What exactly is a "HANDLE"?

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What exactly is a "HANDLE"?

Todd Chester 706

What exactly is a "HANDLE".

A pointer?

A DWORD (32 bits)?

A LDWORD (64bit

And does it vary in 32 bit and 64 bit Windows?

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Answer 1

RLWA32 49,551

The Windows data type HANDLE is documented at windows-data-types. It is a C/C++ typedef that resolves to a void pointer. Consequently, in 32-bit code the size of a HANDLE is four bytes while in 64 bit code it is 8 bytes.

However, in most cases handles should be viewed as opaque objects even though the underlying representation may be a pointer.

Todd Chester 706

Raku code for a HANDLE's size:

    use NativeCall;  
    constant ptrsize is export = nativesizeof(Pointer);   
    say "My ptr size is ", ptrsize;   
    constant HANDLE = ptrsize == 4 ?? uint32 !! uint64;

RLWA32 49,551 Reputation points

2022-11-30T22:24:48.347+00:00

Does the above snippet in Raku establish HANDLE as a polymorphic unsigned integer data type whose storage size is determined by 32-bit versus 64-bit architecture?
Todd Chester 706 Reputation points

2022-11-30T22:34:45.457+00:00

Yes. But I am still having issues with NativeCall:

expected NativeCall::Types::Pointer[NativeCall::Types::void]

It does not like getting a cardinal (unsigned integer)
RLWA32 49,551 Reputation points

2022-11-30T22:46:58.867+00:00

Can Raku work with pointers without dereferencing them?
Todd Chester 706 Reputation points

2022-11-30T22:52:22.9+00:00

yes. It is somewhat a mystery to me, but "supposedly" if you declare something as a Pointer Native Call leaves it alone.
RLWA32 49,551 Reputation points

2022-11-30T22:59:00.747+00:00

But didn't you already unsuccessfully try using the Raku equivalent of a void pointer where the windows API calls for a HANDLE?
Todd Chester 706 Reputation points

2022-11-30T23:03:16.833+00:00

Yup!

my $Handle = WTSOpenServerA $lpBuffer; # let Raku figure out what $Handle is

my $Handle = WTS_CURRENT_SERVER_HANDLE; # let Raku figure out what $Handle is

I am currently dying (no error message) at

$RtnCode = memcpy_s $SessionArray, $Length , $ppSessionInf, $Length ;

I am double checking all my types at the moment. I think I have $ppSessionInf mis-declared or it de-referenced on me

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What exactly is a "HANDLE"?

my $Handle = WTSOpenServerA $lpBuffer; # let Raku figure out what $Handle is

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