CODEWITHSUNDEEP
filemfclockingdelete-file
user25749
user25749

Reputation: 4905

How to delete a file which is locked?

I am writing a desktop application under Windows in C++ MFC.

The application creates a index file, and writes information to it again and again.

If the application crashes, the next time the application starts it will delete the crashed index file and create a new one. I think in certain cases, the index file will be locked. It will be a disaster if I can not delete the locked index file.

How can I guarantee that I can delete the file and create a new one? I can make sure no other application opens the index file. It cannot be deleted just because of an application crash.

Can any one help?

Upvotes: 2

Views: 2664

Answers (6)

user3029478
user3029478

Reputation: 196

For a one-off solution, boot into safe mode and delete it. I had a .exe on my C: drive get locked while I was building it in a compiler, and nothing could remove it including a reboot. However, in Safe Mode I could delete it.

Upvotes: 0

fbmnds
fbmnds

Reputation: 77

I can recommend using this tool: http://lockhunter.com/download.htm

It helped me to unlock my Skype account on Windows 8 by being able to delete '%appdata%/Skype/my-user-profile' while other tools and procedures did not help in my case (ref. to "another skype instance may exist", which bites a lot of other users also since long).

Upvotes: 0

erikkallen
erikkallen

Reputation: 34421

Sometimes it's possible to rename a locked file. You should probably fix the real problem rather than the symptom, though.

Upvotes: 0

Kirill V. Lyadvinsky
Kirill V. Lyadvinsky

Reputation: 99685

To unlock file you should close all handles associated with it. The best way to do it is to terminate crashed application that still running (and owns file handle).

To find crashed application you could use technique that described in this article. That is what Process Explorer does when you search handles of files with specified name.

Upvotes: 3

Grubsnik
Grubsnik

Reputation: 929

Most likely the answer is "you cannot delete a locked file". The OS won't let you.

Instead I would work around it with something like this.

  • Check for existing index files, delete them if no locks are present.
  • Create a new index file, if the first "name" is taken, check for index01 and so forth until you find one not in use, then use that as your indexfile for this execution of the program.
  • On normal exit, clear your index file.

Bonus credit: allow users to "recover" a crashed index file instead of deleting them automatically.

Upvotes: 0

RichieHindle
RichieHindle

Reputation: 281835

If there's no process keeping the file open, there's no way it can remain locked. You might find that as long as your crashed process does actually die (rather than hanging) you have no problem.

If you really do need to be sure that you can delete the file from one process while another process has it open, you need both processes to open it with the FILE_SHARE_DELETE flag.

Upvotes: 7

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