Re: calling a function from a dll

I never could get the "C type parser" of Win32::API to work. I always had more luck manually constructing the parameter string using the P and I chars, and then using unpack for strings passed in and out.

In your case, maybe the following construct works:

$function = Win32::API->new('NSLClientLibrary', 'XYZDecrypt', 'PPP', '
+I');

sub call_function {
    my ($value, $key, $encrypted) = @_;
    # Here we pad $value to the expected length, to avoid a buffer ove
+rrun
    # I guess that the result is at most as long as the encrypted stri
+ng
    $value = ' ' x length $encrypted;
    $function->( $value, $key, $encrypted );
    $value =~ s!\0.*!!; # we assume that the first \0 returned indicat
+es end of the string
    return $value
};
[download]

Comment on Re: calling a function from a dll Select or Download Code

Replies are listed 'Best First'.
Re^2: calling a function from a dll by BrowserUk (Patriarch) on Dec 31, 2012 at 20:02 UTC
$value =~ s!\0.!!; # we assume that the first \0 returned indicates end of the string* That is a pretty bad assumption. BSTRs are fixed length arrays of unsigned shorts with a prefix length and can contain multiple nulls. See http://blogs.msdn.com/b/ericlippert/archive/2003/09/12/52976.aspx With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]
Re^3: calling a function from a dll by nikosv (Deacon) on Jan 04, 2013 at 06:28 UTC
what is interesting is that the prefix length is a byte count and not a character count,although BSTR is always Unicode So to find the end of the string you have to get to the stored length which is stored in the first 2 bytes the example at : BSTR layout shows the byte count and the terminated nulls,both required by BSTR	[reply]
Re^2: calling a function from a dll by nmeijer (Initiate) on Dec 31, 2012 at 19:03 UTC
Am I perhaps calling the function wrong or something? as I get a Not a CODE reference at xx.pl line 14 which is where the $function is called in the sub routine #!/usr/bin/perl use Win32::API; my $function = Win32::API->new('C:\XYZClientLibrary\x86\XYZClientLibra +ry.dll', 'XYZDecrypt', 'PPP', 'I'); print call_function('9','8B3A06617FEC4276A5711FBA4861B467', '[000001]C +0808FC9B3062D91E7B9B1D9A7B79216'); sub call_function { my ($value, $key, $encrypted) = @_; # Here we pad $value to the expected length, to avoid a buffer ove +rrun # I guess that the result is at most as long as the encrypted stri +ng $value = ' ' x length($encrypted); print (" $value, $key, $encrypted\n"); $value = $function->( $value, $key, $encrypted ); $value =~ s!\0.*!!; # we assume that the first \0 returned indicat +es end of the string return $value }; [download]	[reply] [d/l]
Re^3: calling a function from a dll by roboticus (Chancellor) on Dec 31, 2012 at 19:26 UTC
nmeijer: Looking at the Win32::API docs, it looks like line 14 should be: `$value = $function->Call( $value, $key, $encrypted );` [download] ...roboticus When your only tool is a hammer, all problems look like your thumb.	[reply] [d/l]