quick and dirty pure lua webassembly interpreter
implement imports, binary parsing fixes
+84
-28
+9
-7
constants.lua
+9
-7
constants.lua
···
206
206
-- Types are represented as an array where each element represents an operand:
207
207
-- * "b": byte
208
208
-- * "u": u32
209
+
-- * "d": u32 index (needs to be incremented by 1 to account for lua 1-indexed arrays)
210
+
-- (used for all index types except label indices, and _not_ memory offsets)
209
211
-- * "U": u64
210
212
-- * "i": i32
211
213
-- * "I": i64
···
219
221
[c.OP_BR] = {"u"},
220
222
[c.OP_BR_IF] = {"u"},
221
223
[c.OP_BR_TABLE] = {"Vu", "u"},
222
-
[c.OP_CALL] = {"u"},
223
-
[c.OP_CALL_INDIRECT] = {"u", "b"},
224
+
[c.OP_CALL] = {"d"},
225
+
[c.OP_CALL_INDIRECT] = {"d", "b"},
224
226
-- parametric
225
227
-- variable
226
-
[c.OP_LOCAL_GET] = {"u"},
227
-
[c.OP_LOCAL_SET] = {"u"},
228
-
[c.OP_LOCAL_TEE] = {"u"},
229
-
[c.OP_GLOBAL_GET] = {"u"},
230
-
[c.OP_GLOBAL_SET] = {"u"},
228
+
[c.OP_LOCAL_GET] = {"d"},
229
+
[c.OP_LOCAL_SET] = {"d"},
230
+
[c.OP_LOCAL_TEE] = {"d"},
231
+
[c.OP_GLOBAL_GET] = {"d"},
232
+
[c.OP_GLOBAL_SET] = {"d"},
231
233
-- memory
232
234
[c.OP_I32_LOAD] = {"u", "u"},
233
235
[c.OP_I64_LOAD] = {"u", "u"},
+7
strutil.lua
+7
strutil.lua
+68
-21
wasmlib.lua
+68
-21
wasmlib.lua
···
6
6
local memory = require("memory")
7
7
local intutil = require("intutil")
8
8
local fileutil = require("fileutil")
9
+
local strutil = require("strutil")
9
10
10
11
wasmlib.VM = {
12
+
numImportedFuncs = 0,
11
13
stack = {},
12
14
stackFrames = {},
13
15
labelStack = {},
···
15
17
types = {},
16
18
memory = {},
17
19
globals = {},
20
+
imports = {},
18
21
}
19
22
20
23
function wasmlib.VM:new()
···
413
416
end
414
417
415
418
function wasmlib.VM:step()
419
+
if self:curFrame().pc >= #self:curBody() then
420
+
self:ret()
421
+
return
422
+
end
423
+
416
424
local opcode = self:nextArg()
417
425
418
426
local c = constants.opcodes
···
569
577
return idx + 4
570
578
end
571
579
572
-
function wasmlib.VM:parseCustom(bytes, idx)
580
+
function wasmlib.VM:parseCustom(bytes, idx) -- luacheck: no unused args
573
581
-- ignore custom sections
574
582
local szlen, size = intutil.fromuleb128(bytes, idx)
575
583
return idx + szlen + size
···
612
620
return idx
613
621
end
614
622
615
-
function wasmlib.VM:parseImports(bytes, idx) -- TODO
616
-
print("warning: skipping imports section")
617
-
local szlen, size = intutil.fromuleb128(bytes, idx)
618
-
return idx + szlen + size
623
+
function wasmlib.VM:parseImports(bytes, idx, imports)
624
+
local szlen, _ = intutil.fromuleb128(bytes, idx)
625
+
idx = idx + szlen
626
+
local nilen, numImports = intutil.fromuleb128(bytes, idx)
627
+
idx = idx + nilen
628
+
629
+
for _ = 1, numImports do
630
+
local mnllen, mnameLen = intutil.fromuleb128(bytes, idx)
631
+
idx = idx + mnllen
632
+
local moduleName = strutil.bytestostr(bytes, idx, mnameLen)
633
+
idx = idx + mnameLen
634
+
local nllen, nameLen = intutil.fromuleb128(bytes, idx)
635
+
idx = idx + nllen
636
+
local importName = strutil.bytestostr(bytes, idx, nameLen)
637
+
idx = idx + nameLen
638
+
639
+
local importType = bytes[idx]
640
+
idx = idx + 1
641
+
642
+
if importType == 0x00 then
643
+
local typeidx = bytes[idx]
644
+
idx = idx + 1
645
+
table.insert(self.functions, {
646
+
typeidx = typeidx + 1,
647
+
import = imports[moduleName][importName],
648
+
})
649
+
elseif importType == 0x01 then
650
+
error("table imports not supported")
651
+
elseif importType == 0x02 then
652
+
error("memory imports not supported")
653
+
elseif importType == 0x03 then
654
+
error("global imports not supported")
655
+
else
656
+
error("invalid import type "..importType)
657
+
end
658
+
end
659
+
660
+
self.numImportedFuncs = #self.functions
661
+
return idx
619
662
end
620
663
621
664
function wasmlib.VM:parseFunctions(bytes, idx)
···
624
667
local nflen, numFuncs = intutil.fromuleb128(bytes, idx)
625
668
idx = idx + nflen
626
669
627
-
for i = 1, numFuncs do -- TODO handle imported functions
670
+
