user/dev discussion of public-inbox itself
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From: Eric Wong <e@80x24.org>
To: meta@public-inbox.org
Subject: [PATCH 01/19] spawn: pi_fork_exec: restore parent sigmask in child
Date: Sun,  7 Feb 2021 08:51:43 +0000	[thread overview]
Message-ID: <20210207085201.13871-2-e@80x24.org> (raw)
In-Reply-To: <20210207085201.13871-1-e@80x24.org>

We continue to unblock SIGCHLD unconditionally, but also
any signals not blocked by the parent (wq_worker).

This will allow Ctrl-C (SIGINT) to stop "git clone" and allow
git-clone cleanup to be performed and other long-running
processes when pi_fork_exec supports setpgid(2).  This won't
affect existing daemons on systems with signalfd(2) or
EVFILT_SIGNAL at all, since those run with signals blocked
anyways.
---
 lib/PublicInbox/Spawn.pm   | 26 ++++++++++++--------------
 lib/PublicInbox/SpawnPP.pm |  6 ++----
 2 files changed, 14 insertions(+), 18 deletions(-)

diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index f7dcb024..bac24dd1 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -82,20 +82,20 @@ int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
 	const char *filename = SvPV_nolen(file);
 	pid_t pid;
 	char **argv, **envp;
-	sigset_t set, old, cset;
+	sigset_t set, old;
 	int ret, perrnum, cerrnum = 0;
+	int chld_is_member;
 
 	AV2C_COPY(argv, cmd);
 	AV2C_COPY(envp, env);
 
-	ret = sigfillset(&set);
-	assert(ret == 0 && "BUG calling sigfillset");
-	ret = sigprocmask(SIG_SETMASK, &set, &old);
-	assert(ret == 0 && "BUG calling sigprocmask to block");
-	ret = sigemptyset(&cset);
-	assert(ret == 0 && "BUG calling sigemptyset");
-	ret = sigaddset(&cset, SIGCHLD);
-	assert(ret == 0 && "BUG calling sigaddset for SIGCHLD");
+	if (sigfillset(&set)) return -1;
+	if (sigprocmask(SIG_SETMASK, &set, &old)) return -1;
+	chld_is_member = sigismember(&old, SIGCHLD);
+	if (chld_is_member < 0) return -1;
+	if (chld_is_member > 0)
+		sigdelset(&old, SIGCHLD);
+
 	pid = vfork();
 	if (pid == 0) {
 		int sig;
@@ -127,15 +127,13 @@ int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
 				exit_err(&cerrnum);
 		}
 
-		/*
-		 * don't bother unblocking other signals for now, just SIGCHLD.
-		 * we don't want signals to the group taking out a subprocess
-		 */
-		(void)sigprocmask(SIG_UNBLOCK, &cset, NULL);
+		(void)sigprocmask(SIG_SETMASK, &old, NULL);
 		execve(filename, argv, envp);
 		exit_err(&cerrnum);
 	}
 	perrnum = errno;
+	if (chld_is_member > 0)
+		sigaddset(&old, SIGCHLD);
 	ret = sigprocmask(SIG_SETMASK, &old, NULL);
 	assert(ret == 0 && "BUG calling sigprocmask to restore");
 	if (cerrnum) {
diff --git a/lib/PublicInbox/SpawnPP.pm b/lib/PublicInbox/SpawnPP.pm
index b0ad4da5..f64b95dc 100644
--- a/lib/PublicInbox/SpawnPP.pm
+++ b/lib/PublicInbox/SpawnPP.pm
@@ -37,10 +37,8 @@ sub pi_fork_exec ($$$$$$) {
 			chdir $cd or die "chdir $cd: $!";
 		}
 		$SIG{$_} = 'DEFAULT' for keys %SIG;
-		my $cset = POSIX::SigSet->new();
-		$cset->addset(POSIX::SIGCHLD) or die "can't add SIGCHLD: $!";
-		sigprocmask(SIG_UNBLOCK, $cset) or
-					die "can't unblock SIGCHLD: $!";
+		$old->delset(POSIX::SIGCHLD) or die "delset SIGCHLD: $!";
+		sigprocmask(SIG_SETMASK, $old) or die "SETMASK: ~SIGCHLD: $!";
 		if ($ENV{MOD_PERL}) {
 			exec which('env'), '-i', @$env, @$cmd;
 			die "exec env -i ... $cmd->[0] failed: $!\n";

  reply	other threads:[~2021-02-07  8:52 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-07  8:51 [PATCH 00/19] lei import Maildir, remote mboxrd fixes Eric Wong
2021-02-07  8:51 ` Eric Wong [this message]
2021-02-07  8:51 ` [PATCH 02/19] spawn: pi_fork_exec: support "pgid" Eric Wong
2021-02-07 23:10   ` dprintf(3) portability? [was [02/19] spawn: pi_fork_exec: support "pgid"] Eric Wong
2021-02-07  8:51 ` [PATCH 03/19] lei add-external: handle interrupts with --mirror Eric Wong
2021-02-07  8:51 ` [PATCH 04/19] spawn_pp: die more consistently in child Eric Wong
2021-02-07  8:51 ` [PATCH 05/19] ipc: do not die inside wq_worker child process Eric Wong
2021-02-07  8:51 ` [PATCH 06/19] ipc: trim down the Storable checks Eric Wong
2021-02-07  8:51 ` [PATCH 07/19] Makefile.PL: depend on IO::Uncompress::Gunzip Eric Wong
2021-02-07  8:51 ` [PATCH 08/19] xapcmd: avoid potential die surprise in children Eric Wong
2021-02-07  8:51 ` [PATCH 09/19] tests: guard setup_public_inboxes for SQLite and Xapian Eric Wong
2021-02-07  8:51 ` [PATCH 10/19] Revert "ipc: add support for asynchronous callbacks" Eric Wong
2021-02-07  8:51 ` [PATCH 11/19] ipc: wq_do => wq_io_do Eric Wong
2021-02-07  8:51 ` [PATCH 12/19] lei: more consistent IPC exit and error handling Eric Wong
2021-02-07  8:51 ` [PATCH 13/19] lei: remove --mua-cmd alias for --mua Eric Wong
2021-02-07  8:51 ` [PATCH 14/19] lei: replace --thread with --threads Eric Wong
2021-02-07  8:51 ` [PATCH 15/19] lei q: improve remote mboxrd UX Eric Wong
2021-02-07  9:32   ` [PATCH 20/19] lei_xsearch: allow quieting regular mset progress, too Eric Wong
2021-02-07  8:51 ` [PATCH 16/19] lei q: SIGWINCH process group with the terminal Eric Wong
2021-02-07  8:51 ` [PATCH 17/19] lei import: support Maildirs Eric Wong
2021-02-07  8:52 ` [PATCH 18/19] imap: avoid unnecessary on-stack delete Eric Wong
2021-02-07  8:52 ` [PATCH 19/19] httpd/async: " Eric Wong
2021-02-07 10:40 ` [PATCH 21/19] lei q: fix arbitrary --mua command handling Eric Wong

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