WriteFile on Physical Drives with Windows 7

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4.00/5 (1 vote)

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I have a piece of code that writes sectors to a physical disk using WriteFile. This works fine under Win XP, but not under Windows 7 (Not tried Vista). It returns an error code of ERROR_ACCESS_DENIED. Having read http://msdn.microsoft.com/en-us/library/aa365747%28VS.85%29.aspx[^] I can see that I should be dismounting or locking the volumes associated with the physical device. I added code to enumerate the volumes and called DeviceIoControl with FSCTL_LOCK_VOLUME. Now when I call WriteFile I get the error code ERROR_DEVICE_CHANGED, even if I repeat the WriteFile call.

What should I be doing?

Posted 27-Jul-10 22:18pm

Anorexic Tribble

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2 solutions

Solution 1

Did you try running it by right clicking on the EXE and select "Run as administrator"?

Posted 27-Jul-10 22:44pm

«_Superman_»

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Anorexic Tribble 28-Jul-10 6:15am

Yes I am running as admin

Member 7894601 6-Jan-15 23:25pm

I have a question.Please help me.Are you trying using the disk number or drive letter to createFile

Anorexic Tribble 10-Jan-15 7:38am

I use both disk numbers and volume letters. What is your question?

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Aescleal · Accepted Answer · 2010-07-27T23:02:00

Solution 2

Vista and Windows 7 don't let you write to physical disks or partitions that have mounted file systems on, even as an administrator.

After locking the drive you have to dismount it and get rid of the DOS device. To dismount the drive use DeviceIoControl with FSCTL_DISMOUNT_VOLUME. To get rid of the DOS device (i.e. the drive letter) call DefineDosDevice with DDD_RAW_TARGET_PATH | DDD_REMOVE_DEFINITION | DDD_EXACT_MATCH_ON_REMOVE.

Hope that helps,

Cheers,

Ash

Posted 27-Jul-10 23:02pm

Aescleal

Comments

Sauro Viti 28-Jul-10 5:19am

Reason for my vote of 5
Very useful information

Anorexic Tribble 28-Jul-10 6:17am

Tried DefineDosDevice on "E"

Also tried DeleteVolumeMountPoint

But still getting ERROR_DEVICE_CHANGED

Aescleal 28-Jul-10 7:07am

it sounds like you've still got something with a mounted file system on there. If you've done the three things I outlined (lock the volume, dismount it, remove DOS device) for each volume on the physical disk then I can't think of a lot else to try, sorry!

[I know, don't you hate it when people tell you "It works for me..."]