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Re: stolen uint's

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From:
William Michels via perl6-users
Date:
January 29, 2020 19:17
Subject:
Re: stolen uint's
Message ID:
CAA99HCyZcVL7RuqRoouOj5YAro2ohv7vhCpu+yjqsfqjtG5M1w@mail.gmail.com
> "I am not posting it here as it is several hundred lines long and then I'd get the finger wagged at me.  Everything is spread across several modules."

On the contrary, this email list is the perfect place to put up
nascent Raku/Perl6 that you're having problems with. The issue is you
making the effort to post a small plain-text **reproducible example**
of problems you're having with Raku/Perl6 code. (Otherwise, it matters
not to me whether your code is 20 lines or 200 lines long).

 But frankly you'll get more answers to your questions if 1) your code
example is short, and 2) other people can copy your code into their
REPLs and can reproduce your issue.

HTH,  Bill.





On Wed, Jan 29, 2020 at 10:34 AM ToddAndMargo via perl6-users
<perl6-users@perl.org> wrote:
>
> On 2020-01-29 00:43, Tobias Boege wrote:
> > On Tue, 28 Jan 2020, ToddAndMargo via perl6-users wrote:
> >> This all came up when I tried to match
> >>
> >>        RegSetValueExW(
> >>            _In_ HKEY hKey,
> >>            _In_opt_ LPCWSTR lpValueName,
> >>            _Reserved_ DWORD Reserved,
> >>            _In_ DWORD dwType,
> >>            _In_reads_bytes_opt_(cbData) CONST BYTE * lpData,
> >>            _In_ DWORD cbData
> >>
> >> where CbData can either be a UTF little endian C string,
> >> terminated by a nul or a four byte little endian
> >> unsigned integer (no two's complement allowed) depending
> >> on the value of lpValueName (REG_SZ, REG_DWORD, etc.)
> >>
> >> I wound up doing this:
> >>
> >> subset StrOrDword where Str | UInt;
> >> sub WinRegSetValue( WinRegHives $Hive, Str $SubKey, Str $KeyName, ValueNames
> >> $ValueType, StrOrDword $ValueData, Bool $Debug = False )
> >>                      returns DWORD is export( :WinRegSetValue ) {
> >
> > Are you really 100% sure that you interpreted this API correctly? I see how
> > a DWORD cbData can be a four-byte unsigned integer: it gives the length of
> > lpData in bytes, as documented [1].
> >
> > But then a DWORD is 4 bytes long. Reusing these 4 bytes for an alternative
> > interface where you may pass a UTF-whatever string that is at most 4 bytes
> > encoded, including the NUL terminator... seems too insane. And there is no
> > mention of that in the documentation page [1]. I do not think that cbData
> > is ever used for anything but to indicate the length of the buffer lpData.
> > It is lpData which can have a multitude of types (and serialization formats),
> > the intended one to be taken from the dwType argument (not lpValueName).
> >
> > My advice is still the same I gave in my very first reply to this thread:
> > make your function a multi and write a candidate for each dwType. You have
> > to write different code for serializing an integer vs. a string to pass as
> > lpData anyway and the compiler can detect native types in multi dispatch
> > for you:
> >
> >    # REG_DWORD
> >    multi WinRegSetValue(…, uint32 $data) {
> >        use experimental :pack;
> >        RegSetValueExW(…, REG_DWORD, pack("L", $data), 4)
> >    }
> >
> >    # REG_SZ
> >    multi WinRegSetValue(…, Str $data) {
> >        my $blob = "$data\0".encode
> >        RegSetValueExW(…, REG_SZ, $blob, $blob.bytes)
> >    }
> >
> >    # REG_BINARY
> >    multi WinRegSetValue(…, blob8 $data) {
> >        RegSetValueExW(…, REG_BINARY, $data, $data.bytes)
> >    }
> >
> > Regards,
> > Tobias
> >
> > [1] https://docs.microsoft.com/en-us/windows/win32/api/winreg/nf-winreg-regsetvalueexw
> >
>
>
>
> Hi Tobias,
>
> I don't have to get so complicated.  Code looks sweet
> though.  I will probably write it down for use
> on other things. Thank you!
>
> Oh yes.  I can pass it strings and DWORD with ease.
>
> I check the value of lpValueName and then proceed.
>
> lpData is basically an array of bytes.  I set the
> bytes up based on lpValueName.  And you have to
> tell cbData how many bytes are legitimate
> in lpData.
>
> It they pass me a string for REG_DWORD or a UInt for
> a REG_SZ, I wag the finger wagged at them big time.
> For example:
>
>     if $ValueData.^name  ne "Int"  || $ValueData < 0  {   # UInt gets
> "boxed" to an Int
>        $ErrStr = "ERROR: $SubName\n\n" ~
>                  "   ValueData must be an Unsigned Integer when used
> with $ValueType\n\n" ~
>                  "   Cowardly exiting\n\n";
>        say $ErrStr;
>        WinMsg( "ValueData Error", $ErrStr );
>        exit;
>     }
>
> Hmmmmm... I forgot the "Bummer Dude!"
>
> Would you like to see the actual code?  I am not
> posting it here as it is several hundred lines long
> and then I'd get the finger wagged at me.  Every
> thing is spread across several modules.
>
> -T

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