Bug in Regwrite in HKEY_LOCAL_MACHINE

[wiens]

Hello,

When you write registry key it will not work in HKEY_LOCAL_MACHINE:

RegWrite, REG_SZ, HKEY_LOCAL_MACHINE\SOFTWARE\TestKey, MyValueName, Test Value

When you write registry it works fine in HKEY_CURRENT_USER:

RegWrite, REG_SZ, HKEY_CURRENT_USER\SOFTWARE\TestKey, MyValueName, Test Value

So the bug is in HKEY_LOCAL_MACHINE.
By the way you don't need any admin rights to write this key in HKEY_LOCAL_MACHINE if you do it manually.

This issue exist in AHK version 1.1.30.01.

[just me]

By the way you don't need any admin rights to write this key in HKEY_LOCAL_MACHINE if you do it manually.

Interesting, on my Win 10 system I need them.

ErrorLevel

[v1.1.04+]: This command is able to throw an exception on failure. For more information, see Runtime Errors.

ErrorLevel is set to 1 if there was a problem or 0 otherwise.

A_LastError is set to the result of the operating system's GetLastError() function.

What do they tell you?

[wiens]

The values are:
ErrorLevel = 1
A_LastError = 5

[wiens]

What is causing this error if it is not in admin rights?

[CloakerSmoker]

Edit: About a minute after hitting submit I stumbled across this (On a totally different MSDN page in my defense):

When you call the RegOpenKeyEx function, the system checks the requested access rights... If the user does not have the correct access to the registry key, the open operation fails.

So the problem is that your account doesn't have permission to create the key, which matches what you got for ErrorLevel and LastError.
However, I'm not sure why RegEdit would let you while RegWrite fails.

The rest of this post is incorrect, so you can just ignore it.

Spoiler

It looks like this isn't an error on AutoHotkey's side as far as I can tell.
When the RegCreateKeyEx WinAPI function is called by AHK (in RegWrite) to open/create a key it's supposed to return ERROR_SUCCESS and create the key, however it can instead fail and return ERROR_ACCESS_DENIED (0x5) alongside setting AHK's ErrorLevel, which matches what you got for ErrorLevel and LastError.

I'm pretty sure RegCreateKeyEx is mistakenly returning ERROR_ACCESS_DENIED/failing because it thinks you are trying to create a key that's a direct child of HKLM (Which is intended behavior only when trying to create direct children, but not for all keys in HKLM. See the MSDN remark below)

An application cannot create a key that is a direct child of HKEY_USERS or HKEY_LOCAL_MACHINE. An application can create subkeys in lower levels of the HKEY_USERS or HKEY_LOCAL_MACHINE trees.

Similar behavior is noted in the comments of RegWrite for HKCU, and considering that HKCU is a alias of a subkey in HKEY_USERS (The only other tree that has this protection) and also has this problem, it looks like we should be blaming RegCreateKeyEx for not being able to create keys further down in the two protected trees without admin even when it says it is possible.

Code: Select all

	// The following works even on root keys (i.e. blank subkey), although values can't be created/written to
	// HKCU's root level, perhaps because it's an alias for a subkey inside HKEY_USERS.  Even when RegOpenKeyEx()
	// is used on HKCU (which is probably redundant since it's a pre-opened key?), the API can't create values
	// there even though RegEdit can.

Aka the only workaround I can see is to just do the registry changes from an elevated process.
Although I find it incredibly hard to believe a problem like this wouldn't go unfixed for long, so I might be totally wrong here. Apologies if I am.

[XShayanX]

I'm on v1.1.30.01 currently, any news on when this is going to get fixed? I have the same issue, I can't write to HKLM.
This is my thread: https://www.autohotkey.com/boards/viewtopic.php?f=76&t=67974&p=292326#p292326

[just me]

The values are:
ErrorLevel = 1
A_LastError = 5

ERROR_ACCESS_DENIED

5 (0x5)

Access is denied.

Source

[swagfag]

never heard of writing to HKLM not requiring admin access. ur regedit must have been running elevated

[XShayanX]

@just me Nice I just saw your post here, so it means we're on the same boat, I understand that I'm getting Access denied (Error 5) but I am running my script as Administrator, I don't know what I'm missing?

[gwarble]

try it from your same shk script with Run, %comspec% reg add hklm/...

Then you will make sure both methods are using the same elevation coming from the same process... My guess is they will act the same, I’ll try on my machine later

[wiens]

gwarble, it didn't work with that workaround for me.

[gwarble]

that means its an elevation/permission issue as was first recommended

[lexikos]

I doubt there's a bug here.

What does MsgBox % A_IsAdmin say?

What permissions does your account have to this registry key? You can check by right clicking on the key in regedit and selecting Permissions....

With UAC set to "Notify me only when applications try to make changes to my computer (default)", it will not notify you when you launch certain system applications, such as regedit, even though they are elevated to admin. Some system applications will only run with limited permissions if the current user is not a member of the Administrators group, while others will not run at all in that situation, or will require you to enter an admin username and password.