Importing calls to access Windows registry

Importing calls to access Windows registry

[czgrr]

Hello everybody, my turn to ask a question.

I am using ObjectAda 7.1.1 on Windows NT 4.0. I am trying to access the
registry, but I am coming across link errors which I have not been able to
fix. Something obvious, I expect, but just not to me! This was based on code
from a Windows 95 application in ActivAda (83) which works.

I only have Ada83 experience, so please let me know if anything you might
provide in a solution is only available in Ada95, or only in ObjectAda AFAYK.

I am doing this for one of a few functions I want...

  TYPE windows_integer_type IS RANGE -2**31 .. ( 2**31 - 1 ) ;
  FOR windows_integer_type'SIZE USE 32 ;

  TYPE string_pointer_type         IS ACCESS STRING ;
  TYPE string_pointer_pointer_type IS ACCESS string_pointer_type ;

  FUNCTION RegOpenKey
             ( key         :        SYSTEM.ADDRESS ;               -- IN
               subkey      :        STRING ;                       -- IN
               key_address :        string_pointer_pointer_type )  -- OUT
                             RETURN windows_integer_type ;
  PRAGMA IMPORT ( WIN32, RegOpenKey ) ;

but I get the following link error...

registry_server.obj : error LNK2001: unresolved external symbol _RegOpenKey@12

What am I doing wrong?

Cheers in advance,
czgrr

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Re: Importing calls to access Windows registry

[Tom Moran]

The immediate answer to your link errors, as pointed out by
Sune Falck, is to add advapi32.lib to your link.

As a comment, I'd also suggest you can save yourself a lot of
typing and probably a lot of grief by using the package
Interfaces.C, instead of defining your own "windows_integer_type"
etc and using your own code to append nulls to Ada Strings and
using System.Address.

In Claw we (internally) use RegOpenKeyEx like
     function Reg_Open_Key_Ex(Key     :        Claw.Win32.HKey;
                              lpszSubKey:      Claw.Win32.Lpcstr;
                              dwReserved:      Claw.DWord := 0;
                              samDesired:      Key_Access_Options;
                              phkResult:       PHKey)
     return Reg_Error_Code_Type;
     pragma Import(Stdcall, Reg_Open_Key_Ex, "RegOpenKeyExA");
inside
    procedure Open (Key    : in out Key_Type;
                    Parent : in Key_Type;
                    Name   : in String;
                    Access_Capability : in Access_Capabilities :=
ALLOW_ALL_ACCESS;
                    Creation_Option : Creation_Options := Open_Only);
which uses it with
     C_Name : Interfaces.C.Char_Array
         := Interfaces.C.To_C(Name, Append_Nul=>True);
     Handle : aliased Claw.Win32.HKey;
...
     Result := Reg_Open_Key_Ex(Parent.Handle,
                                 C_Name(0)'Unchecked_Access,
                                 0,     -- reserved
                                 Access_Code(Access_Capability),
                                 Handle'Unchecked_Access);

Re: Importing calls to access Windows registry

[dennison]

In article <37331c0b.1253787@news.pacbell.net>,
  tmoran@bix.com (Tom Moran) wrote:
> As a comment, I'd also suggest you can save yourself a lot of
> typing and probably a lot of grief by using the package
> Interfaces.C, instead of defining your own "windows_integer_type"
> etc and using your own code to append nulls to Ada Strings and
> using System.Address.

Generally that may be the case, but in his case it was *ported* code, so it
will not save him any typing to change. However, it may indeed save him
grief.

--
T.E.D.

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Re: Importing calls to access Windows registry

[Sune Falck]

RegOpenKey is in the advapi32.dll so you must somehow add
advapi32.lib to the linker command line.

One way might be to add ...objecta\apilib as a search path in the
Objectada IDE
Another alternativ is to set the environment variable LIB so 
that it includes the ...objecta\apilib directory and then add
-ll advapi32.lib to the adabuild command.


>I am using ObjectAda 7.1.1 on Windows NT 4.0. I am trying to access the
>registry, but I am coming across link errors which I have not been able to
>fix. Something obvious, I expect, but just not to me! This was based on code
>
>registry_server.obj : error LNK2001: unresolved external symbol _RegOpenKey@12
>
>What am I doing wrong?
>
>Cheers in advance,
>czgrr
>

Re: Importing calls to access Windows registry

[czgrr]

Thanks to all who replied, I can now link the library in successfully.
For anyone else who is interested...

1. In "Project/Settings/Link/Pass to linker" I added:
c:\progra~2\aonix\objectada\apilib\advapi32.lib
(it didn't like "Program Files" in the path, even with quotes)

2. In the source file I added:
PRAGMA Linker_Options ( "-defaultlib:advapi32" ) ;

3. For the specification of RegOpenKey, the import statement was
changed to:
PRAGMA IMPORT ( STDCALL, RegOpenKey, "RegOpenKeyA" ) ;

TTFN,
czgrr

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