* Al Viro: > On Wed, Feb 12, 2020 at 08:15:08PM +0100, Florian Weimer wrote: > >> | Further, I've found some inconsistent behavior with ext4: chmod on the >> | magic symlink fails with EOPNOTSUPP as in Florian's test, but fchmod >> | on the O_PATH fd succeeds and changes the symlink mode. This is with >> | 5.4. Cany anyone else confirm this? Is it a problem? >> >> It looks broken to me because fchmod (as an inode-changing operation) >> is not supposed to work on O_PATH descriptors. > > Why? O_PATH does have an associated inode just fine; where does > that "not supposed to" come from? It fails on most file systems right now. I thought that was expected. Other system calls (fsetxattr IIRC) do not work on O_PATH descriptors, either. I assumed that an O_PATH descriptor was not intending to confer that capability. Even openat fails. Although fchmod does succeed on read-only descriptors, which is a bit strange.
