proc/eval: Support type casts between basic types

_fixtures/testvariables3.go

@@ -93,11 +93,14 @@ func main() {
 	m2 := map[int]*astruct{1: &astruct{10, 11}}
 	m3 := map[astruct]int{{1, 1}: 42, {2, 2}: 43}
 	up1 := unsafe.Pointer(&i1)
+	i4 := 800
+	i5 := -3
+	i6 := -500
 
 	var amb1 = 1
 	runtime.Breakpoint()
 	for amb1 := 0; amb1 < 10; amb1++ {
 		fmt.Println(amb1)
 	}
-	fmt.Println(i1, i2, i3, p1, amb1, s1, a1, p2, p3, s2, as1, str1, f1, fn1, fn2, nilslice, nilptr, ch1, chnil, m1, mnil, m2, m3, up1)
+	fmt.Println(i1, i2, i3, p1, amb1, s1, a1, p2, p3, s2, as1, str1, f1, fn1, fn2, nilslice, nilptr, ch1, chnil, m1, mnil, m2, m3, up1, i4, i5, i6)
 }

proc/eval.go

@@ -3,6 +3,7 @@ package proc
 import (
 	"bytes"
 	"debug/dwarf"
+	"encoding/binary"
 	"fmt"
 	"go/ast"
 	"go/constant"
@@ -165,7 +166,7 @@ func (scope *EvalScope) evalTypeCast(node *ast.CallExpr) (*Variable, error) {
 		fnnode = p.X
 	}
 
-	var typ dwarf.Type
+	var styp, typ dwarf.Type
 
 	if snode, ok := fnnode.(*ast.StarExpr); ok {
 		// Pointer types only appear in the dwarf informations when
@@ -177,33 +178,103 @@ func (scope *EvalScope) evalTypeCast(node *ast.CallExpr) (*Variable, error) {
 			return nil, err
 		}
 		typ = &dwarf.PtrType{dwarf.CommonType{int64(scope.Thread.dbp.arch.PtrSize()), exprToString(fnnode)}, ptyp}
+		styp = typ
 	} else {
-		typ, err = scope.findType(exprToString(fnnode))
+		styp, err = scope.findType(exprToString(fnnode))
 		if err != nil {
 			return nil, err
 		}
+		typ = resolveTypedef(styp)
 	}
 
-	// only supports cast of integer constants into pointers
-	ptyp, isptrtyp := typ.(*dwarf.PtrType)
-	if !isptrtyp {
-		return nil, fmt.Errorf("can not convert \"%s\" to %s", exprToString(node.Args[0]), typ.String())
-	}
+	converr := fmt.Errorf("can not convert \"%s\" to %s", exprToString(node.Args[0]), typ.String())
 
-	switch argv.Kind {
-	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		// ok
-	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
-		// ok
-	default:
-		return nil, fmt.Errorf("can not convert \"%s\" to %s", exprToString(node.Args[0]), typ.String())
+	v := newVariable("", 0, styp, scope.Thread)
+	v.loaded = true
+
+	switch ttyp := typ.(type) {
+	case *dwarf.PtrType:
+		switch argv.Kind {
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			// ok
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			// ok
+		default:
+			return nil, converr
+		}
+
+		n, _ := constant.Int64Val(argv.Value)
+
+		v.Children = []Variable{*newVariable("", uintptr(n), ttyp.Type, scope.Thread)}
+		return v, nil
+
+	case *dwarf.UintType:
+		switch argv.Kind {
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			n, _ := constant.Int64Val(argv.Value)
+			v.Value = constant.MakeUint64(convertInt(uint64(n), false, ttyp.Size()))
+			return v, nil
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			n, _ := constant.Uint64Val(argv.Value)
+			v.Value = constant.MakeUint64(convertInt(n, false, ttyp.Size()))
+			return v, nil
+		case reflect.Float32, reflect.Float64:
+			x, _ := constant.Float64Val(argv.Value)
+			v.Value = constant.MakeUint64(uint64(x))
+			return v, nil
+		}
+	case *dwarf.IntType:
+		switch argv.Kind {
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			n, _ := constant.Int64Val(argv.Value)
+			v.Value = constant.MakeInt64(int64(convertInt(uint64(n), true, ttyp.Size())))
+			return v, nil
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			n, _ := constant.Uint64Val(argv.Value)
+			v.Value = constant.MakeInt64(int64(convertInt(n, true, ttyp.Size())))
+			return v, nil
+		case reflect.Float32, reflect.Float64:
+			x, _ := constant.Float64Val(argv.Value)
+			v.Value = constant.MakeInt64(int64(x))
+			return v, nil
+		}
+	case *dwarf.FloatType:
+		switch argv.Kind {
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			fallthrough
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			fallthrough
+		case reflect.Float32, reflect.Float64:
+			v.Value = argv.Value
+			return v, nil
+		}
+	case *dwarf.ComplexType:
+		switch argv.Kind {
+		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+			fallthrough
+		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			fallthrough
+		case reflect.Float32, reflect.Float64:
+			v.Value = argv.Value
+			return v, nil
+		}
 	}
 
