Get selinux username and level for a given linux username
#include <selinux/selinux.h>
int getseuserbyname(const char *linuxuser, char **selinuxuser, char **level);
getseuserbyname() retrieves the SELinux username and security level associated with a given Linux username. The SELinux username and security level can then be passed to other libselinux functions such as get_ordered_context_list_with_level(3) and get_default_context_with_level(3).
The returned SELinux username and level should be freed by the caller using free.
On success, 0 is returned. On failure, -1 is returned and errno is set appropriately.
The errors documented for the stat(2) system call are also applicable here.