X-Git-Url: http://www.git.stargrave.org/?a=blobdiff_plain;f=lib%2FPublicInbox%2FSpawn.pm;h=e0a51c2167e829549d20683470aa55b02c3556b5;hb=74f027ca317067f7ae7289b15465d6a49078f65c;hp=f90d8f6d3dd2d9d7f1ea6a73c8f41a70eaf718bf;hpb=761baa2a300e426885675a01e4773193ab7101ff;p=public-inbox.git

diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index f90d8f6d..e0a51c21 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -1,4 +1,4 @@
-# Copyright (C) 2016-2020 all contributors <meta@public-inbox.org>
+# Copyright (C) 2016-2021 all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 #
 # This allows vfork to be used for spawning subprocesses if
@@ -10,23 +10,33 @@
 # daemons (inside the PSGI code (-httpd) and -nntpd).  The short-lived
 # scripts (-mda, -index, -learn, -init) either use IPC::run or standard
 # Perl routines.
+#
+# There'll probably be more OS-level C stuff here, down the line.
+# We don't want too many DSOs: https://udrepper.livejournal.com/8790.html
 
 package PublicInbox::Spawn;
 use strict;
-use warnings;
-use base qw(Exporter);
+use parent qw(Exporter);
 use Symbol qw(gensym);
+use Fcntl qw(LOCK_EX SEEK_SET);
+use IO::Handle ();
 use PublicInbox::ProcessPipe;
-our @EXPORT_OK = qw/which spawn popen_rd/;
-sub RLIMITS () { qw(RLIMIT_CPU RLIMIT_CORE RLIMIT_DATA) }
+our @EXPORT_OK = qw(which spawn popen_rd run_die nodatacow_dir);
+our @RLIMITS = qw(RLIMIT_CPU RLIMIT_CORE RLIMIT_DATA);
 
-my $vfork_spawn = <<'VFORK_SPAWN';
+BEGIN {
+	my $all_libc = <<'ALL_LIBC'; # all *nix systems we support
+#include <sys/resource.h>
+#include <sys/socket.h>
 #include <sys/types.h>
-#include <sys/uio.h>
 #include <sys/time.h>
-#include <sys/resource.h>
+#include <sys/uio.h>
 #include <unistd.h>
 #include <stdlib.h>
+#include <errno.h>
+#include <time.h>
+#include <stdio.h>
+#include <string.h>
 
 /* some platforms need alloca.h, but some don't */
 #if defined(__GNUC__) && !defined(alloca)
@@ -57,9 +67,10 @@ my $vfork_spawn = <<'VFORK_SPAWN';
 } while (0)
 
 /* needs to be safe inside a vfork'ed process */
-static void exit_err(int *cerrnum)
+static void exit_err(const char *fn, volatile int *cerrnum)
 {
 	*cerrnum = errno;
+	write(2, fn, strlen(fn));
 	_exit(1);
 }
 
@@ -69,7 +80,7 @@ static void exit_err(int *cerrnum)
  * Be sure to update PublicInbox::SpawnPP if this changes
  */
 int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
-		 const char *cd)
+		 const char *cd, int pgid)
 {
 	AV *redir = (AV *)SvRV(redirref);
 	AV *cmd = (AV *)SvRV(cmdref);
@@ -78,40 +89,44 @@ 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;
-	int ret, perrnum, cerrnum = 0;
+	sigset_t set, old;
+	int ret, perrnum;
+	volatile int cerrnum = 0; /* shared due to vfork */
+	int chld_is_member;
+	I32 max_fd = av_len(redir);
 
 	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;
-		I32 i, child_fd, max = av_len(redir);
+		I32 i, child_fd, max_rlim;
 
