Site Health incorrectly reports low disk space available for updates when disk_free_space function disabled

[sdowney2002]

Beginning in 6.3.1, specifically with the change introduced in ticket #59116, Site Health incorrectly reports that "disk space is critically low" when the disk_free_space function is disabled by the web host.

Previously, in 6.3, Site Health correctly reported that it "could not determine available disk space" when the disk_free_space function was disabled.

[ironprogrammer]

Welcome to Trac, @sdowney2002, and thanks for the report!

Would you please share more information on the environment/configuration where this occurs? I was unable to reproduce the issue.

[ironprogrammer]

Reproduction Report

Steps to Test

Starting from WordPress 6.3:

1. In php.ini, disable disk_free_space() by adding the line: disable_functions = disk_free_space.
2. Restart the web server.
3. Navigate to Site Health, and expand the disk space security notice. Observe the message.
4. Upgrade to WordPress 6.3.1, then repeat Step 3.

Environment

• Hardware: MacBook Pro Apple M1 Pro
• OS: macOS 13.5.1
• Server: nginx/1.25.2
• PHP: 8.2.9
• WordPress: 6.3, 6.3.1, and 6.3.2-alpha-56487

Actual Results

• ❌ Before and after the 6.3->6.3.1 upgrade the notice indicates: "Could not determine available disk space for updates." Unable to reproduce.

Supplemental Artifacts

Figure 1: Disk space notice and after upgrade to 6.3.1.

[waterfire]

This seems to be an issue related to WPEngine having disabled disk_free_space

I'm also getting the same "Available disk space is critically low, less than 20 MB available. Proceed with caution, updates may fail." error as reported by @sdowney2002 in WordPress 6.4.

This is the environment:

• WordPress 6.4
• Server: Linux 5.4.0-1107-gcp x86_64
• PHP: 8.2.11 (Supports 64bit values)

​https://snipboard.io/Fbh30r.jpg