From 5808636263d72b635a46100a7e7037074dad8f75 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@yhbt.net>
Date: Sat, 27 Jun 2020 10:03:35 +0000
Subject: kqnotify|fake_inotify: detect Maildir write ops

We need to detect link(2) and rename(2) in other apps
writing to the Maildir.

We'll be removing the Filesys::Notify::Simple from -watch
in favor of using IO::KQueue or Linux::Inotify2 directly.
Ensure non-inotify emulations can support everything we
expect for Maildir writers.
---
 lib/PublicInbox/KQNotify.pm | 38 ++++++++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

(limited to 'lib/PublicInbox/KQNotify.pm')

diff --git a/lib/PublicInbox/KQNotify.pm b/lib/PublicInbox/KQNotify.pm
index 110594cc..9673b442 100644
--- a/lib/PublicInbox/KQNotify.pm
+++ b/lib/PublicInbox/KQNotify.pm
@@ -7,6 +7,11 @@ package PublicInbox::KQNotify;
 use strict;
 use IO::KQueue;
 use PublicInbox::DSKQXS; # wraps IO::KQueue for fork-safe DESTROY
+use PublicInbox::FakeInotify;
+use Time::HiRes qw(stat);
+
+# NOTE_EXTEND detects rename(2), NOTE_WRITE detects link(2)
+sub MOVED_TO_OR_CREATE () { NOTE_EXTEND|NOTE_WRITE }
 
 sub new {
 	my ($class) = @_;
@@ -15,19 +20,28 @@ sub new {
 
 sub watch {
 	my ($self, $path, $mask, $cb) = @_;
-	open(my $fh, '<', $path) or return;
+	my ($fh, $cls, @extra);
+	if (-d $path) {
+		opendir($fh, $path) or return;
+		my @st = stat($fh);
+		@extra = ($path, $st[10]); # 10: ctime
+		$cls = 'PublicInbox::KQNotify::Watchdir';
+	} else {
+		open($fh, '<', $path) or return;
+		$cls = 'PublicInbox::KQNotify::Watch';
+	}
 	my $ident = fileno($fh);
 	$self->{dskq}->{kq}->EV_SET($ident, # ident
 		EVFILT_VNODE, # filter
 		EV_ADD | EV_CLEAR, # flags
 		$mask, # fflags
 		0, 0); # data, udata
-	if ($mask == NOTE_WRITE) {
-		$self->{watch}->{$ident} = [ $fh, $cb ];
+	if ($mask == NOTE_WRITE || $mask == MOVED_TO_OR_CREATE) {
+		$self->{watch}->{$ident} = [ $fh, $cb, @extra ];
 	} else {
 		die "TODO Not implemented: $mask";
 	}
-	bless \$fh, 'PublicInbox::KQNotify::Watch';
+	bless \$fh, $cls;
 }
 
 # emulate Linux::Inotify::fileno
@@ -48,8 +62,15 @@ sub poll {
 	for my $kev (@kevents) {
 		my $ident = $kev->[KQ_IDENT];
 		my $mask = $kev->[KQ_FFLAGS];
-		if (($mask & NOTE_WRITE) == NOTE_WRITE) {
-			eval { $self->{watch}->{$ident}->[1]->() };
+		my ($dh, $cb, $path, $old_ctime) = @{$self->{watch}->{$ident}};
+		if (!defined($path) && ($mask & NOTE_WRITE) == NOTE_WRITE) {
+			eval { $cb->() };
+		} elsif ($mask & MOVED_TO_OR_CREATE) {
+			my @new_st = stat($path) or next;
+			$self->{watch}->{$ident}->[3] = $new_st[10]; # ctime
+			rewinddir($dh);
+			PublicInbox::FakeInotify::on_new_files($dh, $cb,
+							$path, $old_ctime);
 		}
 	}
 }
@@ -59,4 +80,9 @@ use strict;
 
 sub cancel { close ${$_[0]} or die "close: $!" }
 
+package PublicInbox::KQNotify::Watchdir;
+use strict;
+
+sub cancel { closedir ${$_[0]} or die "closedir: $!" }
+
 1;
-- 
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