-		for (child_fd = 0; child_fd <= max; child_fd++) {
+		for (child_fd = 0; child_fd <= max_fd; child_fd++) {
 			SV **parent = av_fetch(redir, child_fd, 0);
 			int parent_fd = SvIV(*parent);
 			if (parent_fd == child_fd)
 				continue;
 			if (dup2(parent_fd, child_fd) < 0)
-				exit_err(&cerrnum);
+				exit_err("dup2", &cerrnum);
 		}
+		if (pgid >= 0 && setpgid(0, pgid) < 0)
+			exit_err("setpgid", &cerrnum);
 		for (sig = 1; sig < NSIG; sig++)
 			signal(sig, SIG_DFL); /* ignore errors on signals */
 		if (*cd && chdir(cd) < 0)
-			exit_err(&cerrnum);
+			exit_err("chdir", &cerrnum);
 
-		max = av_len(rlim);
-		for (i = 0; i < max; i += 3) {
+		max_rlim = av_len(rlim);
+		for (i = 0; i < max_rlim; i += 3) {
 			struct rlimit rl;
 			SV **res = av_fetch(rlim, i, 0);
 			SV **soft = av_fetch(rlim, i + 1, 0);
@@ -120,66 +135,249 @@ int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
 			rl.rlim_cur = SvIV(*soft);
 			rl.rlim_max = SvIV(*hard);
 			if (setrlimit(SvIV(*res), &rl) < 0)
-				exit_err(&cerrnum);
+				exit_err("setrlimit", &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);
+		exit_err("execve", &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) {
+		int err_fd = STDERR_FILENO;
+		if (err_fd <= max_fd) {
+			SV **parent = av_fetch(redir, err_fd, 0);
+			err_fd = SvIV(*parent);
+		}
 		if (pid > 0)
 			waitpid(pid, NULL, 0);
 		pid = -1;
+		/* continue message started by exit_err in child */
+		dprintf(err_fd, ": %s\n", strerror(cerrnum));
 		errno = cerrnum;
 	} else if (perrnum) {
 		errno = perrnum;
 	}
 	return (int)pid;
 }
-VFORK_SPAWN
-
-my $inline_dir = $ENV{PERL_INLINE_DIRECTORY} //= (
-		$ENV{XDG_CACHE_HOME} //
-		( ($ENV{HOME} // '/nonexistent').'/.cache' )
-	).'/public-inbox/inline-c';
-
-$vfork_spawn = undef unless -d $inline_dir && -w _;
-if (defined $vfork_spawn) {
-	# Inline 0.64 or later has locking in multi-process env,
-	# but we support 0.5 on Debian wheezy
-	use Fcntl qw(:flock);
-	eval {
-		my $f = "$inline_dir/.public-inbox.lock";
-		open my $fh, '>', $f or die "failed to open $f: $!\n";
-		flock($fh, LOCK_EX) or die "LOCK_EX failed on $f: $!\n";
-		eval 'use Inline C => $vfork_spawn';
-		my $err = $@;
-		flock($fh, LOCK_UN) or die "LOCK_UN failed on $f: $!\n";
-		die $err if $err;
-	};
-	if ($@) {
-		warn "Inline::C failed for vfork: $@\n";
-		$vfork_spawn = undef;
+
+static int sleep_wait(unsigned *tries, int err)
+{
+	const struct timespec req = { 0, 100000000 }; /* 100ms */
+	switch (err) {
+	case ENOBUFS: case ENOMEM: case ETOOMANYREFS:
+		if (++*tries < 50) {
+			fprintf(stderr, "sleeping on sendmsg: %s (#%u)\n",
+				strerror(err), *tries);
+			nanosleep(&req, NULL);
+			return 1;
+		}
+	default:
+		return 0;
+	}
+}
+
+#if defined(CMSG_SPACE) && defined(CMSG_LEN)
+#define SEND_FD_CAPA 10
+#define SEND_FD_SPACE (SEND_FD_CAPA * sizeof(int))
+union my_cmsg {
+	struct cmsghdr hdr;
+	char pad[sizeof(struct cmsghdr) + 16 + SEND_FD_SPACE];
+};
+
+SV *send_cmd4(PerlIO *s, SV *svfds, SV *data, int flags)
+{
+	struct msghdr msg = { 0 };
+	union my_cmsg cmsg = { 0 };
+	STRLEN dlen = 0;
+	struct iovec iov;
+	ssize_t sent;
