hakurei/internal/pkg/asm.go

package pkg

import (
	"encoding/binary"
	"fmt"
	"io"
	"strconv"
	"strings"
)

type asmOutLine struct {
	pos       int
	word      int
	kindData  int64
	valueData []byte
	indent    int
	kind      string
	value     string
}

var spacingLine = asmOutLine{
	pos:       -1,
	kindData:  -1,
	valueData: nil,
	indent:    0,
	kind:      "",
	value:     "",
}

func Disassemble(r io.Reader, real bool, showHeader bool, force bool, raw bool) (s string, err error) {
	var lines []asmOutLine
	sb := new(strings.Builder)
	header := true
	pos := new(int)

	for err == nil {
		if header {
			var kind uint64
			var size uint64
			var bsize []byte
			p := *pos
			if _, kind, err = nextUint64(r, pos); err != nil {
				break
			}
			if bsize, size, err = nextUint64(r, pos); err != nil {
				break
			}
			if showHeader {
				lines = append(lines, asmOutLine{p, 8, int64(kind), bsize, 0, "head  " + intToKind(kind), ""})
			}
			for i := 0; uint64(i) < size; i++ {
				var did Checksum
				var dkind uint64
				p := *pos
				if _, dkind, err = nextUint64(r, pos); err != nil {
					break
				}
				if _, did, err = nextIdent(r, pos); err != nil {
					break
				}
				if showHeader {
					lines = append(lines, asmOutLine{p, 8, int64(dkind), nil, 1, intToKind(dkind), Encode(did)})
				}
			}
			header = false
		}
		var k uint32
		p := *pos
		if _, k, err = nextUint32(r, pos); err != nil {
			break
		}
		kind := IRValueKind(k)
		switch kind {
		case IRKindEnd:
			var a uint32
			var ba []byte
			if ba, a, err = nextUint32(r, pos); err != nil {
				break
			}
			if a&1 != 0 {
				var sum Checksum
				if _, sum, err = nextIdent(r, pos); err != nil {
					break
				}
				lines = append(lines, asmOutLine{p, 4, int64(kind), ba, 1, "end ", Encode(sum)})
			} else {
				lines = append(lines, asmOutLine{p, 4, int64(kind), []byte{0, 0, 0, 0}, 1, "end ", ""})
			}
			lines = append(lines, spacingLine)
			header = true
			continue

		case IRKindIdent:
			var a []byte
			// discard ancillary
			if a, _, err = nextUint32(r, pos); err != nil {
				break
			}
			var sum Checksum
			if _, sum, err = nextIdent(r, pos); err != nil {
				break
			}

			lines = append(lines, asmOutLine{p, 4, int64(kind), a, 1, "id  ", Encode(sum)})
			continue
		case IRKindUint32:
			var i uint32
			var bi []byte
			if bi, i, err = nextUint32(r, pos); err != nil {
				break
			}
			lines = append(lines, asmOutLine{p, 4, int64(kind), bi, 1, "int ", strconv.FormatUint(uint64(i), 10)})
		case IRKindString:
			var l uint32
			var bl []byte
			if bl, l, err = nextUint32(r, pos); err != nil {
				break
			}
			s := make([]byte, l+(wordSize-(l)%wordSize)%wordSize)
			var n int
			if n, err = r.Read(s); err != nil {
				break
			}
			*pos = *pos + n

			lines = append(lines, asmOutLine{p, 4, int64(kind), bl, 1, "str ", strconv.Quote(string(s[:l]))})
			continue
		default:
			var bi []byte
			if bi, _, err = nextUint32(r, pos); err != nil {
				break
			}
			lines = append(lines, asmOutLine{p, 4, int64(kind), bi, 1, "????", ""})
		}
	}
	if err != io.EOF {
		return
	}
	err = nil
	for _, line := range lines {
		if raw {
			if line.pos != -1 {
				sb.WriteString(fmt.Sprintf("%s\t%s\n", line.kind, line.value))
			}
		} else {
			if line.pos == -1 {
				sb.WriteString("\n")
			} else if line.word == 4 {
				sb.WriteString(fmt.Sprintf("%06x:  %04x %04x%s          %s  %s\n", line.pos, binary.LittleEndian.AppendUint32(nil, uint32(line.kindData)), line.valueData, headerSpacing(showHeader), line.kind, line.value))
			} else {
				kind := binary.LittleEndian.AppendUint64(nil, uint64(line.kindData))
				value := line.valueData
				if len(value) == 8 {
					sb.WriteString(fmt.Sprintf("%06x:  %04x %04x %04x %04x      %s  %s\n", line.pos, kind[:4], kind[4:], value[:4], value[4:], line.kind, line.value))
				} else {
					sb.WriteString(fmt.Sprintf("%06x:  %04x %04x                        %s  %s\n", line.pos, kind[:4], kind[4:], line.kind, line.value))
				}

			}
		}

	}
	return sb.String(), err
}
func nextUint32(r io.Reader, pos *int) ([]byte, uint32, error) {
	i := make([]byte, 4)
	_, err := r.Read(i)
	if err != nil {
		return i, 0, err
	}
	p := *pos + 4
	*pos = p
	return i, binary.LittleEndian.Uint32(i), nil
}
func nextUint64(r io.Reader, pos *int) ([]byte, uint64, error) {
	i := make([]byte, 8)
	_, err := r.Read(i)
	if err != nil {
		return i, 0, err
	}
	p := *pos + 8
	*pos = p
	return i, binary.LittleEndian.Uint64(i), nil
}
func nextIdent(r io.Reader, pos *int) ([]byte, Checksum, error) {
	i := make([]byte, 48)
	if _, err := r.Read(i); err != nil {
		return i, Checksum{}, err
	}
	p := *pos + 48
	*pos = p
	return i, Checksum(i), nil
}
func intToKind(i uint64) string {
	switch Kind(i) {
	case KindHTTPGet:
		return "http"
	case KindTar:
		return "tar "
	case KindExec:
		return "exec"
	case KindExecNet:
		return "exen"
	case KindFile:
		return "file"
	default:
		return fmt.Sprintf("$%d  ", i-KindCustomOffset)
	}
}
func headerSpacing(showHeader bool) string {
	if showHeader {
		return "              "
	}

	return ""
}