for i = self.numImportedFuncs + 1, self.numImportedFuncs + numFuncs do
628
671
local tilen, typeidx = intutil.fromuleb128(bytes, idx)
629
672
idx = idx + tilen
630
-
self.functions[i] = { typeidx = typeidx }
673
+
self.functions[i] = { typeidx = typeidx + 1 }
631
674
end
632
675
633
676
return idx
634
677
end
635
678
636
-
function wasmlib.VM:parseTables(bytes, idx) -- TODO
679
+
function wasmlib.VM:parseTables(bytes, idx, imports) -- luacheck: no unused args
637
680
print("warning: skipping tables section")
638
681
local szlen, size = intutil.fromuleb128(bytes, idx)
639
682
return idx + szlen + size
···
708
751
return idx
709
752
end
710
753
711
-
function wasmlib.VM:parseExports(bytes, idx) -- TODO
754
+
function wasmlib.VM:parseExports(bytes, idx) -- luacheck: no unused args
712
755
print("warning: skipping exports section")
713
756
local szlen, size = intutil.fromuleb128(bytes, idx)
714
757
return idx + szlen + size
715
758
end
716
759
717
-
function wasmlib.VM:parseStart(bytes, idx) -- TODO
760
+
function wasmlib.VM:parseStart(bytes, idx) -- luacheck: no unused args
718
761
print("warning: skipping start section")
719
762
local szlen, size = intutil.fromuleb128(bytes, idx)
720
763
return idx + szlen + size
721
764
end
722
765
723
-
function wasmlib.VM:parseElements(bytes, idx) -- TODO
766
+
function wasmlib.VM:parseElements(bytes, idx) -- luacheck: no unused args
724
767
print("warning: skipping elements section")
725
768
local szlen, size = intutil.fromuleb128(bytes, idx)
726
769
return idx + szlen + size
727
770
end
728
771
729
-
function wasmlib.VM:parseCode(bytes, idx) -- TODO
772
+
function wasmlib.VM:parseCode(bytes, idx)
730
773
local szlen, _ = intutil.fromuleb128(bytes, idx)
731
774
idx = idx + szlen
732
775
local nclen, numCode = intutil.fromuleb128(bytes, idx)
733
776
idx = idx + nclen
734
777
735
-
for i = 1, numCode do -- TODO handle imported functions
778
+
for i = self.numImportedFuncs + 1, self.numImportedFuncs + numCode do
736
779
-- size (ignored, not needed for decoding)
737
780
local cszlen, _ = intutil.fromuleb128(bytes, idx)
738
781
idx = idx + cszlen
···
776
819
end
777
820
778
821
local operands = constants.operandTypes[opcode] or {}
779
-
for _ = 1, #operands do
780
-
local operand = operands[i]
822
+
for j = 1, #operands do
823
+
local operand = operands[j]
781
824
if operand == "b" then
782
825
local a = bytes[idx]
783
826
idx = idx + 1
784
827
table.insert(body, a)
785
-
elseif operand == "u" or operand == "U" then
828
+
elseif operand == "u" or operand == "U" or operand == "d" then
786
829
local alen, a = intutil.fromuleb128(bytes, idx)
830
+
if operand == "d" then a = a + 1 end
787
831
idx = idx + alen
788
832
table.insert(body, a)
789
833
elseif operand == "i" then
···
812
856
end
813
857
until nestDepth == -1 -- expr is terminated with an END opcode which isn't part of any control flow structure,
814
858
-- therefore the nestDepth should end up at -1
859
+
self.functions[i].body = body
815
860
end
816
861
817
862
return idx
818
863
end
819
864
820
-
function wasmlib.VM:parseData(bytes, idx) -- TODO
865
+
function wasmlib.VM:parseData(bytes, idx)
821
866
local szlen, _ = intutil.fromuleb128(bytes, idx)
822
867
idx = idx + szlen
823
868
local ndlen, numData = intutil.fromuleb128(bytes, idx)
···
844
889
return idx
845
890
end
846
891
847
-
function wasmlib.VM:instantiate(bytes)
892
+
function wasmlib.VM:instantiate(bytes, imports)
893
+
self.imports = imports or {}
894
+
848
895
local idx = 1
849
896
idx = checkMagic(bytes, idx)
850
897
idx = checkVersion(bytes, idx)
···
872
919
if sectParser == nil then
873
920
error("unsupported section type " .. sectId)
874
921
end
875
-
idx = sectParser(self, bytes, idx)
922
+
idx = sectParser(self, bytes, idx, imports)
876
923
end
877
924
end
878
925
879
-
function wasmlib.VM:instantiateFile(path)
880
-
self:instantiate(fileutil.readBytes(path))
926
+
function wasmlib.VM:instantiateFile(path, imports)
927
+
self:instantiate(fileutil.readBytes(path), imports)
881
928
end
882
929
883
930
return wasmlib