lib LibC
	struct Passwd
		pw_name    : Char*
		pw_passwd  : Char*
		pw_uid     : UInt
		pw_gid     : UInt
		pw_gecos   : Char*
		pw_dir     : UInt
		pw_shell   : Char*
	end

	fun setuid(Int32) : Int32
	fun setgid(Int32) : Int32
	fun getpwnam(Char*) : Passwd*
end

module System
	def self.become_user(user_name : String)
		pointer = LibC.getpwnam user_name.to_unsafe

		if pointer.null?
			return nil
		end

		passwd = pointer.value

		become_user passwd.pw_uid, passwd.pw_uid
	end

	def self.become_user(uid, gid)
		r = LibC.setgid gid
		raise Errno.new "setgid" if r != 0

		r = LibC.setuid uid
		raise Errno.new "setuid" if r != 0
	end
end
#def get_uid_gid(user_name : String)
#	pointer = LibC.getpwnam user_name.to_unsafe
#
#	if pointer.null?
#		return nil
#	end
#
#	passwd = pointer.value
#
#	{passwd.pw_uid, passwd.pw_gid}
#end

#uid, gid = get_uid_gid("http").not_nil!
#LibC.setuid uid
#LibC.setgid gid

#puts Process.run "whoami", output: Process::Redirect::Inherit