I want to get all the CLSIDs keys that are under the HKEY_CLASSES_ROOT\\SOFTWARE\\Classes\\CLSID key.
I know that that key is mirror for merged HKEY_LOCAL_MACHINE\\SOFTWARE\\Classes\\CLSID and HKEY_CURRENT_USER\\SOFTWARE\\Classes\\CLSID keys.
So far I can enumerate all HKEY_CLASSES_ROOT\\SOFTWARE\\Classes\\CLSID (HKEY_LOCAL_MACHINE\\... and HKEY_CURRENT_USER\\... as well) and get that key's names into std::wstring[]. But when I try to open that keys:
//CLSID = e.g. L"{CAFEEFAC-0013-0001-0001-ABCDEFFEDCBB}"
firstKey = HKEY_LOCAL_MACHINE;
keysPath = L"\\SOFTWARE\\Classes\\CLSID\\"+CLSID;
if(x64System)
regsam = KEY_ALL_ACCESS|KEY_WOW64_64KEY; //on my system
else
regsam = KEY_ALL_ACCESS;
result = RegOpenKeyEx(firstKey, keysPath.c_str(), 0, regsam, &outputKey);
It works only for HKEY_CURRENT_USER, for HKEY_LOCAL_MACHINE it returns ERROR_ACCESS_DENIED. Even when I run my program as administrator (in regedit.exe I can see that key's name is good, if it wouldn't error message would be not found, not ERROR_ACCESS_DENIED anyway).
So what should I do to access that keys? I'm sure that some programs can access that keys. Or at least how to get their default value (it is all I want from them)?
In my program I can only list their names with RegQueryInfoKey but cannot access them with RegOpenKeyEx.
Even as an admin you don't have KEY_ALL_ACCESS on HKLM when UAC is enabled. If you want or need KEY_ALL_ACCESS you Need to run your program elevated.
Reduce your rights to the needed Level. If you only want to read just use KEY_READ!
And take care that you have an embedded manifest, without a manifest you might get access, but tis access is virtualized and you don't get access to the real key.
Related
In Windows 7 (32 bit), I consistently get error 5 (access denied) when I call ::RegOpenKeyEx on HKEY_LOCAL_MACHINE if I am not running in Administrator mode.
This is my code:
result = ::RegOpenKeyEx(HKEY_LOCAL_MACHINE, _T("SOFTWARE\\MyCompany\\MyApp"), 0, KEY_QUERY_VALUE, &keySoftware)
I am trying to build an app that can be installed for an entire machine as opposed to a specific user. Therefore my installer (which does run in Administrator mode) writes to HKEY_LOCAL_MACHINE, and the installer works fine.
I'd like my app to be able to read the data that my installer has put into the registry. I don't want to change any of the registry data. I have also tried using KEY_READ and KEY_EXECUTE instead of KEY_QUERY_VALUE. But it seems that no matter what I do, I cannot read from HKEY_LOCAL_MACHINE without using an elevated status. What am I missing here?
Your installer needs to adjust the security permissions on your Registry key so that non-admin users are allowed to access it. Have a look at RegSetKeySecurity(), or your installer's equivalent, or any number of command-line tools that are available. You can create a DACL that enables read-only access for the Everyone user group, or for specific user accounts.
Update: since you are using Inno Setup, try this in your Registry setup:
[Registry]
Root: HKLM; Subkey: "Software\MyCompany\MyApp"; Permissions: everyone-read
Or:
[Registry]
Root: HKLM; Subkey: "Software\MyCompany\MyApp"; Permissions: users-read
Your code as I was writing this answer:
result = ::RegOpenKeyEx(HKEY_LOCAL_MACHINE, _T("SOFTWARE\\MyCompany\\MyApp"), 0, KEY_QUERY_VALUE, &keySoftware)
RegOpenKeyEx doesn't support general paths, just direct key names.
To use it you would have to iterate your way down the hierarchy.
SHRegOpenUSKey is one alternative that does support general paths:
HUSKEY keySoftware;
LSTATUS const result = ::SHRegOpenUSKey(
L"Software\\Microsoft\\MediaPlayer", KEY_QUERY_VALUE, 0, &keySoftware, TRUE
);
I have a registry entry I can't seem to read in C++, but it shows up in Regedit.
Using the following C++ snippet:
openResult=RegOpenKeyEx( HKEY_LOCAL_MACHINE, _TEXT("SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\v4\\Full"), 0, KEY_READ, &root);
readResult1=RegQueryValueEx(root, _TEXT("InstallPath"), NULL, NULL, data1, &size);
readResult2=RegQueryValueEx(root, _TEXT("fake_entry"), NULL, NULL, data2, &size);
I get Error 2, ERROR_FILE_NOT_FOUND for my second RegQueryValueEx() call.
