github.com/taubyte/vm-wasm-utils@v1.0.2/binary/import.go (about)

     1  package binary
     2  
     3  import (
     4  	"bytes"
     5  	"fmt"
     6  
     7  	wasm "github.com/taubyte/vm-wasm-utils"
     8  	"github.com/taubyte/vm-wasm-utils/leb128"
     9  )
    10  
    11  func decodeImport(
    12  	r *bytes.Reader,
    13  	idx uint32,
    14  	memorySizer func(minPages uint32, maxPages *uint32) (min, capacity, max uint32),
    15  	enabledFeatures wasm.Features,
    16  ) (i *wasm.Import, err error) {
    17  	i = &wasm.Import{}
    18  	if i.Module, _, err = decodeUTF8(r, "import module"); err != nil {
    19  		return nil, fmt.Errorf("import[%d] error decoding module: %w", idx, err)
    20  	}
    21  
    22  	if i.Name, _, err = decodeUTF8(r, "import name"); err != nil {
    23  		return nil, fmt.Errorf("import[%d] error decoding name: %w", idx, err)
    24  	}
    25  
    26  	b, err := r.ReadByte()
    27  	if err != nil {
    28  		return nil, fmt.Errorf("import[%d] error decoding type: %w", idx, err)
    29  	}
    30  	i.Type = b
    31  	switch i.Type {
    32  	case wasm.ExternTypeFunc:
    33  		i.DescFunc, _, err = leb128.DecodeUint32(r)
    34  	case wasm.ExternTypeTable:
    35  		i.DescTable, err = decodeTable(r, enabledFeatures)
    36  	case wasm.ExternTypeMemory:
    37  		i.DescMem, err = decodeMemory(r, memorySizer)
    38  	case wasm.ExternTypeGlobal:
    39  		i.DescGlobal, err = decodeGlobalType(r)
    40  	default:
    41  		err = fmt.Errorf("%w: invalid byte for importdesc: %#x", ErrInvalidByte, b)
    42  	}
    43  	if err != nil {
    44  		return nil, fmt.Errorf("import[%d] %s[%s.%s]: %w", idx, wasm.ExternTypeName(i.Type), i.Module, i.Name, err)
    45  	}
    46  	return
    47  }
    48  
    49  // encodeImport returns the wasm.Import encoded in WebAssembly 1.0 (20191205) Binary Format.
    50  //
    51  // See https://www.w3.org/TR/2019/REC-wasm-core-1-20191205/#binary-import
    52  func encodeImport(i *wasm.Import) []byte {
    53  	data := encodeSizePrefixed([]byte(i.Module))
    54  	data = append(data, encodeSizePrefixed([]byte(i.Name))...)
    55  	data = append(data, i.Type)
    56  	switch i.Type {
    57  	case wasm.ExternTypeFunc:
    58  		data = append(data, leb128.EncodeUint32(i.DescFunc)...)
    59  	case wasm.ExternTypeTable:
    60  		data = append(data, wasm.RefTypeFuncref)
    61  		data = append(data, encodeLimitsType(i.DescTable.Min, i.DescTable.Max)...)
    62  	case wasm.ExternTypeMemory:
    63  		maxPtr := &i.DescMem.Max
    64  		if !i.DescMem.IsMaxEncoded {
    65  			maxPtr = nil
    66  		}
    67  		data = append(data, encodeLimitsType(i.DescMem.Min, maxPtr)...)
    68  	case wasm.ExternTypeGlobal:
    69  		g := i.DescGlobal
    70  		var mutable byte
    71  		if g.Mutable {
    72  			mutable = 1
    73  		}
    74  		data = append(data, g.ValType, mutable)
    75  	default:
    76  		panic(fmt.Errorf("invalid externtype: %s", wasm.ExternTypeName(i.Type)))
    77  	}
    78  	return data
    79  }