FileManagement: Hide the FEX RootFS fd from /proc/self/fd take 2 #4158
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Apparently Chromium/CEF can chroot or otherwise sandbox the filesystem away before forking and checking for directory FDs, making /proc inaccessible, which means we can't stat it for our inode check, breaking the hiding. So, double down on things and do what Chromium does: open an fd to /proc ahead of time, so that continues to work. Then we use it to update the inode of our RootFS fd instead, and finally, also do the /proc fd itself to hide that one too. We also don't need to check the st_dev of /proc more than once, since that's not expected to change anyway. Fixes cefsimple.
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Apparently Chromium/CEF can chroot or otherwise sandbox the filesystem away before forking and checking for directory FDs, making /proc inaccessible, which means we can't stat it for our inode check, breaking the hiding.
So, double down on things and do what Chromium does: open an fd to /proc ahead of time, so that continues to work. Then we use it to update the inode of our RootFS fd instead, and finally, also do the /proc fd itself to hide that one too.
We also don't need to check the st_dev of /proc more than once, since that's not expected to change anyway.
Fixes cefsimple.