How to correctly retrieve battery serial number? - delphi

Question

In Delphi 7 I'm working on a library implementing an object encapsulating information about the batteries attached to a system. It's working well, except for retrieving the serial number for the battery.
The code I am using for this call is as follows:
function TBattery.GetSerialNumber(hbat: THandle): boolean;
var
bqi: TBatteryQueryInformation;
Serial: PWideChar;
SerialSize,
dwOut: DWORD;
begin
Result := False;
if hbat <> INVALID_HANDLE_VALUE then
begin
ZeroMemory(#bqi, SizeOf(bqi));
dwOut := 0;
bqi.BatteryTag := FBatteryTag;
bqi.InformationLevel := BatterySerialNumber;
SerialSize := 2048;
GetMem(Serial, SerialSize);
try
ZeroMemory(Serial, SerialSize);
Result := DeviceIoControl(hbat, IOCTL_BATTERY_QUERY_INFORMATION, #bqi,
SizeOf(bqi), Serial, SerialSize, #dwOut, nil);
if Result then
FSerialNumber := Serial;
finally
FreeMem(Serial, SerialSize);
end;
end;
end;
Unfortunately, DeviceIoControl() always returns False and if I check GetLastError() afterwards then it comes back with error 87, "the parameter is incorrect."
This doesn't make much sense, because the code works perfectly well if I simply change the InformationLevel from BatterySerialNumber to BatteryUniqueID, say. Also, I've used the handle to the battery (hbat) in other calls in the code before GetSerialNumber and they all work fine, and I can call others after this one fails as well, so that's not the issue.
Any ideas? I'm really at a loss.

