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section.go
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section.go
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// Copyright 2017~2022 The Bottos Authors
// This file is part of the Bottos Chain library.
// Created by Rocket Core Team of Bottos.
// This program is free software: you can distribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Bottos. If not, see <http://www.gnu.org/licenses/>.
// Copyright 2017 The go-interpreter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package wasm
import (
"bytes"
"errors"
"fmt"
"io"
"io/ioutil"
"github.com/bottos-project/bottos/vm/wasm/wasm/internal/readpos"
"github.com/bottos-project/bottos/vm/wasm/wasm/leb128"
log "github.com/cihub/seelog"
)
// SectionID is a 1-byte code that encodes the section code of both known and custom sections.
type SectionID uint8
const (
// SectionIDCustom customed section id
SectionIDCustom SectionID = 0
// SectionIDType type id
SectionIDType SectionID = 1
// SectionIDImport import id
SectionIDImport SectionID = 2
// SectionIDFunction function id
SectionIDFunction SectionID = 3
// SectionIDTable table id
SectionIDTable SectionID = 4
// SectionIDMemory memory id
SectionIDMemory SectionID = 5
// SectionIDGlobal global id
SectionIDGlobal SectionID = 6
// SectionIDExport export id
SectionIDExport SectionID = 7
// SectionIDStart start id
SectionIDStart SectionID = 8
// SectionIDElement element id
SectionIDElement SectionID = 9
// SectionIDCode code id
SectionIDCode SectionID = 10
// SectionIDData data id
SectionIDData SectionID = 11
)
func (s SectionID) String() string {
n, ok := map[SectionID]string{
SectionIDCustom: "custom",
SectionIDType: "type",
SectionIDImport: "import",
SectionIDFunction: "function",
SectionIDTable: "table",
SectionIDMemory: "memory",
SectionIDGlobal: "global",
SectionIDExport: "export",
SectionIDStart: "start",
SectionIDElement: "element",
SectionIDCode: "code",
SectionIDData: "data",
}[s]
if !ok {
return "unknown"
}
return n
}
// Section is a declared section in a WASM module.
type Section struct {
Start int64
End int64
ID SectionID
// Size of this section in bytes
PayloadLen uint32
// Section name, empty if id != 0
Name string
Bytes []byte
}
// InvalidSectionIDError invalid section id
type InvalidSectionIDError SectionID
func (e InvalidSectionIDError) Error() string {
return fmt.Sprintf("wasm: invalid section ID %d", e)
}
// InvalidCodeIndexError invalid code index
type InvalidCodeIndexError int
func (e InvalidCodeIndexError) Error() string {
return fmt.Sprintf("wasm: invalid index to code section: %d", int(e))
}
// ErrUnsupportedSection unsupported section
var ErrUnsupportedSection = errors.New("wasm: unsupported section")
// MissingSectionError missing section error
type MissingSectionError SectionID
func (e MissingSectionError) Error() string {
return fmt.Sprintf("wasm: missing section %s", SectionID(e).String())
}
// reads a valid section from r. The first return value is true if and only if
// the module has been completely read.
func (m *Module) readSection(r *readpos.ReadPos) (bool, error) {
var err error
var id uint32
log.Trace("Reading section ID")
if id, err = leb128.ReadVarUint32(r); err != nil {
if err == io.EOF { // no bytes were read, the reader is empty
return true, nil
}
return false, err
}
s := Section{ID: SectionID(id)}
log.Trace("Reading payload length")
if s.PayloadLen, err = leb128.ReadVarUint32(r); err != nil {
return false, nil
}
payloadDataLen := s.PayloadLen
if s.ID == SectionIDCustom {
nameLen, nameLenSize, err := leb128.ReadVarUint32Size(r)
if err != nil {
return false, err
}
payloadDataLen -= uint32(nameLenSize)
if s.Name, err = readString(r, int(nameLen)); err != nil {
return false, err
}
payloadDataLen -= uint32(len(s.Name))
}
log.Trace("Section payload length: %d", payloadDataLen)
s.Start = r.CurPos
sectionBytes := new(bytes.Buffer)
sectionBytes.Grow(int(payloadDataLen))
sectionReader := io.LimitReader(io.TeeReader(r, sectionBytes), int64(payloadDataLen))
switch s.ID {
case SectionIDCustom:
log.Trace("section custom")
if err = m.readSectionCustom(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Other = append(m.Other, s)
}
case SectionIDType:
log.Trace("section type")
if err = m.readSectionTypes(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Types.Section = s
