system call to set file ACLs in linux

sharad · 03-15-2007, 01:13 AM

Hi all,

Can anybody tell me the answer of following query.

setfacl command uses which system call to set the ACLs of files &
directories in linux.

Kindly waiting for your reply.

Thanks & Regards,

Sharad.

anomie · 03-15-2007, 09:53 AM

You should be able to determine this using strace.

cirosantilli · 04-25-2019, 05:06 AM

Code:

strace -f -s999 -v setfacl -m u:cirsan01:rwx myfile

tells it uses getxattr with attribute "system.posix_acl_access":

Code:

setxattr("myfile", "system.posix_acl_access", "\2\0\0\0\1\0\6\0\377\377\377\377\2\0\7\0aO\0\0\4\0\6\0\377\377\377\377\20\0\7\0\377\377\377\377 \0\4\0\377\377\377\377", 44, 0) = 0

Tested in Ubuntu 16.04 on an ext4 filesystem.