Thu, 08 Jul 2010 01:11:12 +0100
make_squishy: Fix traceback on modules that couldn't be found on the filesystem (thanks Valerio)
34 | 1 | -- Minichunkspy: Disassemble and reassemble chunks. |
2 | -- Copyright M Joonas Pihlaja 2009 | |
3 | -- MIT license | |
4 | -- | |
5 | -- minichunkspy = require"minichunkspy" | |
6 | -- | |
7 | -- chunk = string.dump(loadfile"blabla.lua") | |
8 | -- disassembled_chunk = minichunkspy.disassemble(chunk) | |
9 | -- chunk = minichunkspy.assemble(disassembled_chunk) | |
10 | -- assert(minichunkspy.validate(<function or chunk>)) | |
11 | -- | |
12 | -- Tested on little-endian 32 bit platforms. Modify | |
13 | -- the Size_t type to be a 64 bit integer to make it work | |
14 | -- for 64 bit systems, and set BIG_ENDIAN = true for | |
15 | -- big-endian systems. | |
16 | local string, table, math = string, table, math | |
17 | local ipairs, setmetatable, type, assert = ipairs, setmetatable, type, assert | |
18 | local _ = __END_OF_GLOBALS__ | |
19 | local string_char, string_byte, string_sub = string.char, string.byte, string.sub | |
20 | local table_concat = table.concat | |
21 | local math_abs, math_ldexp, math_frexp = math.abs, math.ldexp, math.frexp | |
22 | local Inf = math.huge | |
23 | local Nan = Inf - Inf | |
24 | ||
25 | local BIG_ENDIAN = false --twiddle this for your platform. | |
26 | ||
27 | local function construct (class, ...) | |
28 | return class.new(class, ...) | |
29 | end | |
30 | ||
31 | local mt_memo = {} | |
32 | ||
33 | local Field = construct{ | |
34 | new = | |
35 | function (class, self) | |
36 | local self = self or {} | |
37 | local mt = mt_memo[class] or { | |
38 | __index = class, | |
39 | __call = construct | |
40 | } | |
41 | mt_memo[class] = mt | |
42 | return setmetatable(self, mt) | |
43 | end, | |
44 | } | |
45 | ||
46 | local None = Field{ | |
47 | unpack = function (self, bytes, ix) return nil, ix end, | |
48 | pack = function (self, val) return "" end | |
49 | } | |
50 | ||
51 | local char_memo = {} | |
52 | ||
53 | local function char(n) | |
54 | local field = char_memo[n] or Field{ | |
55 | unpack = function (self, bytes, ix) | |
56 | return string_sub(bytes, ix, ix+n-1), ix+n | |
57 | end, | |
58 | pack = function (self, val) return string_sub(val, 1, n) end | |
59 | } | |
60 | char_memo[n] = field | |
61 | return field | |
62 | end | |
63 | ||
64 | local uint8 = Field{ | |
65 | unpack = function (self, bytes, ix) | |
66 | return string_byte(bytes, ix, ix), ix+1 | |
67 | end, | |
68 | pack = function (self, val) return string_char(val) end | |
69 | } | |
70 | ||
71 | local uint32 = Field{ | |
72 | unpack = | |
73 | function (self, bytes, ix) | |
74 | local a,b,c,d = string_byte(bytes, ix, ix+3) | |
75 | if BIG_ENDIAN then a,b,c,d = d,c,b,a end | |
76 | return a + b*256 + c*256^2 + d*256^3, ix+4 | |
77 | end, | |
78 | pack = | |
79 | function (self, val) | |
80 | assert(type(val) == "number", | |
81 | "unexpected value type to pack as an uint32") | |
82 | local a,b,c,d | |
83 | d = val % 2^32 | |
84 | a = d % 256; d = (d - a) / 256 | |
85 | b = d % 256; d = (d - b) / 256 | |
86 | c = d % 256; d = (d - c) / 256 | |
87 | if BIG_ENDIAN then a,b,c,d = d,c,b,a end | |
