APFS synthetic symbolic link traversing broken

Number:rdar://FB9341328 Date Originated:16.06.2021
Status:Open Resolved:
Product:macOS Product Version:11.4 (build 20F71)
Classification: Reproducible:yes

This is a bug report about synthetic symbolic links in APFS.

I investigated the following CMake issue where I noticed that something is broken at the macOS kernel level:

$ cat /etc/synthetic.conf 
w	Users/gregorj/w

$ pwd                                        

$ stat ../../../Users/gregorj/src/cmake/Modules/CMakeCCompilerABI.c 
stat: ../../../Users/gregorj/src/cmake/Modules/CMakeCCompilerABI.c: stat: No such file or directory

$ stat /Users/gregorj/src/cmake/Modules/CMakeCCompilerABI.c 
16777220 20730161 -rw-r--r-- 1 gregorj staff 0 511 "Nov 21 16:13:29 2020" "Nov 21 16:13:29 2020" "Nov 21 16:13:29 2020" "Nov 21 16:13:29 2020" 4096 8 0 /Users/gregorj/src/cmake/Modules/CMakeCCompilerABI.c

If the pwd is “/w/dev/test_void_p_size” I’d expect that ../../.. is at the filesystem root (“/“). But listing files by  “ls ../../..” reveals files from “/Users/gregorj” instead. Strangely “cd ../../.. && ls” works as expected.

I tested on macOS 11.4 (build 20F71)



Please note: Reports posted here will not necessarily be seen by Apple. All problems should be submitted at bugreport.apple.com before they are posted here. Please only post information for Radars that you have filed yourself, and please do not include Apple confidential information in your posts. Thank you!