}
case SectionIDImport:
log.Trace("section import")
if err = m.readSectionImports(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Import.Section = s
}
case SectionIDFunction:
log.Trace("section function")
if err = m.readSectionFunctions(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Function.Section = s
}
case SectionIDTable:
log.Trace("section table")
if err = m.readSectionTables(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Table.Section = s
}
case SectionIDMemory:
log.Trace("section memory")
if err = m.readSectionMemories(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Memory.Section = s
}
case SectionIDGlobal:
log.Trace("section global")
if err = m.readSectionGlobals(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Global.Section = s
}
case SectionIDExport:
log.Trace("section export")
if err = m.readSectionExports(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Export.Section = s
}
case SectionIDStart:
log.Trace("section start")
if err = m.readSectionStart(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Start.Section = s
}
case SectionIDElement:
log.Trace("section element")
if err = m.readSectionElements(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Elements.Section = s
}
case SectionIDCode:
log.Trace("section code")
if err = m.readSectionCode(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Code.Section = s
}
case SectionIDData:
log.Trace("section data")
if err = m.readSectionData(sectionReader); err == nil {
s.End = r.CurPos
s.Bytes = sectionBytes.Bytes()
m.Data.Section = s
}
default:
return false, InvalidSectionIDError(s.ID)
}
log.Trace(err)
return false, err
}
func (m *Module) readSectionCustom(r io.Reader) error {
_, err := io.Copy(ioutil.Discard, r)
return err
}
// SectionTypes declares all function signatures that will be used in a module.
type SectionTypes struct {
Section
Entries []FunctionSig
}
func (m *Module) readSectionTypes(r io.Reader) error {
s := &SectionTypes{}
count, err := leb128.ReadVarUint32(r)
if err != nil {
return err
}
s.Entries = make([]FunctionSig, int(count))
for i := range s.Entries {
if s.Entries[i], err = readFunction(r); err != nil {
return err
}
}
m.Types = s
return nil
}
// SectionImports declares all imports that will be used in the module.
type SectionImports struct {
Section
Entries []ImportEntry
}
func (m *Module) readSectionImports(r io.Reader) error {
s := &SectionImports{}
count, err := leb128.ReadVarUint32(r)
if err != nil {
return err
}
s.Entries = make([]ImportEntry, count)
for i := range s.Entries {
s.Entries[i], err = readImportEntry(r)
if err != nil {
return err
}
}
m.Import = s
return nil
}
func readImportEntry(r io.Reader) (ImportEntry, error) {
i := ImportEntry{}
modLen, err := leb128.ReadVarUint32(r)
if err != nil {
return i, err
}
if i.ModuleName, err = readString(r, int(modLen)); err != nil {
return i, err
}
fieldLen, err := leb128.ReadVarUint32(r)
if err != nil {
return i, err
}
if i.FieldName, err = readString(r, int(fieldLen)); err != nil {
return i, err
}
if i.Kind, err = readExternal(r); err != nil {
return i, err
}
switch i.Kind {
case ExternalFunction:
log.Trace("importing function")
var t uint32
t, err = leb128.ReadVarUint32(r)
i.Type = FuncImport{t}
case ExternalTable:
log.Trace("importing table")
var table *Table
table, err = readTable(r)
if table != nil {
i.Type = TableImport{*table}
}
case ExternalMemory:
log.Trace("importing memory")
var mem *Memory
mem, err = readMemory(r)
if mem != nil {
i.Type = MemoryImport{*mem}
}
case ExternalGlobal:
log.Trace("importing global var")
var gl *GlobalVar
gl, err = readGlobalVar(r)
if gl != nil {
i.Type = GlobalVarImport{*gl}
}
default:
return i, InvalidExternalError(i.Kind)
}
return i, err
}
// SectionFunctions declares the signature of all functions defined in the module (in the code section)
type SectionFunctions struct {
Section
// Sequences of indices into (FunctionSignatues).Entries
Types []uint32
}
func (m *Module) readSectionFunctions(r io.Reader) error {
s := &SectionFunctions{}
count, err := leb128.ReadVarUint32(r)
if err != nil {
return err
}
s.Types = make([]uint32, count)
for i := range s.Types {
t, err := leb128.ReadVarUint32(r)
if err != nil {
return err
}
s.Types[i] = t
}
m.Function = s
return nil
}
// SectionTables describes all tables declared by a module.
