File : gnatcom-errors.adb


------------------------------------------------------------------------------
--                                                                          --
--      GNATCOM - Ada 95 COM/DCOM/COM+ Development Framework and Tools      --
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--                      G N A T C O M . E R R O R S                         --
--                                                                          --
--                                B o d y                                   --
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--                            $Revision: 1.3 $
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--             Copyright (C) 1999, 2000, 2001 David Botton                  --
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------------------------------------------------------------------------------

with Ada.Unchecked_Conversion;
with Ada.Exceptions;
with Interfaces.C;
with System.Storage_Elements;

package body GNATCOM.Errors is

   use type GNATCOM.Types.HRESULT;

   function Strip (Image_String : String) return String;
   --  Strips the space prefix off an Type'Image

   TLS_Index : GNATCOM.Types.DWORD;
   --  Thread local storage index for last HRESULT

   function TlsAlloc return GNATCOM.Types.DWORD;
   pragma Import (StdCall, TlsAlloc, "TlsAlloc");
   --  Returns a TLS Index used to access OS allocated thread storage for
   --  last HRESULT

   procedure TlsSetValue
     (Index  : GNATCOM.Types.DWORD;
      Result : GNATCOM.Types.HRESULT);
   pragma Import (StdCall, TlsSetValue, "TlsSetValue");
   --  Sets the HRESULT in to the TLS storage

   function TlsGetValue (Index : GNATCOM.Types.DWORD)
                        return GNATCOM.Types.HRESULT;
   pragma Import (StdCall, TlsGetValue, "TlsGetValue");
   --  Gets the HRESULT ouf of TLS storage

   FORMAT_MESSAGE_FROM_SYSTEM : constant := 4096;
   procedure FormatMessage
     (dwFlags      : GNATCOM.Types.DWORD := FORMAT_MESSAGE_FROM_SYSTEM;
      lpSource     : Interfaces.C.unsigned_long := 0;
      hr           : GNATCOM.Types.HRESULT;
      dwLanguageId : Interfaces.C.unsigned_long := 0;
      lpBuffer     : Interfaces.C.char_array;
      nSize        : Interfaces.C.unsigned_long;
      Arguments    : Interfaces.C.unsigned_long := 0);
   pragma Import (StdCall, FormatMessage, "FormatMessageA");
   --  Returns a string representation of an HRESULT

   ---------------
   -- SUCCEEDED --
   ---------------

   function SUCCEEDED (Result : GNATCOM.Types.HRESULT)
     return Boolean
   is
      use type Interfaces.C.long;

      function To_Long is
         new Ada.Unchecked_Conversion (GNATCOM.Types.HRESULT,
                                       Interfaces.C.long);
   begin
      if To_Long (Result) >= 0 then
         return True;
      else
         return False;
      end if;
   end SUCCEEDED;

   ------------
   -- FAILED --
   ------------

   function FAILED (Result : GNATCOM.Types.HRESULT)
     return Boolean
   is
   begin
      return not (SUCCEEDED (Result));
   end FAILED;

   ---------------
   -- To_String --
   ---------------

   function To_String (Result : GNATCOM.Types.HRESULT)
     return String
   is
      MAX_ERROR : constant := 1024;
      Message   : Interfaces.C.char_array (0 .. MAX_ERROR) :=
        (others => Interfaces.C.nul);
   begin
         FormatMessage (hr       => Result,
                        lpbuffer => Message,
                        nsize    => MAX_ERROR);
         return Interfaces.C.To_Ada (Message);
   end To_String;

   -----------------
   -- Error_Check --
   -----------------

   procedure Error_Check (Result : in GNATCOM.Types.HRESULT) is
   begin
      Set_Last_HRESULT (Result);

      if FAILED (Result) then
         declare
            Message : String := To_String (Result);
         begin
            case Result is
               when E_NOTIMPL =>
                  Ada.Exceptions.Raise_Exception
                    (NOT_IMPLEMENTED_ERROR'Identity,
                     Message);
               when E_OUTOFMEMORY =>
                  Ada.Exceptions.Raise_Exception
                    (OUT_OF_MEMORY_ERROR'Identity,
                     Message);
               when E_INVALIDARG =>
                  Ada.Exceptions.Raise_Exception
                    (INVALID_ARGUMENT_ERROR'Identity,
                     Message);
               when E_NOINTERFACE =>
                  Ada.Exceptions.Raise_Exception
                    (NO_INTERFACE_ERROR'Identity,
                     Message);
               when E_POINTER =>
                  Ada.Exceptions.Raise_Exception
                    (INVALID_POINTER_ERROR'Identity,
                     Message);
               when E_ABORT =>
                  Ada.Exceptions.Raise_Exception
                    (ABORT_ERROR'Identity,
                     Message);
               when E_FAIL =>
                  Ada.Exceptions.Raise_Exception
                    (COM_ERROR'Identity,
                     Message);
               when E_ACCESSDENIED =>
                  Ada.Exceptions.Raise_Exception
                    (ACCESS_DENIED_ERROR'Identity,
                     Message);
               when E_UNEXPECTED =>
                  Ada.Exceptions.Raise_Exception
                    (UNEXPECTED_ERROR'Identity,
                     Message);
               when CO_E_OBJNOTCONNECTED =>
                  Ada.Exceptions.Raise_Exception
                    (OBJECT_NOT_CONNECTED_ERROR'Identity,
                     Message);
               when others =>
                  Ada.Exceptions.Raise_Exception
                    (COM_ERROR'Identity,
                     "HRESULT (" &
                     Strip (GNATCOM.Types.HRESULT'Image (Result)) & ") : " &
                     Message);
            end case;
         end;
      end if;
   end Error_Check;

   -------------------
   -- Logical_Check --
   -------------------

   function Logical_Check (Result : in GNATCOM.Types.HRESULT)
     return Boolean
   is
   begin
      Set_Last_HRESULT (Result);

      if Result = S_FALSE then
         return False;
      elsif SUCCEEDED (Result) then
         return True;
      else
         Error_Check (Result);

         --  Should never be called since Error_Check will raise and
         --  exception. Placed here to avoid compiler warnings.
         return False;
      end if;

   end Logical_Check;

   ---------------
   -- To_String --
   ---------------

   function To_String (Address : System.Address) return String
   is
      use System.Storage_Elements;
   begin
      return Strip (To_Integer (Address)'Img);
   end To_String;

   ----------------------
   -- Get_Last_HRESULT --
   ----------------------

   function Get_Last_HRESULT return GNATCOM.Types.HRESULT is
   begin
      return TlsGetValue (TLS_Index);
   end Get_Last_HRESULT;

   ----------------------
   -- Set_Last_HRESULT --
   ----------------------

   procedure Set_Last_HRESULT (Result : GNATCOM.Types.HRESULT) is
   begin
      TlsSetValue (TLS_Index, Result);
   end Set_Last_HRESULT;

   -----------
   -- Strip --
   -----------

   function Strip (Image_String : String) return String
   is
   begin
      return Image_String (Image_String'First + 1 .. Image_String'Last);
   end Strip;

begin
   TLS_Index := TlsAlloc;
end GNATCOM.Errors;