func (uls UnknownLoaders) Load(r reader.Reader, payloadLen uint32) (err error) {
defer func() {
err = errutil.ErrorOrPanic(recover())
}()
load := loader.L{r}
nameLen := load.Varuint32()
if nameLen > maxSectionNameLen {
panic(errors.New("unknown section name is too long"))
}
name := string(load.Bytes(nameLen))
if f := uls[name]; f != nil {
if err := f(name, load); err != nil {
panic(err)
}
} else {
if _, err := io.CopyN(ioutil.Discard, load, int64(payloadLen)); err != nil {
panic(err)
}
}
return
}
func (ns *NameSection) Load(_ string, r reader.Reader) (err error) {
defer func() {
err = errutil.ErrorOrPanic(recover())
}()
load := loader.L{r}
count := load.Varuint32()
ns.FunctionNames = make([]FunctionName, count)
for i := range ns.FunctionNames {
fn := &ns.FunctionNames[i]
funNameLen := load.Varuint32()
fn.FunName = string(load.Bytes(funNameLen))
localCount := load.Varuint32()
fn.LocalNames = make([]string, localCount)
for j := range fn.LocalNames {
localNameLen := load.Varuint32()
fn.LocalNames[j] = string(load.Bytes(localNameLen))
}
}
return
}
func (m *Module) genData(load loader.L) {
if debug {
debugf("data section")
debugDepth++
}
if m.memoryOffset&15 != 0 {
// not 16-byte aligned? (assume at least 8-byte alignment.)
n := len(m.globals)
m.globals = append(m.globals, global{})
m.data = appendGlobalsData(m.data, m.globals[n:])
m.memoryOffset = len(m.data)
}
for i := range load.Count() {
if debug {
debugf("data segment")
debugDepth++
}
if index := load.Varuint32(); index != 0 {
panic(fmt.Errorf("unsupported memory index: %d", index))
}
offset := readOffsetInitExpr(load, m)
size := load.Varuint32()
needMemorySize := int64(offset) + int64(size)
if needMemorySize >= int64(m.memoryLimits.initial) {
panic(fmt.Errorf("memory segment #%d exceeds initial memory size", i))
}
needDataSize := int64(m.memoryOffset) + needMemorySize
if needDataSize > int64(len(m.data)) {
if int64(cap(m.data)) >= needDataSize {
m.data = m.data[:needDataSize]
} else {
buf := make([]byte, needDataSize)
copy(buf, m.data)
m.data = buf
}
}
dataOffset := m.memoryOffset + int(offset)
load.Into(m.data[dataOffset:needDataSize])
if debug {
debugDepth--
debugf("data segmented: offset=0x%x size=0x%x", offset, size)
}
}
if debug {
debugDepth--
debugf("data sectioned")
}
}
func readSectionHeader(load loader.L, expectId byte, idError string) (ok bool) {
id, err := load.ReadByte()
if err != nil {
if err == io.EOF {
return
}
panic(err)
}
if id != expectId {
panic(errors.New(idError))
}
load.Varuint32() // payload len
ok = true
return
}
func copySection(w io.Writer, r reader.Reader, expectId byte) (ok bool) {
store := storer{w}
load := loader.L{Reader: r}
loop:
for {
id, err := load.ReadByte()
if err != nil {
if err == io.EOF {
return
}
panic(err)
}
switch {
case id == sectionids.Unknown:
payloadLen := load.Varuint32()
if _, err := io.CopyN(ioutil.Discard, load, int64(payloadLen)); err != nil {
panic(err)
}
case id == expectId:
store.Byte(id)
break loop
default:
load.UnreadByte()
return
}
}
payloadLen := load.Varuint32()
store.Varuint32(payloadLen)
if _, err := io.CopyN(store, load, int64(payloadLen)); err != nil {
panic(err)
}
ok = true
return
}
func readInitExpr(load loader.L, m *Module) (valueBits uint64, t types.T) {
op := opcode(load.Byte())
switch op {
case opcodeI32Const:
valueBits = uint64(int64(load.Varint32()))
t = types.I32
case opcodeI64Const:
valueBits = uint64(load.Varint64())
t = types.I64
case opcodeF32Const:
valueBits = uint64(load.Uint32())
t = types.F32
case opcodeF64Const:
valueBits = load.Uint64()
t = types.F64
case opcodeGetGlobal:
i := load.Varuint32()
if i >= uint32(m.numImportGlobals) {
panic(fmt.Errorf("import global index out of bounds in initializer expression: %d", i))
}
g := m.globals[i]
valueBits = g.init
t = g.t
default:
panic(fmt.Errorf("unsupported operation in initializer expression: %s", op))
}
if op := opcode(load.Byte()); op != opcodeEnd {
panic(fmt.Errorf("unexpected operation in initializer expression when expecting end: %s", op))
}
return
}
func readResizableLimits(load loader.L, maxInitial, maxMaximum uint32, scale int) resizableLimits {
flags := load.Varuint32()
initial := load.Varuint32()
if initial > maxInitial {
panic(fmt.Errorf("initial memory size is too large: %d", initial))
}
maximum := maxMaximum
if (flags & resizableLimitsFlagMaximum) != 0 {
maximum = load.Varuint32()
if maximum > maxMaximum {
maximum = maxMaximum
}
if maximum < initial {
panic(fmt.Errorf("maximum memory size %d is smaller than initial memory size %d", maximum, initial))
}
}
return resizableLimits{int(initial) * scale, int(maximum) * scale, true}
}
func (m moduleLoader) loadUntil(load loader.L, untilSection byte) byte {
var header struct {
MagicNumber uint32
Version uint32
}
if err := binary.Read(load, binary.LittleEndian, &header); err != nil {
panic(err)
}
if header.MagicNumber != moduleMagicNumber {
panic(errors.New("not a WebAssembly module"))
}
if header.Version != moduleVersion {
panic(fmt.Errorf("unsupported module version: %d", header.Version))
}
var skipSection func(byte, uint32) error
if m.UnknownSectionLoader != nil {
skipSection = func(id byte, payloadLen uint32) (err error) {
if id == sectionids.Unknown {
err = m.UnknownSectionLoader(load, payloadLen)
} else {
_, err = io.CopyN(ioutil.Discard, load, int64(payloadLen))
}
return
}
} else {
skipSection = func(id byte, payloadLen uint32) (err error) {
_, err = io.CopyN(ioutil.Discard, load, int64(payloadLen))
return
}
}
var seenId byte
for {
id, err := load.ReadByte()
if err != nil {
if err == io.EOF {
return 0
}
panic(err)
}
if id != sectionids.Unknown {
if id <= seenId {
panic(fmt.Errorf("section 0x%x follows section 0x%x", id, seenId))
}
seenId = id
}
if id >= untilSection {
load.UnreadByte()
return id
}
payloadLen := load.Varuint32()
if f := sectionLoaders[id]; f != nil {
f(m, load)
} else if err := skipSection(id, payloadLen); err != nil {
panic(err)
}
}
}