Re: how do I read registry key?

[ToddAndMargo via perl6-users]

My Latest with Wolf's recommendations.  Now I
can open and close the key, but still am getting
an invalid parameter trying to read the key


    K:\Windows\NtUtil>perl6 -I. -e "use WinMount :GetLUA; say GetLUA();"
    RegOpenKeyExW
    RegOpenKeyExW   RtnCode 0

    RegQueryValueExW
    1
    2
    RegQueryValueExW   RtnCode 87  (87 = ERROR_INVALID_PARAMETER)
    lpData pointer 0
    lpcbData data length 0

    RegCloseKey
    RegCloseKey   RtnCode 0

    True

    # unit module WinMount;
    # WinMount.pm6

    #`{

       Utilities to mount and dismound drive partitions
       Note: LUA must be unset (0x00000000) for mount to function 
prpoperly

       raku -I. -c WinMount.pm6

    }

    use NativeCall;
    use WinPopUps :WinMsg;


    # Reference to types and values: 
http://dsource.org/projects/tango/ticket/820

    constant BYTE    := uint8;
    constant WCHAR   := uint16;
    constant DWORD   := int32;
    constant REGSAM  := int32;
    constant WCHARS  := CArray[WCHAR];
    constant BYTES   := CArray[BYTE];

    constant HKEY_CURRENT_USER  = 0x80000001;
    constant HKEY_LOCAL_MACHINE = 0x80000002;
    constant KEY_QUERY_VALUE   = 1;
    constant ERROR_SUCCESS     = 0; # Yeah, I know. The Win-Api uses 0 
for success and other values to indicate errors
    constant REG_SZ = 1;

    constant KEY_READ      = 0x20019;
    constant KEY_SET_VALUE = 0x0002;
    constant REG_DWORD     = 0x00000004;



    sub to-c-str( Str $str ) returns CArray[WCHAR]  is export( 
:to-c-str ) {
       my @str := CArray[WCHAR].new;
       for ( $str.comb ).kv -> $i, $char { @str[$i] = $char.ord; }
       @str[ $str.chars ] = 0;
       @str;
    }


    sub wstr( Str $str ) returns WCHARS  is export( :wstr ) {
        CArray[WCHAR].new( $str.comb.map: *.ord )
    }


    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

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

        Win32 return codes:

https://docs.microsoft.com/en-us/windows/win32/debug/system-error-codes--0-499-

    }

       my Str $SubName = &?ROUTINE.name;
       my Str $OS      = $*KERNEL.name;
       if not $OS eq "win32" { say "Sorry, $SubName only work in 
Windows."; exit; }

       my Bool  $LUA = True;
       my       $RtnCode;

       my Str   $SubKey = 
Q[SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\];
       my Str   $Key = Q[EnableLUA];

       my       $lpSubKey    = wstr( $SubKey );
       my       $lpValueName = wstr( $Key );
       # my $lpSubKey    = CArray[uint8].new($Key.encode.list);
       # my $lpValueName = CArray[uint8].new($SubKey.encode.list);


       my int32 $Handle;
       my int32 $ulOptions = 0;
       my int32 $lpData;
       my int32 $lpcbData;
       my int32 $lpReserved = 1;


    #`{
        Open the key:

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

https://docs.microsoft.com/en-us/windows/win32/sysinfo/registry-key-security-and-access-rights
        C++
        LSTATUS RegOpenKeyExW(
           HKEY    hKey,          # Hive name (HKEY_LOCAL_MACHINE)
           LPCWSTR lpSubKey,      # path to the 
key(/SOFTWARE/Microsoft/Windows/CurrentVersion/Policies/System/EnableLUA)
           DWORD   ulOptions,     # 0
           REGSAM  samDesired,    # KEY_READ (0x20019), KEY_SET_VALUE 
(0x0002)
           PHKEY   phkResult      # A pointer to a variable that 
receives a handle to the opened key
        );
    }
       say "RegOpenKeyExW";
       sub RegOpenKeyExW( DWORD, WCHARS, DWORD, DWORD, DWORD is rw) is 
native("Kernel32.dll") returns DWORD { * };
       $RtnCode = RegOpenKeyExW( HKEY_LOCAL_MACHINE, $lpSubKey, 
$ulOptions, KEY_READ, $Handle );
       say "RegOpenKeyExW   RtnCode $RtnCode\n";



    #`{
        Read the key:
        use RegQueryValueExW if you know key and value name

https://docs.microsoft.com/en-us/windows/win32/api/winreg/nf-winreg-regqueryvalueexw
        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
        );
    }
       say "RegQueryValueExW";
       sub RegQueryValueExW( DWORD, WCHARS, DWORD, DWORD, DWORD is rw, 
DWORD is rw ) is native("Kernel32.dll") returns DWORD { * };
    say "1";
       $RtnCode = RegQueryValueExW( $Handle, $lpValueName, $lpReserved, 
REG_DWORD, $lpData, $lpcbData );
    say "2";
       say "RegQueryValueExW   RtnCode $RtnCode  (87 = 
ERROR_INVALID_PARAMETER)\nlpData pointer $lpData\nlpcbData data length 
$lpcbData\n";



    #`{
        Close the key

https://docs.microsoft.com/en-us/windows/win32/api/winreg/nf-winreg-regclosekey
        C++
        LSTATUS RegCloseKey(
           HKEY hKey    # handle to the open key to be closed.  See 
RegOpenKeyExW phkResult
        );
    }
       say "RegCloseKey";
       sub RegCloseKey( DWORD ) is native("Kernel32.dll") returns DWORD 
{ * };
       $RtnCode = RegCloseKey( $Handle );
       say "RegCloseKey   RtnCode $RtnCode\n";


       return $LUA;
    }