79 lines
2.2 KiB
Go
79 lines
2.2 KiB
Go
package binary
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import (
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"bytes"
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"fmt"
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"github.com/tetratelabs/wabin/leb128"
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"github.com/tetratelabs/wabin/wasm"
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)
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func decodeImport(
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r *bytes.Reader,
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idx uint32,
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features wasm.CoreFeatures,
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) (i *wasm.Import, err error) {
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i = &wasm.Import{}
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if i.Module, _, err = decodeUTF8(r, "import module"); err != nil {
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return nil, fmt.Errorf("import[%d] error decoding module: %w", idx, err)
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}
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if i.Name, _, err = decodeUTF8(r, "import name"); err != nil {
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return nil, fmt.Errorf("import[%d] error decoding name: %w", idx, err)
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}
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b, err := r.ReadByte()
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if err != nil {
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return nil, fmt.Errorf("import[%d] error decoding type: %w", idx, err)
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}
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i.Type = b
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switch i.Type {
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case wasm.ExternTypeFunc:
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i.DescFunc, _, err = leb128.DecodeUint32(r)
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case wasm.ExternTypeTable:
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i.DescTable, err = decodeTable(r, features)
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case wasm.ExternTypeMemory:
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i.DescMem, err = decodeMemory(r)
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case wasm.ExternTypeGlobal:
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i.DescGlobal, err = decodeGlobalType(r)
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default:
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err = fmt.Errorf("%w: invalid byte for importdesc: %#x", ErrInvalidByte, b)
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}
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if err != nil {
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return nil, fmt.Errorf("import[%d] %s[%s.%s]: %w", idx, wasm.ExternTypeName(i.Type), i.Module, i.Name, err)
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}
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return
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}
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// encodeImport returns the wasm.Import encoded in WebAssembly Binary Format.
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//
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// See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#binary-import
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func encodeImport(i *wasm.Import) []byte {
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data := encodeSizePrefixed([]byte(i.Module))
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data = append(data, encodeSizePrefixed([]byte(i.Name))...)
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data = append(data, i.Type)
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switch i.Type {
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case wasm.ExternTypeFunc:
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data = append(data, leb128.EncodeUint32(i.DescFunc)...)
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case wasm.ExternTypeTable:
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data = append(data, wasm.RefTypeFuncref)
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data = append(data, encodeLimitsType(i.DescTable.Min, i.DescTable.Max)...)
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case wasm.ExternTypeMemory:
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maxPtr := &i.DescMem.Max
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if !i.DescMem.IsMaxEncoded {
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maxPtr = nil
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}
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data = append(data, encodeLimitsType(i.DescMem.Min, maxPtr)...)
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case wasm.ExternTypeGlobal:
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g := i.DescGlobal
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var mutable byte
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if g.Mutable {
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mutable = 1
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}
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data = append(data, g.ValType, mutable)
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default:
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panic(fmt.Errorf("invalid externtype: %s", wasm.ExternTypeName(i.Type)))
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}
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return data
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}
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