NS_GET_OWNER_UID - discovering the owner of a user namespace

       The  NS_GET_OWNER_UID  operation can be used to discover the owner user ID of a user namespace (i.e., the
       effective user ID of the process that created the user namespace).

       fd refers to a /proc/pid/ns/user file.

       The owner user ID is returned in the uid_t pointed to by the third argument.

EINVALfd does not refer to a user namespace.

       Linux 4.11.

       NS_GET_OWNER_UID - discovering the owner of a user namespace

       On success, 0 is returned.  On error, -1 is returned, and errno is set to indicate the error.

ioctl(2), ioctl_nsfs(2)

Linux man-pages 6.9.1                              2024-06-13                           NS_GET_OWNER_UID(2const)

       Linux.

#include<linux/nsfs.h>  /* Definition of NS_GET_OWNER_UID */
       #include<sys/ioctl.h>intioctl(intfd,NS_GET_OWNER_UID,uid_t*uid);