mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-12-21 17:52:12 +00:00
1e7b32490d
This allows for building GoToSocial with [SQLite transpiled to WASM](https://github.com/ncruces/go-sqlite3) and accessed through [Wazero](https://wazero.io/).
270 lines
8.8 KiB
Go
270 lines
8.8 KiB
Go
package binary
|
|
|
|
import (
|
|
"bytes"
|
|
"errors"
|
|
"fmt"
|
|
|
|
"github.com/tetratelabs/wazero/api"
|
|
"github.com/tetratelabs/wazero/internal/leb128"
|
|
"github.com/tetratelabs/wazero/internal/wasm"
|
|
)
|
|
|
|
func ensureElementKindFuncRef(r *bytes.Reader) error {
|
|
elemKind, err := r.ReadByte()
|
|
if err != nil {
|
|
return fmt.Errorf("read element prefix: %w", err)
|
|
}
|
|
if elemKind != 0x0 { // ElemKind is fixed to 0x0 now: https://www.w3.org/TR/2022/WD-wasm-core-2-20220419/binary/modules.html#element-section
|
|
return fmt.Errorf("element kind must be zero but was 0x%x", elemKind)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func decodeElementInitValueVector(r *bytes.Reader) ([]wasm.Index, error) {
|
|
vs, _, err := leb128.DecodeUint32(r)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("get size of vector: %w", err)
|
|
}
|
|
|
|
vec := make([]wasm.Index, vs)
|
|
for i := range vec {
|
|
u32, _, err := leb128.DecodeUint32(r)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("read function index: %w", err)
|
|
}
|
|
|
|
if u32 >= wasm.MaximumFunctionIndex {
|
|
return nil, fmt.Errorf("too large function index in Element init: %d", u32)
|
|
}
|
|
vec[i] = u32
|
|
}
|
|
return vec, nil
|
|
}
|
|
|
|
func decodeElementConstExprVector(r *bytes.Reader, elemType wasm.RefType, enabledFeatures api.CoreFeatures) ([]wasm.Index, error) {
|
|
vs, _, err := leb128.DecodeUint32(r)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("failed to get the size of constexpr vector: %w", err)
|
|
}
|
|
vec := make([]wasm.Index, vs)
|
|
for i := range vec {
|
|
var expr wasm.ConstantExpression
|
|
err := decodeConstantExpression(r, enabledFeatures, &expr)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
switch expr.Opcode {
|
|
case wasm.OpcodeRefFunc:
|
|
if elemType != wasm.RefTypeFuncref {
|
|
return nil, fmt.Errorf("element type mismatch: want %s, but constexpr has funcref", wasm.RefTypeName(elemType))
|
|
}
|
|
v, _, _ := leb128.LoadUint32(expr.Data)
|
|
if v >= wasm.MaximumFunctionIndex {
|
|
return nil, fmt.Errorf("too large function index in Element init: %d", v)
|
|
}
|
|
vec[i] = v
|
|
case wasm.OpcodeRefNull:
|
|
if elemType != expr.Data[0] {
|
|
return nil, fmt.Errorf("element type mismatch: want %s, but constexpr has %s",
|
|
wasm.RefTypeName(elemType), wasm.RefTypeName(expr.Data[0]))
|
|
}
|
|
vec[i] = wasm.ElementInitNullReference
|
|
case wasm.OpcodeGlobalGet:
|
|
i32, _, _ := leb128.LoadInt32(expr.Data)
|
|
// Resolving the reference type from globals is done at instantiation phase. See the comment on
|
|
// wasm.elementInitImportedGlobalReferenceType.
