How I can closehandle usb device when it is already ejected

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5.00/5 (2 votes)

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I connect to my USB device through function

C++

HANDLE hDevice = CreateFile("\\\\.\\dev_name",
  GENERIC_READ | GENERIC_WRITE,
  0,
  NULL,
  OPEN_EXISTING,
  FILE_ATTRIBUTE_NORMAL,
  NULL);

If my usb device was suprisely removed and after that I tried CloseHandle Windows crash to BSOD. What can I do to make the handle close correctly?

What I have tried:

I tried use RegisterDeviceNotification to track device event DBT_DEVICEQUERYREMOVE, but this event does not seem to be triggered if device was suprisely removed.

Posted 27-Nov-19 1:43am

MaxSandi

Updated 27-Nov-19 20:21pm

Leo Chapiro

v2

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11917640 Member 27-Nov-19 10:48am

Try DBT_DEVICEREMOVECOMPLETE.

MaxSandi 28-Nov-19 5:03am

DBT_DEVICEREMOVECOMPLETE called after usb device was removed, and if I used CloseHandle Windows crashed.

[no name] 28-Nov-19 10:16am

Only an idea: E.g. Process Explorer from Sysinternals shows you all the handles used by a process. So I would check with Process Explorer whether the handle disappears if the usb is removed.
If the handle disappears in Process Explorer you "only" need a way to get the list of Handles in use programatically and check whether your Handle is still in the list.
I'm aware, it's a crazy idea ;)

[Edit]
This maybe can help to get the list of handles: Listing Used Files[^]

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Leo Chapiro · Answer 1 · 2019-11-27T03:24:00

If the USB device has been unplugged, your handle will be invalid, there is nothing to do!
I would put the CloseHandle in try/catch block and set the handle to INVALID_HANDLE if it fails.
Try something like this:

C++

HANDLE hDevice = CreateFile("\\\\.\\dev_name",
    GENERIC_READ | GENERIC_WRITE,
    0,
    NULL,
    OPEN_EXISTING,
    FILE_ATTRIBUTE_NORMAL,
    NULL);

// Do something with it (ReadFile/WriteFile) ...

try
{
  if (hDevice != INVALID_HANDLE_VALUE)
       CloseHandle(hDevice);
}
catch(...)
{
  hDevice = INVALID_HANDLE_VALUE;
}

KarstenK · Answer 2 · 2019-11-27T20:21:00

Solution 2

Check that the handle is valid with GetHandleInformation. Read it for further details.

Posted 27-Nov-19 20:21pm

KarstenK

How I can closehandle usb device when it is already ejected

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How I can closehandle usb device when it is already ejected

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