88 | return string_char(a,b,c,d) | |
89 | end | |
90 | } | |
91 | ||
92 | local int32 = uint32{ | |
93 | unpack = function (self, bytes, ix) | |
94 | local val, ix = uint32:unpack(bytes, ix) | |
95 | return val < 2^32 and val or (val - 2^31), ix | |
96 | end | |
97 | } | |
98 | ||
99 | local Byte = uint8 | |
100 | local Size_t = uint32 | |
101 | local Integer = int32 | |
102 | ||
103 | -- Opaque types: | |
104 | local Number = char(8) | |
105 | local Insn = char(4) | |
106 | ||
107 | local Struct = Field{ | |
108 | unpack = | |
109 | function (self, bytes, ix) | |
110 | local val = {} | |
111 | local i,j = 1,1 | |
112 | while self[i] do | |
113 | local field = self[i] | |
114 | local key = field.name | |
115 | if not key then key, j = j, j+1 end | |
116 | --print("unpacking struct field", key, " at index ", ix) | |
117 | val[key], ix = field:unpack(bytes, ix) | |
118 | i = i+1 | |
119 | end | |
120 | return val, ix | |
121 | end, | |
122 | pack = | |
123 | function (self, val) | |
124 | local data = {} | |
125 | local i,j = 1,1 | |
126 | while self[i] do | |
127 | local field = self[i] | |
128 | local key = field.name | |
129 | if not key then key, j = j, j+1 end | |
130 | data[i] = field:pack(val[key]) | |
131 | i = i+1 | |
132 | end | |
133 | return table_concat(data) | |
134 | end | |
135 | } | |
136 | ||
137 | local List = Field{ | |
138 | unpack = | |
139 | function (self, bytes, ix) | |
140 | local len, ix = Integer:unpack(bytes, ix) | |
141 | local vals = {} | |
142 | local field = self.type | |
143 | for i=1,len do | |
144 | --print("unpacking list field", i, " at index ", ix) | |
145 | vals[i], ix = field:unpack(bytes, ix) | |
146 | end | |
147 | return vals, ix | |
148 | end, | |
149 | pack = | |
150 | function (self, vals) | |
151 | local len = #vals | |
152 | local data = { Integer:pack(len) } | |
153 | local field = self.type | |
154 | for i=1,len do | |
155 | data[#data+1] = field:pack(vals[i]) | |
156 | end | |
157 | return table_concat(data) | |
158 | end | |
159 | } | |
160 | ||
161 | local Boolean = Field{ | |
162 | unpack = | |
163 | function (self, bytes, ix) | |
164 | local val, ix = Integer:unpack(bytes, ix) | |
165 | assert(val == 0 or val == 1, | |
166 | "unpacked an unexpected value "..val.." for a Boolean") | |
167 | return val == 1, ix | |
168 | end, | |
169 | pack = | |
170 | function (self, val) | |
171 | assert(type(val) == "boolean", | |
172 | "unexpected value type to pack as a Boolean") | |
173 | return Integer:pack(val and 1 or 0) | |
174 | end | |
175 | } | |
176 | ||
177 | local String = Field{ | |
178 | unpack = | |
179 | function (self, bytes, ix) | |
180 | local len, ix = Integer:unpack(bytes, ix) | |
181 | local val = nil | |
182 | if len > 0 then | |
183 | -- len includes trailing nul byte; ignore it | |
184 | local string_len = len - 1 | |
185 | val = bytes:sub(ix, ix+string_len-1) | |
186 | end | |
187 | return val, ix + len | |
188 | end, | |
189 | pack = | |
190 | function (self, val) | |
191 | assert(type(val) == "nil" or type(val) == "string", | |
192 | "unexpected value type to pack as a String") | |
193 | if val == nil then | |
194 | return Integer:pack(0) | |
195 | end | |
196 | return Integer:pack(#val+1) .. val .. "\000" | |