type SectionTables struct {
Section
Entries []Table
}
func (m *Module) readSectionTables(r io.Reader) error {
s := &SectionTables{}
count, err := leb128.ReadVarUint32(r)
if err != nil {
return err
}
s.Entries = make([]Table, count)
for i := range s.Entries {
t, err := readTable(r)
if err != nil {
return err
}
s.Entries[i] = *t
}
m.Table = s
return err
}
// SectionMemories describes all linaer memories used by a module.
type SectionMemories struct {
Section
Entries []Memory
}
func (m *Module) readSectionMemories(r io.Reader) error {
s := &SectionMemories{}
count, err := leb128.ReadVarUint32(r)
if err != nil {
return err
}
s.Entries = make([]Memory, count)
for i := range s.Entries {
m, err := readMemory(r)
if err != nil {
return err
}
s.Entries[i] = *m
}
m.Memory = s
return err
}
// SectionGlobals defines the value of all global variables declared in a module.
type SectionGlobals struct {
Section
Globals []GlobalEntry
}
func (m *Module) readSectionGlobals(r io.Reader) error {
s := &SectionGlobals{}
count, err := leb128.ReadVarUint32(r)
if err != nil {
return err
}
s.Globals = make([]GlobalEntry, count)
log.Trace("%d global entries\n", count)
for i := range s.Globals {
s.Globals[i], err = readGlobalEntry(r)
if err != nil {
return err
}
}
m.Global = s
return nil
}
// GlobalEntry declares a global variable.
type GlobalEntry struct {
Type *GlobalVar // Type holds information about the value type and mutability of the variable
Init []byte // Init is an initializer expression that computes the initial value of the variable
envGlobal *EnvGlobal
}
func readGlobalEntry(r io.Reader) (e GlobalEntry, err error) {
log.Trace("reading global_type")
e.Type, err = readGlobalVar(r)
if err != nil {
log.Trace("Error!")
return
}
log.Trace("reading init expr")
// init_expr is delimited by opcode "end" (0x0b)
e.Init, err = readInitExpr(r)
log.Trace("Value:", e.Init)
return e, err
}
// SectionExports declares the export section of a module
type SectionExports struct {
Section
Entries map[string]ExportEntry
}
// DuplicateExportError duplicated export
type DuplicateExportError string
func (e DuplicateExportError) Error() string {
return fmt.Sprintf("Duplicate export entry: %s", e)
}
func (m *Module) readSectionExports(r io.Reader) error {
s := &SectionExports{}
count, err := leb128.ReadVarUint32(r)
if err != nil {
return err
}
s.Entries = make(map[string]ExportEntry, count)
for i := uint32(0); i < count; i++ {
entry, err := readExportEntry(r)
if err != nil {
return err
}
if _, exists := s.Entries[entry.FieldStr]; exists {
return DuplicateExportError(entry.FieldStr)
}
s.Entries[entry.FieldStr] = entry
}
m.Export = s
return nil
}
// ExportEntry represents an exported entry by the module
type ExportEntry struct {
FieldStr string
Kind External
Index uint32
}
func readExportEntry(r io.Reader) (ExportEntry, error) {
e := ExportEntry{}
fieldLen, err := leb128.ReadVarUint32(r)
if e.FieldStr, err = readString(r, int(fieldLen)); err != nil {
return e, err
}
if e.Kind, err = readExternal(r); err != nil {
return e, err
}
e.Index, err = leb128.ReadVarUint32(r)
return e, err
}
// SectionStartFunction represents the start function section.
type SectionStartFunction struct {
Section
Index uint32 // The index of the start function into the global index space.
}
func (m *Module) readSectionStart(r io.Reader) error {
s := &SectionStartFunction{}
var err error
s.Index, err = leb128.ReadVarUint32(r)
if err != nil {
return err
}
m.Start = s
return nil
}
// SectionElements describes the initial contents of a table's elements.
type SectionElements struct {
Section
Entries []ElementSegment
}
func (m *Module) readSectionElements(r io.Reader) error {
s := &SectionElements{}
count, err := leb128.ReadVarUint32(r)
if err != nil {
return err
}
s.Entries = make([]ElementSegment, count)
for i := range s.Entries {
s.Entries[i], err = readElementSegment(r)
if err != nil {
return err
}
}
m.Elements = s
return nil
}
// ElementSegment describes a group of repeated elements that begin at a specified offset
type ElementSegment struct {
Index uint32 // The index into the global table space, should always be 0 in the MVP.
