lei: avoid ETOOMANYREFS, cleanup imports

As with PublicInbox::IPC, we'll attempt to bump RLIMIT_NOFILE
and transparently workaround ETOOMANYREFS.  If that fails,
we'll give the user a hint to bump RLIMIT_NOFILE since
ETOOMANYREFS is an uncommon error which users may be unfamiliar
with.

Found while stress testing for segfaults.

1 files changed, 20 insertions, 9 deletions

diff --git a/script/lei b/script/lei
index f92dd302..58f0dbe9 100755
--- a/script/lei
+++ b/script/lei
@@ -4,10 +4,9 @@
 use strict;
 use v5.10.1;
 use Socket qw(AF_UNIX SOCK_SEQPACKET MSG_EOR pack_sockaddr_un);
-use Errno qw(EINTR ECONNRESET);
 use PublicInbox::CmdIPC4;
 my $narg = 5;
-my ($sock, $pwd);
+my $sock;
 my $recv_cmd = PublicInbox::CmdIPC4->can('recv_cmd4');
 my $send_cmd = PublicInbox::CmdIPC4->can('send_cmd4') // do {
         require PublicInbox::Spawn; # takes ~50ms even if built *sigh*
@@ -73,20 +72,32 @@ connect($path): $! (after attempted daemon start)
 Falling back to (slow) one-shot mode
 
         }
-        1;
-}) { # (Socket::MsgHdr|Inline::C), $sock, $pwd are all available:
+        # (Socket::MsgHdr|Inline::C), $sock are all available:
         open my $dh, '<', '.' or die "open(.) $!";
         my $buf = join("\0", scalar(@ARGV), @ARGV);
         while (my ($k, $v) = each %ENV) { $buf .= "\0$k=$v" }
         $buf .= "\0\0";
-        $send_cmd->($sock, [ 0, 1, 2, fileno($dh) ], $buf, MSG_EOR) or
-                die "sendmsg: $!";
+        my $n = $send_cmd->($sock, [0, 1, 2, fileno($dh)], $buf, MSG_EOR);
+        if (!$n && $!{ETOOMANYREFS} && eval { require BSD::Resource }) {
+                my $NOFILE = BSD::Resource::RLIMIT_NOFILE();
+                my ($s, $h) = BSD::Resource::getrlimit($NOFILE);
+                if ($s < $h && BSD::Resource::setrlimit($NOFILE, $h, $h)) {
+                        $n = $send_cmd->($sock, [0, 1, 2, fileno($dh)],
+                                        $buf, MSG_EOR);
+                }
+        }
+        if (!$n) {
+                die "sendmsg: $! (check RLIMIT_NOFILE)\n" if $!{ETOOMANYREFS};
+                die "sendmsg: $!\n";
+        }
+        1;
+}) { # connected and request sent to lei-daemon, wait for responses or EOF
         my $x_it_code = 0;
         while (1) {
-                my (@fds) = $recv_cmd->($sock, $buf, 4096 * 33);
+                my (@fds) = $recv_cmd->($sock, my $buf, 4096 * 33);
                 if (scalar(@fds) == 1 && !defined($fds[0])) {
-                        last if $! == ECONNRESET;
-                        next if $! == EINTR;
+                        next if $!{EINTR};
+                        last if $!{ECONNRESET};
                         die "recvmsg: $!";
                 }
                 last if $buf eq '';