lei: test SIGPIPE, stop xsearch workers on client abort

The new test ensures consistency between oneshot and
client/daemon users.  Cancelling an in-progress result now also
stops xsearch workers to avoid wasted CPU and I/O.

Note the lei->atfork_child_wq usage changes, it is to workaround
a bug in Perl 5: http://nntp.perl.org/group/perl.perl5.porters/258784
<CAHhgV8hPbcmkzWizp6Vijw921M5BOXixj4+zTh3nRS9vRBYk8w@mail.gmail.com>

This switches the internal protocol to use SOCK_SEQPACKET
AF_UNIX sockets to prevent merging messages from the daemon to
client to run pager and kill/exit the client script.

1 files changed, 54 insertions, 20 deletions

diff --git a/script/lei b/script/lei
index 5c32ab88..9610a876 100755
--- a/script/lei
+++ b/script/lei
@@ -3,32 +3,47 @@
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 use strict;
 use v5.10.1;
-use Socket qw(AF_UNIX SOCK_STREAM pack_sockaddr_un);
+use Socket qw(AF_UNIX SOCK_SEQPACKET MSG_EOR pack_sockaddr_un);
+use Errno qw(EINTR ECONNRESET);
 use PublicInbox::CmdIPC4;
 my $narg = 4;
+my ($sock, $pwd);
 my $recv_cmd = PublicInbox::CmdIPC4->can('recv_cmd4');
 my $send_cmd = PublicInbox::CmdIPC4->can('send_cmd4') // do {
         require PublicInbox::Spawn; # takes ~50ms even if built *sigh*
-        $narg = 4;
         $recv_cmd = PublicInbox::Spawn->can('recv_cmd4');
         PublicInbox::Spawn->can('send_cmd4');
 };
 
+sub sigchld {
+        my ($sig) = @_;
+        my $flags = $sig ? POSIX::WNOHANG() : 0;
+        while (waitpid(-1, $flags) > 0) {}
+}
+
 sub exec_cmd {
         my ($fds, $argc, @argv) = @_;
-        my %env = map { split(/=/, $_, 2) } splice(@argv, $argc);
-        my @m = (*STDIN{IO}, '<&=',  *STDOUT{IO}, '>&=',
-                *STDERR{IO}, '>&=');
+        my @m = (*STDIN{IO}, '<&=',  *STDOUT{IO}, '>&=', *STDERR{IO}, '>&=');
+        my @rdr;
         for my $fd (@$fds) {
                 my ($old_io, $mode) = splice(@m, 0, 2);
-                open($old_io, $mode, $fd) or die "open $mode$fd: $!";
+                open(my $tmpfh, $mode, $fd) or die "open $mode$fd: $!";
+                push @rdr, $old_io, $mode, $tmpfh;
+        }
+        require POSIX; # WNOHANG
+        $SIG{CHLD} = \&sigchld;
+        my $pid = fork // die "fork: $!";
+        if ($pid == 0) {
+                my %env = map { split(/=/, $_, 2) } splice(@argv, $argc);
+                while (my ($old_io, $mode, $tmpfh) = splice(@rdr, 0, 3)) {
+                        open $old_io, $mode, $tmpfh or die "open $mode: $!";
+                }
+                %ENV = (%ENV, %env);
+                exec(@argv);
+                die "exec: @argv: $!";
         }
-        %ENV = (%ENV, %env);
-        exec(@argv);
-        die "exec: @argv: $!";
 }
 
-my ($sock, $pwd);
 if ($send_cmd && eval {
         my $path = do {
                 my $runtime_dir = ($ENV{XDG_RUNTIME_DIR} // '') . '/lei';
@@ -40,10 +55,10 @@ if ($send_cmd && eval {
                         require File::Path;
                         File::Path::mkpath($runtime_dir, 0, 0700);
                 }
-                "$runtime_dir/$narg.sock";
+                "$runtime_dir/$narg.seq.sock";
         };
         my $addr = pack_sockaddr_un($path);
-        socket($sock, AF_UNIX, SOCK_STREAM, 0) or die "socket: $!";
+        socket($sock, AF_UNIX, SOCK_SEQPACKET, 0) or die "socket: $!";
         unless (connect($sock, $addr)) { # start the daemon if not started
                 local $ENV{PERL5LIB} = join(':', @INC);
                 open(my $daemon, '-|', $^X, qw[-MPublicInbox::LEI
@@ -73,22 +88,41 @@ Falling back to (slow) one-shot mode
         }
         1;
 }) { # (Socket::MsgHdr|Inline::C), $sock, $pwd are all available:
-        local $ENV{PWD} = $pwd;
+        $ENV{PWD} = $pwd;
         my $buf = join("\0", scalar(@ARGV), @ARGV);
         while (my ($k, $v) = each %ENV) { $buf .= "\0$k=$v" }
         $buf .= "\0\0";
-        select $sock;
-        $| = 1; # unbuffer selected $sock
-        $send_cmd->($sock, [ 0, 1, 2 ], $buf, 0);
-        while (my (@fds) = $recv_cmd->($sock, $buf, 4096 * 33)) {
-                if ($buf =~ /\Aexit=([0-9]+)\n\z/) {
-                        exit($1);
-                } elsif ($buf =~ /\Aexec (.+)\n\z/) {
+        $send_cmd->($sock, [ 0, 1, 2 ], $buf, MSG_EOR);
+        $SIG{TERM} = $SIG{INT} = $SIG{QUIT} = sub {
+                my ($sig) = @_; # 'TERM', not an integer :<
+                $SIG{$sig} = 'DEFAULT';
+                kill($sig, $$); # exit($signo + 128)
+        };
+        my $x_it_code = 0;
+        while (1) {
+                my (@fds) = $recv_cmd->($sock, $buf, 4096 * 33);
+                if (scalar(@fds) == 1 && !defined($fds[0])) {
+                        last if $! == ECONNRESET;
+                        next if $! == EINTR;
+                        die "recvmsg: $!";
+                }
+                last if $buf eq '';
+                if ($buf =~ /\Ax_it ([0-9]+)\z/) {
+                        $x_it_code = $1 + 0;
+                        last;
+                } elsif ($buf =~ /\Aexec (.+)\z/) {
                         exec_cmd(\@fds, split(/\0/, $1));
                 } else {
+                        sigchld();
                         die $buf;
                 }
         }
+        sigchld();
+        if (my $sig = ($x_it_code & 127)) {
+                kill $sig, $$;
+                sleep;
+        }
+        exit($x_it_code >> 8);
 } else { # for systems lacking Socket::MsgHdr or Inline::C
         warn $@ if $@;
         require PublicInbox::LEI;