sd_pid_get_owner_uid - Man Page

#include <systemd/sd-login​.h>

int sd_pid_get_owner_uid(pid_t pid, uid_t *uid);

int sd_pid_get_session(pid_t pid, char **session);

int sd_pid_get_user_unit(pid_t pid, char **unit);

int sd_pid_get_unit(pid_t pid, char **unit);

int sd_pid_get_machine_name(pid_t pid, char **name);

int sd_pid_get_slice(pid_t pid, char **slice);

int sd_pid_get_user_slice(pid_t pid, char **slice);

int sd_pid_get_cgroup(pid_t pid, char **cgroup);

int sd_pidfd_get_owner_uid(int pidfd, uid_t *uid);

int sd_pidfd_get_session(int pidfd, char **session);

int sd_pidfd_get_user_unit(int pidfd, char **unit);

int sd_pidfd_get_unit(int pidfd, char **unit);

int sd_pidfd_get_machine_name(int pidfd, char **name);

int sd_pidfd_get_slice(int pidfd, char **slice);

int sd_pidfd_get_user_slice(int pidfd, char **slice);

int sd_pidfd_get_cgroup(int pidfd, char **cgroup);

int sd_peer_get_owner_uid(int fd, uid_t *uid);

int sd_peer_get_session(int fd, char **session);

int sd_peer_get_user_unit(int fd, char **unit);

int sd_peer_get_unit(int fd, char **unit);

int sd_peer_get_machine_name(int fd, char **name);

int sd_peer_get_slice(int fd, char **slice);

int sd_peer_get_user_slice(int fd, char **slice);

int sd_peer_get_cgroup(int fd, char **cgroup);

sd_pid_get_owner_uid() may be used to determine the Unix UID (user identifier) which owns the login session or systemd user unit of a process identified by the specified PID​. For processes which are not part of a login session and not managed by a user manager, this function will fail with -ENODATA​.

sd_pid_get_session() may be used to determine the login session identifier of a process identified by the specified process identifier​. The session identifier is a short string, suitable for usage in file system paths​. Please note the login session may be limited to a stub process or two​. User processes may instead be started from their systemd user manager, e​.g​. GUI applications started using DBus activation, as well as service processes which are shared between multiple logins of the same user​. For processes which are not part of a login session, this function will fail with -ENODATA​. The returned string needs to be freed with the libc free(3) call after use​.

sd_pid_get_user_unit() may be used to determine the systemd user unit (i​.e​. user service or scope unit) identifier of a process identified by the specified PID​. The unit name is a short string, suitable for usage in file system paths​. For processes which are not managed by a user manager, this function will fail with -ENODATA​. The returned string needs to be freed with the libc free(3) call after use​.

sd_pid_get_unit() may be used to determine the systemd system unit (i​.e​. system service or scope unit) identifier of a process identified by the specified PID​. The unit name is a short string, suitable for usage in file system paths​. Note that not all processes are part of a system unit/service​. For processes not being part of a systemd system unit, this function will fail with -ENODATA​. (More specifically, this call will not work for kernel threads​.) The returned string needs to be freed with the libc free(3) call after use​.

sd_pid_get_machine_name() may be used to determine the name of the VM or container is a member of​. The machine name is a short string, suitable for usage in file system paths​. The returned string needs to be freed with the libc free(3) call after use​. For processes not part of a VM or container, this function fails with -ENODATA​.

sd_pid_get_slice() may be used to determine the slice unit the process is a member of​. See systemd.slice(5) for details about slices​. The returned string needs to be freed with the libc free(3) call after use​.

Similarly, sd_pid_get_user_slice() returns the user slice (as managed by the user's systemd instance) of a process​.

sd_pid_get_cgroup() returns the control group path of the specified process, relative to the root of the hierarchy​. Returns the path without trailing slash, except for processes located in the root control group, where "/" is returned​. To find the actual control group path in the file system, the returned path needs to be prefixed with /sys/fs/cgroup/​.

If the pid parameter of any of these functions is passed as 0, the operation is executed for the calling process​.

The sd_pidfd_get_owner_uid(), sd_pidfd_get_session(), sd_pidfd_get_user_unit(), sd_pidfd_get_unit(), sd_pidfd_get_machine_name(), sd_pidfd_get_slice(), sd_pidfd_get_user_slice() and sd_pidfd_get_cgroup() calls operate similarly to their PID counterparts, but accept a PIDFD instead of a PID, which means they are not subject to recycle race conditions as the process is pinned by the file descriptor during the whole duration of the invocation​. Note that these require a kernel that supports PIDFD​. A suitable file descriptor may be acquired via pidfd_open(2)​.

The sd_peer_get_owner_uid(), sd_peer_get_session(), sd_peer_get_user_unit(), sd_peer_get_unit(), sd_peer_get_machine_name(), sd_peer_get_slice(), sd_peer_get_user_slice() and sd_peer_get_cgroup() calls operate similarly to their PID counterparts, but accept a connected AF_UNIX socket and retrieve information about the connected peer process​. Note that these fields are retrieved via /proc/, and hence are not suitable for authorization purposes, as they are subject to races​.

On success, these calls return 0 or a positive integer​. On failure, these calls return a negative errno-style error code​.

Functions described here are available as a shared library, which can be compiled against and linked to with the libsystemd ​pkg-config(1) file​.

Note that the login session identifier as returned by sd_pid_get_session() is completely unrelated to the process session identifier as returned by getsid(2)​.

sd_peer_get_cgroup(), sd_peer_get_machine_name(), sd_peer_get_owner_uid(), sd_peer_get_session(), sd_peer_get_slice(), sd_peer_get_unit(), sd_peer_get_user_slice(), sd_peer_get_user_unit(), sd_pid_get_cgroup(), sd_pid_get_machine_name(), sd_pid_get_owner_uid(), sd_pid_get_session(), sd_pid_get_slice(), sd_pid_get_unit(), sd_pid_get_user_slice(), and sd_pid_get_user_unit() were added in version 236​.

sd_pidfd_get_owner_uid(), sd_pidfd_get_session(), sd_pidfd_get_user_unit(), sd_pidfd_get_unit(), sd_pidfd_get_machine_name(), sd_pidfd_get_slice(), sd_pidfd_get_user_slice(), and sd_pidfd_get_cgroup() were added in version 253​.

systemd(1), sd-login(3), sd_session_is_active(3), getsid(2), systemd.slice(5), systemd-machined.service(8)