dll call works perfectly in 8.5 but crashes in 8.2.1

[czinottawa]

Hello all,

I have developed  ssh drivers  for LabVIEW that utilize Extraputty.dll, puTTY.exe

The drivers work perfectly when run on a windows XP machine with LabVIEW 8.5.  weather run from IDE or compiled to executable

however, we have standardized on 8.2.1 and so I converted the project to 8.2.1 on a windows xp machine, and the drivers crash every time regardless what I do.

after further investigation, I determined that LabVIEW crashes just after returning from the call to connexion in sshOpenSession.vi

I have doublechecked the function prototype and it seems to be correct, also the calling convention is stdcall

I did the following test: add an extra argument to connexion  of type unsigned int and assign it the value 195935983 (0xbadbeef) and ran the top level sshTestFixture, and confirmed that 0xbadbeef is the last value popped from the stack as you can see circled in red in the attached jpeg .

I have included the 8.2.1 vesion and the 8.5 version of my ssh drivers.

you will need the following to test my VIs

1. labview 8.5

2. labview 8.2.1

3. a computer running  openssh as a target

sshTestFixture.vi is the top level driver tester application

if you want to build an executable, then ensure that putty.exe, ExtraPutty.dll and lua5.1.dll are included in the build and they have to appear 1 directory level below the executable.

the drivers write to the windows registry the first time that they are executed for the following purposes

1. disable puTTY ssh host key addition popup

2. add puTTY.exe directory path as an environment variable

these additions have no adverse effect on your computer, except if you use putty, then it will automatically accept keys without prompting you, however you can look at subVI WriteRegistryKeyValueHCU.vi  to find out how to undo it

thanks in advance

cz

[Tanya_V]

Hi cziottawa,

Before installing all your drivers, would it be possible to post the LabVIEW crash log, so we can take a look at that first?

Also, could you simplify your code in such a way that the problem is reproducible with one or a small number of VIs?

Thanks!

[czinottawa]

I have stripped down the subVIs:

instructions:  use the zipped package called sshDriversDebug82.zip

1. double click sshDriverDebuggingTop Level.vi

2. specify IP address, password, username, click run

Expected result after step 2:

the first time you run the the vi , you will see a  messagebox  informing the user to reboot the PC

the 2nd time (after rebooting the PC).  you will see the ssh host key acceptance dialog box from puTTY,  it might be hidden behind the subVI, so you might need to minimize the subVI to get to it

3. click no

Expected result after step 3:

in 8.5: subVI executes without a crash

in 8.2.1 abrupt crash with no crash logs

thansk in advance

Carlos

[kehander]

I don't have LabVIEW handy right now, but is the configuration very different between the two machines you are using?  In the past, I've had some strange problems with DLL calls when the DLL wasn't located in LabVIEW's path.

If all else fails, I sometimes find it constructive to do some low-level debugging with Process Monitor, available at http://technet.microsoft.com/en-us/sysinternals/bb896645.aspx .  It can help establish if there's some file access somewhere that isn't working correctly (that is, if LabVIEW is looking for the DLL in a particular place and not finding it), but it's a bit tricky to use.

[czinottawa]

the configuration of the PCs is not identical. They have different hardware and differnt software packages install.  I also built an executable with 8.2.1 and ran it on a 3rd PC with the same result ... crash

I believe that the DLL is in the path of LabVIEW because we get to the SSH key acceptance dialog box from puTTY. it is after we return from the function call, that problems appear (in the form of a crash).

also the DLL itself has to be passed an environment variable, and I get confirmation of that too by seeing the SSH Key acceptiance box from puTTY

thanks

Carlos