accounts/abi: add basic support for error types (#23161)

This is the initial step for support of Solidity errors in contract bindings.
As of this change, errors can be decoded, but are not supported in
bindings yet.

Closes #23157

accounts/abi/error_handling.go

@@ -0,0 +1,82 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package abi
+
+import (
+	"errors"
+	"fmt"
+	"reflect"
+)
+
+var (
+	errBadBool = errors.New("abi: improperly encoded boolean value")
+)
+
+// formatSliceString formats the reflection kind with the given slice size
+// and returns a formatted string representation.
+func formatSliceString(kind reflect.Kind, sliceSize int) string {
+	if sliceSize == -1 {
+		return fmt.Sprintf("[]%v", kind)
+	}
+	return fmt.Sprintf("[%d]%v", sliceSize, kind)
+}
+
+// sliceTypeCheck checks that the given slice can by assigned to the reflection
+// type in t.
+func sliceTypeCheck(t Type, val reflect.Value) error {
+	if val.Kind() != reflect.Slice && val.Kind() != reflect.Array {
+		return typeErr(formatSliceString(t.GetType().Kind(), t.Size), val.Type())
+	}
+
+	if t.T == ArrayTy && val.Len() != t.Size {
+		return typeErr(formatSliceString(t.Elem.GetType().Kind(), t.Size), formatSliceString(val.Type().Elem().Kind(), val.Len()))
+	}
+
+	if t.Elem.T == SliceTy || t.Elem.T == ArrayTy {
+		if val.Len() > 0 {
+			return sliceTypeCheck(*t.Elem, val.Index(0))
+		}
+	}
+
+	if val.Type().Elem().Kind() != t.Elem.GetType().Kind() {
+		return typeErr(formatSliceString(t.Elem.GetType().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.T == SliceTy || t.T == ArrayTy {
+		return sliceTypeCheck(t, value)
+	}
+
+	// Check base type validity. Element types will be checked later on.
+	if t.GetType().Kind() != value.Kind() {
+		return typeErr(t.GetType().Kind(), value.Kind())
+	} else if t.T == FixedBytesTy && t.Size != value.Len() {
+		return typeErr(t.GetType(), value.Type())
+	} else {
+		return nil
+	}
+
+}
+
+// typeErr returns a formatted type casting error.
+func typeErr(expected, got interface{}) error {
+	return fmt.Errorf("abi: cannot use %v as type %v as argument", got, expected)
+}