Implement verifier as writer

go/vm/debug.go

@@ -1,121 +1,165 @@
 package vm
 
 import (
+	"bytes"
 	"fmt"
+	"io"
+	"log"
 )
 
-
+// ToString verifies all instructions in bytecode and returns an assmebly code instruction for it.
 func ToString(b []byte) (string, error) {
+	buf := bytes.NewBuffer(nil)
+	n, err := ParseAll(b, buf)
+	if err != nil {
+		return "", err
+	}
+	log.Printf("Total %v bytes written to string buffer", n)
+	return buf.String(), nil
+}
+
+// ParseAll parses and verifies all instructions from bytecode.
+//
+// If writer is not nil, the parsed instruction as assembly code line string is written to it.
+//
+// Bytecode is consumed (and written) one instruction at a time.
+//
+// It fails on any parse error encountered before the bytecode EOF is reached.
+func ParseAll(b []byte, w io.Writer) (int, error) {
 	var s string
+	var rs string
+	var rn int
 	running := true
 	for running {
 		op, bb, err := opSplit(b)
 		b = bb
 		if err != nil {
-			return "", err
+			return rn, err
 		}
-		opString := OpcodeString[op]
+		s = OpcodeString[op]
-		if opString == "" {
+		if s == "" {
-			return "", fmt.Errorf("unknown opcode: %v", op)
+			return rn, fmt.Errorf("unknown opcode: %v", op)
 		}
-		s += opString
 
 		switch op {
 		case CATCH:
 			r, n, m, bb, err := ParseCatch(b)
 			b = bb
-			if err != nil {
+			if err == nil {
-				return "", err
+				if w != nil {
-			}
 					vv := 0
 					if m {
 						vv = 1
 					}
-			s = fmt.Sprintf("%s %s %v %v # invertmatch=%v", s, r, n, vv, m)
+					if w != nil {
+						rs = fmt.Sprintf("%s %s %v %v # invertmatch=%v\n", s, r, n, vv, m)
+					}
+				}
+			}
 		case CROAK:
 			n, m, bb, err := ParseCroak(b)
 			b = bb
-			if err != nil {
+			if err == nil {
-				return "", err
+				if w != nil {
-			}
 					vv := 0
 					if m {
 						vv = 1
 					}
-			s = fmt.Sprintf("%s %v %v # invertmatch=%v", s, n, vv, m)
+					rs = fmt.Sprintf("%s %v %v # invertmatch=%v\n", s, n, vv, m)
+				}
+			}
 		case LOAD:
 			r, n, bb, err := ParseLoad(b)
 			b = bb
-			if err != nil {
+			if err == nil {
-				return "", err
+				if w != nil {
+					rs = fmt.Sprintf("%s %s %v\n", s, r, n)
+				}
 			}
-			s = fmt.Sprintf("%s %s %v", s, r, n)
 		case RELOAD:
 			r, bb, err := ParseReload(b)
 			b = bb
-			if err != nil {
+			if err == nil {
-				return "", err
+				if w != nil {
+					rs = fmt.Sprintf("%s %s\n", s, r)
+				}
 			}
-			s = fmt.Sprintf("%s %s", s, r)
 		case MAP:
 			r, bb, err := ParseMap(b)
 			b = bb
-			if err != nil {
+			if err == nil {
-				return "", err
+				if w != nil {
+					rs = fmt.Sprintf("%s %s\n", s, r)
+				}
 			}
-			s = fmt.Sprintf("%s %s", s, r)
 		case MOVE:
 			r, bb, err := ParseMove(b)
 			b = bb
-			if err != nil {
+			if err == nil {
-				return "", err
+				if w != nil {
+					rs = fmt.Sprintf("%s %s\n", s, r)
+				}
 			}
-			s = fmt.Sprintf("%s %s", s, r)
 		case INCMP:
 			r, v, bb, err := ParseInCmp(b)
 			b = bb
-			if err != nil {
+			if err == nil {
-				return "", err
+				if w != nil {
+					rs = fmt.Sprintf("%s %s %s\n", s, r, v)
+				}
 			}
-			s = fmt.Sprintf("%s %s %s", s, r, v)
 		case HALT:
 			b, err = ParseHalt(b)
-			if err != nil {
+			rs = "HALT\n"
-				return "", err
-			}
 		case MSIZE:
 			r, v, bb, err := ParseMSize(b)
 			b = bb
-			if err != nil {
+			if err == nil {
-				return "", err
+				if w != nil {
+					rs = fmt.Sprintf("%s %v %v\n", s, r, v)
+				}
 			}
-			s = fmt.Sprintf("%s %v %v", s, r, v)
 		case MOUT:
 			r, v, bb, err := ParseMOut(b)
 			b = bb
-			if err != nil {
+			if err == nil {
-				return "", err
+				if w != nil {
+					rs = fmt.Sprintf("%s %s \"%s\"\n", s, r, v)
+				}
 			}
-			s = fmt.Sprintf("%s %s \"%s\"", s, r, v)
 		case MNEXT:
 			r, v, bb, err := ParseMNext(b)
 			b = bb
-			if err != nil {
+			if err == nil {
-				return "", err
+				if w != nil {
+					rs = fmt.Sprintf("%s %s \"%s\"\n", s, r, v)
+				}
 			}
-			s = fmt.Sprintf("%s %s \"%s\"", s, r, v)
 		case MPREV:
 			r, v, bb, err := ParseMPrev(b)
 			b = bb
+			if err == nil {
+				if w != nil {
+					rs = fmt.Sprintf("%s %s \"%s\"\n", s, r, v)
+				}
+			}
+		}
 		if err != nil {
-				return "", err
+			return rn, err
 		}
-			s = fmt.Sprintf("%s %s \"%s\"", s, r, v)
+		if w != nil {
+			n, err := io.WriteString(w, rs)
+			if err != nil {
+				return rn, err
 			}
-		s += "\n"
+			rn += n
+			log.Printf("wrote %v bytes from instruction %v", n, s)
+		}
+
+		//rs += "\n"
 		if len(b) == 0 {
 			running = false
 		}
 	}
-	return s, nil
+	return rn, nil
 }

go/vm/debug_test.go

@@ -152,3 +152,18 @@ HALT
 		t.Fatalf("expected:\n\t%v\ngot:\n\t%v", expect, r)
 	}
 }
+
+func TestVerifyMultiple(t *testing.T) {
+	b := NewLine(nil, INCMP, []string{"1", "foo"}, nil, nil)
+	b = NewLine(b, INCMP, []string{"2", "bar"}, nil, nil)
+	b = NewLine(b, CATCH, []string{"aiee"}, []byte{0x02, 0x9a}, []uint8{0})
+	b = NewLine(b, LOAD, []string{"inky"}, []byte{0x2a}, nil)
+	b = NewLine(b, HALT, nil, nil, nil)
+	n, err := ParseAll(b, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if n != 0 {
+		t.Fatalf("expected write count to be 0, was %v (how is that possible)", n)
+	}
+}