lei: allow Ctrl-C to interrupt IMAP+NNTP reads

Mail::IMAPClient and Net::NNTP remain synchronous APIs with
indefinite wait times on slow/unreliable connections or servers.

Since these APIs don't play nicely with signalfd or
EVFILT_SIGNAL, we will temporarily drop the reliable (but
sometimes delayed) signal handling mechanisms in favor of the
less reliable built-in signal handling of Perl to provide a
best-effort attempt to handle signals during slow operations.

diff --git a/lib/PublicInbox/NetReader.pm b/lib/PublicInbox/NetReader.pm
index 7e861f5f1f8893ae369b8f75206ce76ad9395c15..b95022b36853cbc01c0f410039a3ffd92ea163cf 100644 (file)
--- a/lib/PublicInbox/NetReader.pm
+++ b/lib/PublicInbox/NetReader.pm
@@ -7,6 +7,7 @@ use v5.12;
 use parent qw(Exporter PublicInbox::IPC);
 use PublicInbox::Eml;
 use PublicInbox::Config;
+use PublicInbox::DS;
 our %IMAPflags2kw = map {; "\\\u$_" => $_ } qw(seen answered flagged draft);
 $IMAPflags2kw{'$Forwarded'} = 'forwarded';  # RFC 5550
 
@@ -61,6 +62,7 @@ sub mic_new ($$$$) {
        my %mic_arg = (%$mic_arg, Keepalive => 1);
        my $sa = $self->{cfg_opt}->{$sec}->{-proxy_cfg} || $self->{-proxy_cli};
        my ($mic, $s, $t);
+       my $restore = PublicInbox::DS::allow_sigs qw(INT QUIT TERM);
        if ($sa) {
                # this `require' needed for worker[1..Inf], since socks_args
                # only got called in worker[0]
@@ -226,6 +228,7 @@ sub nn_new ($$$$) {
                ($Net_NNTP, $new) = qw(PublicInbox::NetNNTPSocks new_socks);
                $nn_arg->{SocksDebug} = 1 if $nn_arg->{Debug};
        }
+       my $restore = PublicInbox::DS::allow_sigs qw(INT QUIT TERM);
        do {
                $! = 0;
                $nn = $Net_NNTP->$new(%$nn_arg);
@@ -567,12 +570,14 @@ sub each_old_flags ($$$$) {
        for (my $n = 1; $n <= $l_uid; $n += $bs) {
                my $end = $n + $bs;
                $end = $l_uid if $end > $l_uid;
+               my $restore = PublicInbox::DS::allow_sigs qw(INT QUIT TERM);
                my $r = $mic->fetch_hash("$n:$end", 'FLAGS');
                if (!$r) {
                        return if $!{EINTR} && $self->{quit};
                        return "E: $uri UID FETCH $n:$end error: " .
                                $mic->LastError." \$!=$!"
                }
+               undef $restore;
                while (my ($uid, $per_uid) = each %$r) {
                        my $kw = flags2kw($self, $uri, $uid, $per_uid->{FLAGS})
                                // next;
@@ -611,12 +616,14 @@ sub _imap_fetch_bodies ($$$$) {
                my @batch = splice(@$uids, 0, $bs);
                my $batch = join(',', @batch);
                local $0 = "UID:$batch $mbx $sec";
+               my $restore = PublicInbox::DS::allow_sigs qw(INT QUIT TERM);
                my $r = $mic->fetch_hash($batch, $req, 'FLAGS');
                unless ($r) { # network error?
                        last if $!{EINTR} && $self->{quit};
                        $err = "E: $uri UID FETCH $batch error: $!";
                        last;
                }
+               undef $restore;
                for my $uid (@batch) {
                        # messages get deleted, so holes appear
                        my $per_uid = delete $r->{$uid} // next;
@@ -640,6 +647,7 @@ sub _imap_fetch_all ($$$) {
        # we need to check for mailbox writability to see if we care about
        # FLAGS from already-imported messages.
        my $cmd = $self->folder_select;
+       my $restore = PublicInbox::DS::allow_sigs qw(INT QUIT TERM);
        $mic->$cmd($mbx) or return "E: \U$cmd\E $mbx ($sec) failed: $!";
 
        my ($r_uidval, $r_uidnext, $perm_fl);
@@ -657,6 +665,7 @@ sub _imap_fetch_all ($$$) {
 E: $orig_uri UIDVALIDITY mismatch (got $r_uidval)
 EOF
 
+       undef $restore;
        my $uri = $orig_uri->clone;
        my $single_uid = $uri->uid;
        my ($itrk, $l_uid, $l_uidval) = itrk_last($self, $uri, $r_uidval, $mic);
@@ -782,6 +791,7 @@ sub nn_get {
        my $nntp_cfg = $self->{cfg_opt}->{$sec};
        $nn = nn_new($self, $nn_arg, $nntp_cfg, $uri) or return;
        if (my $postconn = $nntp_cfg->{-postconn}) {
+               my $restore = PublicInbox::DS::allow_sigs qw(INT QUIT TERM);
                for my $m_arg (@$postconn) {
                        my ($method, @args) = @$m_arg;
                        $nn->$method(@args) and next;
@@ -796,11 +806,13 @@ sub _nntp_fetch_all ($$$) {
        my ($self, $nn, $uri) = @_;
        my ($group, $num_a, $num_b) = $uri->group;
        my $sec = uri_section($uri);
+       my $restore = PublicInbox::DS::allow_sigs qw(INT QUIT TERM);
        my ($nr, $beg, $end) = $nn->group($group);
        unless (defined($nr)) {
                my $msg = ndump($nn->message);
                return "E: GROUP $group <$sec> $msg";
        }
+       undef $restore;
        (defined($num_a) && defined($num_b) && $num_a > $num_b) and
                return "E: $uri: backwards range: $num_a > $num_b";
        if (defined($num_a)) { # no article numbers in mail_sync.sqlite3
@@ -833,6 +845,7 @@ sub _nntp_fetch_all ($$$) {
                        $itrk->update_last(0, $last_art) if $itrk;
                        $n = $self->{max_batch};
                }
+               $restore = PublicInbox::DS::allow_sigs qw(INT QUIT TERM);
                my $raw = $nn->article($art);
                unless (defined($raw)) {
                        my $msg = ndump($nn->message);
@@ -844,6 +857,7 @@ sub _nntp_fetch_all ($$$) {
                                next;
                        }
                }
+               undef $restore;
                $raw = join('', @$raw);
                $raw =~ s/\r\n/\n/sg;
                my ($eml_cb, @args) = @{$self->{eml_each}};