runc init: remove some code #3113
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runc init is special. For one thing, it needs to do a few things before main(), so we have func init() that checks if we're init and does that. What happens next is main() is called, which does some options parsing, figures out it needs to call initCommand.Action and so it does. Now, main() is entirely unnecessary -- we can do everything right from init(). Hopefully the change makes things slightly less complicated. From a user's perspective, the only change is runc help no longer lists 'runc init` (which I think it also good). Signed-off-by: Kir Kolyshkin <[email protected]>
As pointed out in TODO item added by commit 64bb59f, it is not necessary to have a special sync mechanism for cgroupns, as the parent adds runc init to cgroup way earlier (before sending nl bootstrap data. This sync was added by commit df3fa11, which was also added a second cgroup manager.Apply() call, later removed in commit d1ba8e3. It seems the original author had the idea to wait for that second Apply(). Fixes: df3fa11 Signed-off-by: Kir Kolyshkin <[email protected]>
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cyphar
reviewed
Jul 29, 2021
| func init() { | ||
| if len(os.Args) > 1 && os.Args[1] == "init" { | ||
| // This is the golang entry point for runc init, executed | ||
| // before main() but after libcontainer/nsenter's nsexec(). |
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Might not hurt to mention the function never returns (since this all ends in execve) so main never actually runs.
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I had something like that but eventually removed it as this is somewhat clear (for one thing, the code within the block ends with a panic).
I will try to improve this further in #3114 (which is a followup to this PR).
mrunalp
approved these changes
Jul 29, 2021
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Remove some code from runc init which is not needed. Please review commit-by-commit.