send and receive all 3 FDs at once

We'll always be transferring stdin, stdout, and stderr together
for lei.  Perhaps I lack imagination or foresight, but I can't
think of a reason to send more or less FDs.

2 files changed, 48 insertions, 32 deletions

diff --git a/lib/PublicInbox/LEI.pm b/lib/PublicInbox/LEI.pm
index 6f98c934..3ad5e01a 100644
--- a/lib/PublicInbox/LEI.pm
+++ b/lib/PublicInbox/LEI.pm
@@ -25,7 +25,7 @@ use Text::Wrap qw(wrap);
 use File::Path qw(mkpath);
 use File::Spec;
 our $quit = \&CORE::exit;
-my $recv_fd;
+my $recv_3fds;
 my $GLP = Getopt::Long::Parser->new;
 $GLP->configure(qw(gnu_getopt no_ignore_case auto_abbrev));
 my $GLP_PASS = Getopt::Long::Parser->new;
@@ -614,25 +614,26 @@ sub accept_dispatch { # Listener {post_accept} callback
         my $self = bless { sock => $sock }, __PACKAGE__;
         vec(my $rin = '', fileno($sock), 1) = 1;
         # `say $sock' triggers "die" in lei(1)
-        for my $i (0..2) {
-                if (select(my $rout = $rin, undef, undef, 1)) {
-                        my $fd = $recv_fd->(fileno($sock));
-                        if ($fd >= 0) {
-                                my $rdr = ($fd == 0 ? '<&=' : '>&=');
+        if (select(my $rout = $rin, undef, undef, 1)) {
+                my @fds = $recv_3fds->(fileno($sock));
+                if (scalar(@fds) == 3) {
+                        my $i = 0;
+                        for my $rdr (qw(<&= >&= >&=)) {
+                                my $fd = shift(@fds);
                                 if (open(my $fh, $rdr, $fd)) {
-                                        $self->{$i} = $fh;
-                                } else {
+                                        $self->{$i++} = $fh;
+                                }  else {
                                         say $sock "open($rdr$fd) (FD=$i): $!";
                                         return;
                                 }
-                        } else {
-                                say $sock "recv FD=$i: $!";
-                                return;
                         }
                 } else {
-                        say $sock "timed out waiting to recv FD=$i";
+                        say $sock "recv_3fds failed: $!";
                         return;
                 }
+        } else {
+                say $sock "timed out waiting to recv FDs";
+                return;
         }
         # $ARGV_STR = join("]\0[", @ARGV);
         # $ENV_STR = join('', map { "$_=$ENV{$_}\0" } keys %ENV);
@@ -672,7 +673,7 @@ sub lazy_start {
         my $dev_ino_expect = pack('dd', $st[0], $st[1]); # dev+ino
         pipe(my ($eof_r, $eof_w)) or die "pipe: $!";
         my $oldset = PublicInbox::Sigfd::block_signals();
-        $recv_fd = PublicInbox::Spawn->can('recv_fd') or die
+        $recv_3fds = PublicInbox::Spawn->can('recv_3fds') or die
                 "Inline::C not installed/configured or IO::FDPass missing\n";
         require PublicInbox::Listener;
         require PublicInbox::EOFpipe;
diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index 4ca94b9f..61e95433 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -207,56 +207,67 @@ my $fdpass = <<'FDPASS';
 #include <sys/socket.h>
 
 #if defined(CMSG_SPACE) && defined(CMSG_LEN)
+struct my_3fds { int fds[3]; };
 union my_cmsg {
         struct cmsghdr hdr;
-        char pad[sizeof(struct cmsghdr)+8+sizeof(int)+8];
+        char pad[sizeof(struct cmsghdr)+ 8 + sizeof(struct my_3fds) + 8];
 };
 
-int send_fd(int sockfd, int fd)
+int send_3fds(int sockfd, int infd, int outfd, int errfd)
 {
         struct msghdr msg = { 0 };
         struct iovec iov;
         union my_cmsg cmsg = { 0 };
+        int *fdp;
+        size_t i;
 
