bug#25620: mkdir ignores set-group-id bit in mode argument

[Pádraig Brady]

On 04/02/17 10:34, Alexander Syvak wrote:
> Hi!
> 
> I have a directory structure
> 
> address@hidden:~/address@hidden/test_dir$ ll
> total 20
> drwxrwsr-x 5 as root 4096 лют  4 20:26 ./
> drwsr-sr-x 7 as as   4096 лют  4 19:58 ../
> drwxrwsr-x 3 as root 4096 лют  4 20:23 td/
> drwxrwsr-x 3 as root 4096 лют  4 20:27 test/
> 
> I have executed
> 
> mkdir -p test/test --mode=7777
> 
> address@hidden:~/address@hidden/test_dir$ ll test
> total 12
> drwxrwsr-x 3 as root 4096 лют  4 20:27 ./
> drwxrwsr-x 5 as root 4096 лют  4 20:26 ../
> drwsrw*x*rwt 2 as root 4096 лют  4 20:27 test/
> 
> As you can see the set-group-id bit is not set in directory test/test.
> 
> Author is David MacKenzie
> Version of GNU coreutils is 8.25
> 
> umask was 0002.
> 

Is this NFS or if not what file system is it?
usually test/test would auto inherit the g+s bit even if not specified.

What does an strace look like? For me on ext4 it's:

  mkdir("test", 07755) = 0
  open("test", ...) = 3
  fstat(3, {st_mode=S_IFDIR|S_ISGID|S_ISVTX|0755, ...}) = 0
  fchmod(3, 07777) = 0

cheers,
Pádraig