wasicall: fix iovec encoding

go.mod

@@ -8,7 +8,7 @@ require (
 	github.com/google/pprof v0.0.0-20230510103437-eeec1cb781c3
 	github.com/google/uuid v1.3.0
 	github.com/klauspost/compress v1.16.5
-	github.com/stealthrocket/wasi-go v0.3.0
+	github.com/stealthrocket/wasi-go v0.3.1-0.20230603195135-80f8c0d13ce3
 	github.com/stealthrocket/wazergo v0.19.0
 	github.com/stealthrocket/wzprof v0.1.5
 	github.com/tetratelabs/wazero v1.1.1-0.20230522055633-256b7a4bf970

go.sum

@@ -10,6 +10,8 @@ github.com/klauspost/compress v1.16.5 h1:IFV2oUNUzZaz+XyusxpLzpzS8Pt5rh0Z16For/d
 github.com/klauspost/compress v1.16.5/go.mod h1:ntbaceVETuRiXiv4DpjP66DpAtAGkEQskQzEyD//IeE=
 github.com/stealthrocket/wasi-go v0.3.0 h1:+L+DfnHkBmOkUmCbsyO9j1KPqsAFu426jD3HH/7BABc=
 github.com/stealthrocket/wasi-go v0.3.0/go.mod h1:LBhZHvAroNNQTejkVTMJZ01ssj3jXF+3Lkbru4cTzGQ=
+github.com/stealthrocket/wasi-go v0.3.1-0.20230603195135-80f8c0d13ce3 h1:rBxTTdWnXV5ZkNQDKKiV9tdPLdRYlCY0m0I6KaH+Uj4=
+github.com/stealthrocket/wasi-go v0.3.1-0.20230603195135-80f8c0d13ce3/go.mod h1:LBhZHvAroNNQTejkVTMJZ01ssj3jXF+3Lkbru4cTzGQ=
 github.com/stealthrocket/wazergo v0.19.0 h1:0ZBya2fBURvV+I2hGl0vcuQ8dgoUvllxQ7aYlZSA5nI=
 github.com/stealthrocket/wazergo v0.19.0/go.mod h1:riI0hxw4ndZA5e6z7PesHg2BtTftcZaMxRcoiGGipTs=
 github.com/stealthrocket/wzprof v0.1.5 h1:abEwQF9KtqV7UQ0hWk7431vul9/FxOg1eRCqwEKo9/4=

internal/timemachine/wasicall/codec.go

@@ -1268,7 +1268,7 @@ func encodeIOVecs(buffer []byte, iovecs []IOVec) []byte {
 }
 
 func encodeIOVecsPrefix(buffer []byte, iovecs []IOVec, size Size) []byte {
-	if size == 0 {
+	if int32(size) <= 0 {
 		return encodeU32(buffer, 0)
 	}
 	prefixCount := 0

internal/timemachine/wasicall/codec_test.go

@@ -0,0 +1,56 @@
+package wasicall
+
+import (
+	"testing"
+
+	"github.com/stealthrocket/timecraft/internal/assert"
+	"github.com/stealthrocket/wasi-go"
+)
+
+func TestEncodeIOVecsPrefixSameSize(t *testing.T) {
+	v := wasi.IOVec("hello world")
+
+	encoded := encodeIOVecsPrefix(nil, []wasi.IOVec{v}, 11)
+	assert.Equal(t, len(encoded), 4+4+11)
+
+	decoded, leftover, err := decodeIOVecs(encoded, nil)
+	assert.OK(t, err)
+	assert.Equal(t, len(leftover), 0)
+	assert.DeepEqual(t, decoded, []wasi.IOVec{v})
+}
+
+func TestEncodeIOVecsPrefixShortSize(t *testing.T) {
+	v := wasi.IOVec("hello world")
+
+	encoded := encodeIOVecsPrefix(nil, []wasi.IOVec{v}, 5)
+	assert.Equal(t, len(encoded), 4+4+5)
+
+	decoded, leftover, err := decodeIOVecs(encoded, nil)
+	assert.OK(t, err)
+	assert.Equal(t, len(leftover), 0)
+	assert.DeepEqual(t, decoded, []wasi.IOVec{v[:5]})
+}
+
+func TestEncodeIOVecsPrefixZeroSize(t *testing.T) {
+	v := wasi.IOVec("hello world")
+
+	encoded := encodeIOVecsPrefix(nil, []wasi.IOVec{v}, 0)
+	assert.Equal(t, len(encoded), 4)
+
+	decoded, leftover, err := decodeIOVecs(encoded, nil)
+	assert.OK(t, err)
+	assert.Equal(t, len(leftover), 0)
+	assert.DeepEqual(t, decoded, ([]wasi.IOVec)(nil))
+}
+
+func TestEncodeIOVecsPrefixNegativeSize(t *testing.T) {
+	v := wasi.IOVec("hello world")
+
+	encoded := encodeIOVecsPrefix(nil, []wasi.IOVec{v}, ^wasi.Size(0))
+	assert.Equal(t, len(encoded), 4)
+
+	decoded, leftover, err := decodeIOVecs(encoded, nil)
+	assert.OK(t, err)
+	assert.Equal(t, len(leftover), 0)
+	assert.DeepEqual(t, decoded, ([]wasi.IOVec)(nil))
+}