Re: how do I read registry key?

[ToddAndMargo via perl6-users]

On 2019-12-25 21:48, WFB wrote:


On Wed, 25 Dec 2019 at 23:10, ToddAndMargo via perl6-users 
<perl6-users@perl.org <mailto:perl6-users@perl.org>> wrote:

    Hi All,

    Windows

    
https://docs.microsoft.com/en-us/windows/win32/sysinfo/retrieving-data-from-the-registry

    How do I use this to read retrieve a value of a registry key?

    Many thanks,
    -T


Hi Todd,

Two things comes to mind for solving this. First, you use the Windows 
Commandline command REG together with "run". See REG /? for more 
information.
Or second, use NativeCall to use the Windows API calls similar to your 
MessageBox module.
Your link shows the needed API calls.

BTW, hat would be also a great module for pushing to 
https://modules.raku.org/.

Greetings,
Wolf

Hi Wolf,

I am trying to do it with native call.  So far, I get

$ perl6 -I. -e "use WinMount :GetLUA; say GetLUA();"
===SORRY!=== Error while compiling /home/CDs/Windows/NtUtil/WinMount.pm6 
(WinMount)
Calling RegQueryValueExW(Str, NativeCall::Types::CArray[uint16], int, 
NativeCall::Types::CArray[uint16]) will never work with declared 
signature (NativeCall::Types::CArray[uint16] $, 
NativeCall::Types::CArray[uint16] $, int32, 
NativeCall::Types::CArray[uint16] $ --> int32)
at /home/CDs/Windows/NtUtil/WinMount.pm6 (WinMount):69
------>    $DWord = ⏏RegQueryValueExW( "HKEY_LOCAL_MACHINE",

I am doing something wrong:

<part of WinMount.pm6>
constant WCHAR = uint16;





sub to-c-str( Str $str ) returns CArray[WCHAR]  {

   my @str := CArray[WCHAR].new;

   for ( $str.comb ).kv -> $i, $char { @str[$i] = $char.ord; }

   @str[ $str.chars ] = 0;

   @str;

}







sub GetLUA() is export( :GetLUA ) {



#`{



Returns the LUA value in the registry to True (0x00000001) or False 
(0x00000000)




[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System]

          "EnableLUA"=dword:00000000



    use RegQueryValueExW if you know key and value name


https://docs.microsoft.com/en-us/windows/win32/api/winreg/nf-winreg-regqueryvalueexw

    https://docs.perl6.org/language/nativecall



    C++



    LSTATUS RegQueryValueExW(

       HKEY    hKey,          # Hive name (HKEY_LOCAL_MACHINE)

       LPCWSTR lpValueName,   # path to the 
key(/SOFTWARE/Microsoft/Windows/CurrentVersion/Policies/System/EnableLUA)

       LPDWORD lpReserved,    # give it "int32" without the quotes to 
give it a NULL

       LPDWORD lpType,        # Registry Value Type (REG_DWORD which is 
32 bit)

       LPBYTE  lpData,        # Pointer to the return value

       LPDWORD lpcbData       # number of bytes in the return value

);



}

   my Str $SubName = &?ROUTINE.name;

   my Str $OS      = $*KERNEL.name;

   if not $OS eq "win32" { say "Sorry, $SubName only work in Windows."; 
exit; }



   constant hKey               = CArray[WCHAR];

   constant lpValueName        = CArray[WCHAR];

   constant INT                = int32;

   constant lpType             = CArray[WCHAR];

   constant lpData             = Pointer[void];

   constant lpcbData           = uint32;



   my Bool $LUA = True;

   my int32 $DWord;

   my int32 $DLen;



   sub RegQueryValueExW( hKey, lpValueName, INT, lpType ) is 
native('user32') returns INT { * };



   $DWord = RegQueryValueExW( "HKEY_LOCAL_MACHINE",

                         to-c-str( 
"/SOFTWARE/Microsoft/Windows/CurrentVersion/Policies/System/EnableLUA" ),

                         int32,

                         to-c-str( "REG_DWORD" ) );



   if  $DWord == 0  { $LUA = False; }

   return $LUA;

}


</part of WinMount.pm6>