1package binary
 2
 3import (
 4	"bytes"
 5	"fmt"
 6	"io"
 7	"unicode/utf8"
 8	"unsafe"
 9
10	"github.com/tetratelabs/wazero/internal/leb128"
11	"github.com/tetratelabs/wazero/internal/wasm"
12)
13
14func decodeValueTypes(r *bytes.Reader, num uint32) ([]wasm.ValueType, error) {
15	if num == 0 {
16		return nil, nil
17	}
18
19	ret := make([]wasm.ValueType, num)
20	_, err := io.ReadFull(r, ret)
21	if err != nil {
22		return nil, err
23	}
24
25	for _, v := range ret {
26		switch v {
27		case wasm.ValueTypeI32, wasm.ValueTypeF32, wasm.ValueTypeI64, wasm.ValueTypeF64,
28			wasm.ValueTypeExternref, wasm.ValueTypeFuncref, wasm.ValueTypeV128:
29		default:
30			return nil, fmt.Errorf("invalid value type: %d", v)
31		}
32	}
33	return ret, nil
34}
35
36// decodeUTF8 decodes a size prefixed string from the reader, returning it and the count of bytes read.
37// contextFormat and contextArgs apply an error format when present
38func decodeUTF8(r *bytes.Reader, contextFormat string, contextArgs ...interface{}) (string, uint32, error) {
39	size, sizeOfSize, err := leb128.DecodeUint32(r)
40	if err != nil {
41		return "", 0, fmt.Errorf("failed to read %s size: %w", fmt.Sprintf(contextFormat, contextArgs...), err)
42	}
43
44	if size == 0 {
45		return "", uint32(sizeOfSize), nil
46	}
47
48	buf := make([]byte, size)
49	if _, err = io.ReadFull(r, buf); err != nil {
50		return "", 0, fmt.Errorf("failed to read %s: %w", fmt.Sprintf(contextFormat, contextArgs...), err)
51	}
52
53	if !utf8.Valid(buf) {
54		return "", 0, fmt.Errorf("%s is not valid UTF-8", fmt.Sprintf(contextFormat, contextArgs...))
55	}
56
57	ret := unsafe.String(&buf[0], int(size))
58	return ret, size + uint32(sizeOfSize), nil
59}