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Kir Kolyshkin 750738b5d1 os: make use of pidfd on linux
Use Process.handle field to store pidfd, and make use of it. Only use
pidfd functionality if all the needed syscalls are available.

1. StartProcess: obtain the pidfd from the kernel, if available,
   using the functionality added by CL 520266. Note we could not modify
   syscall.StartProcess to return pidfd directly because it is a public
   API and its callers do not expect it, so we have to use ensurePidfd
   and getPidfd.

2. (*Process).Kill: use pidfdSendSignal, if the syscall is available
   and pidfd is known. This is slightly more complicated than it should
   be, since the syscall can be blocked by e.g. seccomp security policy,
   therefore the need for a function to check if it's actually working,
   and a soft fallback to kill. Perhaps this precaution is not really
   needed.

3. (*Process).Wait: use pidfdWait, if available, otherwise fall back to
   using waitid/wait4. This is also more complicated than expected due
   to struct siginfo_t idiosyncrasy.

NOTE pidfdSendSignal and pidfdWait are used without a race workaround
(blockUntilWaitable and sigMu, added by CL 23967) because with pidfd,
PID recycle issue doesn't exist (IOW, pidfd, unlike PID, is guaranteed
to refer to one particular process) and thus the race doesn't exist
either.

For #62654.
Updates #13987.

Change-Id: I22ebcc7142b16a3a94c422d2f32504d1a80e8a8f
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/528438
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2024-02-21 21:26:00 +00:00
.github github: switch seen/expected order in issue forms 2024-01-04 23:31:17 +00:00
api net: add KeepAliveConfig and implement SetKeepAliveConfig 2024-02-20 06:04:31 +00:00
doc net: add KeepAliveConfig and implement SetKeepAliveConfig 2024-02-20 06:04:31 +00:00
lib/time lib/time: update to 2024a/2024a 2024-02-02 18:20:41 +00:00
misc misc/wasm: support new wasmtime CLI 2023-11-19 21:11:54 +00:00
src os: make use of pidfd on linux 2024-02-21 21:26:00 +00:00
test cmd/compile/internal/typecheck: remove constant bounds check 2024-02-20 22:29:14 +00:00
.gitattributes all: treat all files as binary, but check in .bat with CRLF 2020-06-08 15:31:43 +00:00
.gitignore internal/platform,cmd/dist: export the list of supported platforms 2023-06-22 19:44:52 +00:00
codereview.cfg codereview.cfg: add codereview.cfg for master branch 2021-02-19 18:44:53 +00:00
CONTRIBUTING.md doc: normalize proposal-process links 2023-03-29 22:00:27 +00:00
go.env cmd/go: additional doc-inspired tests and bug fixes 2023-06-06 19:18:46 +00:00
LICENSE doc: revert copyright date to 2009 2016-06-01 22:40:04 +00:00
PATENTS LICENSE: separate, change PATENTS text 2010-12-06 16:31:59 -05:00
README.md README: update from CC-BY-3.0 to CC-BY-4.0 2022-11-02 20:14:56 +00:00
SECURITY.md SECURITY.md: update the Reporting a Vulnerability link 2023-09-22 21:17:24 +00:00

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