Maybe the functionality changed over the years but the examples are wrong.
It does NOT return [subfolder] => ACL
At the moment (PHP5) the usage and answer of imap_getacl is the following:
You ask for the folder and get the ACLs for exactly this folder (no Wildcards)
Example:
When you have the folder Business in your mailbox
print_r(imap_getacl($connection , "user/john.doe/Business"));
returns the following:
Array
(
[john.doe@example.com] => lrswipkxtecda
[cyrus@example.com] => lrswipkxtecd
[secretary@example.com] => lrsp
[department@example.com] => lrs
)
Which means you have to loop over your directories (imap_list) and list the ACL for ever folder seperately.