accounts/abi: improve type handling, add event support (ethereum#14743)

accounts/abi/abi.go

@@ -20,10 +20,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"reflect"
-	"strings"
-
-	"github.com/ethereum/go-ethereum/common"
 )
 
 // The ABI holds information about a contract's context and available
@@ -76,106 +72,27 @@ func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error) {
 	return append(method.Id(), arguments...), nil
 }
 
-// these variable are used to determine certain types during type assertion for
-// assignment.
-var (
-	r_interSlice = reflect.TypeOf([]interface{}{})
-	r_hash       = reflect.TypeOf(common.Hash{})
-	r_bytes      = reflect.TypeOf([]byte{})
-	r_byte       = reflect.TypeOf(byte(0))
-)
-
 // Unpack output in v according to the abi specification
-func (abi ABI) Unpack(v interface{}, name string, output []byte) error {
-	var method = abi.Methods[name]
-
-	if len(output) == 0 {
-		return fmt.Errorf("abi: unmarshalling empty output")
-	}
-
-	// make sure the passed value is a pointer
-	valueOf := reflect.ValueOf(v)
-	if reflect.Ptr != valueOf.Kind() {
-		return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
+func (abi ABI) Unpack(v interface{}, name string, output []byte) (err error) {
+	if err = bytesAreProper(output); err != nil {
+		return err
 	}
-
-	var (
-		value = valueOf.Elem()
-		typ   = value.Type()
-	)
-
-	if len(method.Outputs) > 1 {
-		switch value.Kind() {
-		// struct will match named return values to the struct's field
-		// names
-		case reflect.Struct:
-			for i := 0; i < len(method.Outputs); i++ {
-				marshalledValue, err := toGoType(i, method.Outputs[i], output)
-				if err != nil {
-					return err
-				}
-				reflectValue := reflect.ValueOf(marshalledValue)
-
-				for j := 0; j < typ.NumField(); j++ {
-					field := typ.Field(j)
-					// TODO read tags: `abi:"fieldName"`
-					if field.Name == strings.ToUpper(method.Outputs[i].Name[:1])+method.Outputs[i].Name[1:] {
-						if err := set(value.Field(j), reflectValue, method.Outputs[i]); err != nil {
-							return err
-						}
-					}
-				}
-			}
-		case reflect.Slice:
-			if !value.Type().AssignableTo(r_interSlice) {
-				return fmt.Errorf("abi: cannot marshal tuple in to slice %T (only []interface{} is supported)", v)
-			}
-
-			// if the slice already contains values, set those instead of the interface slice itself.
-			if value.Len() > 0 {
-				if len(method.Outputs) > value.Len() {
-					return fmt.Errorf("abi: cannot marshal in to slices of unequal size (require: %v, got: %v)", len(method.Outputs), value.Len())
-				}
-
-				for i := 0; i < len(method.Outputs); i++ {
-					marshalledValue, err := toGoType(i, method.Outputs[i], output)
-					if err != nil {
-						return err
-					}
-					reflectValue := reflect.ValueOf(marshalledValue)
-					if err := set(value.Index(i).Elem(), reflectValue, method.Outputs[i]); err != nil {
-						return err
-					}
-				}
-				return nil
-			}
-
-			// create a new slice and start appending the unmarshalled
-			// values to the new interface slice.
-			z := reflect.MakeSlice(typ, 0, len(method.Outputs))
-			for i := 0; i < len(method.Outputs); i++ {
-				marshalledValue, err := toGoType(i, method.Outputs[i], output)
-				if err != nil {
-					return err
-				}
-				z = reflect.Append(z, reflect.ValueOf(marshalledValue))
-			}
-			value.Set(z)
-		default:
-			return fmt.Errorf("abi: cannot unmarshal tuple in to %v", typ)
-		}
-
+	// since there can't be naming collisions with contracts and events,
+	// we need to decide whether we're calling a method or an event
+	var unpack unpacker
+	if method, ok := abi.Methods[name]; ok {
+		unpack = method
+	} else if event, ok := abi.Events[name]; ok {
+		unpack = event
 	} else {
-		marshalledValue, err := toGoType(0, method.Outputs[0], output)
-		if err != nil {
-			return err
-		}
-		if err := set(value, reflect.ValueOf(marshalledValue), method.Outputs[0]); err != nil {
-			return err
-		}
+		return fmt.Errorf("abi: could not locate named method or event.")
 	}
 
