ipc: start supporting sending/receiving more than 3 FDs

Actually, sending 4 FDs will be useful for lei internal xsearch
work once we start accepting input from stdin.  It won't be used
with the lightweight lei(1) client, however.

For WWW (eventually), a single FD may be enough.

8 files changed, 60 insertions, 48 deletions

diff --git a/lib/PublicInbox/CmdIPC1.pm b/lib/PublicInbox/CmdIPC1.pm
index 0eed8bed..de6e54ef 100644
--- a/lib/PublicInbox/CmdIPC1.pm
+++ b/lib/PublicInbox/CmdIPC1.pm
@@ -10,17 +10,19 @@ BEGIN { eval {
 require IO::FDPass; # XS, available in all major distros
 no warnings 'once';
 
-*send_cmd1 = sub ($$$$$$) { # (sock, in, out, err, buf, flags) = @_;
-        for (1..3) {
-                IO::FDPass::send(fileno($_[0]), $_[$_]) or
+*send_cmd1 = sub ($$$$) { # (sock, fds, buf, flags) = @_;
+        my ($sock, $fds, undef, $flags) = @_;
+        for my $fd (@$fds) {
+                IO::FDPass::send(fileno($sock), $fd) or
                                         die "IO::FDPass::send: $!";
         }
-        send($_[0], $_[4], $_[5]) or die "send $!";
+        send($sock, $_[2], $flags) or die "send $!";
 };
 
-*recv_cmd1 = sub ($$$) {
-        my ($s, undef, $len) = @_;
-        my @fds = map { IO::FDPass::recv(fileno($s)) } (0..2);
+*recv_cmd1 = sub ($$$;$) {
+        my ($s, undef, $len, $nfds) = @_;
+        $nfds //= 3;
+        my @fds = map { IO::FDPass::recv(fileno($s)) } (1..$nfds);
         recv($s, $_[1], $len, 0) // die "recv: $!";
         length($_[1]) == 0 ? () : @fds;
 };
diff --git a/lib/PublicInbox/CmdIPC4.pm b/lib/PublicInbox/CmdIPC4.pm
index 90fca62d..c4fcb0d6 100644
--- a/lib/PublicInbox/CmdIPC4.pm
+++ b/lib/PublicInbox/CmdIPC4.pm
@@ -13,10 +13,12 @@ require Socket::MsgHdr; # XS
 no warnings 'once';
 
 # 3 FDs per-sendmsg(2) + buffer
-*send_cmd4 = sub ($$$$$$) { # (sock, in, out, err, buf, flags) = @_;
-        my $mh = Socket::MsgHdr->new(buf => $_[4]);
-        $mh->cmsghdr(SOL_SOCKET, SCM_RIGHTS, pack('iii', @_[1,2,3]));
-        Socket::MsgHdr::sendmsg($_[0], $mh, $_[5]) or die "sendmsg: $!";
+*send_cmd4 = sub ($$$$) { # (sock, fds, buf, flags) = @_;
+        my ($sock, $fds, undef, $flags) = @_;
+        my $mh = Socket::MsgHdr->new(buf => $_[2]);
+        $mh->cmsghdr(SOL_SOCKET, SCM_RIGHTS,
+                        pack('i' x scalar(@$fds), @$fds));
+        Socket::MsgHdr::sendmsg($sock, $mh, $flags) or die "sendmsg: $!";
 };
 
 *recv_cmd4 = sub ($$$) {
@@ -26,7 +28,7 @@ no warnings 'once';
         $_[1] = $mh->buf;
         return () if $r == 0;
         my (undef, undef, $data) = $mh->cmsghdr;
-        unpack('iii', $data);
+        unpack('i' x (length($data) / 4), $data);
 };
 
 } } # /eval /BEGIN
diff --git a/lib/PublicInbox/IPC.pm b/lib/PublicInbox/IPC.pm
index be5b2f45..b0a0bfb5 100644
--- a/lib/PublicInbox/IPC.pm
+++ b/lib/PublicInbox/IPC.pm
@@ -263,16 +263,15 @@ sub wq_worker_loop ($) {
 }
 
 sub wq_do { # always async
-        my ($self, $sub, $in, $out, $err, @args) = @_;
+        my ($self, $sub, $ios, @args) = @_;
         if (my $s1 = $self->{-wq_s1}) { # run in worker
-                $_ = fileno($_) for ($in, $out, $err);
-                $send_cmd->($s1, $in, $out, $err,
-                                freeze([$sub, @args]), MSG_EOR);
+                my $fds = [ map { fileno($_) } @$ios ];
+                $send_cmd->($s1, $fds, freeze([$sub, @args]), MSG_EOR);
         } else {
-                @$self{0, 1, 2} = ($in, $out, $err);
+                @$self{0..$#$ios} = @$ios;
                 eval { $self->$sub(@args) };
                 warn "wq_do: $@" if $@;
-                delete @$self{0, 1, 2};
+                delete @$self{0..$#$ios};
         }
 }
 
