Greetings,
I have so many questions... ;)
But let's start with a few basic ones. I'm upgrading my backup and
recovery tools for Catalina and I find myself making assumptions about
firm links that I'd like confirm. Here are my burning questions:
(1) Are firm links and their target always the same relative path?
I've written a few "firm link exploration" tools and I find that
(thankfully!) the relative path of a firm link and its target are always
the same, with respect to their volumes. For example:
/Users -> /System/Volumes/Data/Users
/usr/share/snmp -> /System/Volumes/Data/usr/share/snmp
/System/Library/CoreServices/CoreTypes.bundle/Contents/Library ->
/System/Volumes/Data/System/Library/CoreServices/CoreTypes.bundle/Contents/Library
Said another way, is this a requirement of firm links or is this just a
Catalina convention? Is Apple reserving the right to create something
like this in a future version:
/usr/share/snmp -> /System/Volumes/Data/Library/Application
Support/Network/SNMP
(2) Are firm links always on the R/O volume?
In other words, are firm links only created on the R/O system volume and
always target something on its data volume? (I wrote some code to scan
for firm links and I can only find them on the R/O system volume, but I
wanted to ask.)
(3) Are firm links readable?
In the WWDC 2019 video "What's New in the Apple File Systems", firm
links are described as "a special kind of sym link". Are these readable?
I haven't found a new enum vtype defined (i.e. no new VFRMLNK), nor have
I discovered a firm link equivalent for O_NOFOLLOW or O_SYMLINK that
would allow one to open the contents of a firm link. Without these, it
would appear that firm links are opaque filesystem structures that
user-land apps cannot plumb.
This question is just idle curiosity; I don't currently have any real
need to read firm links.
Cheers,
James Bucanek
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Filesystem-dev mailing list (Filesystem-dev@lists.apple.com)
Help/Unsubscribe/Update your Subscription:
https://lists.apple.com/mailman/options/filesystem-dev/archive%40mail-archive.com
This email sent to arch...@mail-archive.com
