Utilities view has calculation errors when there are no data sources

[paulgevers]

Describe the bug

[Background / thanks]
I am in the process of packaging Cacti 1.2.19 and found that you adopted my CI test. Thanks for doing that.

[Issue]
I ran tests/tools/check_all_pages.sh (after minor tweaks for Debian specifics) on a fresh installed cacti in a fresh container and it fails with:

ERROR: Fail - Unexpected output in /usr/share/cacti/site/log/cacti.log:
2021-11-21 08:18:55 - ERROR PHP WARNING: Division by zero in file: /usr/share/cacti/site/utilities.php  on line: 2229
2021-11-21 08:18:55 - CMDPHP PHP ERROR WARNING Backtrace:  (/utilities.php[84]:boost_display_run_status(), /utilities.php[2229]:CactiErrorHandler())
2021-11-21 08:18:55 - ERROR PHP WARNING: Division by zero in file: /usr/share/cacti/site/utilities.php  on line: 2339
2021-11-21 08:18:55 - CMDPHP PHP ERROR WARNING Backtrace:  (/utilities.php[84]:boost_display_run_status(), /utilities.php[2339]:CactiErrorHandler())

As this is a fresh install, I'm not surprised that $data_sources is zero. However, utilities.php#L2229 and utilities.php#L2239 unilaterally divide by the value.

As this obviously is a weird situation (no data_sources at all) I'm not sure if you want to properly fix this, but it would make the test simpler (I now added the error to the list of ignored errors).

To Reproduce

Steps to reproduce the behavior:

1. On a fresh install without any data sources run tests/tools/check_all_pages.sh

Expected behavior

check_all_pages.sh should pass.

Desktop (please complete the following information)

• OS: Debian testing

• wget

• 1.21.2

[majed17]

i upgraded from php7 to 8, also this version of cacti, and applied the change mentioned here, but i am still getting:

-  CMDPHP PHP ERROR WARNING Backtrace:   (/cmd_realtime.php[201]:cacti_snmp_session_get(),  /lib/snmp.php[492]:SNMP->get(), CactiErrorHandler())
--
2021/11/29 16:12:55 - ERROR PHP WARNING: SNMP::get(): Fatal error:  USM generic error in file: /usr/share/cacti/lib/snmp.php  on line: 492

[netniV]

@majed17 that should be logged as a separate issue. Whilst they are all PHP 8 related, it is easier to track them individually. The USM generic may be something out of our hands though if it's in the core PHP libraries, all we would do is trap the error. There is a change we made to suppress PHP errors around SNMP-GET for that reason though I'm not sure if that's in 1.2.19 or not without searching.