From: Eric Wong <e@80x24.org>
To: meta@public-inbox.org
Subject: [PATCH 2/4] process_pipe: warn hackers off using it for bidirectional pipes
Date: Wed, 25 Jan 2023 10:18:33 +0000 [thread overview]
Message-ID: <20230125101835.882567-3-e@80x24.org> (raw)
In-Reply-To: <20230125101835.882567-1-e@80x24.org>
While most uses of ->DESTROY happens in a predictable order in
long-lived daemons, process teardown on exit is chaotic and not
subject to ordering guarantees, so we must keep both ends of a
`git cat-file --batch*' pipe at the same level in the object
hierarchy.
Drop an old Carp import while I'm in the area.
---
lib/PublicInbox/Git.pm | 1 +
lib/PublicInbox/ProcessPipe.pm | 6 ++++--
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm
index ff3ac40f..a3813bf2 100644
--- a/lib/PublicInbox/Git.pm
+++ b/lib/PublicInbox/Git.pm
@@ -156,6 +156,7 @@ sub _bidi_pipe {
$self->{$err} = $fh;
$rdr->{2} = $fh;
}
+ # see lib/PublicInbox/ProcessPipe.pm for why we don't use that here
my ($in_r, $p) = popen_rd(\@cmd, undef, $rdr);
awaitpid($self->{$pid} = $p, undef);
$self->{"$pid.owner"} = $$;
diff --git a/lib/PublicInbox/ProcessPipe.pm b/lib/PublicInbox/ProcessPipe.pm
index 068631c6..1bc792c4 100644
--- a/lib/PublicInbox/ProcessPipe.pm
+++ b/lib/PublicInbox/ProcessPipe.pm
@@ -1,10 +1,12 @@
# Copyright (C) all contributors <meta@public-inbox.org>
# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
-# a tied handle for auto reaping of children tied to a pipe, see perltie(1)
+# a tied handle for auto reaping of children tied to a read-only pipe, see perltie(1)
+# DO NOT use this as-is for bidirectional pipes/sockets (e.g. in PublicInbox::Git),
+# both ends of the pipe must be at the same level of the Perl object hierarchy
+# to ensure orderly destruction.
package PublicInbox::ProcessPipe;
use v5.12;
-use Carp qw(carp);
use PublicInbox::DS qw(awaitpid);
sub waitcb { # awaitpid callback
next prev parent reply other threads:[~2023-01-25 10:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-25 10:18 [PATCH 0/4] git-related updates Eric Wong
2023-01-25 10:18 ` [PATCH 1/4] git: use core.abbrev=no on git 2.31+ Eric Wong
2023-01-25 10:18 ` Eric Wong [this message]
2023-01-25 10:18 ` [PATCH 3/4] git: drop needless ENOENT import Eric Wong
2023-01-25 10:18 ` [PATCH 4/4] git: reduce delete ops in _destroy Eric Wong
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