-	return nil
+	// requires a struct to unpack into for a tuple return...
+	if unpack.isTupleReturn() {
+		return unpack.tupleUnpack(v, output)
+	}
+	return unpack.singleUnpack(v, output)
 }
 
 func (abi *ABI) UnmarshalJSON(data []byte) error {

accounts/abi/abi_test.go

@@ -29,25 +29,6 @@ import (
 	"github.com/ethereum/go-ethereum/crypto"
 )
 
-// formatSilceOutput add padding to the value and adds a size
-func formatSliceOutput(v ...[]byte) []byte {
-	off := common.LeftPadBytes(big.NewInt(int64(len(v))).Bytes(), 32)
-	output := append(off, make([]byte, 0, len(v)*32)...)
-
-	for _, value := range v {
-		output = append(output, common.LeftPadBytes(value, 32)...)
-	}
-	return output
-}
-
-// quick helper padding
-func pad(input []byte, size int, left bool) []byte {
-	if left {
-		return common.LeftPadBytes(input, size)
-	}
-	return common.RightPadBytes(input, size)
-}
-
 const jsondata = `
 [
 	{ "type" : "function", "name" : "balance", "constant" : true },
@@ -191,7 +172,7 @@ func TestMethodSignature(t *testing.T) {
 		t.Errorf("expected ids to match %x != %x", m.Id(), idexp)
 	}
 
-	uintt, _ := NewType("uint")
+	uintt, _ := NewType("uint256")
 	m = Method{"foo", false, []Argument{{"bar", uintt, false}}, nil}
 	exp = "foo(uint256)"
 	if m.Sig() != exp {

accounts/abi/bind/bind_test.go

@@ -472,7 +472,7 @@ func TestBindings(t *testing.T) {
 		t.Fatalf("failed to create temporary workspace: %v", err)
 	}
 	defer os.RemoveAll(ws)
-
+	
 	pkg := filepath.Join(ws, "bindtest")
 	if err = os.MkdirAll(pkg, 0700); err != nil {
 		t.Fatalf("failed to create package: %v", err)

accounts/abi/error.go

@@ -39,43 +39,43 @@ func formatSliceString(kind reflect.Kind, sliceSize int) string {
 // type in t.
 func sliceTypeCheck(t Type, val reflect.Value) error {
 	if val.Kind() != reflect.Slice && val.Kind() != reflect.Array {
-		return typeErr(formatSliceString(t.Kind, t.SliceSize), val.Type())
+		return typeErr(formatSliceString(t.Kind, t.Size), val.Type())
 	}
-	if t.IsArray && val.Len() != t.SliceSize {
-		return typeErr(formatSliceString(t.Elem.Kind, t.SliceSize), formatSliceString(val.Type().Elem().Kind(), val.Len()))
+
+	if t.T == ArrayTy && val.Len() != t.Size {
+		return typeErr(formatSliceString(t.Elem.Kind, t.Size), formatSliceString(val.Type().Elem().Kind(), val.Len()))
 	}
 
-	if t.Elem.IsSlice {
+	if t.Elem.T == SliceTy {
 		if val.Len() > 0 {
 			return sliceTypeCheck(*t.Elem, val.Index(0))
 		}
-	} else if t.Elem.IsArray {
+	} else if t.Elem.T == ArrayTy {
 		return sliceTypeCheck(*t.Elem, val.Index(0))
 	}
 
 	if elemKind := val.Type().Elem().Kind(); elemKind != t.Elem.Kind {
-		return typeErr(formatSliceString(t.Elem.Kind, t.SliceSize), val.Type())
+		return typeErr(formatSliceString(t.Elem.Kind, t.Size), val.Type())
 	}
 	return nil
 }
 
 // typeCheck checks that the given reflection value can be assigned to the reflection
 // type in t.
 func typeCheck(t Type, value reflect.Value) error {
-	if t.IsSlice || t.IsArray {
+	if t.T == SliceTy || t.T == ArrayTy {
 		return sliceTypeCheck(t, value)
 	}
 
 	// Check base type validity. Element types will be checked later on.
 	if t.Kind != value.Kind() {
 		return typeErr(t.Kind, value.Kind())
+	} else if t.T == FixedBytesTy && t.Size != value.Len() {
+		return typeErr(t.Type, value.Type())
+	} else {
+		return nil
 	}
-	return nil
-}
 
