On Tue, 25 Mar 2025 at 17:19, Thomas Wolff <t...@towo.net> wrote: > > [oops, used wrong Reply function] > > Am 24.03.2025 um 21:58 schrieb Corinna Vinschen: > > On Mar 24 21:42, Thomas Wolff wrote: > >> > >> Am 24.03.2025 um 17:08 schrieb Jeffrey Altman: > >>> On 3/24/2025 10:25 AM, Martin Wege via Cygwin wrote: > >>>> Hello, > >>>> > >>>> another wishlist entry (old one): > >>>> read/write NTFS alternate data streams via openat(O_XATTR) > >>> From my perspective as a filesystem developer, Extended Attributes and > >>> Alternate Data Streams are different concepts which I believe are > >>> inappropriate to mix. > >>> > >>> Filesystems can implement one, the other, both or neither. > >>> > >>> An Extended Attribute is a name:value pair that can be attached to an > >>> inode. The size of individual values and the sum of the value sizes > >>> are often quite constrained because they are stored in the inode > >>> metadata. Copying an inode is guaranteed to copy the Extended Attributes. > >>> > >>> Alternate Data Streams are typically represented as independent > >>> inodes. The Alternate Data Stream namespace can be represented by a > >>> directory inode referenced from the file inode. Each ADS inode might > >>> have their own Extended Attributes to go along with the data stream. > >>> ACLs on ADS inodes can also be independent of the ACL on the primary > >>> inode depending upon the implementation. > >>> > >>> Therefore, I am reluctant to see openat(O_XATTR) be used to access > >>> alternate data streams. > >>> > >>> Jeffrey Altman > >> Why not use the Windows syntax? > >> cat file.txt:ads.txt > >> etc. (Was this discussed before?) > >> Thomas > > The colon is a valid filename character in Cygwin, it will be converted > > to the UNICODE private use area: > > https://cygwin.com/cygwin-ug-net/using-specialnames.html#pathnames-specialchars > > > > Therefore you can't use the colon to specify streams. > > > > > > Corinna > OK, so what about a slash? Handling the base file like a directory for > access and listing...
ResierFS tried that, and Linus Torvalds personally crushed John Reiser for that. bash has cd -@ dir and cd -@ file to go into a virtual O_XATTR dir, UNIX has /bin/runat to do the same Lionel
