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package binary
import (
"bytes"
"fmt"
"io"
"github.com/tetratelabs/wazero/api"
"github.com/tetratelabs/wazero/internal/leb128"
"github.com/tetratelabs/wazero/internal/wasm"
)
func decodeTypeSection(enabledFeatures api.CoreFeatures, r *bytes.Reader) ([]wasm.FunctionType, error) {
vs, _, err := leb128.DecodeUint32(r)
if err != nil {
return nil, fmt.Errorf("get size of vector: %w", err)
}
result := make([]wasm.FunctionType, vs)
for i := uint32(0); i < vs; i++ {
if err = decodeFunctionType(enabledFeatures, r, &result[i]); err != nil {
return nil, fmt.Errorf("read %d-th type: %v", i, err)
}
}
return result, nil
}
// decodeImportSection decodes the decoded import segments plus the count per wasm.ExternType.
func decodeImportSection(
r *bytes.Reader,
memorySizer memorySizer,
memoryLimitPages uint32,
enabledFeatures api.CoreFeatures,
) (result []wasm.Import,
perModule map[string][]*wasm.Import,
funcCount, globalCount, memoryCount, tableCount wasm.Index, err error,
) {
vs, _, err := leb128.DecodeUint32(r)
if err != nil {
err = fmt.Errorf("get size of vector: %w", err)
return
}
perModule = make(map[string][]*wasm.Import)
result = make([]wasm.Import, vs)
for i := uint32(0); i < vs; i++ {
imp := &result[i]
if err = decodeImport(r, i, memorySizer, memoryLimitPages, enabledFeatures, imp); err != nil {
return
}
switch imp.Type {
case wasm.ExternTypeFunc:
imp.IndexPerType = funcCount
funcCount++
case wasm.ExternTypeGlobal:
imp.IndexPerType = globalCount
globalCount++
case wasm.ExternTypeMemory:
imp.IndexPerType = memoryCount
memoryCount++
case wasm.ExternTypeTable:
imp.IndexPerType = tableCount
tableCount++
}
perModule[imp.Module] = append(perModule[imp.Module], imp)
}
return
}
func decodeFunctionSection(r *bytes.Reader) ([]uint32, error) {
vs, _, err := leb128.DecodeUint32(r)
if err != nil {
return nil, fmt.Errorf("get size of vector: %w", err)
}
result := make([]uint32, vs)
for i := uint32(0); i < vs; i++ {
if result[i], _, err = leb128.DecodeUint32(r); err != nil {
return nil, fmt.Errorf("get type index: %w", err)
}
}
return result, err
}
func decodeTableSection(r *bytes.Reader, enabledFeatures api.CoreFeatures) ([]wasm.Table, error) {
vs, _, err := leb128.DecodeUint32(r)
if err != nil {
return nil, fmt.Errorf("error reading size")
}
if vs > 1 {
if err := enabledFeatures.RequireEnabled(api.CoreFeatureReferenceTypes); err != nil {
return nil, fmt.Errorf("at most one table allowed in module as %w", err)
}
}
ret := make([]wasm.Table, vs)
for i := range ret {
err = decodeTable(r, enabledFeatures, &ret[i])
if err != nil {
return nil, err
}
}
return ret, nil
}
func decodeMemorySection(
r *bytes.Reader,
enabledFeatures api.CoreFeatures,
memorySizer memorySizer,
memoryLimitPages uint32,
) (*wasm.Memory, error) {
vs, _, err := leb128.DecodeUint32(r)
if err != nil {
return nil, fmt.Errorf("error reading size")
}
if vs > 1 {
return nil, fmt.Errorf("at most one memory allowed in module, but read %d", vs)
} else if vs == 0 {
// memory count can be zero.
return nil, nil
}
return decodeMemory(r, enabledFeatures, memorySizer, memoryLimitPages)
}
func decodeGlobalSection(r *bytes.Reader, enabledFeatures api.CoreFeatures) ([]wasm.Global, error) {
vs, _, err := leb128.DecodeUint32(r)
if err != nil {
return nil, fmt.Errorf("get size of vector: %w", err)
}
result := make([]wasm.Global, vs)
for i := uint32(0); i < vs; i++ {
if err = decodeGlobal(r, enabledFeatures, &result[i]); err != nil {
return nil, fmt.Errorf("global[%d]: %w", i, err)
}
}
return result, nil
}
func decodeExportSection(r *bytes.Reader) ([]wasm.Export, map[string]*wasm.Export, error) {
vs, _, sizeErr := leb128.DecodeUint32(r)
if sizeErr != nil {
return nil, nil, fmt.Errorf("get size of vector: %v", sizeErr)
}
exportMap := make(map[string]*wasm.Export, vs)
exportSection := make([]wasm.Export, vs)
for i := wasm.Index(0); i < vs; i++ {
export := &exportSection[i]
err := decodeExport(r, export)
if err != nil {
return nil, nil, fmt.Errorf("read export: %w", err)
}
if _, ok := exportMap[export.Name]; ok {
return nil, nil, fmt.Errorf("export[%d] duplicates name %q", i, export.Name)
} else {
exportMap[export.Name] = export
}
}
return exportSection, exportMap, nil
}
func decodeStartSection(r *bytes.Reader) (*wasm.Index, error) {
vs, _, err := leb128.DecodeUint32(r)
if err != nil {
return nil, fmt.Errorf("get function index: %w", err)
}
return &vs, nil
}
func decodeElementSection(r *bytes.Reader, enabledFeatures api.CoreFeatures) ([]wasm.ElementSegment, error) {
vs, _, err := leb128.DecodeUint32(r)
if err != nil {
return nil, fmt.Errorf("get size of vector: %w", err)
}
result := make([]wasm.ElementSegment, vs)
for i := uint32(0); i < vs; i++ {
if err = decodeElementSegment(r, enabledFeatures, &result[i]); err != nil {
return nil, fmt.Errorf("read element: %w", err)
}
}
return result, nil
}
func decodeCodeSection(r *bytes.Reader) ([]wasm.Code, error) {
codeSectionStart := uint64(r.Len())
vs, _, err := leb128.DecodeUint32(r)
if err != nil {
return nil, fmt.Errorf("get size of vector: %w", err)
}
result := make([]wasm.Code, vs)
for i := uint32(0); i < vs; i++ {
err = decodeCode(r, codeSectionStart, &result[i])
if err != nil {
return nil, fmt.Errorf("read %d-th code segment: %v", i, err)
}
}
return result, nil
}
func decodeDataSection(r *bytes.Reader, enabledFeatures api.CoreFeatures) ([]wasm.DataSegment, error) {
vs, _, err := leb128.DecodeUint32(r)
if err != nil {
return nil, fmt.Errorf("get size of vector: %w", err)
}
result := make([]wasm.DataSegment, vs)
for i := uint32(0); i < vs; i++ {
if err = decodeDataSegment(r, enabledFeatures, &result[i]); err != nil {
return nil, fmt.Errorf("read data segment: %w", err)
}
}
return result, nil
}
func decodeDataCountSection(r *bytes.Reader) (count *uint32, err error) {
v, _, err := leb128.DecodeUint32(r)
if err != nil && err != io.EOF {
// data count is optional, so EOF is fine.
return nil, err
}
return &v, nil
}
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