AutoHotkey Community

x64 applications write to the registry here:
HKEY_LOCAL_MACHINE\SOFTWARE

x32 applications on x64 are intercepted by the system and write here:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node

This is transparent to the user.
(description from microsoft http://support.microsoft.com/kb/896459)

When x32 apps read from the registry the read from here:
HKEY_LOCAL_MACHINE\SOFTWARE
but the system again intercepts and gets the values from:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node

What happens if a x32 application (like an autohotkey script .ahk or compiled) tries to read from a key that belongs to a x64 application?
That the call is intercepted by the system and you get an empty result, because it looks for it on HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node

So, there is no way to read keys from HKEY_LOCAL_MACHINE\SOFTWARE with a x32 application if they were written by a x64 application.


p.e:
Maya2008 32 installed on Windows XP 32
Result: C:\Program Files\3D\Maya2008

Maya2008 64 installed on Windows XP 64
The same RegRead code
Result:
Nothing.....

Manually create in the registry a duplicate on HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node:

And again the same code
Result: C:\Program Files\3D\Maya2008_fake_path

Sorry for the late reply. Currently, I think the only way to access entries that exist only in the 64-bit section of the registry is by calling a function like RegOpenKeyEx() via DllCall and passing to it the KEY_WOW64_64KEY flag.

For details, see:
http://msdn2.microsoft.com/en-gb/library/aa384129.aspx
http://msdn2.microsoft.com/en-us/library/ms724878.aspx

The current behavior is an intentional limitation imposed by Microsoft on 32-bit apps running in a 64-bit environment. Therefore, I've moved this to Wish List in the hope that a future version will provide a built-in means to access the 64-bit-only areas of the registry.

I know this thread is quite old, but I'm running into the same issue with needing to read a registry entry made by a 64 bit application using AHK. I'm not familiar with how to use the dllcall with Advapi32.dll. I would appreciate any help with syntax as I'm sure I'm doing it wrong. Below is a test I'm trying to run. I created a key under SYSTEM just to test, but the message box is still returning a blank. I can read the value just fine with regread.

_________________
Regards,
Dave B.

There are a number of problems with your code:

• HKEY_LOCAL_MACHINE and KEY_QUERY_VALUE are constants defined in the Windows header files. You must use the corresponding numeric values.
• Quote marks are required when assigning a literal string using :=. If SYSTEM has not been assigned a value, sKeyName:=SYSTEM will assign sKeyName a blank value.
• DllCall sets ErrorLevel to -2 or -4. -2 because you've omitted the arg types, and -4 because RegOpenKeyEx and QueryValueEx do not exist. Use RegOpenKeyExA and RegQueryValueExA.
• Once you specify the correct arg types, you'll also need to initialize vValue using VarSetCapacity.

Try the following:
(Tested only on 32-bit Vista.)

Thanks for the pointers everyone - I also needed a fix for this and the details in this post helped perfect.
Just wanted to paste in a working sample that combines Chris and Lexikos notes above:

Thanks a TON guys. That working example is perfect. I'm not that knowledgeable in using dllcall (or most of AHK anyway!). I appreciate all the help. Too bad I wasn't smart enough to figure out the syntax until the last 2 posts

_________________
Regards,
Dave B.

Posted full RegRead64() and RegWrite64() functions on this page:

http://www.autohotkey.com/forum/viewtopic.php?p=241769