.Dd June 18, 2024
.Dt SETINIT 2
.Os
.Sh NAME
.Nm setinit
.Nd become and locate init
.Sh SYNOPSIS
.In unistd.h
.Ft int
.Fn getinit "pid_t pid"
.Ft int
.Fn setinit void
.Sh DESCRIPTION
.Fn setinit
sets the current process as the init process for itself and its subsequently
created descendant processes.
.Fn setinit
runs
.Xr setsid 2
to create a new session (and process group) and can fail for the same reasons as
.Xr setsid 2 .
.Pp
.Fn getinit
returns the init process for the process specified in
.Fa pid ,
or the current process if
.Fa pid
is zero.
.Pp
Orphaned descendant processes are reparented to their init process.
If an init process exits, all descendant processes atomically receive the
.Dv SIGKILL
signal and become unable to create new processes and threads.
.Sh RETURN VALUES
.Fn setinit
returns the pid of the init process (the current process) on success, or -1 on
error and
.Va error
is set appropriately.
.Pp
.Fn getinit
returns the returns the pid of the init process, or -1 on
error and
.Va error
is set appropriately.
.Sh ERRORS
.Fn setinit
will fail if:
.Bl -tag -width "12345678"
.It Er EPERM
The process is already a process group leader, a session leader, or an init
process.
.El
.Pp
.Fn getinit
will fail if:
.Bl -tag -width "12345678"
.It Er ESRCH
The process specified in
.Fa pid
does not exist.
.El
.Sh SEE ALSO
.Xr getpgrp 2 ,
.Xr getsid 2 ,
.Xr psctl 2 ,
.Xr setpgrp 2 ,
.Xr setsid 2 ,
.Xr init 8
.Sh HISTORY
The
.Fn getinit
and
.Fn setinit
system calls originally appeared in Sortix 1.1.