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Re^4: Win32::API::Struct: Pointers of Pointers

by esskar (Deacon)
on Jun 29, 2006 at 13:36 UTC ( #558312=note: print w/ replies, xml ) Need Help??


in reply to Re^3: Win32::API::Struct: Pointers of Pointers
in thread Win32::API::Struct: Pointers of Pointers

okay. i get 87 as a result, which means: The parameter is incorrect.

now i tried the following:

sub query_users { my ( $self, $filename ) = @_; my $func = import_api( 'advapi32', 'QueryUsersOnEncryptedFile', 'PP', 'N' ) +; die "Could not import API QueryUsersOnEncryptedFile: $!" unless defined $func; $filename = make_unicode( File::Spec->canonpath($filename) ); print "filename: $filename\n"; my $encCertHashList = Win32::API::Struct->new( 'ENCRYPTION_CERTIFI +CATE_HASH_LIST' ); print "retval: " . $func->Call( $filename, $encCertHashList) . "\n +"; print $encCertHashList->{nCert_Hash}, "\n"; $encCertHashList = Win32::API::Struct->new( 'ENCRYPTION_CERTIFICAT +E_HASH_LIST' ); print "retval: " . $func->Call( $filename, \$encCertHashList) . "\ +n"; print $encCertHashList->{nCert_Hash}, "\n"; $encCertHashList = " " x 1024; print "retval: " . $func->Call( $filename, $encCertHashList) . "\n +"; print $encCertHashList, "\n"; $encCertHashList = " " x 1024; print "retval: " . $func->Call( $filename, \$encCertHashList) . "\ +n"; print $encCertHashList, "\n"; }
as a result i get
filename: C : \ e f s . p l retval: 0 Use of uninitialized value in print at C:/Perl/site/lib/Win32/Security +/EFS.pm line 180, <DATA> line 164. retval: 0 Use of uninitialized value in print at C:/Perl/site/lib/Win32/Security +/EFS.pm line 184, <DATA> line 164. retval: 0 @&#9830; retval: 0
in this case, the call works. but the structure is not really filled.
btw. the file is encrypted!


Comment on Re^4: Win32::API::Struct: Pointers of Pointers
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Re^5: Win32::API::Struct: Pointers of Pointers
by BrowserUk (Pope) on Jun 29, 2006 at 13:59 UTC

    I'm getting much the same results. No errors, just nothing returned in the buffer :(

    I'm using the C source code from here as a reference. Maybe it will give you some clues I'm not seeing?

    I'll update if I have any success.


    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
      that's what i mean. it is a pointer of a pointer. The function alloactes the needed memory itself. here is the prove
      sub query_users { my ( $self, $filename ) = @_; my $func = import_api( 'advapi32', 'QueryUsersOnEncryptedFile', 'P +P', 'N' ); die "Could not import API QueryUsersOnEncryptedFile: $!" unless defined $func; $filename = make_unicode( File::Spec->canonpath($filename) ); + my $ptr = " " x 4; # 4 == sizeof(void*) my $result = $func->Call( "$filename", $ptr ); print "result: $result\n"; return undef if $result; my $address = unpack( "L*", $ptr ); printf("0x%08x\n", $address); }
      i think i have to switch to XS at this point.

        In theory, this should work...but it doesn't.

        #! perl -slw use strict; use Encode; use Devel::Peek; use Win32::API::Prototype; ApiLink( 'advapi32', q[ DWORD QueryUsersOnEncryptedFile( LPCWSTR lpFileName, ULONG pUsers ) ]) or die $^E; my $buffer = chr(0) x 4; print Dump( $buffer ); my $pointer = unpack 'L!', pack 'P', $buffer; printf "%08x\n", $pointer; my $uFile = encode( 'UTF-16LE', $_ = $ARGV[ 0 ], 1 ); print $uFile; QueryUsersOnEncryptedFile( $uFile, $pointer ) or die "$! : $^E"; print Dump( \$buffer ); print unpack 'C*',$buffer;

        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.

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