Delphi - How to get list of USB removable hard drives and memory sticks?
In my application (Delphi), I need to list all the USB storage devices. These can be either flash memory sticks or external storage drives.
There is a Jvcl
component JvDriveCombo
, and it has the DriveType
property - the problem is if I select DriveType := Fixed
then in addition to the external drive, it also lists the internal drives (C:\
, D:\
etc). However, I only want to list the external drives.
I believe there is DeviceIoControl function (I saw it on MSDN) but I have no idea of how to use it.
I wonder if anyone can help me with the proper way / code to list USB storage devices?
Thanks.
EDIT:
I just found some sample code and am posting it here:
uses .... jwawinbase, JwaWinIoctl;
procedure TForm1.Button1Click(Sender: TObject);
var
DriveCmdStr: string;
DriveHandle: THandle;
ADriveLetter: string;
hp: STORAGE_HOTPLUG_INFO;
rlen: DWORD;
begin
ADriveLetter := 'H';
DriveCmdStr := Format('\\.\%s:', [ADriveLetter]);
DriveHandle := CreateFile(PChar(DriveCmdStr), GENERIC_READ, FILE开发者_StackOverflow_SHARE_WRITE,
nil, OPEN_EXISTING, 0, 0);
if DriveHandle = INVALID_HANDLE_VALUE then
Exit;
DeviceIoControl(DriveHandle, IOCTL_STORAGE_GET_HOTPLUG_INFO, nil, 0, @hp,
SizeOf(hp), @rlen, nil);
CloseHandle(DriveHandle);
if hp.MediaRemovable then
showmessage('media removable');
end;
Now I would like to just know how to enumerate all the drive letters. Which is the most efficient function?
{$MINENUMSIZE 4}
const
IOCTL_STORAGE_QUERY_PROPERTY = $002D1400;
type
STORAGE_QUERY_TYPE = (PropertyStandardQuery = 0, PropertyExistsQuery, PropertyMaskQuery, PropertyQueryMaxDefined);
TStorageQueryType = STORAGE_QUERY_TYPE;
STORAGE_PROPERTY_ID = (StorageDeviceProperty = 0, StorageAdapterProperty);
TStoragePropertyID = STORAGE_PROPERTY_ID;
STORAGE_PROPERTY_QUERY = packed record
PropertyId: STORAGE_PROPERTY_ID;
QueryType: STORAGE_QUERY_TYPE;
AdditionalParameters: array [0..9] of AnsiChar;
end;
TStoragePropertyQuery = STORAGE_PROPERTY_QUERY;
STORAGE_BUS_TYPE = (BusTypeUnknown = 0, BusTypeScsi, BusTypeAtapi, BusTypeAta, BusType1394, BusTypeSsa, BusTypeFibre,
BusTypeUsb, BusTypeRAID, BusTypeiScsi, BusTypeSas, BusTypeSata, BusTypeMaxReserved = $7F);
TStorageBusType = STORAGE_BUS_TYPE;
STORAGE_DEVICE_DESCRIPTOR = packed record
Version: DWORD;
Size: DWORD;
DeviceType: Byte;
DeviceTypeModifier: Byte;
RemovableMedia: Boolean;
CommandQueueing: Boolean;
VendorIdOffset: DWORD;
ProductIdOffset: DWORD;
ProductRevisionOffset: DWORD;
SerialNumberOffset: DWORD;
BusType: STORAGE_BUS_TYPE;
RawPropertiesLength: DWORD;
RawDeviceProperties: array [0..0] of AnsiChar;
end;
TStorageDeviceDescriptor = STORAGE_DEVICE_DESCRIPTOR;
function GetBusType(Drive: AnsiChar): TStorageBusType;
var
H: THandle;
Query: TStoragePropertyQuery;
dwBytesReturned: DWORD;
Buffer: array [0..1023] of Byte;
sdd: TStorageDeviceDescriptor absolute Buffer;
OldMode: UINT;
begin
Result := BusTypeUnknown;
OldMode := SetErrorMode(SEM_FAILCRITICALERRORS);
try
H := CreateFile(PChar(Format('\\.\%s:', [AnsiLowerCase(Drive)])), 0, FILE_SHARE_READ or FILE_SHARE_WRITE, nil,
OPEN_EXISTING, 0, 0);
if H <> INVALID_HANDLE_VALUE then
begin
try
dwBytesReturned := 0;
FillChar(Query, SizeOf(Query), 0);
FillChar(Buffer, SizeOf(Buffer), 0);
sdd.Size := SizeOf(Buffer);
