Hi, On 2022-02-09 16:42:30 -0600, Justin Pryzby wrote: > On Wed, Feb 09, 2022 at 02:00:04PM -0800, Andres Freund wrote: > > On linux we can do so by a) checking if readlink(/proc/self/fd/$fd) points > > to > > a filename ending in " (deleted)", b) doing fstat(fd) and checking if > > st_nlink > > == 0. > > You could also stat() the file in proc/self/fd/N and compare st_ino. It > "looks" like a symlink (in which case that wouldn't work) but it's actually a > Very Special File. You can even recover deleted, still-opened files that > way..
Yea, the readlink() thing above relies on it being a /proc/self/fd/$fd being a "Very Special File". In most places we'd not have convenient access to a inode / filename to compare it to. I don't think there's any additional information we could gain anyway, compared to looking at st_nlink == 0 and then doing a readlink() to get the filename? > PS. I didn't know pg_upgrade knew about Reply-To ;) Ugh, formatting fail... Greetings, Andres Freund