From 4e6ba5229e3f079087d9965caf2a35ee277e5cbc Mon Sep 17 00:00:00 2001
From: Ilia Ross <ilia@ross.gdn>
Date: Fri, 28 Aug 2026 02:46:40 +0200
Subject: [PATCH] Fix binary log retention limit on MariaDB

---
 mysql/help/binlogs.html         | 11 ++++++-----
 mysql/help/binlogs_expire.html  |  5 +++++
 mysql/help/binlogs_maxsize.html |  2 +-
 mysql/mysql-lib.pl              | 11 +++++++++++
 mysql/save_binlogs.cgi          |  8 +++++---
 t/mysql-lib.t                   | 15 +++++++++++++++
 6 files changed, 43 insertions(+), 9 deletions(-)

diff --git a/mysql/help/binlogs.html b/mysql/help/binlogs.html
index 265ae6044..73d2adf9e 100644
--- a/mysql/help/binlogs.html
+++ b/mysql/help/binlogs.html
@@ -8,11 +8,12 @@ point-in-time recovery of backups. <p>
 When binary logging is enabled, log files are written under the configured
 base name and grow as changes are made. To stop them from filling up the disk,
 a retention period can be set after which old logs are automatically deleted,
-or old logs can be deleted immediately using the form at the bottom of the
-page. <p>
+or old logs can be deleted immediately on the <b>Delete Logs</b> tab. The
+button at the bottom of the page closes the current log and starts a new one,
+giving backups and log deletion a clean boundary. <p>
 
-For any changes on this page to take effect, the MySQL server must be
-re-started, either with the <b>Save and Restart MySQL</b> button or using the
-buttons on the module's main page. <p>
+Configuration changes only take effect once the MySQL server is re-started,
+either with the <b>Save and Restart MySQL</b> button or using the buttons on
+the module's main page. Deleting and rotating logs happen immediately. <p>
 
 <footer>
diff --git a/mysql/help/binlogs_expire.html b/mysql/help/binlogs_expire.html
index a2b8b4790..b0ccbc984 100644
--- a/mysql/help/binlogs_expire.html
+++ b/mysql/help/binlogs_expire.html
@@ -5,3 +5,8 @@ them automatically. Without a limit, logs will grow until they fill up the
 disk. For point-in-time recovery the retention period must be at least as long
 as the interval between full backups, so that all transactions since the last
 backup remain available for replay.</p>
+
+<p>A value of <tt>0</tt> disables automatic deletion entirely. Fractions of a
+day like <tt>0.5</tt> are supported on MySQL 8 and MariaDB 10.6 or later.
+MariaDB always limits retention to 99 days, while MySQL 8 accepts up to
+49710 days.</p>
diff --git a/mysql/help/binlogs_maxsize.html b/mysql/help/binlogs_maxsize.html
index ab2ec8d55..059462c51 100644
--- a/mysql/help/binlogs_maxsize.html
+++ b/mysql/help/binlogs_maxsize.html
@@ -3,4 +3,4 @@
 <p>When a binary log file reaches this size, the server closes it and starts
 writing a new one. Smaller files make deleting old logs and point-in-time
 recovery more granular, at the cost of more files. The server accepts sizes
-between 4 kB and 1 GB, which is also the default.</p>
+between 4 kB and 1 GB, and defaults to the 1 GB maximum.</p>
diff --git a/mysql/mysql-lib.pl b/mysql/mysql-lib.pl
index c013a0572..3c29f7420 100755
--- a/mysql/mysql-lib.pl
+++ b/mysql/mysql-lib.pl
@@ -1288,6 +1288,17 @@ my ($days) = @_;
 return int($days * 86400 + 0.5);
 }
 
+# get_binlog_expire_max([variant])
+# Returns the maximum retention in seconds that this or the given database
+# variant accepts, which is 99 days on MariaDB but the full 32-bit range
+# on MySQL
+sub get_binlog_expire_max
+{
+my ($variant) = @_;
+($variant) = (&get_mysql_variant_cached())[1] if (!$variant);
+return $variant eq "mariadb" ? 8553600 : 4294967295;
+}
+
 # get_mysql_variant_cached()
 # Like get_remote_mysql_variant, but falls back to the version detected at
 # module setup time when the server cannot be queried, such as when it is
diff --git a/mysql/save_binlogs.cgi b/mysql/save_binlogs.cgi
index 794f37d36..cea2a1703 100755
--- a/mysql/save_binlogs.cgi
+++ b/mysql/save_binlogs.cgi
@@ -123,11 +123,13 @@ else {
 		&error($text{'binlogs_eexpire'});
 	my $days = $in{'expire'} + 0;
 	if ($newexpire) {
-		# The seconds variable is limited to 32 bits
+		# The seconds variable is limited to 99 days on MariaDB, and
+		# to 32 bits on MySQL
 		my $secs = &parse_binlog_expire_days($days);
-		$secs <= 4294967295 ||
+		my $max = &get_binlog_expire_max($variant);
+		$secs <= $max ||
 			&error(&text('binlogs_eexpiremax',
-				&format_binlog_expire_days(4294967295)));
+				&format_binlog_expire_days($max)));
 		&save_directive($conf, $mysqld, "expire_logs_days", [ ]);
 		&save_directive($conf, $mysqld, "binlog_expire_logs_seconds",
 				[ $secs ]);
diff --git a/t/mysql-lib.t b/t/mysql-lib.t
index d77e3544e..025d6bce4 100644
--- a/t/mysql-lib.t
+++ b/t/mysql-lib.t
@@ -138,4 +138,19 @@ subtest 'binary log retention limit covers the full 32-bit range' => sub {
 	   'whole days below the maximum stay within the limit');
 };
 
+subtest 'retention maximum is variant specific' => sub {
+	is(main::get_binlog_expire_max('mysql'), 4294967295,
+	   'MySQL accepts the full 32-bit seconds range');
+	is(main::get_binlog_expire_max('mariadb'), 8553600,
+	   'MariaDB is limited to 99 days of seconds');
+	is(main::parse_binlog_expire_days(99),
+	   main::get_binlog_expire_max('mariadb'),
+	   'exactly 99 days is accepted on MariaDB');
+	cmp_ok(main::parse_binlog_expire_days('99.000012'), '>',
+	   main::get_binlog_expire_max('mariadb'),
+	   'just over 99 days exceeds the MariaDB limit');
+	is(main::format_binlog_expire_days(8553600), '99',
+	   'the MariaDB maximum displays as 99 days');
+};
+
 done_testing();