+	AV *fds = (AV *)SvRV(svfds);
+	I32 i, nfds = av_len(fds) + 1;
+	int *fdp;
+	unsigned tries = 0;
+
+	if (SvOK(data)) {
+		iov.iov_base = SvPV(data, dlen);
+		iov.iov_len = dlen;
+	}
+	if (!dlen) { /* must be non-zero */
+		iov.iov_base = &msg.msg_namelen; /* whatever */
+		iov.iov_len = 1;
+	}
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+	if (nfds) {
+		if (nfds > SEND_FD_CAPA) {
+			fprintf(stderr, "FIXME: bump SEND_FD_CAPA=%d\n", nfds);
+			nfds = SEND_FD_CAPA;
+		}
+		msg.msg_control = &cmsg.hdr;
+		msg.msg_controllen = CMSG_SPACE(nfds * sizeof(int));
+		cmsg.hdr.cmsg_level = SOL_SOCKET;
+		cmsg.hdr.cmsg_type = SCM_RIGHTS;
+		cmsg.hdr.cmsg_len = CMSG_LEN(nfds * sizeof(int));
+		fdp = (int *)CMSG_DATA(&cmsg.hdr);
+		for (i = 0; i < nfds; i++) {
+			SV **fd = av_fetch(fds, i, 0);
+			*fdp++ = SvIV(*fd);
+		}
+	}
+	do {
+		sent = sendmsg(PerlIO_fileno(s), &msg, flags);
+	} while (sent < 0 && sleep_wait(&tries, errno));
+	return sent >= 0 ? newSViv(sent) : &PL_sv_undef;
+}
+
+void recv_cmd4(PerlIO *s, SV *buf, STRLEN n)
+{
+	union my_cmsg cmsg = { 0 };
+	struct msghdr msg = { 0 };
+	struct iovec iov;
+	ssize_t i;
+	Inline_Stack_Vars;
+	Inline_Stack_Reset;
+
+	if (!SvOK(buf))
+		sv_setpvn(buf, "", 0);
+	iov.iov_base = SvGROW(buf, n + 1);
+	iov.iov_len = n;
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+	msg.msg_control = &cmsg.hdr;
+	msg.msg_controllen = CMSG_SPACE(SEND_FD_SPACE);
+
+	i = recvmsg(PerlIO_fileno(s), &msg, 0);
+	if (i < 0)
+		Inline_Stack_Push(&PL_sv_undef);
+	else
+		SvCUR_set(buf, i);
+	if (i > 0 && cmsg.hdr.cmsg_level == SOL_SOCKET &&
+			cmsg.hdr.cmsg_type == SCM_RIGHTS) {
+		size_t len = cmsg.hdr.cmsg_len;
+		int *fdp = (int *)CMSG_DATA(&cmsg.hdr);
+		for (i = 0; CMSG_LEN((i + 1) * sizeof(int)) <= len; i++)
+			Inline_Stack_Push(sv_2mortal(newSViv(*fdp++)));
 	}
+	Inline_Stack_Done;
 }
+#endif /* defined(CMSG_SPACE) && defined(CMSG_LEN) */
+ALL_LIBC
+
+# btrfs on Linux is copy-on-write (COW) by default.  As of Linux 5.7,
+# this still leads to fragmentation for SQLite and Xapian files where
+# random I/O happens, so we disable COW just for SQLite files and Xapian
+# directories.  Disabling COW disables checksumming, so we only do this
+# for regeneratable files, and not canonical git storage (git doesn't
+# checksum refs, only data under $GIT_DIR/objects).
+	my $set_nodatacow = $^O eq 'linux' ? <<'SET_NODATACOW' : '';
+#include <sys/ioctl.h>
+#include <sys/vfs.h>
+#include <linux/magic.h>
+#include <linux/fs.h>
+#include <dirent.h>
+
+void nodatacow_fd(int fd)
+{
+	struct statfs buf;
+	int val = 0;
+
+	if (fstatfs(fd, &buf) < 0) {
+		fprintf(stderr, "fstatfs: %s\\n", strerror(errno));
+		return;
+	}
+
+	/* only btrfs is known to have this problem, so skip for non-btrfs */
+	if (buf.f_type != BTRFS_SUPER_MAGIC)
+		return;
+
+	if (ioctl(fd, FS_IOC_GETFLAGS, &val) < 0) {
+		fprintf(stderr, "FS_IOC_GET_FLAGS: %s\\n", strerror(errno));
+		return;
+	}
+	val |= FS_NOCOW_FL;
+	if (ioctl(fd, FS_IOC_SETFLAGS, &val) < 0)
+		fprintf(stderr, "FS_IOC_SET_FLAGS: %s\\n", strerror(errno));
+}
+
+void nodatacow_dir(const char *dir)
+{
+	DIR *dh = opendir(dir);
+	int fd;
 
