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-- lib/supple/request.lua
--
-- Sandbox (for) Untrusted Procedure Partitioning (in) Lua Engine
--
-- Contextual object storage and identification. Wrapping and unwrapping.
--
-- Copyright 2012 Daniel Silverstone <dsilvers@digital-scurf.org>
--
-- For licence terms, see COPYING
--
local gc = collectgarbage
local capi = require 'supple.capi'
local track = require 'supple.track'
local my_objects_by_obj = {}
local my_objects_by_tag = {}
local my_objects_expn_by_tag = {}
local my_name = "UNSET"
local my_counter = 0
local their_objects_by_tag = setmetatable({}, { __mode="v" })
local their_objects_by_obj = setmetatable({}, { __mode="k" })
local their_objects_refcnt = {}
local proc_call = nil
local type = capi.rawtype
local function clean_down(call_other_end)
track.enter("clean_down")
-- And force a full GC
gc "collect"
gc "collect"
gc "collect"
-- Call the other end if needed
if call_other_end then
proc_call("supple:clean_down", "__call")
end
-- And forget all our local objects
my_objects_by_obj = {}
my_objects_by_tag = {}
my_objects_expn_by_tag = {}
track.leave("clean_down")
end
local function set_name(newname)
my_name = newname
end
local function get_name()
return my_name
end
local function set_proc_call(pc)
proc_call = pc
end
local integral = {
["nil"] = true,
boolean = true,
string = true,
number = true,
}
local function new_tag(special_tag)
local retstr = special_tag
if not retstr then
if not my_name:match("%%d") then
retstr = ("%s:%d"):format(my_name, my_counter)
else
retstr = my_name:format(my_counter)
end
my_counter = my_counter + 1
end
return retstr
end
local function give(obj, special_tag)
-- If the object is integral, return it directly
if integral[type(obj)] then
return obj
end
-- If the passed object is one of their objects then "unwrap" it by
-- returning their tag.
track.enter("give", tostring(obj), tostring(special_tag))
local tag = their_objects_by_obj[obj];
if tag then
track.leave("give", "theirs", tag)
return { tag = tag }
end
-- If it's one of our objects which has already been wrapped, return our
-- tag
local tag = my_objects_by_obj[obj]
if tag then
track.leave("give", "ours", tag)
return my_objects_expn_by_tag[tag]
end
-- otherwise wrap it freshly for us and return that.
local tag = new_tag(special_tag)
local expn = capi.explain(obj, tag)
my_objects_by_obj[obj] = tag
my_objects_by_tag[tag] = obj
my_objects_expn_by_tag[tag] = expn
track.leave("give", "ours, new", tag)
return expn
end
local function receive(obj)
-- If the object is integral, return it directly
if integral[type(obj)] then
return obj
end
-- It's not integral, so it must be a tagged object
assert(type(obj) == "table")
assert(type(obj.tag) == "string")
local tag = obj.tag
track.enter("receive", tag)
-- First up, is it one of our objects?
local ret = my_objects_by_tag[tag]
if ret then
track.leave("receive", "ours", tostring(ret))
return ret
end
-- Now is it a known one of their objects?
ret = their_objects_by_tag[tag]
if ret then
track.leave("receive", "theirs", tostring(ret))
return ret
end
-- Okay, prepare a proxy?
assert(type(obj.type) == "string", "Type string expected, got " .. type(obj.type) .. " preparing proxy for " .. obj.tag)
local proxy, mt = capi.new_proxy(obj.type)
assert(capi.type(proxy) == obj.type)
their_objects_by_tag[tag] = proxy
their_objects_by_obj[proxy] = tag
their_objects_refcnt[tag] = (their_objects_refcnt[tag] or 0) + 1
-- Fill out the metatable
obj.methods = obj.methods or {}
if obj.type == "function" then
obj.methods[#obj.methods+1] = "__call"
end
if obj.type == "table" then
obj.methods[#obj.methods+1] = "__len"
obj.methods[#obj.methods+1] = "__index"
obj.methods[#obj.methods+1] = "__newindex"
obj.methods[#obj.methods+1] = "__next"
end
for _, name in ipairs(obj.methods or {}) do
local function meta_func(mobj, ...)
track.enter("meta_func", tostring(mobj), tag, name)
local ret = {proc_call(tag, name, ...)}
track.leave("meta_func", tostring(mobj), tag, name)
return unpack(ret)
end
mt[name] = meta_func
end
function mt:__gc()
their_objects_refcnt[tag] = their_objects_refcnt[tag] - 1
if their_objects_refcnt[tag] == 0 then
their_objects_refcnt[tag] = nil
proc_call(tag, "__gc")
end
end
-- And return the proxy object
track.leave("receive", "theirs, new", tostring(proxy))
return proxy
end
local function forget_mine(tag)
track.enter("forget_mine", tag)
local obj = my_objects_by_tag[tag]
assert(obj, "Trying to forget nil object: " .. tag)
my_objects_by_tag[tag] = nil
my_objects_by_obj[obj] = nil
my_objects_expn_by_tag[tag] = nil
track.leave("forget_mine", tag)
end
local function find_tag(obj)
if my_objects_by_obj[obj] then
return "my", my_objects_by_obj[obj]
end
if their_objects_by_obj[obj] then
return "their", their_objects_by_obj[obj]
end
end
local function get_object_anchor()
local ret = {}
for obj in pairs(their_objects_by_obj) do
ret[obj] = true
end
for obj in pairs(my_objects_by_obj) do
ret[obj] = true
end
return ret
end
return {
set_name = set_name,
get_name = get_name,
set_proc_call = set_proc_call,
give = give,
receive = receive,
clean_down = clean_down,
forget_mine = forget_mine,
find_tag = find_tag,
get_object_anchor = get_object_anchor,
}
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