Board index » cppbuilder » AV - Stack getting trashed - HELP!

2006-04-22 06:57:03 AM
cppbuilder39
I need to use the following code to get the MAC address on Win XP and 2k3.
It should work fine....
However, when execution gets to the lines (marked below) the stack gets
completely trashed. I have isolated the problem into a test app. You can
reproduce it by creating a new BCB project, drop a button on the form and
add this code.
Does it work on your system? Please help!
BCB6 Patched.
TIA
----------------
#include <winsock2.h>
#include "Iptypes.h"
#include "Iphlpapi.h"
typedef ULONG (*TGetAdaptersAddresses)(ULONG Family, ULONG Flags, PVOID
Reserved, PIP_ADAPTER_ADDRESSES pAdapterAddresses, PULONG pOutBufLen);
void __fastcall TForm10::Button1Click(TObject *Sender)
{
HINSTANCE hinst = LoadLibrary("Iphlpapi.dll");
AnsiString AMacAddress = EmptyStr;
if(NULL != hinst)
{
try
{
try
{
TGetAdaptersAddresses pGetAdaptersAddresses =
(TGetAdaptersAddresses)GetProcAddress(hinst, "GetAdaptersAddresses");
if(NULL != pGetAdaptersAddresses)
{
IP_ADAPTER_ADDRESSES * pAddresses = NULL;
try
{
ULONG outBufLen = 0;
// Make an initial call to GetAdaptersAddresses to
get the
// size needed into the outBufLen variable
if (pGetAdaptersAddresses(AF_INET, 0, NULL,
pAddresses, &outBufLen) == ERROR_BUFFER_OVERFLOW)
{
if (pAddresses)
GlobalFree(pAddresses);
pAddresses = (IP_ADAPTER_ADDRESSES*)new unsigned
char[outBufLen];
}
// Make a second call to GetAdapters Addresses to
get the actual data we want
if (pGetAdaptersAddresses(AF_INET, 0, NULL,
pAddresses, &outBufLen) == NO_ERROR)
{
// successful,
unsigned char * MACData =
pAddresses->PhysicalAddress;
////////<<---------------- As this next loop
executes - the stack gets trashed !!! WHY???
DWORD i;
for (i = 0; i <
pAddresses->PhysicalAddressLength; i++)
AMacAddress = AMacAddress + Format("%.2X:",
ARRAYOFCONST(( MACData[i] )));
AMacAddress =
AMacAddress.Delete(AMacAddress.Length(), 1); // take off the last colon
}
}
__finally
{
if (pAddresses)
delete [] pAddresses;
}
}
}
catch(...)
{
AMacAddress = "UNKNOWN MAC ADDR";
}
}
__finally
{
FreeLibrary(hinst);
}
}
MessageDlg(AMacAddress, mtWarning, TMsgDlgButtons() << mbOK, 0);
}
 

"Borland Lover" < XXXX@XXXXX.COM >wrote in message
See below.
compiler's default conention is used. Under C++, the default is __cdecl,
which is NOT the convention that GetAdaptersAddresses() actually uses. If
you look at the documentation for GetAdatersAddresses(), it uses WINAPI for
the calling convention, which in turn usually resolves to __stdcall. Win32
API functions always use the __stdcall convention (wsprintf() is about the
only API function that uses __cdecl instead). __cdecl and _stdcall
manipulate the stack very differently.
Use this code instead:
typedef ULONG (WINAPI *TGetAdaptersAddresses)(ULONG Family, ULONG Flags,
PVOID Reserved, PIP_ADAPTER_ADDRESSES pAdapterAddresses, PULONG pOutBufLen);
void __fastcall TForm10::Button1Click(TObject *Sender)
{
HINSTANCE hinst = LoadLibrary("Iphlpapi.dll");
AnsiString AMacAddress;
if( NULL != hinst )
{
try
{
TGetAdaptersAddresses pGetAdaptersAddresses =
(TGetAdaptersAddresses) GetProcAddress(hinst, TEXT("GetAdaptersAddresses"));
if( NULL != pGetAdaptersAddresses )
{
IP_ADAPTER_ADDRESSES * pAddresses = NULL;
try
{
ULONG outBufLen = 0;
ULONG ulErr = pGetAdaptersAddresses(AF_INET, 0,
NULL, NULL, &outBufLen);
if( ERROR_BUFFER_OVERFLOW == ulErr )
{
pAddresses = (IP_ADAPTER_ADDRESSES*) new
BYTE[outBufLen];
ulErr = pGetAdaptersAddresses(AF_INET, 0, NULL,
pAddresses, &outBufLen);
}
if( (NO_ERROR == ulErr) && (0 !=
pAddresses->PhysicalAddressLength) )
{
AMacAddress.SetLength((pAddresses->PhysicalAddressLength * 3) - 1);
char *ptr = AMacAddress.c_str();
LPBYTE MACData = pAddresses->PhysicalAddress;
sprintf(ptr, "%02X", MACData[0]);
ptr += 2;
for(DWORD i = 1; i <
pAddresses->PhysicalAddressLength; ++i)
{
sprintf(ptr, ":%02X", MACData[i]);
ptr += 3;
}
}
}
__finally
{
delete [] pAddresses;
}
}
}
catch(...)
{
AMacAddress = "UNKNOWN MAC ADDR";
}
FreeLibrary(hinst);
}
MessageDlg(AMacAddress, mtWarning, TMsgDlgButtons() << mbOK, 0);
}
Gambit
 

"Remy Lebeau (TeamB)" < XXXX@XXXXX.COM >wrote in message
 

{smallsort}

What about these two functions :
GetAdaptersInfo - it does not specify a calling convention in the MSDN.
What do I use in BCB?
UuidCreateSequential - it specifies RPC_ENTRY. What do I use in BCB?
I am loading and calling both right now without specifying the calling
convention - and they seem to be working fine. Is this a fluke?
TIA
 

"Borland Lover" < XXXX@XXXXX.COM >wrote in message
except for wsprintf() which uses __cdecl instead. If you look in
iphlpapi.h, where GetAdaptersInfo() is actually declared, you can see that:
DWORD
WINAPI // <-- here
GetAdaptersInfo(
PIP_ADAPTER_INFO pAdapterInfo, PULONG pOutBufLen
);
is actually in the declaration.
free to choose its own. As you have already seen earlier, the compiler can
chose the wrong convention and mess up the runtime behavior as a result.
Gambit
 

Thank you Remy.
"Remy Lebeau (TeamB)" < XXXX@XXXXX.COM >wrote
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