Re: [TUHS] Who's behind the UNIX filesystem permission implementation

The "useful layer of indirection" story carries the seeds of its own problem, if you consider xattr on files. They always prove harder to deal with, lie in cat -v extended options, cannot be invoked without bigger wetware cache memory than I hold, which requires a retreat to the man page, and crop up at the worst possible times, such as when you are doing buildworld installworld sequences, they blow up, and you have xattr locked files with setuid bit littering the FS tree. chmod can't do them with octal bit settings or they lie in octal spaces I don't understand further up from 777 Necessary but evil. What I like about user/group/other is that the group memberships list is independent, but maps into the tested space in the flags for chmod. If I want to grant somebody permission in group sense, I make sure we share a group and I arrange for the group to be set. If I cannot make the dir be group the same, I use --x permissions on other to give them transitive rights down into the file. It would be possible to argue creat(e) was a distinct permission from write. I think I heard Dennis say he regretted some aspects of the model around "is write the same as create" at an AUUG once, (I mean more than just his joke about calling it creat() not create() -he actually said there were arguments both sides to breaking out more modes of behaviour on things, and modifying the contents of a created named entity is not the same as naming it) And Microslop and xattr and I think VMS do indeed go to the "I can make things as well as change things" place. So yes, write permissions on the directory are the "proper" place to say "you can make things" but then you're in an indirection: the dir block is not the file, the file name is in the dir block, oh dear, so maybe we mean we want Apples resource fork and the data fork, a model I could never understand? No please.. but.. then again.. Oh dear. Its just a projection into a UNIX FS to make this a file and a .attr file, thats not how Apple "Ideated" it, but still. All designs come with costs. I guess if you like apple pie, you can dream about peaches, but peaches aren't apples. On Thu, Aug 1, 2019 at 8:36 AM William Corcoran <wlc(a)jctaylor.com> wrote: