"URGENT" : How to find whether a file is already open or not by any application .

Yogish · 08-13-2008, 04:12 AM

Hi,

I trying to delete a folder containing some files.
Before deleting i want to check whether any file in the folder is already open by any other application.
I cannot use "lsof" command.
Is there any function or api which will help me in this?

Thanks,
Yogish

burschik · 08-13-2008, 04:30 AM

As far as I know, lsof uses the information in /proc/$PID/fd (and others) to find open files. You could do the same manually, provided you have the necessary privileges.

pwc101 · 08-13-2008, 04:32 AM

man fuser?

What's wrong with lsof?

chakka.lokesh · 08-13-2008, 05:17 AM

I think he is asking about any function in c-language rather than a command / tool.

chrism01 · 08-13-2008, 07:09 PM

Can i just point out you need a locking mechanism, otherwise you could get a race condition.
That is,

1. you check if any files are open.
2. by the time you've checked eg file3, someone has opened file1
3. even if (2.) does not obtain, it takes a finite amt of time to move (in your code) to your unlink() for each file, by which time, again, someone has opened a file....

chakka.lokesh · 08-13-2008, 11:21 PM

Quote:

Originally Posted by chrism01

1. you check if any files are open.

hey chrism01

he is asking how to do that?

chrism01 · 08-14-2008, 02:20 AM

Actually, he's asking how to check if a file is open, and stating he can't use lsof. At a guess he wants to do it direct in C, although he doesn't specify the lang, which would help.
I was just pointing out the generic logic, which is a lock/race condition. Just checking if a file is open (and he's talking about a bunch so he can delete an entire dir) doesn't mean its safe to delete the dir.
You'd need to check/delete each file as you go to avoid that.
Its a classic prob in file txfr dirs.

chakka.lokesh · 08-15-2008, 01:03 AM

Quote:

Originally Posted by chrism01

I was just pointing out the generic logic, which is a lock/race condition.

my guess is that, the file is opened by entirely different process, probably by different application or some thing like that, but not by the process he is running.