Using Windows ACL-functions
lazarus / 34-Windows

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ChrisTG · 2014-07-08 09:15

Hi there,

I'm trying to use function GetNamedSecurityInfo() to read the ACL of a
folder structure.
The code looks like this:
Code: [Select]dwError := GetNamedSecurityInfo(pAnsiChar(Filename),
SE_FILE_OBJECT, DACL_SECURITY_INFORMATION, nil, nil, @ExistingDacl,
nil, @psd);
Unfortunately the compiler complains:
Code: [Select]D:\workspace\Libs\MyFileUtils.pas(54,70) Error:
Incompatible type for arg no. 2: Got "SE_OBJECT_TYPE", expected
"_SE_OBJECT_TYPE"
If I try to change to _SE_FILE_OBJECT, I get the following error
message:
Code: [Select]D:\workspace\Libs\MyFileUtils.pas(54,71) Error:
Identifier not found "_SE_FILE_OBJECT"

Strange is, that the function is defined in JwaAclApi as:
Code: [Select]function GetNamedSecurityInfo(pObjectName: LPTSTR;
ObjectType: SE_OBJECT_TYPE;
  SecurityInfo: SECURITY_INFORMATION; ppsidOwner, ppsidGroup: PPSID;
ppDacl,
  ppSacl: PPACL; var ppSecurityDescriptor: PSECURITY_DESCRIPTOR):
DWORD; stdcall;
So, from my point of view SE_FILE_OBJECT should be fine??

Has anyone a solution for this problem?

TIA,
Chris

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marcov · 2014-07-08 09:29

Probably you have some identifier conflict, or multiple
getnamedsecurityinfo declarations. Maybe Jedi and FPC Windows unit
both define it.

 IOW two different units export the same identifier, and the compiler
wants the type one that belongs to the getnamedsecurityinfo call, but
you pass a type declared in some other unit.

Try to make a minimal program with only the GetNamedSecurityInfo call
(it must only be compilable, not runnable). If that succeeds, then
start adding your own units till it goes wrong.

Usually such conflicts are worked around by prefixing the identifiers
(getnamesecurityinfo and SE_FILE_OBJECT or its type) with the unit
name (e.g. jwaaclapi.getnamedsecurityinfo etc)

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ChrisTG · 2014-07-08 09:40

Hi marcov,

thanks for your reply!

Ok, I've created a "bare minimun" version of the problem.
But I still don't see any double definitions that could cause the
error.
I've attached the project files to this post, could you please drop a
quick look on them?

Thanks,
Chris

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Cyrax · 2014-07-08 09:45

Quote from: ChrisTG on July 08, 2014, 11:15:26 amHi there,

I'm trying to use function GetNamedSecurityInfo() to read the ACL of a
folder structure.
The code looks like this:
Code: [Select]dwError := GetNamedSecurityInfo(pAnsiChar(Filename),
SE_FILE_OBJECT, DACL_SECURITY_INFORMATION, nil, nil, @ExistingDacl,
nil, @psd);
...

You need to declare new variable which have type of SE_FILE_OBJECT and
feed it to GetNamedSecurityInfo function.

Like this:
Code: [Select]  Var
    AFileObject : SE_FILE_OBJECT;
...
dwError := GetNamedSecurityInfo(pAnsiChar(Filename), AFileObject,
DACL_SECURITY_INFORMATION, nil, nil, @ExistingDacl, nil, @psd);

And I think you need to same for DACL_SECURITY_INFORMATION.

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Cyrax · 2014-07-08 09:48

Quote from: ChrisTG on July 08, 2014, 11:40:36 amHi marcov,

thanks for your reply!

Ok, I've created a "bare minimun" version of the problem.
But I still don't see any double definitions that could cause the
error.
I've attached the project files to this post, could you please drop a
quick look on them?

Thanks,
Chris

Remove Windows, JwaAclApi and JwaAccCtrl units from uses clause. Then
add only JwaWindows in there.

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ChrisTG · 2014-07-08 10:13

Hi Cyrax,

thanks for your reply.

Removing all but JwaWindows solves the problem with the stripped down
example project, but I can't use that as a solution in my normal
project since I need units like "Windows" there.
Defining variables and passing them to the function call instead of
the types does not change anything. The compiler still complains about
an incompatible type.
Where is that "correct" SE_FILE_OBJECT defined? Can I use something
like <UnitWithCorrectDefinition>.SE_FILE_OBJECT in my code? Would that
work?

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ChrisTG · 2014-07-08 10:22

I think I figured it out. I simply have to write "JwaWindows." in
front of ALL references in that function call. This way the complier
gets the right definitions and the code can be compiled without
errors.
Strange, that this is not needed in Delphi.

However, my problem is solved - so thanks again for your support!

cheers,
Chris

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marcov · 2014-07-08 10:30

Maybe Free Pascal has some of these declarations in unit Windows.  The
delphi behaviour might be version specific

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Leledumbo · 2014-07-08 14:29

JWA prefix means the unit comes from JEDI Windows API project, which
is initially made to be Delphi compatible. FPC also wraps Windows API,
but the content might not be compatible with JWA / Delphi one.

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marcov · 2014-07-08 14:30

JWAwindows is afaik also not compatible with Delphi windows.  Put the
jedi units last in the uses clause.