My host machine is ArchLinux and I'm running Apache in a CentOS guest. I have the vhost configuration and all the site code in a shared folder. To be able to put the vhost configuration in a shared folder I mounted the shared folder as apache:apache.
shared /mnt/shared vboxsf defaults,uid=48,gid=48 0 0
When I'm editing files in the host, Apache will consistently start sending old versions of the file with trailing characters. In vim, they show up as ^@, so I guess they're null characters. The number of null characters is related to the number of changes I make even if I edit the first line, null characters show up at the end. If I were to speculate, it looks like a bad diff.
If I stop httpd, umount, remount, and start httpd the file looks fine. Just restarting httpd doesn't help.
How would I go about debugging the mount? Nothing jumped out at me in /var/log.