_edit_lock timestamp does not update on autosave() of non-changed, non-draft posts

[benbalter]

Admin_ajax does not properly update the _edit_lock timestamp in posts when:

1. The post->post_status != draft, and
2. The content of the post has not changed since the last autosave ping

STR:

1. Open up a post, page, or CPT that's either private or published
2. (wait 2 minutes or 2x your autosave ping, don't make any changes to the content)
3. Log in as another user and navigate to the post
4. User # 2 now has the file lock because User # 1's timestamp has expired

The Problem:

Lines 282 - 283 of autosave.dev.js (trunk) only POSTs auto_draft if it is "1".

Lines 985 - 992 expect non-auto_draft autosaves to post auto_draft as != 1.

Possibly Helpful for Background: r12991

So three possible scenarios:

1. Initial autodraft, auto_draft is posted as 1, line 992 updates _edit_post
2. Post content has changed, it's a true autosave, so _edit_lock gets update through edit_post()
3. Post content has not changed, it's not an autodraft, so auto_draft is not POSTed, and the lock is never updated.

Auto_draft will always either be 1 (and thus ID ='s 0) or not POST'd at all. Admin Ajax erroneously assumes it will be posted as != 1 when not an autodraft.

Proposed Fix:

If auto_draft is not set, update post lock. (patch attached).

Alternatively, could patch autosave.js to pass auto_draft of 0 on every non-auto_draft call.

(tested against trunk)

proposed non-autosave edit_lock patch

Typo fix on behalf of Ben.

This would greatly increase the number of times a post is found that is locked. (And rightfully so.) But therefore needs to be considered with #18515.

I believe this occurs even when post content is changed (and it's not a draft) as edit_post() only occurs on autosave for changed (auto-)drafts, see admin-ajax.php line 972 - 984. The content changing only affects whether or not a revision gets written to the DB.

So I think the situations are:

1. It's a changed (auto-)draft and is overwritten by edit_post() which updates the post lock
2. Otherwise, the post lock isn't updated as isset( $_POST['auto_draft'] ) && ( $_POST['auto_draft'] != '1' is never true.

i.e. _edit_lock is not updated when not draft or not changed.

Verified by editing a post, adding to the content, waiting for the autosave to occur and then checking that the value in the database hasn't changed.

Anyway it's the same fix. Good catch.

That makes more sense.

It appears the bigger problem, then, is that all non-draft posts only remain locked for the first 2 minutes by default (2x Autosave + filters).

In [18709]:

Fix issue where post locks were not updating on autosaves. props benbalter, fixes #18642. see #18515 for more on locking. broken in [12991], see #11889.