As you can see in the image below, my fake_entry exists.
I created this entry via Regedit.
Microsoft's Registry Keys Affected by WOW64 does not include the location I'm trying to read, and as you can see in the picture below, my fake_entry is not in the Wow6432Node location.
Yes, I understand this isn't a registry location I should be changing. I stumbled upon this as I was debugging my code and am curious why my added fake_entry doesn't work.
Yes, I've read about Registry Redirector.
Yes, I've read this question.
Yes, I tried reading fake_entry at SOFTWARE\\Wow6432Node\\Microsoft\\NET Framework Setup\\NDP\\v4\\Full with the same error.
Running Windows 7, 64 bit, C++ in Visual Studio 2010, using ASCII character encoding.
Am I misunderstanding the Registry Redirector?
Is there a problem with my code?
Are there some sort of permission settings on certain portions of the Registry? I'm obviously missing something. Please point me in the right direction.
Try
openResult = RegOpenKeyEx( HKEY_LOCAL_MACHINE, _TEXT("SOFTWARE\\Microsoft\\NET Framework Setup\\NDP\\v4\\Full"), 0, KEY_READ|KEY_WOW64_64KEY, &root);
according to MSDN you should use either KEY_WOW64_64KEY or KEY_WOW64_32KEY for WOW64 access
You are misreading the table of keys affected by WOW64. From the very top of that page:
The following table lists registry keys that are redirected, shared by both 32-bit and 64-bit applications, or redirected and reflected on 64-bit Windows. Subkeys of the keys in this table inherit the parent key's behavior unless otherwise specified. If a key has no parent listed in this table, the key is shared.
The parent of your key is HKLM\Software which is redirected. So your key is also redirected. It inherits that from its parent, as the documentation that I quoted explains.
You'll need to read the 64 bit view using KEY_WOW64_64KEY.
I need to open up and modify a user's registry key from a 32-bit service (note that the user is not logged in at the time.) I do the following:
//For simplicity error checks are not shown
//I also made sure to enable the following privileges:
// SE_RESTORE_NAME, SE_BACKUP_NAME
//"ntuser.dat" = is the file OS uses to load user's profile
if(RegLoadKey(HKEY_LOCAL_MACHINE, L"Test123", L"C:\\Users\\UserA\\ntuser.dat") == ERROR_SUCCESS)
{
HKEY hKey;
DWORD dwRes = RegOpenKeyEx(HKEY_LOCAL_MACHINE,
L"Test123\\Software\\Classes\\Local Settings\\Software\\Microsoft\\Windows\\CurrentVersion\\TrayNotify"),
NULL, KEY_READ | KEY_WOW64_64KEY, &hKey);
//'dwRes' = is returned as 2, or ERROR_FILE_NOT_FOUND
RegUnLoadKey(HKEY_LOCAL_MACHINE, L"Test123");
}
The problem is that the Software\Classes\Local Settings\Software\Microsoft\Windows\CurrentVersion\TrayNotify key isn't loaded, even though I know that it exists in the actual user profile. I can verify that by loading the user account and by using 64-bit regedit.
I suspect that this has something to do with the Wow64 redirection but I can't seem to understand what am I doing wrong?
EDIT: Added error check for the first API.
I think I got it. Two corrections to my original code:
First off, since Vista I need to load Usrclass.dat file for the classes hive and not ntuser.dat. It kinda makes sense because ntuser.dat is a part of a user's roaming profile and Classes\Local Settings does not fit into the picture well. So here's the location of the Usrclass.dat file, which contains non-roaming user data (mostly COM stuff, but some other settings as well):
%LocalAppData%\Microsoft\Windows\Usrclass.dat
The key to open after the user hive loads is:
Test123\Local Settings\Software\Microsoft\Windows\CurrentVersion\TrayNotify
that is because the original HKCU\Software\Classes is redirected to HKU\<UserSID>_Classes that is stored in the Usrclass.dat file.
I need to set ActivePowerScheme by changing it in registry key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\User\PowerSchemes.
So I try to do it with winapi functions RegOpenKeyEx and RegSetValueEx
wchar_t *PowerScheme=TEXT("8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c");
HKEY hRootKey = HKEY_LOCAL_MACHINE;
PWCHAR sKey = TEXT("SYSTEM\\CurrentControlSet\\Control\\Power\\User\\PowerSchemes");
PWCHAR sActivePowerS = TEXT("ActivePowerScheme");
HKEY hKeyResult = NULL;
//open
if (RegOpenKeyEx(hRootKey,sKey,0,KEY_ALL_ACCESS,&hKeyResult)!=ERROR_SUCCESS) {
//it is always failing with error 0 !