-        iov.iov_base = &msg.msg_namelen;
+        iov.iov_base = &msg.msg_namelen; /* whatever */
         iov.iov_len = 1;
         msg.msg_iov = &iov;
         msg.msg_iovlen = 1;
         msg.msg_control = &cmsg.hdr;
-        msg.msg_controllen = CMSG_SPACE(sizeof(int));
+        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(int));
-        *(int *)CMSG_DATA(&cmsg.hdr) = fd;
-
+        cmsg.hdr.cmsg_len = CMSG_LEN(sizeof(struct my_3fds));
+        fdp = (int *)CMSG_DATA(&cmsg.hdr);
+        *fdp++ = infd;
+        *fdp++ = outfd;
+        *fdp++ = errfd;
         return sendmsg(sockfd, &msg, 0) >= 0;
 }
 
-int recv_fd(int sockfd)
+void recv_3fds(int sockfd)
 {
         union my_cmsg cmsg = { 0 };
         struct msghdr msg = { 0 };
         struct iovec iov;
-        int fd = -1;
+        size_t i;
+        Inline_Stack_Vars;
 
-        iov.iov_base = &msg.msg_namelen;
+        iov.iov_base = &msg.msg_namelen; /* whatever */
         iov.iov_len = 1;
         msg.msg_iov = &iov;
         msg.msg_iovlen = 1;
         msg.msg_control = &cmsg.hdr;
-        msg.msg_controllen = CMSG_SPACE(sizeof(int));
+        msg.msg_controllen = CMSG_SPACE(sizeof(struct my_3fds));
 
         if (recvmsg(sockfd, &msg, 0) <= 0)
-                return -1;
+                return;
 
         errno = EDOM;
+        Inline_Stack_Reset;
         if (cmsg.hdr.cmsg_level == SOL_SOCKET &&
                         cmsg.hdr.cmsg_type == SCM_RIGHTS &&
-                        cmsg.hdr.cmsg_len == CMSG_LEN(sizeof(int)))
-                fd = *(int *)CMSG_DATA(&cmsg.hdr);
+                        cmsg.hdr.cmsg_len == CMSG_LEN(sizeof(struct my_3fds))) {
+                int *fdp = (int *)CMSG_DATA(&cmsg.hdr);
+                size_t i;
 
-        return fd;
+                for (i = 0; i < 3; i++)
+                        Inline_Stack_Push(sv_2mortal(newSViv(*fdp++)));
+        }
+        Inline_Stack_Done;
 }
 #endif /* defined(CMSG_SPACE) && defined(CMSG_LEN) */
 FDPASS
@@ -275,7 +286,8 @@ if (defined $vfork_spawn) {
                 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 . $fdpass . $set_nodatacow';
+                eval 'use Inline C => $vfork_spawn.$fdpass.$set_nodatacow';
+                        # . ', BUILD_NOISY => 1';
                 my $err = $@;
                 my $ndc_err;
                 if ($err && $set_nodatacow) { # missing Linux kernel headers
@@ -303,12 +315,15 @@ unless ($set_nodatacow) {
         *nodatacow_fd = \&PublicInbox::NDC_PP::nodatacow_fd;
         *nodatacow_dir = \&PublicInbox::NDC_PP::nodatacow_dir;
 }
-unless (__PACKAGE__->can('recv_fd')) {
+unless (__PACKAGE__->can('recv_3fds')) {
         eval { # try the XS IO::FDPass package
                 require IO::FDPass;
                 no warnings 'once';
-                *recv_fd = \&IO::FDPass::recv;
-                *send_fd = \&IO::FDPass::send;
+                *recv_3fds = sub { map { IO::FDPass::recv($_[0]) } (0..2) };
+                *send_3fds = sub ($$$$) {
+                        my $sockfd = shift;
+                        IO::FDPass::send($sockfd, shift) for (0..2);
+                };
         };
 }