send and receive all 3 FDs at once

[public-inbox.git] / lib / PublicInbox / Spawn.pm

diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index 762a0549bba4e95b5d62693767ab499117ecde93..61e954338ef2f285056feee6c917401630ce9760 100644 (file)
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -201,12 +201,83 @@ void nodatacow_dir(const char *dir)
 }
 SET_NODATACOW
 
+my $fdpass = <<'FDPASS';
+#include <sys/types.h>
+#include <sys/uio.h>
+#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(struct my_3fds) + 8];
+};
+
+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; /* whatever */
+       iov.iov_len = 1;
+       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++ = infd;
+       *fdp++ = outfd;
+       *fdp++ = errfd;
+       return sendmsg(sockfd, &msg, 0) >= 0;
+}
+
+void recv_3fds(int sockfd)
+{
+       union my_cmsg cmsg = { 0 };
+       struct msghdr msg = { 0 };
+       struct iovec iov;
+       size_t i;
+       Inline_Stack_Vars;
+
+       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(struct my_3fds));
+
+       if (recvmsg(sockfd, &msg, 0) <= 0)
+               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(struct my_3fds))) {
+               int *fdp = (int *)CMSG_DATA(&cmsg.hdr);
+               size_t i;
+
+               for (i = 0; i < 3; i++)
+                       Inline_Stack_Push(sv_2mortal(newSViv(*fdp++)));
+       }
+       Inline_Stack_Done;
+}
+#endif /* defined(CMSG_SPACE) && defined(CMSG_LEN) */
+FDPASS
+
 my $inline_dir = $ENV{PERL_INLINE_DIRECTORY} //= (
                $ENV{XDG_CACHE_HOME} //
                ( ($ENV{HOME} // '/nonexistent').'/.cache' )
        ).'/public-inbox/inline-c';
 
-$set_nodatacow = $vfork_spawn = undef unless -d $inline_dir && -w _;
+$set_nodatacow = $vfork_spawn = $fdpass = 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
@@ -215,13 +286,14 @@ 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 . $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
                        $ndc_err = $err;
                        undef $set_nodatacow;
-                       eval 'use Inline C => $vfork_spawn';
+                       eval 'use Inline C => $vfork_spawn . $fdpass';
                }
                flock($fh, LOCK_UN) or die "LOCK_UN failed on $f: $!\n";
                die $err if $err;
@@ -229,7 +301,7 @@ if (defined $vfork_spawn) {
        };
        if ($@) {
                warn "Inline::C failed for vfork: $@\n";
-               $set_nodatacow = $vfork_spawn = undef;
+               $set_nodatacow = $vfork_spawn = $fdpass = undef;
        }
 }
 
@@ -243,8 +315,21 @@ unless ($set_nodatacow) {
        *nodatacow_fd = \&PublicInbox::NDC_PP::nodatacow_fd;
        *nodatacow_dir = \&PublicInbox::NDC_PP::nodatacow_dir;
 }
+unless (__PACKAGE__->can('recv_3fds')) {
+       eval { # try the XS IO::FDPass package
+               require IO::FDPass;
+               no warnings 'once';
+               *recv_3fds = sub { map { IO::FDPass::recv($_[0]) } (0..2) };
+               *send_3fds = sub ($$$$) {
+                       my $sockfd = shift;
+                       IO::FDPass::send($sockfd, shift) for (0..2);
+               };
+       };
+}
+
 undef $set_nodatacow;
 undef $vfork_spawn;
+undef $fdpass;
 
 sub which ($) {
        my ($file) = @_;