On Thu, 11 Jan 2024 at 17:41, Corinna Vinschen via Cygwin <cygwin@cygwin.com> wrote: > > On Jan 11 15:00, Martin Wege via Cygwin wrote: > > On Mon, Jan 8, 2024 at 3:11 PM Corinna Vinschen via Cygwin > > <cygwin@cygwin.com> wrote: > > so this is IMO OK. > > Yeah, but... > > It's not just an open flag, it requires extending functionality of other > APIs and, for full support, tools, see > https://docs.oracle.com/cd/E19253-01/816-5175/6mbba7f02/. > > It's also rather weird to call alternate data streams "extended > attributes", because that's just a small part of streams and it's > already supported via the Linux functions getxattr(2) and friends, see > https://man7.org/linux/man-pages/man2/getxattr.2.html > > > > Apart from that, this sounds like a nice idea for Cygwin 3.6, > > > provided somebody implements it, https://cygwin.com/acronyms/#SHTDI > > > > > > Assuming we can live without actually having a subdir and just > > > allowing to open and create a file with the O_XATTR flag, it might be > > > pretty simple to implement. The path handling code would just have to > > > drop the colon from the list of characters converted to the private-use > > > Unicode area. > > > > > > Implementing the subdir is a bit more complicated, especially when > > > taking opendir/readdir of that virtual subdir into account, but it > > > would certainly be doable. > > > > How do other OSes implement the O_XATTR subdir? > > IDK. But there are a few points we have to keep in mind from the > Solaris man page: > > - Given fd is an open file descriptor, > > openat(fd, ".", O_RDONLY|O_XATTR); > > opens the virtual subdir containing the ADS of a file. It's the > only valid way to open the virtual dir. That's a bit of a relief > because it simplifies handling this in openat(2). > > openat(fd, "foo", ...|O_XATTR); > > allows to create or open an ADS for an open file fd. > > - unlinkat, renameat, fstatat, fchownat, futimesat and fdopendir need to > be made ADS-aware. They only work on ADS if the fd arg already > resolves to an ADS, or if fd is the virtual ADS dir of a file and > (except in case of fdopendir) the path argument is the name of an > existing ADS. > > - pathconf needs to support a new flag XATTR_ENABLED. > > This can be made to work given the current fhandler framework in Cygwin, > but again, https://cygwin.com/acronyms/#SHTDI
bash has cd -@ to enter a virtual dir with XATTRs, if O_XATTR works. Aside from that, I volunteer with testing of O_XATTR, on demand with 1 or 2 students too. Still working on testing the cool and new SEEK_HOLE support in Cygwin Ced -- Cedric Blancher <cedric.blanc...@gmail.com> [https://plus.google.com/u/0/+CedricBlancher/] Institute Pasteur -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