Offset []byte // initializer expression for computing the offset for placing elements, should return an i32 value
Elems []uint32
}
func readElementSegment(r io.Reader) (ElementSegment, error) {
s := ElementSegment{}
var err error
if s.Index, err = leb128.ReadVarUint32(r); err != nil {
return s, err
}
if s.Offset, err = readInitExpr(r); err != nil {
return s, err
}
numElems, err := leb128.ReadVarUint32(r)
if err != nil {
return s, err
}
s.Elems = make([]uint32, numElems)
for i := range s.Elems {
e, err := leb128.ReadVarUint32(r)
if err != nil {
return s, err
}
s.Elems[i] = e
}
return s, nil
}
// SectionCode describes the body for every function declared inside a module.
type SectionCode struct {
Section
Bodies []FunctionBody
}
func (m *Module) readSectionCode(r io.Reader) error {
s := &SectionCode{}
count, err := leb128.ReadVarUint32(r)
if err != nil {
return err
}
s.Bodies = make([]FunctionBody, count)
log.Trace("%d function bodies\n", count)
for i := range s.Bodies {
log.Trace("Reading function %d\n", i)
if s.Bodies[i], err = readFunctionBody(r); err != nil {
return err
}
s.Bodies[i].Module = m
}
m.Code = s
if m.Function == nil || len(m.Function.Types) == 0 {
return MissingSectionError(SectionIDFunction)
}
if len(m.Function.Types) != len(s.Bodies) {
return errors.New("The number of entries in the function and code section are unequal")
}
if m.Types == nil {
return MissingSectionError(SectionIDType)
}
return nil
}
// ErrFunctionNoEnd function no end error
var ErrFunctionNoEnd = errors.New("Function body does not end with 0x0b (end)")
// FunctionBody define the function body
type FunctionBody struct {
Module *Module // The parent module containing this function body, for execution purposes
Locals []LocalEntry
Code []byte
}
func readFunctionBody(r io.Reader) (FunctionBody, error) {
f := FunctionBody{}
bodySize, err := leb128.ReadVarUint32(r)
if err != nil {
return f, err
}
body := make([]byte, bodySize)
if _, err = io.ReadFull(r, body); err != nil {
return f, err
}
bytesReader := bytes.NewBuffer(body)
localCount, err := leb128.ReadVarUint32(bytesReader)
if err != nil {
return f, err
}
f.Locals = make([]LocalEntry, localCount)
for i := range f.Locals {
if f.Locals[i], err = readLocalEntry(bytesReader); err != nil {
return f, err
}
}
log.Trace("bodySize: %d, localCount: %d\n", bodySize, localCount)
code := bytesReader.Bytes()
log.Trace("Read %d bytes for function body", len(code))
if code[len(code)-1] != end {
return f, ErrFunctionNoEnd
}
f.Code = code[:len(code)-1]
return f, nil
}
// LocalEntry define the local entry format
type LocalEntry struct {
Count uint32 // The total number of local variables of the given Type used in the function body
Type ValueType // The type of value stored by the variable
}
func readLocalEntry(r io.Reader) (LocalEntry, error) {
l := LocalEntry{}
var err error
l.Count, err = leb128.ReadVarUint32(r)
if err != nil {
return l, err
}
l.Type, err = readValueType(r)
if err != nil {
return l, err
}
return l, nil
}
// SectionData describes the initial values of a module's linear memory
type SectionData struct {
Section
Entries []DataSegment
}
func (m *Module) readSectionData(r io.Reader) error {
s := &SectionData{}
count, err := leb128.ReadVarUint32(r)
if err != nil {
return err
}
s.Entries = make([]DataSegment, count)
for i := range s.Entries {
if s.Entries[i], err = readDataSegment(r); err != nil {
return err
}
}
m.Data = s
return err
}
// DataSegment describes a group of repeated elements that begin at a specified offset in the linear memory
type DataSegment struct {
Index uint32 // The index into the global linear memory space, should always be 0 in the MVP.
Offset []byte // initializer expression for computing the offset for placing elements, should return an i32 value
Data []byte
}
func readDataSegment(r io.Reader) (DataSegment, error) {
s := DataSegment{}
var err error
if s.Index, err = leb128.ReadVarUint32(r); err != nil {
return s, err
}
if s.Offset, err = readInitExpr(r); err != nil {
return s, err
}
size, err := leb128.ReadVarUint32(r)
if err != nil {
return s, err
}
s.Data, err = readBytes(r, int(size))
return s, err
}