Re: [2.6.16-rc5-m3 PATCH] inotify: add the monitor for the eventsource

From: Yi Yang
Date: Thu Mar 09 2006 - 00:14:52 EST


Arjan van de Ven wrote:
On Thu, 2006-03-09 at 00:33 +0800, Yi Yang wrote:
Current inotify implementation only focus on change of file system, but it doesn't
know who results in this change, this patch adds three fields to struct inotify_event,
tgid, uid and gid, they will save process ID, user ID and user group ID of the process
which leads to change in the file system, such software as anti-virus can make use of this feature to monitor who is modifying a specific file.


this patch appears to change the ABI! That is bad bad bad.
a change of struct inotify_event can't change ABI, can you describe it more clear?
Also, how can you guarantee that "current" is valid and meaningful at
the place you use it to get the user id ??
Of course, current process/thread never disappears before fsnotify_* returns.
Also the process ID part is really bogus, after all the process may have
exited by the time the inotify client gets to it, and the PID may even
already have been reused.

Your concern is correct, but uid and git can give out some hints, I ever considered to
save the name of current process, however that needs a bigger and length-variable
inotify_event struct, moreover, to get the full path name of current process/thread
in kernel will have a big overhead, so I must select a comprise way. In fact, the case
you said is very few.

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