|
|
vec[i] = wasm.WrapGlobalIndexAsElementInit(wasm.Index(i32))
|
|
default:
|
|
return nil, fmt.Errorf("const expr must be either ref.null or ref.func but was %s", wasm.InstructionName(expr.Opcode))
|
|
}
|
|
}
|
|
return vec, nil
|
|
}
|
|
|
|
func decodeElementRefType(r *bytes.Reader) (ret wasm.RefType, err error) {
|
|
ret, err = r.ReadByte()
|
|
if err != nil {
|
|
err = fmt.Errorf("read element ref type: %w", err)
|
|
return
|
|
}
|
|
if ret != wasm.RefTypeFuncref && ret != wasm.RefTypeExternref {
|
|
return 0, errors.New("ref type must be funcref or externref for element as of WebAssembly 2.0")
|
|
}
|
|
return
|
|
}
|
|
|
|
const (
|
|
// The prefix is explained at https://www.w3.org/TR/2022/WD-wasm-core-2-20220419/binary/modules.html#element-section
|
|
|
|
// elementSegmentPrefixLegacy is the legacy prefix and is only valid one before CoreFeatureBulkMemoryOperations.
|
|
elementSegmentPrefixLegacy = iota
|
|
// elementSegmentPrefixPassiveFuncrefValueVector is the passive element whose indexes are encoded as vec(varint), and reftype is fixed to funcref.
|
|
elementSegmentPrefixPassiveFuncrefValueVector
|
|
// elementSegmentPrefixActiveFuncrefValueVectorWithTableIndex is the same as elementSegmentPrefixPassiveFuncrefValueVector but active and table index is encoded.
|
|
elementSegmentPrefixActiveFuncrefValueVectorWithTableIndex
|
|
// elementSegmentPrefixDeclarativeFuncrefValueVector is the same as elementSegmentPrefixPassiveFuncrefValueVector but declarative.
|
|
elementSegmentPrefixDeclarativeFuncrefValueVector
|
|
// elementSegmentPrefixActiveFuncrefConstExprVector is active whoce reftype is fixed to funcref and indexes are encoded as vec(const_expr).
|
|
elementSegmentPrefixActiveFuncrefConstExprVector
|
|
// elementSegmentPrefixPassiveConstExprVector is passive whoce indexes are encoded as vec(const_expr), and reftype is encoded.
|
|
elementSegmentPrefixPassiveConstExprVector
|
|
// elementSegmentPrefixPassiveConstExprVector is active whoce indexes are encoded as vec(const_expr), and reftype and table index are encoded.
|
|
elementSegmentPrefixActiveConstExprVector
|
|
// elementSegmentPrefixDeclarativeConstExprVector is declarative whoce indexes are encoded as vec(const_expr), and reftype is encoded.
|
|
elementSegmentPrefixDeclarativeConstExprVector
|
|
)
|
|
|
|
func decodeElementSegment(r *bytes.Reader, enabledFeatures api.CoreFeatures, ret *wasm.ElementSegment) error {
|
|
prefix, _, err := leb128.DecodeUint32(r)
|
|
if err != nil {
|
|
return fmt.Errorf("read element prefix: %w", err)
|
|
}
|
|
|
|
if prefix != elementSegmentPrefixLegacy {
|
|
if err := enabledFeatures.RequireEnabled(api.CoreFeatureBulkMemoryOperations); err != nil {
|
|
return fmt.Errorf("non-zero prefix for element segment is invalid as %w", err)
|
|
}
|
|
}
|
|
|
|
// Encoding depends on the prefix and described at https://www.w3.org/TR/2022/WD-wasm-core-2-20220419/binary/modules.html#element-section
|
|
switch prefix {
|
|
case elementSegmentPrefixLegacy:
|
|
// Legacy prefix which is WebAssembly 1.0 compatible.
|
|
err = decodeConstantExpression(r, enabledFeatures, &ret.OffsetExpr)
|
|
if err != nil {
|
|
return fmt.Errorf("read expr for offset: %w", err)
|
|
}
|
|
|
|
ret.Init, err = decodeElementInitValueVector(r)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
ret.Mode = wasm.ElementModeActive
|
|
ret.Type = wasm.RefTypeFuncref
|
|
return nil
|
|
case elementSegmentPrefixPassiveFuncrefValueVector:
|
|
// Prefix 1 requires funcref.
