fixup! Add init groups.

init/init.c

@@ -4297,7 +4297,7 @@ int main(int argc, char* argv[])
 	}
 
 	// Prevent recursive init without care.
-	if ( getinit() != getpid() )
+	if ( getinit(0) != getpid() )
 		fatal("System is already managed by an init process");
 
 	// Register handler that shuts down the system when init exits.

kernel/include/sortix/kernel/syscall.h

@@ -97,7 +97,7 @@ int sys_getentropy(void*, size_t);
 uid_t sys_geteuid(void);
 gid_t sys_getgid(void);
 int sys_gethostname(char*, size_t);
-pid_t sys_getinit(void);
+pid_t sys_getinit(pid_t);
 size_t sys_getpagesize(void);
 int sys_getpeername(int, void*, size_t*);
 pid_t sys_getpgid(pid_t);

kernel/process.cpp

@@ -1624,7 +1624,8 @@ pid_t sys_getpgid(pid_t pid)
 pid_t sys_getsid(pid_t pid)
 {
 	ScopedLock lock(&process_family_lock);
-	Process* process = !pid ? CurrentProcess() : CurrentProcess()->GetPTable()->Get(pid);
+	Process* process =
+		!pid ? CurrentProcess() : CurrentProcess()->GetPTable()->Get(pid);
 	if ( !process )
 		return errno = ESRCH, -1;
 	if ( !process->session )
@@ -1632,10 +1633,11 @@ pid_t sys_getsid(pid_t pid)
 	return process->session->pid;
 }
 
-pid_t sys_getinit(void)
+pid_t sys_getinit(pid_t pid)
 {
 	ScopedLock lock(&process_family_lock);
-	Process* process = CurrentProcess();
+	Process* process =
+		!pid ? CurrentProcess() : CurrentProcess()->GetPTable()->Get(pid);
 	if ( !process->init )
 		return errno = ESRCH, -1;
 	return process->init->pid;

libc/Makefile

@@ -781,6 +781,8 @@ MANPAGES2=\
 scram/scram.2 \
 sys/dnsconfig/getdnsconfig.2 \
 sys/dnsconfig/setdnsconfig.2 \
+unistd/setinit.2 \
+unistd/getinit.2 \
 
 MANPAGES3=\
 time/add_leap_seconds.3 \

libc/include/unistd.h

@@ -562,7 +562,7 @@ int exit_thread(int, int, const struct exit_thread*);
 int fchdirat(int, const char*);
 int fchroot(int);
 int fchrootat(int, const char*);
-pid_t getinit(void);
+pid_t getinit(pid_t);
 int memstat(size_t* memused, size_t* memtotal);
 int mkpartition(int fd, off_t start, off_t length);
 pid_t setinit(void);

libc/unistd/getinit.2

@@ -0,0 +1 @@
+setinit.2

libc/unistd/getinit.c

@@ -21,10 +21,9 @@
 
 #include <unistd.h>
 
-DEFN_SYSCALL0(pid_t, sys_getinit, SYSCALL_GETINIT);
+DEFN_SYSCALL1(pid_t, sys_getinit, SYSCALL_GETINIT, pid_t);
 
-// TODO: Should this accept a pid like getsid?
-pid_t getinit(void)
+pid_t getinit(pid_t pid)
 {
-	return sys_getinit();
+	return sys_getinit(pid);
 }

libc/unistd/setinit.2

@@ -0,0 +1,75 @@
+.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 reparanted 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.

share/man/man7/following-development.7

@@ -69,6 +69,21 @@ releasing Sortix x.y, foo." to allow the maintainer to easily
 .Xr grep 1
 for it after a release.
 .Sh CHANGES
+.Ss Add init groups
+The
+.Xr setinit 2
+and
+.Xr getinit 2
+system calls have been added for nested init groups.
+The
+.Dv TIOCSCTTY
+.Xr ioctl 2
+for acquiring a controlling terminal has gained a force flag essential to
+transferring terminals into nested sessions, and the new
+.Dv TIOCUCTTY
+.Xr ioctl 2
+releases a controlling terminal.
+This is a minor compatible ABI change.
 .Ss Add tix-repository(8)
 The new
 .Xr tix-repository 8

utils/halt.c

@@ -39,7 +39,7 @@ int main(int argc, char* argv[])
 	if ( optind < argc )
 		errx(1, "extra operand: %s", argv[optind]);
 
-	pid_t init_pid = getinit();
+	pid_t init_pid = getinit(0);
 	if ( kill(init_pid, SIGQUIT) < 0 )
 		err(1, "kill: %" PRIdPID, init_pid);
 

utils/poweroff.c

@@ -39,7 +39,7 @@ int main(int argc, char* argv[])
 	if ( optind < argc )
 		errx(1, "extra operand: %s", argv[optind]);
 
-	pid_t init_pid = getinit();
+	pid_t init_pid = getinit(0);
 	if ( kill(init_pid, SIGTERM) < 0 )
 		err(1, "kill: %" PRIdPID, init_pid);
 

utils/reboot.c

@@ -39,7 +39,7 @@ int main(int argc, char* argv[])
 	if ( optind < argc )
 		errx(1, "extra operand: %s", argv[optind]);
 
-	pid_t init_pid = getinit();
+	pid_t init_pid = getinit(0);
 	if ( kill(init_pid, SIGINT) < 0 )
 		err(1, "kill: %" PRIdPID, init_pid);