Galera SST scripts shouldn't access grastate.dat

[grooverdan]

When SST scripts they inherit the open file descriptors.

Here we use the GLIBC extensions to fopen, 'e', to ensure
that forked processes don't inherit the file descriptor, and 'x'
which ensure exclusive access.

closes #339

[ayurchen]

Daniel, what is the license if this patch?

[grooverdan]

I assume GPL-2 works for you. If so take it as that. Otherwise Apache-2 at your choice. If you have another preference let me know.

Note: glibc extensions on fopen need to be at end so I discovered https://bugzilla.kernel.org/show_bug.cgi?id=199001

[vasild]

Daniel,

• This patch would only enable the close-on-exec flag on Linux even though other operating systems also support "e".
• It will end up with logically conflicting "a" and "x". Why would one want to append to a file that does not exist? It may work as "wx" but is at least confusing.
• It would fix only this local case, making it hard to reuse the code elsewhere. OTOH, galerautils/src/gu_fdesc.cpp has some code which opens a file with close-on-exec that can be reused.
• The patch is not exhaustive - maybe other fopen(3) or open(2) calls remain without close-on-exec, but I guess making it exhaustive is out of the scope of this pull request.

So, can you use gu::FileDescriptor from galerautils/src/gu_fdesc.cpp to open the file and then use fdopen(3) in galera/src/saved_state.cpp

A BSD licensed patch would be ok.

Thanks!

[grooverdan]

Thanks for the review and tips. May as well make it comprehensive. I'll resubmit.

[ayurchen]

Daniel, we would rather have it as public domain. Is that possible?

[grooverdan]

Contribution under the Codership Individual Contributor License Agreement on behalf of IBM (all approved - hence delay). I tried to sign up on https://www.clahub.com/agreements/codership/galera but failed (clahub/clahub#163)

[grooverdan]

CLA signed now that technical barriers have been lifted.

[vasild]

Daniel, I guess you will upload an updated patch?

[williamdes]

Should this patch be rebased for newer versions ?