Accessing "in Use" Files == ?

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shakuni

Joined: 11 Oct 2007
Posts: 24

shakuni 14 May 2008, 05:53

How can I access the files that are in-use by other processes. Say there is this file called "locked.txt", which is in use by process A. Now how can I copy this file to another location programmatically. Normal methods will fail with the error "The process cannot access the file because it is being used by another process.".

Any ideas ?

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14 May 2008, 05:53

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 19252
Location: In your JS exploiting you and your system

revolution 14 May 2008, 06:26

It depends on how the file is locked. When Process A opens the file it can say what access it wants to allow other process to have.

Win32 SDK: CreateFile wrote:

dwShareMode

Set of bit flags that specifies how the object can be shared. If dwShareMode is 0, the object cannot be shared. Subsequent open operations on the object will fail, until the handle is closed.
To share the object, use a combination of one or more of the following values:

Value Meaning
FILE_SHARE_DELETE Windows NT only: Subsequent open operations on the object will succeed only if delete access is requested.
FILE_SHARE_READ Subsequent open operations on the object will succeed only if read access is requested.
FILE_SHARE_WRITE Subsequent open operations on the object will succeed only if write access is requested.

There are also some other ways to lock only portions of a shared file, all of these things can prevent you from copying a file when it is locked in certain ways.

14 May 2008, 06:26

shakuni

Joined: 11 Oct 2007
Posts: 24

shakuni 14 May 2008, 06:43

Quote:

all of these things can prevent you from copying a file when it is locked in certain ways.

Yes I know that. Now tell me how can I circumvent those locks.

14 May 2008, 06:43

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 19252
Location: In your JS exploiting you and your system

revolution 14 May 2008, 07:57

shakuni wrote:

Yes I know that. Now tell me how can I circumvent those locks.

Close the offending process A
Write a KMD to read the HDD directly to get the data
Rewrite the OS to always allow read access
Use another OS that does not have locks (DOS?)
Patch the kernel to alter the dwShareMode parameter on the fly when opening
Patch process A so that it allows read sharing
Or, the easiest, just accept that sometimes a program needs exclusive access to a file to ensure it doesn't crash or generally go stupid

14 May 2008, 07:57

MichaelH

Joined: 03 May 2005
Posts: 402

MichaelH 14 May 2008, 21:01

MoveFileEx might be what you're looking for -

http://msdn.microsoft.com/en-us/library/aa365240(VS.85).aspx

Does the URL tag work for this forum. I can never get it to work Sad

14 May 2008, 21:01

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 14 May 2008, 22:32

It doesn't work when it has some not really special (apart of the real ones) characters, you have to replace "(" and ")" with its hex counterparts and it will work, example: http://msdn.microsoft.com/en-us/library/aa365240%28VS.85%29.aspx MoveFileEx Function

14 May 2008, 22:32

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