Ubuntu mono patch dont_check_proc_self_exe causes random segfaults in mono

[Michael Casadevall]

Binary package hint: mono

The dont_check_proc_self_exe.dpatch is added to allow mono to work on the LiveCD, but it prevents proper checking of the root folder, and doesn't offer an alterative, causing FTBFS for evolution-sharp, and possibly other packages.

If this patch can't be removed, then I suggest should be modified to check for a file that only exists on the liveCD.
Michael

[Michael Casadevall (mcasadevall)]

Working on replacement patch to resolve these issues.

[Michael Casadevall (mcasadevall)]

Here is some more information and related bugs on the issue:

https://bugs.edge.launchpad.net/ubuntu/+source/linux/+bug/22410.

Essentially, readlink() on /proc/self/exe will return the path of the executable that calls it, but on an unionfs based system, it will return the wrong path (/squashfs/usr/bin/mono). THe old patch simply commented out the check on /proc/self/exe, which obviously was a bad idea, and also causes random segfaults all over the place (currently evolution-sharp is known to FTBFS due to this issue, f-spot also FTBFS if its rebuilt after clearing its dependency issues).

THe replacement patch (which I'm now testing) checks the prefix of any path read via the readlink /proc/self/exe function call, and then strips off the bad section of the path as necessary.

As evolution-sharp is known to trigger this bug, my test will involve building it once in a normal chroot jail, and building it again on the liveCD with the replacement mono. It should success both times if mono has properly been fixed.

[Michael Casadevall (mcasadevall)]

I was able to successfully build evolution-sharp on the liveCD, proving mono works, as well as being able to build it on an actual installation. I can provide a debdiff for the hardy mono if this bug is decided to meet SRU requirements.

[Michael Casadevall (mcasadevall)]

As an addition note, this should also resolve the F-Spot hanging issue since it appears that was related to the same issue. This bug only appears intermittiantly (some things, like compiling evo-sharp always triggered it, while others such as the f-spot bug only happened sometimes).

It should also clear the following bugs:
https://bugs.edge.launchpad.net/ubuntu/+source/mono/+bug/64371
https://bugs.edge.launchpad.net/ubuntu/+source/mono/+bug/90437
https://bugs.edge.launchpad.net/ubuntu/+source/mono/+bug/115162

[Michael Casadevall (mcasadevall)]

It appears while mono has the same patch in Hardy, it is not affected, or I can't find a test suite that will cause a crash.