Use a random name when creating intermediate tmp archive for teleporter backup

[yubiuser]

• What does this PR aim to accomplish?:

Fixes an issue reported here:
https://discourse.pi-hole.net/t/fatal-php-error-with-teleporter/56264/

The user created teleporter backups via cron. The script was running under /tmp. During the backup creation, PHP compresses the data and creates a temporary copy within /tmp with the same filename as the backup. This leads to

PHP Fatal error: Uncaught BadMethodCallException: phar "/tmp/pi-hole-pihole-wf-inside-teleporter_2022-06-30_11-21-35.tar.gz" exists and must be unlinked prior to conversion in /var/www/html/admin/scripts/pi-hole/php/teleporter.php:634 Stack trace: #0 /var/www/html/admin/scripts/pi-hole/php/teleporter.php(634): PharData->compress() #1 {main} thrown in /var/www/html/admin/scripts/pi-hole/php/teleporter.php on line 634

• How does this PR accomplish the above?:

Use a random name when creating intermediate tmp archive for teleporter backup with tempnam(sys_get_temp_dir())

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[dschaper]

Can you use mktemp and not have to worry about changing modes and owners?

[yubiuser]

Do not merge atm. I'll see if I can get this working with tempnam()

[yubiuser]

Using tempnam() now.

rockpi@rockpi-4b:/tmp$ pihole -a -t
rockpi@rockpi-4b:/tmp$ pihole -a -t
rockpi@rockpi-4b:/tmp$ pihole -a -t
rockpi@rockpi-4b:/tmp$ ls -la
....
-rw-r--r--  1 root   root   6045 Jul  3 23:26 pi-hole-rockpi-4b-teleporter_2022-07-03_23-26-22.tar.gz
-rw-r--r--  1 root   root   6045 Jul  3 23:26 pi-hole-rockpi-4b-teleporter_2022-07-03_23-26-23.tar.gz
-rw-r--r--  1 root   root   6047 Jul  3 23:26 pi-hole-rockpi-4b-teleporter_2022-07-03_23-26-24.tar.gz

No issues occurred.

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/pi-hole-ftl-v5-16-web-v5-13-and-core-v5-11-1-released/56384/1