Undefined variable errors may occur when creating a new datasource

[paulgevers]

Describe the bug

As you probably remember, I am running a web crawl in the Debian test framework for the Cacti package. I uploaded Cacti to Debian unstable yesterday, but the test framework shows regressions for all architectures the test is run on: https://qa.debian.org/excuses.php?package=cacti

To Reproduce

Steps to reproduce the behavior:

1. Install a fresh cacti instance

2. Go to 'http://localhost/cacti/data_queries.php?action=edit'

3. Look into the cacti.log file

4. See

2020/11/04 21:19:19 - ERROR PHP NOTICE: Undefined variable: snmp_query in file: /usr/share/cacti/site/data_queries.php  on line: 1194
2020/11/04 21:19:19 - CMDPHP PHP ERROR NOTICE Backtrace:  (/data_queries.php[100]:data_query_edit(), /data_queries.php[1194]:CactiErrorHandler())
2020/11/04 21:19:19 - ERROR PHP NOTICE: Trying to access array offset on value of type null in file: /usr/share/cacti/site/data_queries.php  on line: 1194
2020/11/04 21:19:19 - CMDPHP PHP ERROR NOTICE Backtrace:  (/data_queries.php[100]:data_query_edit(), /data_queries.php[1194]:CactiErrorHandler())
2020/11/04 21:19:19 - ERROR PHP NOTICE: Undefined variable: snmp_query_graph in file: /usr/share/cacti/site/data_queries.php  on line: 1195
2020/11/04 21:19:19 - CMDPHP PHP ERROR NOTICE Backtrace:  (/data_queries.php[100]:data_query_edit(), /data_queries.php[1195]:CactiErrorHandler())
2020/11/04 21:19:19 - ERROR PHP NOTICE: Trying to access array offset on value of type null in file: /usr/share/cacti/site/data_queries.php  on line: 1195
2020/11/04 21:19:19 - CMDPHP PHP ERROR NOTICE Backtrace:  (/data_queries.php[100]:data_query_edit(), /data_queries.php[1195]:CactiErrorHandler())
2020/11/04 21:19:19 - ERROR PHP NOTICE: Undefined variable: snmp_query in file: /usr/share/cacti/site/data_queries.php  on line: 1198
2020/11/04 21:19:19 - CMDPHP PHP ERROR NOTICE Backtrace:  (/data_queries.php[100]:data_query_edit(), /data_queries.php[1198]:CactiErrorHandler())
2020/11/04 21:19:19 - ERROR PHP NOTICE: Trying to access array offset on value of type null in file: /usr/share/cacti/site/data_queries.php  on line: 1198
2020/11/04 21:19:19 - CMDPHP PHP ERROR NOTICE Backtrace:  (/data_queries.php[100]:data_query_edit(), /data_queries.php[1198]:CactiErrorHandler())

Expected behavior

No new errors with respect to previous Cacti versions when recursively crawling the full Cacti website.

Desktop (please complete the following information)

• OS: Linux

• Browser: wget and Firefox-esr

Additional context

https://ci.debian.net/data/autopkgtest/testing/amd64/c/cacti/7954737/log.gz

[netniV]

Just to confirm, that is definitely against the 1.2.x branch correct ?

[paulgevers]

This is the released 1.2.15 tar ball.

[netniV]

OK, thanks I'll have a look shortly.

[netniV]

So this appears to be when creating a new data query, and it hasn't been saved yet. My simple fix would be to add

$snmp_query = array('id' => 0);

in the first if statement's else section but I am not sure yet if that would cause another issue.

[netniV]

diff --git a/data_queries.php b/data_queries.php
index 9d04e09eb..f584d5af5 100644
--- a/data_queries.php
+++ b/data_queries.php
@@ -1074,6 +1074,7 @@ function data_query_edit() {
                $header_label = __esc('Data Queries [edit: %s]', $snmp_query['name']);
        } else {
                $header_label = __('Data Queries [new]');
+               $snmp_query = array('id' => 0);
        }

        form_start('data_queries.php', 'data_queries');

This would be the diff, but I'm not sure it's the final solution yet

[TheWitness]

I've reviewed the bug and have resolved it. Thanks for being there @paulgevers!

[paulgevers]

@TheWitness thanks. Confirming the fix also fixes the issue in the Debian package.