SafeArrays in C

Private Declare Function binaryDataTest Lib "teds.dll" (buf() As Byte) As Long
Private Declare Function retSa Lib "teds.dll" () As Byte()

Private Sub Form_Load()
    
    Dim b() As Byte
    
    List1.AddItem "Testing safe array return type.."
    b() = retSa()
    testByteArray b()
    
    Erase b
    
    List1.AddItem "Testing safe array as argument.."
    retval = binaryDataTest(b)
    If retval > 0 Then
        testByteArray b()
    Else
        List1.AddItem "binaryDataTest failed with: " & retval
    End If
    
End Sub

int file_length(FILE *f)
{
	int pos;
	int end;

	pos = ftell (f);
	fseek (f, 0, SEEK_END);
	end = ftell (f);
	fseek (f, pos, SEEK_SET);

	return end;
}

int __stdcall binaryDataTest(SAFEARRAY** psa)
{
#pragma EXPORT
 
	int retVal = 0;
	FILE* fp = fopen("teds.dll", "rb");
	if(fp==0) return 0;	

	int size = file_length(fp);
	unsigned char* dat = (unsigned char*)malloc(size); 

	memset(dat, 0, size);
	fread(dat, 1, size, fp);
	fclose(fp);

	HRESULT hresult = SafeArrayAllocDescriptor(1,psa);
	if( FAILED(hresult)) goto cleanup;

	(*psa)->rgsabound[0].cElements = size;
        (*psa)->cbElements = 1;  

	hresult = SafeArrayAllocData(*psa);
	if( FAILED(hresult) ) goto cleanup;

	for (long i = 0; i < size - 1; i++)
	{
		hresult = SafeArrayPutElement( *psa, &i, (void *)&dat[i] );
		if(FAILED(hresult))	return 0;		
	}
	
	retVal = 1;

cleanup:
	free(dat);
	return  retVal;

}

SAFEARRAY* __stdcall retSa()
{
#pragma EXPORT
 
	FILE* fp = fopen("teds.dll", "rb");
	if(fp==0) return 0;	

	int size = file_length(fp);
	unsigned char* dat = (unsigned char*)malloc(size); 

	memset(dat, 0, size);
	fread(dat, 1, size, fp);
	fclose(fp);

	SAFEARRAYBOUND arrayBounds[1] = { {size, 0}};
	SAFEARRAY* psa = SafeArrayCreate(VT_I1, 1, arrayBounds);
	SafeArrayLock(psa);

	unsigned char* pData = (unsigned char*)(psa->pvData); 

	for (long i = 0; i < size - 1; i++)
	{
		pData[i] = dat[i];	
	}

	free(dat);
	SafeArrayUnlock(psa);
	return psa;

}