-// varErr returns a formatted error.
-func varErr(expected, got reflect.Kind) error {
-	return typeErr(expected, got)
 }
 
 // typeErr returns a formatted type casting error.

accounts/abi/event.go

@@ -18,6 +18,7 @@ package abi
 
 import (
 	"fmt"
+	"reflect"
 	"strings"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -44,3 +45,93 @@ func (e Event) Id() common.Hash {
 	}
 	return common.BytesToHash(crypto.Keccak256([]byte(fmt.Sprintf("%v(%v)", e.Name, strings.Join(types, ",")))))
 }
+
+// unpacks an event return tuple into a struct of corresponding go types
+//
+// Unpacking can be done into a struct or a slice/array.
+func (e Event) tupleUnpack(v interface{}, output []byte) error {
+	// make sure the passed value is a pointer
+	valueOf := reflect.ValueOf(v)
+	if reflect.Ptr != valueOf.Kind() {
+		return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
+	}
+
+	var (
+		value = valueOf.Elem()
+		typ   = value.Type()
+	)
+
+	if value.Kind() != reflect.Struct {
+		return fmt.Errorf("abi: cannot unmarshal tuple in to %v", typ)
+	}
+
+	j := 0
+	for i := 0; i < len(e.Inputs); i++ {
+		input := e.Inputs[i]
+		if input.Indexed {
+			// can't read, continue
+			continue
+		} else if input.Type.T == ArrayTy {
+			// need to move this up because they read sequentially
+			j += input.Type.Size
+		}
+		marshalledValue, err := toGoType((i+j)*32, input.Type, output)
+		if err != nil {
+			return err
+		}
+		reflectValue := reflect.ValueOf(marshalledValue)
+
+		switch value.Kind() {
+		case reflect.Struct:
+			for j := 0; j < typ.NumField(); j++ {
+				field := typ.Field(j)
+				// TODO read tags: `abi:"fieldName"`
+				if field.Name == strings.ToUpper(e.Inputs[i].Name[:1])+e.Inputs[i].Name[1:] {
+					if err := set(value.Field(j), reflectValue, e.Inputs[i]); err != nil {
+						return err
+					}
+				}
+			}
+		case reflect.Slice, reflect.Array:
+			if value.Len() < i {
+				return fmt.Errorf("abi: insufficient number of arguments for unpack, want %d, got %d", len(e.Inputs), value.Len())
+			}
+			v := value.Index(i)
+			if v.Kind() != reflect.Ptr && v.Kind() != reflect.Interface {
+				return fmt.Errorf("abi: cannot unmarshal %v in to %v", v.Type(), reflectValue.Type())
+			}
+			reflectValue := reflect.ValueOf(marshalledValue)
+			if err := set(v.Elem(), reflectValue, e.Inputs[i]); err != nil {
+				return err
+			}
+		default:
+			return fmt.Errorf("abi: cannot unmarshal tuple in to %v", typ)
+		}
+	}
+	return nil
+}
+
+func (e Event) isTupleReturn() bool { return len(e.Inputs) > 1 }
+
+func (e Event) singleUnpack(v interface{}, output []byte) error {
+	// make sure the passed value is a pointer
+	valueOf := reflect.ValueOf(v)
+	if reflect.Ptr != valueOf.Kind() {
+		return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
+	}
+
+	if e.Inputs[0].Indexed {
+		return fmt.Errorf("abi: attempting to unpack indexed variable into element.")
+	}
+
+	value := valueOf.Elem()
+
+	marshalledValue, err := toGoType(0, e.Inputs[0].Type, output)
+	if err != nil {
+		return err
+	}
+	if err := set(value, reflect.ValueOf(marshalledValue), e.Inputs[0]); err != nil {
+		return err
+	}
+	return nil
+}

accounts/abi/event_test.go

@@ -31,7 +31,7 @@ func TestEventId(t *testing.T) {
 	}{
 		{
 			definition: `[
-			{ "type" : "event", "name" : "balance", "inputs": [{ "name" : "in", "type": "uint" }] },
+			{ "type" : "event", "name" : "balance", "inputs": [{ "name" : "in", "type": "uint256" }] },
 			{ "type" : "event", "name" : "check", "inputs": [{ "name" : "t", "type": "address" }, { "name": "b", "type": "uint256" }] }
 			]`,
 			expectations: map[string]common.Hash{