www: _/text/config/raw Last-Modified: is mm->created_at

This allows IMAP mirrors to keep UIDVALIDITY synchronized (and
"LIST ACTIVE.TIMES" in NNTP).  "lei add-external --mirror" will
automatically set it, as will the combination of
public-inbox-clone + public-inbox-index.

This avoids the need for extra endpoints or config entries,
at least...

3 files changed, 18 insertions, 7 deletions

diff --git a/lib/PublicInbox/LeiMirror.pm b/lib/PublicInbox/LeiMirror.pm
index 5cfa6fea..4be8f70a 100644
--- a/lib/PublicInbox/LeiMirror.pm
+++ b/lib/PublicInbox/LeiMirror.pm
@@ -96,15 +96,15 @@ sub _get_txt { # non-fatal
         my $path = $uri->path;
         chop($path) eq '/' or die "BUG: $uri not canonicalized";
         $uri->path("$path/$endpoint");
-        my $cmd = $self->{curl}->for_uri($lei, $uri, '--compressed');
-        my $ce = "$self->{dst}/$file";
-        my $ft = File::Temp->new(TEMPLATE => "$file-XXXX",
-                                UNLINK => 1, DIR => $self->{dst});
-        my $opt = { 0 => $lei->{0}, 1 => $ft, 2 => $lei->{2} };
+        my $ft = File::Temp->new(TEMPLATE => "$file-XXXX", DIR => $self->{dst});
+        my $f = $ft->filename;
+        my $opt = { 0 => $lei->{0}, 1 => $lei->{1}, 2 => $lei->{2} };
+        my $cmd = $self->{curl}->for_uri($lei, $uri,
+                                        qw(--compressed -R -o), $f);
         my $cerr = run_reap($lei, $cmd, $opt);
         return "$uri missing" if ($cerr >> 8) == 22;
         return "# @$cmd failed (non-fatal)" if $cerr;
-        my $f = $ft->filename;
+        my $ce = "$self->{dst}/$file";
         rename($f, $ce) or return "rename($f, $ce): $! (non-fatal)";
         $ft->unlink_on_destroy(0);
         undef; # success
@@ -122,6 +122,7 @@ sub _try_config {
         my $err = _get_txt($self, qw(_/text/config/raw inbox.config.example));
         return $self->{lei}->err($err) if $err;
         my $f = "$self->{dst}/inbox.config.example";
+        chmod((stat($f))[2] & 0444, $f) or die "chmod(a-w, $f): $!";
         my $cfg = PublicInbox::Config->git_config_dump($f, $self->{lei}->{2});
         my $ibx = $self->{ibx} = {};
         for my $sec (grep(/\Apublicinbox\./, @{$cfg->{-section_order}})) {
diff --git a/lib/PublicInbox/Msgmap.pm b/lib/PublicInbox/Msgmap.pm
index 94a0cbeb..e71f16f8 100644
--- a/lib/PublicInbox/Msgmap.pm
+++ b/lib/PublicInbox/Msgmap.pm
@@ -32,8 +32,15 @@ sub new_file {
         if ($rw) {
                 $dbh->begin_work;
                 create_tables($dbh);
-                $self->created_at(time) unless $self->created_at;
+                unless ($self->created_at) {
+                        my $t;
 
+                        if (blessed($ibx) &&
+                                -f "$ibx->{inboxdir}/inbox.config.example") {
+                                $t = (stat(_))[9]; # mtime set by "curl -R"
+                        }
+                        $self->created_at($t // time);
+                }
                 $self->num_highwater(max($self));
                 $dbh->commit;
         }
diff --git a/lib/PublicInbox/WwwText.pm b/lib/PublicInbox/WwwText.pm
index bb9a0a0f..8b929f74 100644
--- a/lib/PublicInbox/WwwText.pm
+++ b/lib/PublicInbox/WwwText.pm
@@ -8,6 +8,7 @@ use v5.10.1;
 use PublicInbox::Linkify;
 use PublicInbox::WwwStream;
 use PublicInbox::Hval qw(ascii_html prurl);
+use HTTP::Date qw(time2str);
 use URI::Escape qw(uri_escape_utf8);
 use PublicInbox::GzipFilter qw(gzf_maybe);
 our $QP_URL = 'https://xapian.org/docs/queryparser.html';
@@ -171,6 +172,8 @@ sub inbox_config ($$$) {
         my ($ctx, $hdr, $txt) = @_;
         my $ibx = $ctx->{ibx};
         push @$hdr, 'Content-Disposition', 'inline; filename=inbox.config';
+        my $t = eval { $ibx->mm->created_at };
+        push(@$hdr, 'Last-Modified', time2str($t)) if $t;
         my $name = dq_escape($ibx->{name});
         my $inboxdir = '/path/to/top-level-inbox';
         my $base_url = $ibx->base_url($ctx->{env});