Query.PropertyId := StorageDeviceProperty;
Query.QueryType := PropertyStandardQuery;
if DeviceIoControl(H, IOCTL_STORAGE_QUERY_PROPERTY, @Query, SizeOf(Query), @Buffer, SizeOf(Buffer), dwBytesReturned, nil) then
Result := sdd.BusType;
finally
CloseHandle(H);
end;
end;
finally
SetErrorMode(OldMode);
end;
end;
procedure GetUsbDrives(List: TStrings);
var
DriveBits: set of 0..25;
I: Integer;
Drive: AnsiChar;
begin
List.BeginUpdate;
try
Cardinal(DriveBits) := GetLogicalDrives;
for I := 0 to 25 do
if I in DriveBits then
begin
Drive := Chr(Ord('a') + I);
if GetBusType(Drive) = BusTypeUsb then
List.Add(Drive);
end;
finally
List.EndUpdate;
end;
end;
You can access this information using WMI. If you use this SQL you can access information about installed disks.
select * from Win32_diskdrive where size<>NULL
This code retrive information about drives.
procedure TForm1.DoInventario(aWSQL:string; var mmResult:TMemo);
var
Locator:ISWbemLocator;
Services:ISWbemServices;
SObject:ISWbemObject;
ObjSet:ISWbemObjectSet;
Enum:IEnumVariant;
TempObj:OleVariant;
Value:Cardinal;
TS:TStrings;
begin
try
Locator := CoSWbemLocator.Create();
// Conectar con el Servicio de WMI
Services := Locator.ConnectServer(
STR_LOCALHOST, {ordenador local}
STR_CIM2_ROOT, {root}
STR_EMPTY, STR_EMPTY, {usuario y password -en local no son necesarios-}
STR_EMPTY,STR_EMPTY, 0, nil);
// Acceder a los datos
ObjSet := Services.ExecQuery(aWSQL, 'WQL',
wbemFlagReturnImmediately and wbemFlagForwardOnly , nil);
Enum := (ObjSet._NewEnum) as IEnumVariant;
// Hemos encontrado algun objeto?
while (Enum.Next(1, TempObj, Value) = S_OK) do begin
SObject := IUnknown(TempObj) as ISWBemObject;
// encontrado?
if (SObject <> nil) then begin
// Acceder a la propiedad
SObject.Properties_;
// Cargamos las propiedades
TS := TStringList.Create();
try
TS.Add(SObject.GetObjectText_(0));
// lo pasamos al memo
mmResult.Lines.Text := mmResult.Lines.Text + TS.Text;
finally
FreeAndNil(TS);
end;
end;
end;
except
// Recuperar excepciones
end;
end;
You must add ActiveX and WbemScripting_TLB (this must be imported) in your uses. With this you can access all information of the disks.
To retrive the letter of all disk you can combine (retrieve can do with the same code) the access to the classes Win32_LogicalDiskToPartition and Win32_DiskDrive.
select * from Win32_LogicalDiskToPartition
select * from Win32_DiskDrive
If you search WMI you can find more related codes.
Regards.
I'm not sure if you're just looking to enumerate drive letters? The for-loop below does that, going through all letters, regardless of whether there's a drive for that letter.
Or, if you're looking for a different way to find removable drives, there's a function for that below, too. (Yours may be better...) Surprisingly, on my test, Windows.GetDriveType does NOT consider CD drives as removable. USB drives are flagged as removable, as one would expect.
Function RemovableDrive(Drive: char): Boolean;
begin
Result := (Windows.GetDriveType(PChar(Drive + ':\')) = Windows.Drive_Removable);
end;
procedure TForm1.Button1Click(Sender: TObject);
var
Drive: Char;
begin
for Drive := 'A' to 'Z' do
Memo1.Lines.Add('Drive: ' + Drive + ' is ' + BoolToStr(RemovableDrive(Drive), TRUE));
end;
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