NAME

       sd_pid_get_owner_uid, sd_pid_get_session, sd_pid_get_user_unit, sd_pid_get_unit,
       sd_pid_get_machine_name, sd_pid_get_slice, sd_pid_get_user_slice, sd_pid_get_cgroup,
       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,
       sd_pidfd_get_cgroup, 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,
       sd_peer_get_cgroup - Determine the owner uid of the user unit or session, or the session,
       user unit, system unit, container/VM or slice that a specific PID or socket peer belongs
       to

SYNOPSIS

       #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);

DESCRIPTION

       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 unified control group setup is used), or /sys/fs/cgroup/HIERARCHY/ (if the legacy
       multi-hierarchy control group setup is used).

       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.

RETURN VALUE

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

   Errors
       Returned errors may indicate the following problems:

       -ESRCH
           The specified PID does not refer to a running process.

       -EBADF
           The specified socket file descriptor was invalid.

       -ENODATA
           The given field is not specified for the described process or peer.

       -EINVAL
           An input parameter was invalid (out of range, or NULL, where that is not accepted).

       -ENOMEM
           Memory allocation failed.

NOTES

       These APIs are implemented as a shared library, which can be compiled 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).

SEE ALSO

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