[BUMP] [BUG] rename() from outside of the target dir breaks /proc exe symlink.

[Piotr Karbowski]

On 01/16/2015 07:25 PM, Piotr Karbowski wrote:
> On 12/30/2014 11:40 PM, Piotr Karbowski wrote:
> > Hi Al,
> >
> > On 12/27/2014 07:14 PM, Al Viro wrote:
> > > That's because it never _had_ worked.  Note that opening the damn thing
> > > will give the right file - it does not work by traversing the result of
> > > readlink(2).  readlink(2) output on those is not promised to be useful
> > > in all cases; often enough it is, but it won't work on cross-directory
> > > renames, it can't be used to tell a filename that really ends with "
> > > (deleted)"
> > > from a removed file, etc.  Moreover, it only very recently became
> > > usable for
> > > victim names with the last component longer than 40 characters if you
> > > did an
> > > overwriting rename.
> > >
> > > What are you trying to use it for?
> >
> > I am using it to track the origin of running processes. I am working
> > with continuous integration of a Linux embedded software. The tests goes
> > in Linux containers, multiple instances of binary with the same name in
> > a single container/namespace, all with cwd symlink pointing to / which
> > looks from outside virtually the same, the binaries are modified at
> > runtime by coping, modifing and replacing for another execution of the
> > same binary (using patchelf to add additional NEEDED to header or change
> > rpath or dynamic loader and such).
> >
> > In my very usecase, the exe symlink is essential.
>
> *Friendly bump*
>
> Can anything be done about it or is there any other mechanism that I
> could use to get origin of the running binary?

*Even friendlier bump*

-- Piotr.

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