WriteFile to physicaldrive on Win7

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My application requires writing directly to physical drive which is a usb removable storage device. It works ok on xp until Win7 is installed. In this case the WriteFile win32 api returns deny access error (5).

While looking through this board I got the idea how to make the write work: basically the drive mapped to the volume must be removed before writing can begin.

(1) call QueryDosDevice to get device name.
(2) call DefineDosDevice with DDD_RAW_TARGET_PATH | DDD_REMOVE_DEFINITION | DDD_EXACT_MATCH_ON_REMOVE

The volume is then gets removed and WriteFile() returns success. So far so good.

The problem now is: How can I restore the drive mapping?

I tried using DefineDosDevice with DDD_RAW_TARGET_PATH which is kind works but it persist the drive letter even the USB is removed. So if I run the application again it will look for next available drive letter until finally the machine has to reboot.

Any suggestion on mount back a removable storage device? Thanks in advance.

Posted 25-Aug-11 5:29am

csuo

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Sergey Alexandrovich Kryukov 25-Aug-11 23:21pm

You need to explain. If you simply write the file do you think you write to chemical or biological drive or what? :-)
--SA

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csuo · Answer 1 · 2011-08-25T07:38:00

Solution 1

Found the solution:

Undo calling DefineDosDevice().

Before WriteDisk,

Call DeviceIoControl FSCTL_DISMOUNT_VOLUME.

After writing, call IOCTL_STORAGE_LOAD_MEDIA to restore.

Posted 25-Aug-11 7:38am

csuo

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noamshan 20-Dec-11 7:53am

I have the same problem. Tried all the options above, still get ERROR_ACCESS_DENIED after WriteFile. Any ideas?