Safely remove a USB drive using the Win32 API? - c

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?

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

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.

Answer 3

Here is a technet article about removable storage media. Look for DismountNtmsMedia.

Answer 4

Here's a solution in Delphi, that I've modified and put into a service for use in a very large enterprise. Go to: link text
Look for "scapi (Setup & Config Manager API)", and download it. There will be a demo program called USBView that will get you on your way. If you have Delphi, this also includes a TUSBDeviceTree component that you can use to gather information about a USB device when.
Regards

Answer 5

#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