1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
--- Lua module to serialize values as Lua code.
-- From: https://github.com/fab13n/metalua/blob/no-dll/src/lib/serialize.lua
-- License: MIT
-- @copyright 2006-2997 Fabien Fleutot <metalua@gmail.com>
-- @author Fabien Fleutot <metalua@gmail.com>
-- @author ShadowNinja <shadowninja@minetest.net>
--------------------------------------------------------------------------------
--- Serialize an object into a source code string. This string, when passed as
-- an argument to deserialize(), returns an object structurally identical to
-- the original one. The following are currently supported:
-- * Booleans, numbers, strings, and nil.
-- * Functions; uses interpreter-dependent (and sometimes platform-dependent) bytecode!
-- * Tables; they can cantain multiple references and can be recursive, but metatables aren't saved.
-- This works in two phases:
-- 1. Recursively find and record multiple references and recursion.
-- 2. Recursively dump the value into a string.
-- @param x Value to serialize (nil is allowed).
-- @return load()able string containing the value.
function core.serialize(x)
local local_index = 1 -- Top index of the "_" local table in the dump
-- table->nil/1/2 set of tables seen.
-- nil = not seen, 1 = seen once, 2 = seen multiple times.
local seen = {}
-- nest_points are places where a table appears within itself, directly
-- or not. For instance, all of these chunks create nest points in
-- table x: "x = {}; x[x] = 1", "x = {}; x[1] = x",
-- "x = {}; x[1] = {y = {x}}".
-- To handle those, two tables are used by mark_nest_point:
-- * nested - Transient set of tables being currently traversed.
-- Used for detecting nested tables.
-- * nest_points - parent->{key=value, ...} table cantaining the nested
-- keys and values in the parent. They're all dumped after all the
-- other table operations have been performed.
--
-- mark_nest_point(p, k, v) fills nest_points with information required
-- to remember that key/value (k, v) creates a nest point in table
-- parent. It also marks "parent" and the nested item(s) as occuring
-- multiple times, since several references to it will be required in
-- order to patch the nest points.
local nest_points = {}
local nested = {}
local function mark_nest_point(parent, k, v)
local nk, nv = nested[k], nested[v]
local np = nest_points[parent]
if not np then
np = {}
nest_points[parent] = np
end
np[k] = v
seen[parent] = 2
if nk then seen[k] = 2 end
if nv then seen[v] = 2 end
end
-- First phase, list the tables and functions which appear more than
-- once in x.
local function mark_multiple_occurences(x)
local tp = type(x)
if tp ~= "table" and tp ~= "function" then
-- No identity (comparison is done by value, not by instance)
return
end
if seen[x] == 1 then
seen[x] = 2
elseif seen[x] ~= 2 then
seen[x] = 1
end
if tp == "table" then
nested[x] = true
for k, v in pairs(x) do
if nested[k] or nested[v] then
mark_nest_point(x, k, v)
else
mark_multiple_occurences(k)
mark_multiple_occurences(v)
end
end
nested[x] = nil
end
end
local dumped = {} -- object->varname set
local local_defs = {} -- Dumped local definitions as source code lines
-- Mutually recursive local functions:
local dump_val, dump_or_ref_val
-- If x occurs multiple times, dump the local variable rather than
-- the value. If it's the first time it's dumped, also dump the
-- content in local_defs.
function dump_or_ref_val(x)
if seen[x] ~= 2 then
return dump_val(x)
end
local var = dumped[x]
if var then -- Already referenced
return var
end
-- First occurence, create and register reference
local val = dump_val(x)
local i = local_index
local_index = local_index + 1
var = "_["..i.."]"
local_defs[#local_defs + 1] = var.." = "..val
dumped[x] = var
return var
end
-- Second phase. Dump the object; subparts occuring multiple times
-- are dumped in local variables which can be referenced multiple
-- times. Care is taken to dump local vars in a sensible order.
function dump_val(x)
local tp = type(x)
if x == nil then return "nil"
elseif tp == "string" then return string.format("%q", x)
elseif tp == "boolean" then return x and "true" or "false"
elseif tp == "function" then
return string.format("loadstring(%q)", string.dump(x))
elseif tp == "number" then
-- Serialize integers with string.format to prevent
-- scientific notation, which doesn't preserve
-- precision and breaks things like node position
-- hashes. Serialize floats normally.
if math.floor(x) == x then
return string.format("%d", x)
else
return tostring(x)
end
elseif tp == "table" then
local vals = {}
local idx_dumped = {}
local np = nest_points[x]
for i, v in ipairs(x) do
if not np or not np[i] then
vals[#vals + 1] = dump_or_ref_val(v)
end
idx_dumped[i] = true
end
for k, v in pairs(x) do
if (not np or not np[k]) and
not idx_dumped[k] then
vals[#vals + 1] = "["..dump_or_ref_val(k).."] = "
..dump_or_ref_val(v)
end
end
return "{"..table.concat(vals, ", ").."}"
else
error("Can't serialize data of type "..tp)
end
end
local function dump_nest_points()
for parent, vals in pairs(nest_points) do
for k, v in pairs(vals) do
local_defs[#local_defs + 1] = dump_or_ref_val(parent)
.."["..dump_or_ref_val(k).."] = "
..dump_or_ref_val(v)
end
end
end
mark_multiple_occurences(x)
local top_level = dump_or_ref_val(x)
dump_nest_points()
if next(local_defs) then
return "local _ = {}\n"
..table.concat(local_defs, "\n")
.."\nreturn "..top_level
else
return "return "..top_level
end
end
-- Deserialization
local function safe_loadstring(...)
local func, err = loadstring(...)
if func then
setfenv(func, {})
return func
end
return nil, err
end
local function dummy_func() end
function core.deserialize(str, safe)
if type(str) ~= "string" then
return nil, "Cannot deserialize type '"..type(str)
.."'. Argument must be a string."
end
if str:byte(1) == 0x1B then
return nil, "Bytecode prohibited"
end
local f, err = loadstring(str)
if not f then return nil, err end
-- The environment is recreated every time so deseralized code cannot
-- pollute it with permanent references.
setfenv(f, {loadstring = safe and dummy_func or safe_loadstring})
local good, data = pcall(f)
if good then
return data
else
return nil, data
end
end
|