-unless (defined $vfork_spawn) {
-	require PublicInbox::SpawnPP;
-	*pi_fork_exec = \&PublicInbox::SpawnPP::pi_fork_exec
+	if (!dh) croak("opendir(%s): %s", dir, strerror(errno));
+	fd = dirfd(dh);
+	if (fd >= 0)
+		nodatacow_fd(fd);
+	/* ENOTSUP probably won't happen under Linux... */
+	closedir(dh);
 }
+SET_NODATACOW
+
+	my $inline_dir = $ENV{PERL_INLINE_DIRECTORY} //= (
+			$ENV{XDG_CACHE_HOME} //
+			( ($ENV{HOME} // '/nonexistent').'/.cache' )
+		).'/public-inbox/inline-c';
+	warn "$inline_dir exists, not writable\n" if -e $inline_dir && !-w _;
+	$set_nodatacow = $all_libc = undef unless -d _ && -w _;
+	if (defined $all_libc) {
+		my $f = "$inline_dir/.public-inbox.lock";
+		open my $oldout, '>&', \*STDOUT or die "dup(1): $!";
+		open my $olderr, '>&', \*STDERR or die "dup(2): $!";
+		open my $fh, '+>', $f or die "open($f): $!";
+		open STDOUT, '>&', $fh or die "1>$f: $!";
+		open STDERR, '>&', $fh or die "2>$f: $!";
+		STDERR->autoflush(1);
+		STDOUT->autoflush(1);
+
+		# CentOS 7.x ships Inline 0.53, 0.64+ has built-in locking
+		flock($fh, LOCK_EX) or die "LOCK_EX($f): $!";
+		eval <<'EOM';
+use Inline C => $all_libc.$set_nodatacow, BUILD_NOISY => 1;
+EOM
+		my $err = $@;
+		my $ndc_err = '';
+		if ($err && $set_nodatacow) { # missing Linux kernel headers
+			$ndc_err = "with set_nodatacow: <\n$err\n>\n";
+			undef $set_nodatacow;
+			eval <<'EOM';
+use Inline C => $all_libc, BUILD_NOISY => 1;
+EOM
+		};
+		$err = $@;
+		open(STDERR, '>&', $olderr) or warn "restore stderr: $!";
+		open(STDOUT, '>&', $oldout) or warn "restore stdout: $!";
+		if ($err) {
+			seek($fh, 0, SEEK_SET);
+			my @msg = <$fh>;
+			warn "Inline::C build failed:\n",
+				$ndc_err, $err, "\n", @msg;
+			$set_nodatacow = $all_libc = undef;
+		} elsif ($ndc_err) {
+			warn "Inline::C build succeeded w/o set_nodatacow\n",
+				"error $ndc_err";
+		}
+	}
+	unless ($all_libc) {
+		require PublicInbox::SpawnPP;
+		*pi_fork_exec = \&PublicInbox::SpawnPP::pi_fork_exec
+	}
+	unless ($set_nodatacow) {
+		require PublicInbox::NDC_PP;
+		no warnings 'once';
+		*nodatacow_fd = \&PublicInbox::NDC_PP::nodatacow_fd;
+		*nodatacow_dir = \&PublicInbox::NDC_PP::nodatacow_dir;
+	}
+} # /BEGIN
 
