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0 pointsrwmj9y ago0 comments

You missed:

- Unix xattrs have a terrible API and awful command line tools: listxattr(2) returning \0-separated character arrays with lists of attributes that are next to impossible to decipher in C? - check! Hiding certain xattrs by default based only on their names? - check!

- xattrs have magical qualities based on their names, the kernel version, the kernel configuration, and the filesystem mount options (eg. "security.selinux", "trusted.*")

- Some xattrs are \0 terminated (and the APIs set and return the \0 making them very awkward to use from shell scripts), some don't, and some are indeterminate. They can also be binary blobs.

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3 comments · 2 top-level

nailer9y ago· 1 in thread

Is \0 ASCII null?

rwmjOP9y ago

Yes. For more details see http://man7.org/linux/man-pages/man2/listxattr.2.html

ivank9y ago

Also, add too many xattrs and you can no longer get a list of them:

       As noted in xattr(7), the VFS imposes a limit of 64 kB on the size of
       the extended attribute name list returned by listxattr(7).  If the
       total size of attribute names attached to a file exceeds this limit,
       it is no longer possible to retrieve the list of attribute names.

http://man7.org/linux/man-pages/man2/listxattr.2.html

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