@@ -334,7 +333,7 @@ sub wq_worker_decr { # SIGTTOU handler, kills first idle worker
         my ($self) = @_;
         my $workers = $self->{-wq_workers} or return;
         my $s2 = $self->{-wq_s2} // die 'BUG: no wq_s2';
-        $self->wq_do('wq_exit', $s2, $s2, $s2);
+        $self->wq_do('wq_exit', [ $s2, $s2, $s2 ]);
         $self->{-wq_exit_pending}++;
         # caller must call wq_worker_decr_wait in main loop
 }
diff --git a/lib/PublicInbox/LeiXSearch.pm b/lib/PublicInbox/LeiXSearch.pm
index a3010efe..c0df21a8 100644
--- a/lib/PublicInbox/LeiXSearch.pm
+++ b/lib/PublicInbox/LeiXSearch.pm
@@ -150,14 +150,14 @@ sub do_query {
         $io[2]->autoflush(1);
         if ($lei->{opt}->{thread}) {
                 for my $ibxish (@$srcs) {
-                        $self->wq_do('query_thread_mset', @io, $lei, $ibxish);
+                        $self->wq_do('query_thread_mset', \@io, $lei, $ibxish);
                 }
         } else {
-                $self->wq_do('query_mset', @io, $lei, $srcs);
+                $self->wq_do('query_mset', \@io, $lei, $srcs);
         }
         # TODO
         for my $rmt (@{$self->{remotes} // []}) {
-                $self->wq_do('query_thread_mbox', @io, $lei, $rmt);
+                $self->wq_do('query_thread_mbox', \@io, $lei, $rmt);
         }
 }
 
diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index 7d0d9597..b35bf54c 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -209,20 +209,22 @@ my $fdpass = <<'FDPASS';
 #include <sys/socket.h>
 
 #if defined(CMSG_SPACE) && defined(CMSG_LEN)
-struct my_3fds { int fds[3]; };
+#define SEND_FD_CAPA 3
+#define SEND_FD_SPACE (SEND_FD_CAPA * sizeof(int))
 union my_cmsg {
         struct cmsghdr hdr;
-        char pad[sizeof(struct cmsghdr)+ 8 + sizeof(struct my_3fds) + 8];
+        char pad[sizeof(struct cmsghdr) + 16 + SEND_FD_SPACE];
 };
 
-int send_cmd4(PerlIO *s, int in, int out, int err, SV *data, int flags)
+int send_cmd4(PerlIO *s, SV *svfds, SV *data, int flags)
 {
         struct msghdr msg = { 0 };
-        struct iovec iov;
         union my_cmsg cmsg = { 0 };
-        int *fdp;
-        size_t i;
         STRLEN dlen = 0;
+        struct iovec iov;
+        AV *fds = (AV *)SvRV(svfds);
+        I32 i, nfds = av_len(fds) + 1;
+        int *fdp;
 
         if (SvOK(data)) {
                 iov.iov_base = SvPV(data, dlen);
@@ -234,16 +236,22 @@ int send_cmd4(PerlIO *s, int in, int out, int err, SV *data, int flags)
         }
         msg.msg_iov = &iov;
         msg.msg_iovlen = 1;
-        msg.msg_control = &cmsg.hdr;
-        msg.msg_controllen = CMSG_SPACE(sizeof(struct my_3fds));
-
-        cmsg.hdr.cmsg_level = SOL_SOCKET;
-        cmsg.hdr.cmsg_type = SCM_RIGHTS;
-        cmsg.hdr.cmsg_len = CMSG_LEN(sizeof(struct my_3fds));
-        fdp = (int *)CMSG_DATA(&cmsg.hdr);
-        *fdp++ = in;
-        *fdp++ = out;
-        *fdp++ = err;
+        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);
+                }
+        }
         return sendmsg(PerlIO_fileno(s), &msg, flags) >= 0;
 }
 
