Add support to switching back to MySQL

https://github.com/virtualmin/virtualmin-gpl/issues/968#issuecomment-2496441791

mysql/postinstall.pl

@@ -8,4 +8,93 @@ if ($mysql_version && $mysql_version >= 0) {
 	&save_mysql_version($mysql_version);
 	&create_module_info_overrides();
 	}
+
+# Check if we have to use a new MariaDB commands
+my ($mversion, $mvariant) = &get_remote_mysql_variant();
+if (!$config{'mysql_postinstall_config_updated'} &&
+    $config{'mysql_postinstall_config_updated'} !~ /\Q$mvariant\E/i) {
+	if ($mvariant =~ /mariadb/i) {
+		# Switch config to use MariaDB commands
+		if (&compare_version_numbers($mversion, "10.5") > 0) {
+			my $config_updated;
+			foreach my $key (grep { /^mysql(?!_)/ } keys %config) {
+				my $cmd = $config{$key};
+				next if ($cmd !~ /^\//);
+				# Check if symlink
+				if (-l $cmd) {
+					my $target = readlink($cmd);
+					my $dir = $cmd =~ s|/[^/]+$||r;
+					if ($target =~ /^mariadb/i) {
+						# Update config if symlinked
+						# to mariadb
+						$config{$key} = "$dir/$target";
+						$config_updated++;
+						}
+					}
+				# If command doesn't exist, try mariadb version
+				else {
+					my $mariadb_cmd = $cmd;
+					$mariadb_cmd =~ s/mysql(\w+)/mariadb-$1/;
+					if (&has_command($mariadb_cmd)) {
+						$config{$key} = $mariadb_cmd;
+						$config_updated++;
+						}
+					}
+				}
+			if ($config_updated) {
+				# Update start stop commands
+				foreach my $key ('start_cmd', 'stop_cmd') {
+					next if ($config{$key} !~ /systemctl/);
+					$config{$key} =~
+						s/mysql(?:\.service)?$/mariadb/;
+					}
+				# Update config file
+				$config{'mysql_postinstall_config_updated'} =
+					"$mvariant=$mversion";
+				&save_module_config();
+				}
+			}
+		}
+	elsif ($mvariant =~ /mysql/i) {
+		# Switch config to use MySQL commands
+		my $config_updated;
+		foreach my $key (grep { /^mysql(?!_)/ } keys %config) {
+			my $cmd = $config{$key};
+			next if ($cmd !~ /^\//);
+	
+			# Check if symlink
+			if (-l $cmd) {
+				my $target = readlink($cmd);
+				my $dir = $cmd =~ s|/[^/]+$||r;
+				if ($target =~ /^mysql/i) {
+					# Update config if symlinked
+					# to mysql
+					$config{$key} = "$dir/$target";
+					$config_updated++;
+					}
+				}
+			# If command doesn't exist, try mysql version
+			else {
+				my $mysql_cmd = $cmd;
+				$mysql_cmd =~ s/mariadb-(\w+)/mysql$1/;
+				if (&has_command($mysql_cmd)) {
+					$config{$key} = $mysql_cmd;
+					$config_updated++;
+					}
+				}
+			}
+	
+		if ($config_updated) {
+			# Update start stop commands
+			foreach my $key ('start_cmd', 'stop_cmd') {
+				next if ($config{$key} !~ /systemctl/);
+				$config{$key} =~ s/mariadb(?:\.service)?$/mysql/;
+				}
+			# Update config file
+			$config{'mysql_postinstall_config_updated'} =
+				"$mvariant=$mversion";
+			&save_module_config();
+			}
+		}
+	}
 }