freebsd-dev/stand/lua/hook.lua
Kyle Evans 3cb2f5f369 lualoader: add support for .lua configuration files
If a file is specified in loader_conf_files that ends in '.lua', lualoader
will now load and execute that file. These may be used in place of a
traditional loader.conf to use more complicated logic, where some values
may be set based on others or based on the environment that the C bits has
left us with.

Lua scripts are run in a limited environment. In particular, it does not get
access to any modules or, in-fact, anything except environment variable.

A config.buildenv hook has been added so that a local module can add
whatever it may need to to the environment.

When a global var is set in the lua script, it does not immediately alter
the loader environment. Instead, the script's environment is initially
empty and processed only if the whole script executes successfully.
Effectively, a lua configuration file either takes effect or it does not,
an error will not leave it in a half-baked state.

Reviewed by:	bcr (manpages), imp
Differential Revision:	https://reviews.freebsd.org/D28450
2023-05-10 23:10:53 -05:00

84 lines
3.2 KiB
Lua

--
-- SPDX-License-Identifier: BSD-2-Clause-FreeBSD
--
-- Copyright (c) 2018 Kyle Evans <kevans@FreeBSD.org>
--
-- Redistribution and use in source and binary forms, with or without
-- modification, are permitted provided that the following conditions
-- are met:
-- 1. Redistributions of source code must retain the above copyright
-- notice, this list of conditions and the following disclaimer.
-- 2. Redistributions in binary form must reproduce the above copyright
-- notice, this list of conditions and the following disclaimer in the
-- documentation and/or other materials provided with the distribution.
--
-- THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
-- ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
-- IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
-- ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
-- FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-- DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
-- OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
-- HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
-- LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
-- OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
-- SUCH DAMAGE.
--
-- $FreeBSD$
--
local hook = {}
local registered_hooks = {}
-- Module exports
-- Register a hook type; these are the names that hooks may be registered for.
-- It is expected that modules will register all of their hook types upon
-- initial load. Other modules may then, at any time, register a hook for these
-- types.
--
-- Naming convention: hook types should be sensible named, preferably prefixed
-- with the name of the module that registered them. They would also ideally
-- describe an action that may or may not match a function name.
-- e.g. config.reloaded which takes place after config has been reloaded,
-- possibly from a different source.
function hook.registerType(hooktype)
registered_hooks[hooktype] = {}
end
function hook.register(hooktype, hookfunc)
local selected_hooks = registered_hooks[hooktype]
if selected_hooks == nil then
print("Tried registering a hook for an unknown hook type: " ..
hooktype)
return
end
selected_hooks[#selected_hooks + 1] = hookfunc
registered_hooks[hooktype] = selected_hooks
end
-- Takes a hooktype and runs all functions associated with that specific hook
-- type in the order that they were registered in. This ordering should likely
-- not be relied upon.
function hook.runAll(hooktype, data)
local selected_hooks = registered_hooks[hooktype]
if selected_hooks == nil then
-- This message, and the print() above, should only be seen by
-- developers. Hook type registration should have happened at
-- module load, so if this hasn't happened then we have messed
-- up the order in which we've loaded modules and we need to
-- catch that as soon as possible.
print("Tried to run hooks for an unknown hook type: " ..
hooktype)
return 0
end
if #selected_hooks > 0 then
for _, func in ipairs(selected_hooks) do
func(data)
end
end
return #selected_hooks
end
return hook