Re: IPC resource access counting problem

From:

"David Ching" <dc@remove-this.dcsoft.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Thu, 8 Nov 2007 05:13:01 -0800

Message-ID:

<XXDYi.2151$TR5.832@nlpi061.nbdc.sbc.com>

"Neinstein" <sct@picknowl.com.au> wrote in message
news:1194502362.295089.307990@s15g2000prm.googlegroups.com...

Unfortunately DeleteFile will go ahead and delete on Windows ME and
older even if the file is open. Renaming each tmp file or having the
file or aux file contain a counter would be OK I think. But I would
have thought this sort of resource usage problem would be common and
have a nice semaphore type solution to it. Unforunately the usage
count of a CSemaphore is not accessible.

I am surprised to hear DeleteFile() works when the file is still open. I
would double-check the permissions when you open the file and make sure you
specify exclusive access for both reading and writing.

If it still doesn't work, see this link for using #pragma data_seg to
specify a shared global variable which could hold a a simple int containing
number of users of the file. Because it is shared memory of the .exe, if
the .exe crashes, the shared memory will go away also and be cleaned up
automatically:

http://groups.google.com/group/microsoft.public.vc.mfc/browse_thread/thread/4cecc1c450de5633/9bef9a240f3c77b0?hl=en&lnk=st&q=%23pragma+.exe+.dll+dcsoft#9bef9a240f3c77b0

-- David