 sub which ($) {
 	my ($file) = @_;
 	return $file if index($file, '/') >= 0;
-	foreach my $p (split(':', $ENV{PATH})) {
+	for my $p (split(/:/, $ENV{PATH})) {
 		$p .= "/$file";
 		return $p if -x $p;
 	}
@@ -188,20 +386,18 @@ sub which ($) {
 
 sub spawn ($;$$) {
 	my ($cmd, $env, $opts) = @_;
-	my $f = which($cmd->[0]);
-	defined $f or die "$cmd->[0]: command not found\n";
+	my $f = which($cmd->[0]) // die "$cmd->[0]: command not found\n";
 	my @env;
 	$opts ||= {};
-
-	my %env = $env ? (%ENV, %$env) : %ENV;
+	my %env = (%ENV, $env ? %$env : ());
 	while (my ($k, $v) = each %env) {
-		push @env, "$k=$v";
+		push @env, "$k=$v" if defined($v);
 	}
 	my $redir = [];
 	for my $child_fd (0..2) {
 		my $parent_fd = $opts->{$child_fd};
 		if (defined($parent_fd) && $parent_fd !~ /\A[0-9]+\z/) {
-			defined(my $fd = fileno($parent_fd)) or
+			my $fd = fileno($parent_fd) //
 					die "$parent_fd not an IO GLOB? $!";
 			$parent_fd = $fd;
 		}
@@ -209,8 +405,8 @@ sub spawn ($;$$) {
 	}
 	my $rlim = [];
 
-	foreach my $l (RLIMITS()) {
-		defined(my $v = $opts->{$l}) or next;
+	foreach my $l (@RLIMITS) {
+		my $v = $opts->{$l} // next;
 		my $r = eval "require BSD::Resource; BSD::Resource::$l();";
 		unless (defined $r) {
 			warn "$l undefined by BSD::Resource: $@\n";
@@ -219,21 +415,29 @@ sub spawn ($;$$) {
 		push @$rlim, $r, @$v;
 	}
 	my $cd = $opts->{'-C'} // ''; # undef => NULL mapping doesn't work?
-	my $pid = pi_fork_exec($redir, $f, $cmd, \@env, $rlim, $cd);
-	die "fork_exec failed: $!\n" unless $pid > 0;
+	my $pgid = $opts->{pgid} // -1;
+	my $pid = pi_fork_exec($redir, $f, $cmd, \@env, $rlim, $cd, $pgid);
+	die "fork_exec @$cmd failed: $!\n" unless $pid > 0;
 	$pid;
 }
 
 sub popen_rd {
-	my ($cmd, $env, $opts) = @_;
+	my ($cmd, $env, $opt) = @_;
 	pipe(my ($r, $w)) or die "pipe: $!\n";
-	$opts ||= {};
-	$opts->{1} = fileno($w);
-	my $pid = spawn($cmd, $env, $opts);
+	$opt ||= {};
+	$opt->{1} = fileno($w);
+	my $pid = spawn($cmd, $env, $opt);
 	return ($r, $pid) if wantarray;
 	my $ret = gensym;
-	tie *$ret, 'PublicInbox::ProcessPipe', $pid, $r;
+	tie *$ret, 'PublicInbox::ProcessPipe', $pid, $r, @$opt{qw(cb arg)};
 	$ret;
 }
 
+sub run_die ($;$$) {
+	my ($cmd, $env, $rdr) = @_;
+	my $pid = spawn($cmd, $env, $rdr);
+	waitpid($pid, 0) == $pid or die "@$cmd did not finish";
+	$? == 0 or die "@$cmd failed: \$?=$?\n";
+}
+
 1;