Answer 1

The issue it seems related to the dwOut variable which is passed as #dwOut, this variable represents the var lpBytesReturned parameter of the DeviceIoControl which is defined as
function DeviceIoControl(hDevice: THandle; dwIoControlCode: DWORD; lpInBuffer: Pointer;
nInBufferSize: DWORD; lpOutBuffer: Pointer; nOutBufferSize: DWORD;
var lpBytesReturned: DWORD; lpOverlapped: POverlapped): BOOL; stdcall;
So replacing your code by
Result := DeviceIoControl(hbat, IOCTL_BATTERY_QUERY_INFORMATION, #bqi,
SizeOf(bqi), Serial, SerialSize, dwOut, nil);
Must fix the problem.
WinAPI
Also check this code translated to delphi from this msdn entry Enumerating Battery Devices which can help you to detect any additional issues with your code.
uses
SetupApi,
Windows,
SysUtils;
type
BATTERY_QUERY_INFORMATION_LEVEL = (
BatteryInformation,
BatteryGranularityInformation,
BatteryTemperature,
BatteryEstimatedTime,
BatteryDeviceName,
BatteryManufactureDate,
BatteryManufactureName,
BatteryUniqueID,
BatterySerialNumber);
TBatteryQueryInformationLevel = BATTERY_QUERY_INFORMATION_LEVEL;
_BATTERY_QUERY_INFORMATION = record
BatteryTag: ULONG;
InformationLevel: BATTERY_QUERY_INFORMATION_LEVEL;
AtRate: Longint;
end;
BATTERY_QUERY_INFORMATION = _BATTERY_QUERY_INFORMATION;
PBATTERY_QUERY_INFORMATION = ^BATTERY_QUERY_INFORMATION;
TBatteryQueryInformation = BATTERY_QUERY_INFORMATION;
const
GUID_DEVCLASS_BATTERY:TGUID='{72631E54-78A4-11D0-BCF7-00AA00B7B32A}';
//DEFINE_GUID( GUID_DEVCLASS_BATTERY, 0x72631E54, 0x78A4, 0x11D0, 0xBC, 0xF7, 0x00, 0xAA, 0x00, 0xB7, 0xB3, 0x2A );
METHOD_BUFFERED = 0;
FILE_DEVICE_BATTERY = $00000029;
FILE_READ_ACCESS = $0001; // for files and pipes
IOCTL_BATTERY_QUERY_TAG =
(FILE_DEVICE_BATTERY shl 16) or (FILE_READ_ACCESS shl 14) or ($10 shl 2) or (METHOD_BUFFERED);
IOCTL_BATTERY_QUERY_INFORMATION =
(FILE_DEVICE_BATTERY shl 16) or (FILE_READ_ACCESS shl 14) or ($11 shl 2) or (METHOD_BUFFERED);
function GetBatteryInfo(InformationLevel : BATTERY_QUERY_INFORMATION_LEVEL) : string;
var
cbRequired : DWORD;
hdev : HDEVINFO;
idev : Integer;
did : TSPDeviceInterfaceData;
pdidd : PSPDeviceInterfaceDetailData;
hBattery : THandle;
bqi : TBatteryQueryInformation;
dwWait, dwOut : DWORD;
lpOutBuffer: PWideChar;
begin
// enumerate the batteries
hdev := SetupDiGetClassDevs(#GUID_DEVCLASS_BATTERY, nil, 0, DIGCF_PRESENT OR DIGCF_DEVICEINTERFACE);
if ( INVALID_HANDLE_VALUE <> THandle(hdev) ) then
begin
idev:=0;//first battery
ZeroMemory(#did, SizeOf(did));
did.cbSize := SizeOf(did);
if (SetupDiEnumDeviceInterfaces(hdev, nil, GUID_DEVCLASS_BATTERY, idev, did)) then
begin
try
cbRequired := 0;
SetupDiGetDeviceInterfaceDetail(hdev, #did, nil, 0, cbRequired, nil);
if (ERROR_INSUFFICIENT_BUFFER= GetLastError()) then
begin
pdidd:=AllocMem(cbRequired);
try
pdidd.cbSize := SizeOf(TSPDeviceInterfaceDetailData);
if (SetupDiGetDeviceInterfaceDetail(hdev, #did, pdidd, cbRequired, cbRequired, nil)) then
begin
hBattery :=CreateFile(pdidd.DevicePath, GENERIC_READ OR GENERIC_WRITE, FILE_SHARE_READ OR FILE_SHARE_WRITE, nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
if (INVALID_HANDLE_VALUE <> hBattery) then
begin
try
ZeroMemory(#bqi, SizeOf(bqi));
// With the tag, you can query the battery info.
dwWait := 0;
if (DeviceIoControl(hBattery, IOCTL_BATTERY_QUERY_TAG, #dwWait, sizeof(dwWait), #bqi.BatteryTag, sizeof(bqi.BatteryTag), dwOut, nil)) then
begin
lpOutBuffer:=AllocMem(MAX_PATH);
try
ZeroMemory(lpOutBuffer,MAX_PATH);
bqi.InformationLevel:=InformationLevel;
if DeviceIoControl(hBattery, IOCTL_BATTERY_QUERY_INFORMATION, #bqi, SizeOf(BATTERY_QUERY_INFORMATION), lpOutBuffer, 255, dwOut,nil) then
Result:= WideCharToString(lpOutBuffer);
finally
FreeMem(lpOutBuffer);
end;
end;
finally
CloseHandle(hBattery)
end;
end;
end;
finally
FreeMem(pdidd);
end;
end;
finally
SetupDiDestroyDeviceInfoList(hdev);
end;
end;
end;
end;
begin
try
if not LoadsetupAPI then exit;
Writeln(GetBatteryInfo(BatterySerialNumber));
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
readln;
end.
WMI
Finally as aside note, you can use the WMI to retrieve the same info, in this case using the BatteryStaticData WMI class
{$APPTYPE CONSOLE}
uses
SysUtils,
ActiveX,
ComObj,
Variants;
// Battery Static Data
procedure GetBatteryStaticDataInfo;
const
WbemUser ='';
WbemPassword ='';
WbemComputer ='localhost';
wbemFlagForwardOnly = $00000020;
var
FSWbemLocator : OLEVariant;
FWMIService : OLEVariant;
FWbemObjectSet: OLEVariant;
FWbemObject : OLEVariant;
oEnum : IEnumvariant;
iValue : LongWord;
begin;
FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
FWMIService := FSWbemLocator.ConnectServer(WbemComputer, 'root\WMI', WbemUser, WbemPassword);
FWbemObjectSet:= FWMIService.ExecQuery('SELECT SerialNumber FROM BatteryStaticData','WQL',wbemFlagForwardOnly);
oEnum := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
while oEnum.Next(1, FWbemObject, iValue) = 0 do
begin
Writeln(Format('SerialNumber %s',[String(FWbemObject.SerialNumber)]));// String
Writeln('');
FWbemObject:=Unassigned;
end;
end;
begin
try
CoInitialize(nil);
try
GetBatteryStaticDataInfo;
finally
CoUninitialize;
end;
except
on E:EOleException do
Writeln(Format('EOleException %s %x', [E.Message,E.ErrorCode]));
on E:Exception do
Writeln(E.Classname, ':', E.Message);
end;
Writeln('Press Enter to exit');
Readln;
end.

Answer 2

In summary, the code #RRUZ and I posted work fine under Windows 7, as well as other third-party applications. They do not work for retrieving the serial number under Windows XP. I've also tested under WinXP and 7 with base installs of the OS on the exact same hardware, with identical results (success under Windows 7, not under windows XP).
It appears that under WinXP the value BatterySerialNumber for IOCTL_BATTERY_QUERY_INFORMATION's InformationLevel member is not supported, but this is not documented directly in the Windows SDK docs. It is documented that invalid entries should return error 1 (ERROR_INVALID_FUNCTION) for GetLastError(), but in this case is returning 87 (for an invalid parameter) instead. I posit that this is because that value in the enumeration is not valid, so it makes the parameter invalid, but I'm not exactly sure.
Thanks to all for their help, especially #RRUZ for going way above and beyond!
(As an aside, it appears that one can extract the serial number from the battery's Unique ID (Using BatteryUniqueID as the InformationLevel member) and removing the manufacturer name and device name from the unique ID. That's a terrible hack, but it's a semi-viable workaround for Windows XP.)