Fix imapsync for large mailboxes

Where there is a lot of folders in a mailbox the output may be larger
than TEXT will allow (64KiB). Instead use MEDIUMTEXT (16MiB) which
should be ample.

Additionally check that a sync isn't already running before starting
a new one.

Fixes: #1011

data/Dockerfiles/dovecot/imapsync_cron.pl

@@ -33,7 +33,7 @@ open my $file, '<', "/etc/sogo/sieve.creds";
 my $creds = <$file>; 
 close $file;
 my ($master_user, $master_pass) = split /:/, $creds;
-my $sth = $dbh->prepare("SELECT id, user1, user2, host1, authmech1, password1, exclude, port1, enc1, delete2duplicates, maxage, subfolder2, delete1, delete2, automap, skipcrossduplicates, maxbytespersecond FROM imapsync WHERE active = 1 AND (UNIX_TIMESTAMP(NOW()) - UNIX_TIMESTAMP(last_run) > mins_interval * 60 OR last_run IS NULL) ORDER BY last_run");
+my $sth = $dbh->prepare("SELECT id, user1, user2, host1, authmech1, password1, exclude, port1, enc1, delete2duplicates, maxage, subfolder2, delete1, delete2, automap, skipcrossduplicates, maxbytespersecond FROM imapsync WHERE active = 1 AND is_running = 0 AND (UNIX_TIMESTAMP(NOW()) - UNIX_TIMESTAMP(last_run) > mins_interval * 60 OR last_run IS NULL) ORDER BY last_run");
 $sth->execute();
 my $row;
 

data/web/inc/init_db.inc.php

@@ -364,7 +364,7 @@ function init_db_schema() {
           "automap" => "TINYINT(1) NOT NULL DEFAULT '0'",
           "skipcrossduplicates" => "TINYINT(1) NOT NULL DEFAULT '0'",
           "is_running" => "TINYINT(1) NOT NULL DEFAULT '0'",
-          "returned_text" => "TEXT",
+          "returned_text" => "MEDIUMTEXT",
           "last_run" => "TIMESTAMP NULL DEFAULT NULL",
           "created" => "DATETIME(0) NOT NULL DEFAULT NOW(0)",
           "modified" => "DATETIME ON UPDATE CURRENT_TIMESTAMP",