|
|
if err = ensureElementKindFuncRef(r); err != nil {
|
|
return err
|
|
}
|
|
|
|
ret.Init, err = decodeElementInitValueVector(r)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
ret.Mode = wasm.ElementModePassive
|
|
ret.Type = wasm.RefTypeFuncref
|
|
return nil
|
|
case elementSegmentPrefixActiveFuncrefValueVectorWithTableIndex:
|
|
ret.TableIndex, _, err = leb128.DecodeUint32(r)
|
|
if err != nil {
|
|
return fmt.Errorf("get size of vector: %w", err)
|
|
}
|
|
|
|
if ret.TableIndex != 0 {
|
|
if err := enabledFeatures.RequireEnabled(api.CoreFeatureReferenceTypes); err != nil {
|
|
return fmt.Errorf("table index must be zero but was %d: %w", ret.TableIndex, err)
|
|
}
|
|
}
|
|
|
|
err := decodeConstantExpression(r, enabledFeatures, &ret.OffsetExpr)
|
|
if err != nil {
|
|
return fmt.Errorf("read expr for offset: %w", err)
|
|
}
|
|
|
|
// Prefix 2 requires funcref.
|
|
if err = ensureElementKindFuncRef(r); err != nil {
|
|
return err
|
|
}
|
|
|
|
ret.Init, err = decodeElementInitValueVector(r)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
ret.Mode = wasm.ElementModeActive
|
|
ret.Type = wasm.RefTypeFuncref
|
|
return nil
|
|
case elementSegmentPrefixDeclarativeFuncrefValueVector:
|
|
// Prefix 3 requires funcref.
|
|
if err = ensureElementKindFuncRef(r); err != nil {
|
|
return err
|
|
}
|
|
ret.Init, err = decodeElementInitValueVector(r)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
ret.Type = wasm.RefTypeFuncref
|
|
ret.Mode = wasm.ElementModeDeclarative
|
|
return nil
|
|
case elementSegmentPrefixActiveFuncrefConstExprVector:
|
|
err := decodeConstantExpression(r, enabledFeatures, &ret.OffsetExpr)
|
|
if err != nil {
|
|
return fmt.Errorf("read expr for offset: %w", err)
|
|
}
|
|
|
|
ret.Init, err = decodeElementConstExprVector(r, wasm.RefTypeFuncref, enabledFeatures)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
ret.Mode = wasm.ElementModeActive
|
|
ret.Type = wasm.RefTypeFuncref
|
|
return nil
|
|
case elementSegmentPrefixPassiveConstExprVector:
|
|
ret.Type, err = decodeElementRefType(r)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
ret.Init, err = decodeElementConstExprVector(r, ret.Type, enabledFeatures)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
ret.Mode = wasm.ElementModePassive
|
|
return nil
|
|
case elementSegmentPrefixActiveConstExprVector:
|
|
ret.TableIndex, _, err = leb128.DecodeUint32(r)
|
|
if err != nil {
|
|
return fmt.Errorf("get size of vector: %w", err)
|
|
}
|
|
|
|
if ret.TableIndex != 0 {
|
|
if err := enabledFeatures.RequireEnabled(api.CoreFeatureReferenceTypes); err != nil {
|
|
return fmt.Errorf("table index must be zero but was %d: %w", ret.TableIndex, err)
|
|
}
|
|
}
|
|
err := decodeConstantExpression(r, enabledFeatures, &ret.OffsetExpr)
|
|
if err != nil {
|
|
return fmt.Errorf("read expr for offset: %w", err)
|
|
}
|
|
|
|
ret.Type, err = decodeElementRefType(r)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
ret.Init, err = decodeElementConstExprVector(r, ret.Type, enabledFeatures)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
ret.Mode = wasm.ElementModeActive
|
|
return nil
|
|
case elementSegmentPrefixDeclarativeConstExprVector:
|
|
ret.Type, err = decodeElementRefType(r)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
ret.Init, err = decodeElementConstExprVector(r, ret.Type, enabledFeatures)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
ret.Mode = wasm.ElementModeDeclarative
|
|
return nil
|
|
default:
|
|
return fmt.Errorf("invalid element segment prefix: 0x%x", prefix)
|
|
}
|
|
}
|