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Subject: Re: Review Request 53791: Use the stout ELF parser to collect Linux
 rootfs files.
From: Benjamin Bannier <benjamin.bannier@mesosphere.io>
To: Jie Yu <yujie.jay@gmail.com>, Kevin Klues <klueska@gmail.com>,
 Jiang Yan Xu <yan@jxu.me>, Gilbert Song <songzihao1990@gmail.com>
Cc: Benjamin Bannier <benjamin.bannier@mesosphere.io>,
 Mesos ReviewBot <reviews@mesos.apache.org>, James Peach <jpeach@apache.org>,
 mesos <reviews@mesos.apache.org>
Date: Tue, 13 Dec 2016 19:43:57 -0000
Message-ID: <20161213194357.17251.20516@reviews.apache.org>
Auto-Submitted: auto-generated
Sender: Benjamin Bannier <noreply@reviews.apache.org>
References: <20161213101336.17252.65775@reviews.apache.org>
In-Reply-To: <20161213101336.17252.65775@reviews.apache.org>
Reply-To: Benjamin Bannier <benjamin.bannier@mesosphere.io>
archived-at: Tue, 13 Dec 2016 19:44:00 -0000

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> On Dec. 13, 2016, 11:13 a.m., Benjamin Bannier wrote:
> > src/linux/ldd.cpp, lines 82-83
> > <https://reviews.apache.org/r/53791/diff/6/?file=1571593#file1571593line82>
> >
> >     Let's move this up right after the check `needed.contains(path)`.
> >     
> >     Right now in pathological cases like e.g., a`libA` depending on `libB`, and `libB` depending on `libA`, we would recurse indefinitely.
> 
> James Peach wrote:
>     Adding the path to the `needed` set means that we need the path and have already calculated the dependencies for that path. If we add a path before having all its dependencies, we would return early in the `needed.contains(path)` check.

An entry in `needed` is the only indication on whether we have already visited a node in the dependency graph (which is not necessarily a tree).

If you do not add `path` to `needed` before recursing into `collectDependencies`, `path` might be visited again as a dependency in pathological cases involving cyclic shared library dependencies (which the loader might be fine with). In such a case this code would recurse indefinitely.

It looks like a fix might be to add `path` to `needed` after you have found that it currently is not in `needed`, but before you recurse.


- Benjamin


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On Dec. 13, 2016, 7:34 p.m., James Peach wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/53791/
> -----------------------------------------------------------
> 
> (Updated Dec. 13, 2016, 7:34 p.m.)
> 
> 
> Review request for mesos, Gilbert Song, Jie Yu, Kevin Klues, and Jiang Yan Xu.
> 
> 
> Bugs: MESOS-6588
>     https://issues.apache.org/jira/browse/MESOS-6588
> 
> 
> Repository: mesos
> 
> 
> Description
> -------
> 
> The dependencies for the programs we need in the Linux root
> filesystem vary over time and across distributions. Since Stout
> has support for parsing the library dependencies of ELF binaries,
> use this to collect the necessary dependencies when constructing
> a root filesystem for the tests.
> 
> 
> Diffs
> -----
> 
>   src/Makefile.am a4c03c2b918816e6dd8872d37e5208f055619c47 
>   src/tests/containerizer/rootfs.hpp 6bc3835cbb62536ec933ef38c9e15138b8611e5f 
>   src/tests/containerizer/rootfs.cpp PRE-CREATION 
> 
> Diff: https://reviews.apache.org/r/53791/diff/
> 
> 
> Testing
> -------
> 
> sudo make check (Fedora 24)
> 
> 
> Thanks,
> 
> James Peach
> 
>


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