Usage of links can cause inconsistent/confusing diff after restore or changes

[nikop]

It doesn't matter whatever changes are done by hand or snapraid itself (during fix).
After fix operation, diff could still list many "removed" files, that were actually correctly restored.

Small test case:

Create test files:

$ echo "1234567890" > test1.txt
$ ln test1.txt test2.txt
$ ln test1.txt test3.txt
$ ln test1.txt test4.txt

Diff & Sync (this is right)

$ snapraid diff

add test/test1.txt
add test/test2.txt
add test/test3.txt
add test/test4.txt

$ snapraid sync

Let's make small change:

$ mv test1.txt test5.txt

$ snapraid diff

move test/test1.txt -> test/test2.txt
update test/test3.txt
update test/test4.txt
add test/test5.txt
remove test/test2.txt

Here we have one add and one removal, even though we only renamed a file (and two updates)
I think it should detect that test5 and test2 are the same file.

$ mv test5.txt test1.txt

$ snapraid diff

move test/test1.txt -> test/test2.txt
update test/test3.txt
update test/test4.txt
add test/test1.txt
remove test/test2.txt

Even after we are back to original state, diff remains confusing.

[amadvance]

The issue is that SnapRAID considers hard links similarly to soft links. The first one found is considered the real file, and all the other links point to that file. But if they are found in a different order, such relationships are completely different, and they are reported as differences.

It's a known limitation, but I'll consider fixing it in a future version.