-	n, _ := constant.Int64Val(argv.Value)
+	return nil, converr
+}
 
-	v := newVariable("", 0, ptyp, scope.Thread)
-	v.Children = []Variable{*newVariable("", uintptr(n), ptyp.Type, scope.Thread)}
-	return v, nil
+func convertInt(n uint64, signed bool, size int64) uint64 {
+	buf := make([]byte, 64/8)
+	binary.BigEndian.PutUint64(buf, n)
+	m := 64/8 - int(size)
+	s := byte(0)
+	if signed && (buf[m]&0x80 > 0) {
+		s = 0xff
+	}
+	for i := 0; i < m; i++ {
+		buf[i] = s
+	}
+	return uint64(binary.BigEndian.Uint64(buf))
 }
 
 // Evaluates identifier expressions

proc/variables.go

@@ -118,14 +118,7 @@ func newVariable(name string, addr uintptr, dwarfType dwarf.Type, thread *Thread
 		thread:    thread,
 	}
 
-	v.RealType = v.DwarfType
-	for {
-		if tt, ok := v.RealType.(*dwarf.TypedefType); ok {
-			v.RealType = tt.Type
-		} else {
-			break
-		}
-	}
+	v.RealType = resolveTypedef(v.DwarfType)
 
 	switch t := v.RealType.(type) {
 	case *dwarf.PtrType:
@@ -201,6 +194,16 @@ func newVariable(name string, addr uintptr, dwarfType dwarf.Type, thread *Thread
 	return v
 }
 
+func resolveTypedef(typ dwarf.Type) dwarf.Type {
+	for {
+		if tt, ok := typ.(*dwarf.TypedefType); ok {
+			typ = tt.Type
+		} else {
+			return typ
+		}
+	}
+}
+
 func newConstant(val constant.Value, thread *Thread) *Variable {
 	v := &Variable{Value: val, thread: thread, loaded: true}
 	switch val.Kind() {

service/test/variables_test.go

@@ -487,6 +487,16 @@ func TestEvalExpression(t *testing.T) {
 		{"*(i2 + i3)", false, "", "", "", fmt.Errorf("expression \"(i2 + i3)\" (int) can not be dereferenced")},
 		{"i2.member", false, "", "", "", fmt.Errorf("i2 (type int) is not a struct")},
 		{"fmt.Println(\"hello\")", false, "", "", "", fmt.Errorf("no type entry found")},
+
+		// typecasts
+		{"uint(i2)", false, "2", "", "uint", nil},
+		{"int8(i2)", false, "2", "", "int8", nil},
+		{"int(f1)", false, "3", "", "int", nil},
+		{"complex128(f1)", false, "(3 + 0i)", "", "complex128", nil},
+		{"uint8(i4)", false, "32", "", "uint8", nil},
+		{"uint8(i5)", false, "253", "", "uint8", nil},
+		{"int8(i5)", false, "-3", "", "int8", nil},
+		{"int8(i6)", false, "12", "", "int8", nil},
 	}
 
 	withTestProcess("testvariables3", t, func(p *proc.Process, fixture protest.Fixture) {