[fpc-pascal] unexpected termination with no errors

[Gary Doades]

Windows represents exception codes as an unsigned int. The error -1073741819 is actually0xC0000005.

This represents some form of access violation, usually associated with 
trying to write to freed memory,double freeing memory etc. If the stack 
is involved/corrupted then a trackback and useful information would be 
difficult.

Whereabouts down the line a disk full translates into an access 
violation is difficult to say, but it results in a mess to say the least.

Regards,

Gary.

On 15/05/2019 16:43, James Richters wrote:
> It's a simple single thread console app.   I found my problem...  years ago I implemented a batch file to run my program in the test environment to help be with debugging... and what it does is redirect the errors to a file so that if flashed by real quick, I would be able to just look at the file.   Then I just echo the file to the screen, and if I detect an error, I also pause so I can see it.    This a common solution to the windows limitation of not be capable directing STDERR to console AND to a file.
>
> Well the file wasn't reporting the error and it wasn't on the screen... it looked like a normal exit, BUT it was actually giving me the proper report... unfortunately the error was the one thing that my batch file could not possibly display....  EInOutError: Disk Full   DOH!!!  With the disk full my log file could only show up to but not including the error... because it could not write anymore on a full disk... I still don't have a great solution for this... I see methods of implementing something like a Tee function on windows, but the problem is I don't want ALL the output to go to the log, I only want STDERR to go to the log file.... and the screen...  not my output I am sending with the CRT unit that sends colored text for various purposes.  This is such a pain with windows to accomplish this seemingly simple task.    Anyway I know what the problem is and can put in something to detect it.  Maybe I will just check if the errorlevel is negative and if so write a suggestion to the screen that disk full may have caused this and then pause.... since I can't necessarily write anything to the file.
>
> Does anyone know what the errorlevel for EInOutError: Disk Full is  -1073741819,   (I'm not sure it's always that number... ) is this on purpose?, or a bug?, or a side effect of the disk being full so it can't generate the correct error code?   if it was a normal errorcode I would have got that on my screen but since it's less than zero it got treated like a normal exit.... I did fix my batch file to treat anything less than zero as an error..... so it doesn't really matter, I just didn't know they could be negative, but I'm curious why this strange errorlevel.
>
> Jim
>
>
> -----Original Message-----
> From: fpc-pascal <fpc-pascal-bounces at lists.freepascal.org> On Behalf Of Karoly Balogh (Charlie/SGR)
> Sent: Wednesday, May 15, 2019 9:17 AM
> To: FPC-Pascal users discussions <fpc-pascal at lists.freepascal.org>
> Subject: Re: [fpc-pascal] unexpected termination with no errors
>
> Hi,
>
> On Wed, 15 May 2019, James Richters wrote:
>
>> Has anyone encountered anything like this before or know how I can
>> make sure I always get the maximum amount of debugging info when my
>> program crashes?
> Is it a subthreaded app?
>
> The only case when I noticed something similar (under Linux though), when a certain subthread throws an exception, it just silently disappears without any further handling. It doesn't throw any exception, unless you wrap the entire Execute method in a try-except.
>
> (Sidenote: I've been pondering for a while if I should report this as a bug. I think the RTL should put a try-except around there, to show a stacktrace on unhandled exceptions, just like the main thread dying does, but who knows which Delphi de-facto standard behavior would that violate, so meh...)
>
> In Linux/Darwin (on x64/ARM at least), only the thread causing the problem dies, no clue what happens under Windows. Maybe this helps.
>
> Charlie
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