();" will be a strange line even after fixing the problem. Assuming that iFile is declared as "RFile iFile;" in the header file, it does not need any further instantiation.

[raj8nokiaforum]

Ok but what do you suggest i should try doing to fix this. This is happening everytime. Is it a good idea to make RFile an instance of the class rather than local variable?

[symbianyucca]

the crash likely comes from something else, so do try checking the line again.

Also do check the actual panic code: http://www.developer.nokia.com/Commu...ded_panic_code

[raj8nokiaforum]

I hope so because this doesn't seem to make any sense. I already tried that and extended panic code as i told in thread is KERN-EXEC 3 but how do i find the exact place where the panic is coming from except device debugging?

[symbianyucca]

in general, you would not get Kern-Exec 3 with R-Class objects, unless something not-so-usual goes wrong in there. One reason would be stack-overrun, which you could fix by increasing the default stack.

Anyway, I would strongly suggest that you do re-check which line of code is giving this particular panic.

[raj8nokiaforum]

Ok can you provide me some link to HookLogger as well which might help me out in this kind of situation? I am developing on carbide++ 2.7 for S60 3rd FP1

thanks

[symbianyucca]

You don't need any special tools, you could simply use file logging to see what is the line that gets executed last. Also you should write any possible error codes you could get as return values or with TRAP's before you get to the line that causes the panic.

[raj8nokiaforum]

Trying to use RFileLogger like below but i am not able to create the directory or file at the specified path

_LIT(KLogDir,"c:\\data\\");
_LIT(KLogFile,"logfile.txt");
RFileLogger iFileLogger;
	iFileLogger.CreateLog(KLogDir, KLogFile, EFileLoggingModeOverwrite);
    iFileLogger.Write(_L("file declared"));
iFileLogger.CloseLog();
iFileLogger.Close();

i tried different combinations but could not create the directory or file

any idea?

[symbianyucca]

For quick and dirty alternative, you could also try using global notes: http://www.developer.nokia.com/Commu...i/Global_notes

Basically the execution is hanging when note is shown, also do remember that with Global notes the UI focus is taken from the app, thus use it only if your application logic does not do anything on focus changes etc.

[vineet.jain]

I utilized the file logging in the following way:

1) Include the filelogger.h in the project's inc folder (attachment)

2) Include in mmp file : LIBRARY flogger.lib

3) In the pkg file, send a dummy file to the location where you want to create the log directory, E.g.:
(no need to write any code to create the directory & file)

"xyz.txt" - "C:\data\Mylogs\logfile.log"

4) Mention the same name of directory & file in the header attached( filelogger.h)

5) Include the filelogger.h in the source files where you want to create logs & use it as : __LOGSTR_TOFILE("FunctionStarted"); (as defined in filelogger.h)

[raj8nokiaforum]

hi yucca,

i tried the global notes after commenting everything else but still getting KERN-EXEC 3 on app crash on RFile file; line.

[raj8nokiaforum]

Thanks vineet. I will try this for sure.

The issue that i am talking about here is not coming up in emulator. Everything works great there. Its just on the device.

[vineet.jain]

Can you paste here the full code. Also try declaring some other variable as well at the same time when RFile's object is declared(when panic comes) & see if it fails as well( for e.g. declare TBuf<5>iTestBuf or else)

[raj8nokiaforum]

sure here it is:

    RFile file;  <---------control comes at this line and goes to s32file.inl as i mentioned in first comment and app crashes with KERN EXEC 3....emulator is fine with this though
    TInt error = file.Open(iFsSession, KFileData, EFileRead);

    TInt pos = 0;
    TInt fileSize;
    file.Size(fileSize);
    file.Seek(ESeekEnd, pos);

    TUint dataLength = pos;
    const TInt size = fileSize;
    TBuf8<54601>data8;
    pos = 0;
    file.Seek(ESeekStart, pos);
    TInt errRead = file.Read(data8);
    file.Close();
    data8.TrimAll();
    TInt actionTagPos = data8.Find(_L8("action="));
    TInt methodTagPos = data8.Find(_L8("method"));
    iActionUrl.Copy(data8.Mid(actionTagPos+8, methodTagPos-actionTagPos-10));
    TInt optionTagStartPos = data8.Find(_L8("<option>"));
    TInt selectTagEndPos = data8.Find(_L8("</select>"));
    TInt xmlDataLength = selectTagEndPos-optionTagStartPos;
    
    if(iXmlData)
    	{
    	delete iXmlData;
    	iXmlData = NULL;
    	}
    iXmlData = HBufC8::NewL(xmlDataLength+23);
    TInt totalLengthNow = data8.Length();
    iXmlData->Des().Copy(_L8("<countries>"));
    iXmlData->Des().Append(data8.Mid(optionTagStartPos, xmlDataLength));
    iXmlData->Des().Append(_L8("</countries>"));    
    iXmlData->Des().TrimAll();
    
    RFile xmlFile;
    TInt errCreate = xmlFile.Create(iFsSession, KFileXmlData, EFileWrite);
    xmlFile.Write(iXmlData->Des());
    xmlFile.Close();
    TInt errDelete = iFsSession.Delete(KFileData);