Add separate serials flag file for flock in gatekeeper

The flag file is zero-length and simply exists as a place to use flock.
This will eventually allow maintaining a lock while rewriting the serials
file using the traditional copy-and-rename method.

diff --git a/gatekeeper.pl b/gatekeeper.pl
index c32e34a38755f69db49b557de37339dab1180b3d..f69470d2340ffac812aa67b6af037e8a659b87bc 100755 (executable)
--- a/gatekeeper.pl
+++ b/gatekeeper.pl
@@ -2437,6 +2437,12 @@ sub advance_timestamp_ratchet {
   my $new_epoch = shift;
 
   my $serials_path = File::Spec->catfile(CONF_DIR_State, 'serials');
+  my $serials_flag_name = File::Spec->catfile(CONF_DIR_State, 'serials.flag');
+
+  open my $serials_flag, '>', $serials_flag_name
+    or die "open serials flag: $!";
+  flock $serials_flag, LOCK_EX
+    or die "lock serials flag: $!";
 
   # Now we need to flock the our 'serials' file;
   # verify the epoch value there/update it, etc.
@@ -2476,6 +2482,8 @@ sub advance_timestamp_ratchet {
 
   flock(SERIALS,4);            # Release lock
   close(SERIALS);
+  flock $serials_flag, LOCK_UN or die "unlock serials flag: $!";
+  close $serials_flag          or die "close serials flag: $!";
 
   return $old_epoch;
 }