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Icetips Article

Windows API: Creating a GUID
2003-04-29 -- Jim Kane
Newsgroups: comp.lang.clarion

Notice in the c prototype ** ? That means pointer to a pointer. You need to
do one more copy.
What you are getting back is a pointer to the string. My code uses call by
address since the dlls involved are not found on all os but you can use a
lib if all your customers will have nt or higher
  if SELF.CallDllCl.Init(Dllname,SELF.Debug)
    SELF.TakeError('RpcRt4.dll not found','CreateGuid')
    do procret
  end
  SELF.calldllcl.setprocfailcode(1)

  procresult = SELF.calldllcl.call('UuidCreate',plpGuid)
  if procresult<>0
    If procresult = 1824 then
      SELF.TakeError('No NIC in this Machine','CreateGuid')
    elsif res = 1739
      SELF.TakeError('Unable to get NIC Address','CreateGuid')
    else
      SELF.TakeError('UUIDCreate Failed','CreateGuid')
    end
    do procret
  End

  if ~omitted(3) then
    !Convert to a string
    ProcResult=SELF.calldllcl.call('UuidToStringA', plpguid
,address(UuidStrPtr))
    If ProcResult<>0 or ~uuidstrptr then
      SELF.TakeError('Uuidstr fail','CreateGuid')
      do procret
    End

    !Copy string from RPC Owned Memory to CW memory
    if size(pGuidStr)< lstrlen(uuidstrptr)+1 then
      SELF.TakeError('Guid string is too short:
Required='&lstrlen(uuidstrptr) & ' provided='&size(pGuidStr),'CreateGuid')
      do procret
    else
      lstrcpy(address(tempcStr),UuidStrPtr)
      pGuidStr=tempcstr
      res=return:benign
    end
  end
  do procret

procret routine
  !free the RPC Memory, if any was obtained
  if uuidstrptr then
    SELF.calldllcl.call('RpcStringFreeA', address(UuidStrPtr))
  end
  SELF.CallDllCl.kill()
  return res

Notice the extra lstrcpy and finally the call to rpcstringfreeA
Jim Kane

"Charles Ballard"  wrote in message
news:3eaebf1c$1@news.softvelocity.com...
> I believe I have successfully used CoCreateGuid to create the uuid I need,
> but I'm having trouble getting the UuidToString API to work:
>
> I have used LibMaker to generate a .lib for rpcrt4.dll.  I have prototyped
> the functions as such:
>
> !Atomic Equates
> DWORD   EQUATE(LONG)   !4-byte signed
> WORD    EQUATE(USHORT) !2-byte unsigned
> !Compound Equates
> GUID           GROUP,TYPE
> Data1            DWORD
> Data2            WORD
> Data3            WORD
> Data4            STRING(8)
>                END
>
> MODULE('Rpcrt4.DLL')
>   UuidToString(*GUID,*CSTRING),UNSIGNED,PASCAL,RAW,NAME('UuidToStringA')
> END
> MODULE('Ole32.DLL')
>   CoCreateGuid(*GUID),HRESULT,PASCAL,RAW
> END
>
> And I'm calling them like this:
>
>   DATA
> loc:guid    GROUP(GUID).
> loc:guidStr cstring(27)
>   CODE
>   clear(loc:guid)
>   e#=CoCreateGuid(loc:guid)
>   !I seem to have valid data in the group at this point
>   e#=UuidToString(loc:guid,loc:guidStr)
>   !But loc:guidStr gives me garbage here
>
> I get no compile or link errors, but no useable uuid, either.
>
> The MSDN definition of the UuidToString function is this:
>
> RPC_STATUS RPC_ENTRY UuidToString(
>   UUID *Uuid,
>   unsigned char **StringUuid
> );
> Parameters
>   Uuid
>   Pointer to a binary UUID.
>   StringUuid
>   Pointer to a pointer to the string into which the UUID specified in the
> Uuid parameter shall be placed.
> I'm pretty sure I'm using it incorrectly.
> Any ideas?
> Thanks,
> Charles
>
>
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