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

[Piotr Karbowski]

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?

-- Piotr.

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