Kernel/LibC: Add setsid()

kernel/include/kernel/Process.h

@@ -85,6 +85,7 @@ namespace Kernel
 
 		BAN::ErrorOr<long> sys_setuid(uid_t);
 		BAN::ErrorOr<long> sys_setgid(gid_t);
+		BAN::ErrorOr<long> sys_setsid();
 		BAN::ErrorOr<long> sys_seteuid(uid_t);
 		BAN::ErrorOr<long> sys_setegid(gid_t);
 		BAN::ErrorOr<long> sys_setreuid(uid_t, uid_t);

kernel/kernel/Process.cpp

@@ -2001,6 +2001,20 @@ namespace Kernel
 		return BAN::Error::from_errno(EPERM);
 	}
 
+	BAN::ErrorOr<long> Process::sys_setsid()
+	{
+		LockGuard _(m_process_lock);
+
+		if (is_session_leader() || m_pid == m_pgrp)
+			return BAN::Error::from_errno(EPERM);
+
+		m_sid = m_pid;
+		m_pgrp = m_pid;
+		m_controlling_terminal.clear();
+
+		return 0;
+	}
+
 	BAN::ErrorOr<long> Process::sys_seteuid(uid_t uid)
 	{
 		if (uid < 0 || uid >= 1'000'000'000)

userspace/libraries/LibC/include/sys/syscall.h

@@ -25,6 +25,7 @@ __BEGIN_DECLS
 	O(SYS_READ_DIR,			readdir)		\
 	O(SYS_SET_UID,			setuid)			\
 	O(SYS_SET_GID,			setgid)			\
+	O(SYS_SET_SID,			setsid)			\
 	O(SYS_SET_EUID,			seteuid)		\
 	O(SYS_SET_EGID,			setegid)		\
 	O(SYS_SET_REUID,		setreuid)		\

userspace/libraries/LibC/unistd.cpp

@@ -475,6 +475,11 @@ int setgid(gid_t gid)
 	return syscall(SYS_SET_GID, gid);
 }
 
+int setsid(void)
+{
+	return syscall(SYS_SET_SID);
+}
+
 int setreuid(uid_t ruid, uid_t euid)
 {
 	return syscall(SYS_SET_REUID, ruid, euid);