197 | end | |
198 | } | |
199 | ||
200 | local ChunkHeader = Struct{ | |
201 | char(4){name = "signature"}, | |
202 | Byte{name = "version"}, | |
203 | Byte{name = "format"}, | |
204 | Byte{name = "endianness"}, | |
205 | Byte{name = "sizeof_int"}, | |
206 | Byte{name = "sizeof_size_t"}, | |
207 | Byte{name = "sizeof_insn"}, | |
208 | Byte{name = "sizeof_Number"}, | |
209 | Byte{name = "integral_flag"}, | |
210 | } | |
211 | ||
212 | local ConstantTypes = { | |
213 | [0] = None, | |
214 | [1] = Boolean, | |
215 | [3] = Number, | |
216 | [4] = String, | |
217 | } | |
218 | local Constant = Field{ | |
219 | unpack = | |
220 | function (self, bytes, ix) | |
221 | local t, ix = Byte:unpack(bytes, ix) | |
222 | local field = ConstantTypes[t] | |
223 | assert(field, "unknown constant type "..t.." to unpack") | |
224 | local v, ix = field:unpack(bytes, ix) | |
225 | return { | |
226 | type = t, | |
227 | value = v | |
228 | }, ix | |
229 | end, | |
230 | pack = | |
231 | function (self, val) | |
232 | local t, v = val.type, val.value | |
233 | return Byte:pack(t) .. ConstantTypes[t]:pack(v) | |
234 | end | |
235 | } | |
236 | ||
237 | local Local = Struct{ | |
238 | String{name = "name"}, | |
239 | Integer{name = "startpc"}, | |
240 | Integer{name = "endpc"} | |
241 | } | |
242 | ||
243 | local Function = Struct{ | |
244 | String{name = "name"}, | |
245 | Integer{name = "line"}, | |
246 | Integer{name = "last_line"}, | |
247 | Byte{name = "num_upvalues"}, | |
248 | Byte{name = "num_parameters"}, | |
249 | Byte{name = "is_vararg"}, | |
250 | Byte{name = "max_stack_size"}, | |
251 | List{name = "insns", type = Insn}, | |
252 | List{name = "constants", type = Constant}, | |
253 | List{name = "prototypes", type = nil}, --patch type below | |
254 | List{name = "source_lines", type = Integer}, | |
255 | List{name = "locals", type = Local}, | |
256 | List{name = "upvalues", type = String}, | |
257 | } | |
258 | assert(Function[10].name == "prototypes", | |
259 | "missed the function prototype list") | |
260 | Function[10].type = Function | |
261 | ||
262 | local Chunk = Struct{ | |
263 | ChunkHeader{name = "header"}, | |
264 | Function{name = "body"} | |
265 | } | |
266 | ||
267 | local function validate(chunk) | |
268 | if type(chunk) == "function" then | |
269 | return validate(string.dump(chunk)) | |
270 | end | |
271 | local f = Chunk:unpack(chunk, 1) | |
272 | local chunk2 = Chunk:pack(f) | |
273 | ||
274 | if chunk == chunk2 then return true end | |
275 | ||
276 | local i | |
277 | local len = math.min(#chunk, #chunk2) | |
278 | for i=1,len do | |
279 | local a = chunk:sub(i,i) | |
280 | local b = chunk:sub(i,i) | |
281 | if a ~= b then | |
282 | return false, ("chunk roundtripping failed: ".. | |
283 | "first byte difference at index %d"):format(i) | |
284 | end | |
285 | end | |
286 | return false, ("chunk round tripping failed: ".. | |
287 | "original length %d vs. %d"):format(#chunk, #chunk2) | |
288 | end | |
289 | ||
290 | return { | |
291 | disassemble = function (chunk) return Chunk:unpack(chunk, 1) end, | |
292 | assemble = function (disassembled) return Chunk:pack(disassembled) end, | |
293 | validate = validate | |
294 | } |