DWORD dw = GetLastError();
}
But RegOpenKeyEx() is always failing with error 0, that means "Operation completed successfully". And RegSetValueEx() returns same value.
if(RegSetValueEx(hKeyResult,sActivePowerS,0,REG_SZ,
(BYTE *)PowerScheme,wcslen(PowerScheme))!=ERROR_SUCCESS) {
//it is always failing with error 0
DWORD dw = GetLastError();
}
And of course current power scheme doesn't change value. But according to msdn:
"If the function succeeds, the return value is ERROR_SUCCESS.
If the function fails, the return value is a nonzero error code".
I will be grateful to any your answers.
P.S. it compiled in Windows 7 and executed with rights of admin
You are going about this the wrong way. You RARELY need to change stuff in the registry yourself.
Read Power Scheme Management on the MSDN site for the proper way of doing it.
As documentation states, RegOpenKeyEx does not update GetLastError, and return value is the error code itself. Would you mind checking it?
I'd bet you have ERROR_ACCESS_DENIED error here.
UPD: While this perhaps answers your question, you should consider using API suggested by RedX in order to update power management settings. Permissions on this registry key are set (for a reason!) in a way that even Administrators have only read permissions, and not write.
In the comments you state that RegOpenKeyEx returns ERROR_ACCESS_DENIED. This is because you request write access to a key to which you do not have sufficient rights because of UAC. You will need to run your process elevated to write to this key.
As others have correctly pointed out, you should not call GetLastError since RegOpenKeyEx does not set the last error value and instead returns the error code directly. More importantly you should be using the power management API rather than hacking the registry.
Even when you switch to the power management API you will still require administrator rights. You can arrange this by setting requestedExecutionLevel to requireAdministrator in your application manifest.
In Visual Studio you can make this change in the project configuration under Linker | Manifest File | UAC Execution Level.
I am looking for a clean way to check if a registry key exists. I had assumed that RegOpenKey would fail if I tried to open a key that didn't exist, but it doesn't.
I could use string processing to find and open the parent key of the one I'm looking for, and then enumerate the subkeys of that key to find out if the one I'm interested in exists, but that feels both like a performance hog and a weird way to have to implement such a simple function.
I'd guess that you could use RegQueryInfoKey for this somehow, but MSDN doesn't give too many details on how, even if it's possible.
Update: I need the solution in Win32 api, not in managed code, .NET or using any other library.
The docs in MSDN seem to indicate that you should be able to open a key for read permission and get an error if it doesn't exist, like this:
lResult = RegOpenKeyEx (hKeyRoot, lpSubKey, 0, KEY_READ, &hKey);
if (lResult != ERROR_SUCCESS)
{
if (lResult == ERROR_FILE_NOT_FOUND) {
However, I get ERROR_SUCCESS when I try this.
Update 2: My exact code is this:
HKEY subKey = nullptr;
LONG result = RegOpenKeyEx(key, subPath.c_str(), 0, KEY_READ, &subKey);
if (result != ERROR_SUCCESS) {
... but result is ERROR_SUCCESS, even though I'm trying to open a key that does not exist.
Update 3: It looks like you guys are right. This fails on one specific test example (mysteriously). If I try it on any other key, it returns the correct result. Double-checking it with the registry editor still does not show the key. Don't know what to make of all that.
First of all don't worry about performance for stuff like this. Unless you are querying it 100x per sec, it will be more than fast enough. Premature optimization will cause you all kinds of headaches.
RegOpenKeyEx will return ERROR_SUCCESS if it finds the key. Just check against this constant and you are good to go.
RegOpenKey does return an error if the key does not exist. How are you using it? The expected return value is ERROR_FILE_NOT_FOUND.
From your code:
HKEY subKey = nullptr;
LONG result = RegOpenKeyEx(key, subPath.c_str(), 0, KEY_READ, &subKey);
if (result != ERROR_SUCCESS) {
I would look at the value of key and subPath and make sure they are what you expect, and that the key does not actually exist. What is the value of subKey afterwards? It is obviously opening something - try enumerating it to see what the keys and values under it are.
There is no issue with RegOpenKey not returning an error if the key does not exist - I would not try to assume there is some kind of weird OS bug in something as commonly used as the registry.
Maybe you have a registry key that is not visible to you, the user that is running the registry editor, but not to your code? A permissions problem perhaps? Is your code running as an elevated user in windows Vista or server 2008? Did you try running the registry editor as administrator?
Note that beside the "core" Registry functions that start with "Reg" there are also helper functions starting with "SHReg". These are intended for use by the Shell i.e. Explorer but are documented and can be used in normal applications too. They're typically thin wrappers that make some common tasks easier. They're part of the "Shell LightWeight API" (shlwapi.dll)