Improve compatibility for backtrace logging under PHP 8.x

[anarkia1976]

Hi @TheWitness ,

with the latest update i see these errors into cacti logs:

2023-08-24 11:40:34 - CMDPHP PHP ERROR Backtrace: (/plugins/syslog/syslog_process.php[198]:syslog_process_alerts(), /plugins/syslog/functions.php[1186]:syslog_process_alert(), /plugins/syslog/functions.php[1490]:syslog_sendemail(), /plugins/syslog/functions.php[116]:mailer(), /lib/functions.php[5090]:cacti_log(), /lib/functions.php[1365]:strpos(), CactiErrorHandler())
2023-08-24 11:40:34 - ERROR PHP DEPRECATED: strpos(): Passing null to parameter Cacti/plugin_syslog#1 ($haystack) of type string is deprecated in file: /var/www/html/cacti/lib/functions.php on line: 1365
2023-08-24 11:40:34 - CMDPHP PHP ERROR Backtrace: (/plugins/syslog/syslog_process.php[198]:syslog_process_alerts(), /plugins/syslog/functions.php[1186]:syslog_process_alert(), /plugins/syslog/functions.php[1490]:syslog_sendemail(), /plugins/syslog/functions.php[116]:mailer(), /lib/functions.php[5090]:cacti_log(), /lib/functions.php[1363]:strpos(), CactiErrorHandler())
2023-08-24 11:40:34 - ERROR PHP DEPRECATED: strpos(): Passing null to parameter Cacti/plugin_syslog#1 ($haystack) of type string is deprecated in file: /var/www/html/cacti/lib/functions.php on line: 1363
2023-08-24 11:40:34 - CMDPHP PHP ERROR Backtrace: (/plugins/syslog/syslog_process.php[198]:syslog_process_alerts(), /plugins/syslog/functions.php[1186]:syslog_process_alert(), /plugins/syslog/functions.php[1490]:syslog_sendemail(), /plugins/syslog/functions.php[116]:mailer(), /lib/functions.php[5090]:cacti_log(), /lib/functions.php[1361]:strpos(), CactiErrorHandler())
2023-08-24 11:40:34 - ERROR PHP DEPRECATED: strpos(): Passing null to parameter Cacti/plugin_syslog#1 ($haystack) of type string is deprecated in file: /var/www/html/cacti/lib/functions.php on line: 1361
2023-08-24 11:40:34 - CMDPHP PHP ERROR Backtrace: (/plugins/syslog/syslog_process.php[198]:syslog_process_alerts(), /plugins/syslog/functions.php[1186]:syslog_process_alert(), /plugins/syslog/functions.php[1490]:syslog_sendemail(), /plugins/syslog/functions.php[116]:mailer(), /lib/functions.php[5090]:cacti_log(), /lib/functions.php[1359]:strpos(), CactiErrorHandler())
2023-08-24 11:40:34 - ERROR PHP DEPRECATED: strpos(): Passing null to parameter Cacti/plugin_syslog#1 ($haystack) of type string is deprecated in file: /var/www/html/cacti/lib/functions.php on line: 1359
2023-08-24 11:40:34 - MAILER
2023-08-24 11:40:34 - CMDPHP WARNING Backtrace: (/plugins/syslog/syslog_process.php[198]:syslog_process_alerts(), /plugins/syslog/functions.php[1186]:syslog_process_alert(), /plugins/syslog/functions.php[1490]:syslog_sendemail(), /plugins/syslog/functions.php[116]:mailer(), /lib/functions.php[5090]:cacti_debug_backtrace())
2023-08-24 11:40:34 - MAILER WARNING: Mail failed via SMTP from 'example.monitoring <example.monitoring@example.it>', to 's.example@example.example.alert@example.it', cc '', bcc '', and took 1.07 seconds, Subject 'Event Alert - XXXXXX - HA - MEMBER DOWN - VIP', Error: SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting

cacti: latest 1.2.25
syslog: latest source
os: ubuntu22.04
php: PHP 8.1.2
mysql: 10.6.12-MariaDB

thanks a lot. stefano.

[TheWitness]

@anarkia1976, this is actually a Cacti issue associated with PHP8.x.

[TheWitness]

@anarkia1976, simple update to lib/functions.php.

[TheWitness]

@anarkia1976, validate ASAP. Since we are are technically in 1.2.25 freeze, confirmation via your closure that things are normal now is pretty important. CC @netniV just in case.

[TheWitness]

Thanks!