buildah run breaks stdin by setting O_NONBLOCK

[Vogtinator]

Sometimes after running buildah run in a terminal, commands executed afterwards which try to read from stdin fail with EAGAIN. This is because it sets O_NONBLOCK on the FD:

f241:~ # grep flags /proc/self/fdinfo/0; while ! grep 'flags.*4002$' /proc/self/fdinfo/0; do buildah run sle15-working-container /bin/true; echo -n .; done; cat -
flags:  02
....................flags:      04002
cat: -: Resource temporarily unavailable

strace -k shows that this is caused by the runCopyStdio function:

buildah/run_linux.go

Line 1236 in c891ebe

if err := setNonblock(rfd, readDesc[rfd], true); err != nil {

For some reason this doesn't happen all the time and the O_NONBLOCK flag also disappears after some time, even after buildah exited. I suspect that the interactive shell is fixing that up at some point.

[rhatdan]

Is this something buildah could easily change back on exit?

[Vogtinator]

It could just restore the previous descriptor flags, I suppose.

[rhatdan]

Interested in opening a PR?

[Vogtinator]

Interested yes, but I unfortunately don't have the time to get familiar with the code and Go, at least not in the near future...

[rhatdan]

We have talked about this, and we are not sure there is an easy way to fix.

[github-actions]

A friendly reminder that this issue had no activity for 30 days.

[github-actions]

A friendly reminder that this issue had no activity for 30 days.