Safely remove a USB drive using the Win32 API?

Question

How do I remove a USB drive using the Win32 API? I do a lot of work on embedded systems and on one of these I have to copy my programs on a USB stick and insert it into the target hardware.

Since I mostly work on the console I don't like to use the mouse and click on the small task-bar icon hundred times a day.

I'd love to write a little program to do exactly that so I can put it into my makefiles, but I haven't found any API call that does the same thing.

Any ideas?

Pennyroyal

Answer 1

You can use the CM_Request_Device_Eject() function as well as some other possibilities. Consult the following projects and articles:

DevEject: Straightforward. http://www.withopf.com/tools/deveject/

A useful CodeProject article: http://www.codeproject.com/KB/system/RemoveDriveByLetter.aspx

Vladamar

Answer 2

It looks like Sync lets you specify -e to eject removable drives. While not a win32 API, you could probably just call sync -e [drive_letter] from your makefile.

Hakan

But how to know which drive letter has been added for USB drive? I also want to remove USB drives based on volumes like Do not allow USB volume more than 5GG etc. – Pandect

Answer 3

#include<SetupAPI.h>
#include <windows.h>  
#include<initguid.h>
#include <newdev.h>
#include <Cfgmgr32.h>

#pragma comment(lib, "Cfgmgr32.lib")
#pragma comment(lib, "Setupapi.lib")
#pragma comment(lib, "Newdev.lib")

int RemoveDevice(const GUID *guid, const wchar_t *hwID) {
    HDEVINFO m_hDevInfo;
    SP_DEVICE_INTERFACE_DATA         spdid;
    SP_DEVINFO_DATA                  spdd;
    DWORD                            dwSize;
    BYTE Buf[1024];
    PSP_DEVICE_INTERFACE_DETAIL_DATA pspdidd =
        (PSP_DEVICE_INTERFACE_DETAIL_DATA)Buf;

    printf("try to remove device::%ws\n", hwID);

    m_hDevInfo = SetupDiGetClassDevs(guid, NULL, NULL, DIGCF_PRESENT| DIGCF_DEVICEINTERFACE);
    if (m_hDevInfo == INVALID_HANDLE_VALUE)
    {
        printf("GetClassDevs Failed!\n");
        return 0;
    }
    spdid.cbSize = sizeof(spdid);
    for (int i = 0; SetupDiEnumDeviceInterfaces(m_hDevInfo, NULL, guid, i, &spdid); i++) {
        dwSize = 0;
        SetupDiGetDeviceInterfaceDetail(m_hDevInfo,
            &spdid, NULL, 0, &dwSize, NULL);
        if (dwSize != 0 && dwSize <= sizeof(Buf)) {
            pspdidd->cbSize = sizeof(*pspdidd); // 5 Bytes!

            ZeroMemory((PVOID)&spdd, sizeof(spdd));
            spdd.cbSize = sizeof(spdd);

            long res =
                SetupDiGetDeviceInterfaceDetail(m_hDevInfo, &
                    spdid, pspdidd,
                    dwSize, &dwSize,
                    &spdd);
            if (res) {
                OLECHAR* guidString;
                OLECHAR* guidString2;
                StringFromCLSID(&spdd.ClassGuid, &guidString);
                StringFromCLSID(&spdid.InterfaceClassGuid, &guidString2);
                printf("%d, %ws, %ws, %ws\n", spdd.DevInst, pspdidd->DevicePath, guidString, guidString2);
                CoTaskMemFree(guidString);
                CoTaskMemFree(guidString2);
                if (!memcmp(pspdidd->DevicePath, hwID, 2 * lstrlenW(hwID))) {
                    DEVINST DevInstParent = 0;
                    res = CM_Get_Parent(&DevInstParent, spdd.DevInst, 0);
                    for (long tries = 0; tries < 10; tries++) {
                        // sometimes we need some tries...
                        WCHAR VetoNameW[MAX_PATH];
                        PNP_VETO_TYPE VetoType = PNP_VetoTypeUnknown;
                        VetoNameW[0] = 0;

                        res = CM_Request_Device_EjectW(DevInstParent,
                            &VetoType, VetoNameW, MAX_PATH, 0);
                        if ((res == CR_SUCCESS &&
                            VetoType == PNP_VetoTypeUnknown)) {
                            printf("remove %ws success!\n", pspdidd->DevicePath);
                            SetupDiDestroyDeviceInfoList(m_hDevInfo);
                            return 1;
                        }
                        Sleep(500); // required to give the next tries a chance!
                    }
                    break;
                }
            }
        }
    }
    printf("Remove Device Failed!\n");
    SetupDiDestroyDeviceInfoList(m_hDevInfo);
    return 0;
}

int main(){
    GUID GUID_DEVINTERFACE_USB_HUB;
    CLSIDFromString(L"F18A0E88-C30C-11D0-8815-00A0C906BED8", &GUID_DEVINTERFACE_USB_HUB);

    RemoveDevice(&GUID_DEVINTERFACE_USB_HUB, L"\\\\?\\usb#root_hub30");
    return 0;
}

refrences:

How to Prepare a USB Drive for Safe Removal

GUID_DEVINTERFACE

Thordis