@@ -263,17 +271,17 @@ void recv_cmd4(PerlIO *s, SV *buf, STRLEN n)
         msg.msg_iov = &iov;
         msg.msg_iovlen = 1;
         msg.msg_control = &cmsg.hdr;
-        msg.msg_controllen = CMSG_SPACE(sizeof(struct my_3fds));
+        msg.msg_controllen = CMSG_SPACE(SEND_FD_SPACE);
 
         i = recvmsg(PerlIO_fileno(s), &msg, 0);
         if (i < 0)
                 croak("recvmsg: %s", strerror(errno));
         SvCUR_set(buf, i);
         if (i > 0 && cmsg.hdr.cmsg_level == SOL_SOCKET &&
-                        cmsg.hdr.cmsg_type == SCM_RIGHTS &&
-                        cmsg.hdr.cmsg_len == CMSG_LEN(sizeof(struct my_3fds))) {
+                        cmsg.hdr.cmsg_type == SCM_RIGHTS) {
+                size_t len = cmsg.hdr.cmsg_len;
                 int *fdp = (int *)CMSG_DATA(&cmsg.hdr);
-                for (i = 0; i < 3; i++)
+                for (i = 0; CMSG_LEN((i + 1) * sizeof(int)) <= len; i++)
                         Inline_Stack_Push(sv_2mortal(newSViv(*fdp++)));
         }
         Inline_Stack_Done;
diff --git a/script/lei b/script/lei
index d954b9eb..5e30f4d7 100755
--- a/script/lei
+++ b/script/lei
@@ -67,7 +67,7 @@ Falling back to (slow) one-shot mode
         $buf .= "\0\0";
         select $sock;
         $| = 1; # unbuffer selected $sock
-        $send_cmd->($sock, 0, 1, 2, $buf, 0);
+        $send_cmd->($sock, [ 0, 1, 2 ], $buf, 0);
         while ($buf = <$sock>) {
                 $buf =~ /\Aexit=([0-9]+)\n\z/ and exit($1 + 0);
                 die $buf;
diff --git a/t/cmd_ipc.t b/t/cmd_ipc.t
index b9f4d128..22f73c19 100644
--- a/t/cmd_ipc.t
+++ b/t/cmd_ipc.t
@@ -17,7 +17,8 @@ my $do_test = sub { SKIP: {
         my ($s1, $s2);
         my $src = 'some payload' x 40;
         socketpair($s1, $s2, AF_UNIX, $type, 0) or BAIL_OUT $!;
-        $send->($s1, fileno($r), fileno($w), fileno($s1), $src, $flag);
+        my $sfds = [ fileno($r), fileno($w), fileno($s1) ];
+        $send->($s1, $sfds, $src, $flag);
         my (@fds) = $recv->($s2, my $buf, length($src) + 1);
         is($buf, $src, 'got buffer payload '.$desc);
         my ($r1, $w1, $s1a);
@@ -39,7 +40,7 @@ my $do_test = sub { SKIP: {
         if (defined($SOCK_SEQPACKET) && $type == $SOCK_SEQPACKET) {
                 $r1 = $w1 = $s1a = undef;
                 $src = (',' x 1023) . '-' .('.' x 1024);
-                $send->($s1, fileno($r), fileno($w), fileno($s1), $src, $flag);
+                $send->($s1, $sfds, $src, $flag);
                 (@fds) = $recv->($s2, $buf, 1024);
                 is($buf, (',' x 1023) . '-', 'silently truncated buf');
                 $opens->();
diff --git a/t/ipc.t b/t/ipc.t
index 903294c5..d2b6ad4f 100644
--- a/t/ipc.t
+++ b/t/ipc.t
@@ -121,7 +121,7 @@ $warn->autoflush(0);
 local $SIG{__WARN__} = sub { print $warn "PID:$$ ", @_ };
 my @ppids;
 for my $t ('local', 'worker', 'worker again') {
-        $ipc->wq_do('test_write_each_fd', $wa, $wb, $wc, 'hello world');
+        $ipc->wq_do('test_write_each_fd', [ $wa, $wb, $wc ], 'hello world');
         my $i = 0;
         for my $fh ($ra, $rb, $rc) {
                 my $buf = readline($fh);
@@ -129,7 +129,7 @@ for my $t ('local', 'worker', 'worker again') {
                 like($buf, qr/\Ai=$i \d+ hello world\z/, "got expected ($t)");
                 $i++;
         }
-        $ipc->wq_do('test_die', $wa, $wb, $wc);
+        $ipc->wq_do('test_die', [ $wa, $wb, $wc ]);
         my $ppid = $ipc->wq_workers_start('wq', 1);
         push(@ppids, $ppid);
 }
@@ -142,7 +142,7 @@ SKIP: {
         my $pid = fork // BAIL_OUT $!;
         if ($pid == 0) {
                 use POSIX qw(_exit);
-                $ipc->wq_do('test_write_each_fd', $wa, $wb, $wc, $$);
+                $ipc->wq_do('test_write_each_fd', [ $wa, $wb, $wc ], $$);
                 _exit(0);
         } else {
                 my $i = 0;