Re: [BProc] Access to /proc/<pid>/exe

[<er...@he...>]

On Wed, Dec 10, 2003 at 02:04:21PM -0600, William Hachfeld wrote:
> 
> Erik (or whomever else might know the answer to this),
> 
> I'm trying to access, from my master node, the /proc/<pid>/exe file for a
> process running on a slave node. This doesn't appear to work. For example:
> 
> % file /proc/21053/exe
> /proc/21053/exe: unreadable symlink (No such file or directory).
> 
> My assumption would be that something in the virtualization and migration
> process is breaking my ability to access this file. Is that correct? Any
> idea why this doesn't work? Should it work? Is it because accessing this
> file is referencing the ghost process (which has no image) rather than the
> "real" process on the slave?

Bingo.  That's it exactly.  The 'readlink' for that one looks through
the process's memory to find a region tagged as 'VM_EXECUTABLE' and
tells you what file that one is mapped from.

I haven't done anything to try and make it so I guess it shouldn't.
It probably wouldn't be that hard to make it do something reasonable
if you really wanted it to work.  It might get a little weird if
remote processes exec something that doesn't exist on the front end
though.

- Erik