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// 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 (
"fmt"
"reflect"
"strings"
)
// indirect recursively dereferences the value until it either gets the value
// or finds a big.Int
func indirect(v reflect.Value) reflect.Value {
if v.Kind() == reflect.Ptr && v.Elem().Type() != derefbigT {
return indirect(v.Elem())
}
return v
}
// reflectIntKind returns the reflect using the given size and
// unsignedness.
func reflectIntKindAndType(unsigned bool, size int) (reflect.Kind, reflect.Type) {
switch size {
case 8:
if unsigned {
return reflect.Uint8, uint8T
}
return reflect.Int8, int8T
case 16:
if unsigned {
return reflect.Uint16, uint16T
}
return reflect.Int16, int16T
case 32:
if unsigned {
return reflect.Uint32, uint32T
}
return reflect.Int32, int32T
case 64:
if unsigned {
return reflect.Uint64, uint64T
}
return reflect.Int64, int64T
}
return reflect.Ptr, bigT
}
// mustArrayToBytesSlice creates a new byte slice with the exact same size as value
// and copies the bytes in value to the new slice.
func mustArrayToByteSlice(value reflect.Value) reflect.Value {
slice := reflect.MakeSlice(reflect.TypeOf([]byte{}), value.Len(), value.Len())
reflect.Copy(slice, value)
return slice
}
// set attempts to assign src to dst by either setting, copying or otherwise.
//
// set is a bit more lenient when it comes to assignment and doesn't force an as
// strict ruleset as bare `reflect` does.
func set(dst, src reflect.Value, output Argument) error {
dstType := dst.Type()
srcType := src.Type()
switch {
case dstType.AssignableTo(srcType):
dst.Set(src)
case dstType.Kind() == reflect.Interface:
dst.Set(src)
case dstType.Kind() == reflect.Ptr:
return set(dst.Elem(), src, output)
default:
return fmt.Errorf("abi: cannot unmarshal %v in to %v", src.Type(), dst.Type())
}
return nil
}
// requireAssignable assures that `dest` is a pointer and it's not an interface.
func requireAssignable(dst, src reflect.Value) error {
if dst.Kind() != reflect.Ptr && dst.Kind() != reflect.Interface {
return fmt.Errorf("abi: cannot unmarshal %v into %v", src.Type(), dst.Type())
}
return nil
}
// requireUnpackKind verifies preconditions for unpacking `args` into `kind`
func requireUnpackKind(v reflect.Value, t reflect.Type, k reflect.Kind,
args Arguments) error {
switch k {
case reflect.Struct:
case reflect.Slice, reflect.Array:
if minLen := args.LengthNonIndexed(); v.Len() < minLen {
return fmt.Errorf("abi: insufficient number of elements in the list/array for unpack, want %d, got %d",
minLen, v.Len())
}
default:
return fmt.Errorf("abi: cannot unmarshal tuple into %v", t)
}
return nil
}
// mapAbiToStringField maps abi to struct fields.
// first round: for each Exportable field that contains a `abi:""` tag
// and this field name exists in the arguments, pair them together.
// second round: for each argument field that has not been already linked,
// find what variable is expected to be mapped into, if it exists and has not been
// used, pair them.
func mapAbiToStructFields(args Arguments, value reflect.Value) (map[string]string, error) {
typ := value.Type()
abi2struct := make(map[string]string)
struct2abi := make(map[string]string)
// first round ~~~
for i := 0; i < typ.NumField(); i++ {
structFieldName := typ.Field(i).Name
// skip private struct fields.
if structFieldName[:1] != strings.ToUpper(structFieldName[:1]) {
continue
}
// skip fields that have no abi:"" tag.
var ok bool
var tagName string
if tagName, ok = typ.Field(i).Tag.Lookup("abi"); !ok {
continue
}
// check if tag is empty.
if tagName == "" {
return nil, fmt.Errorf("struct: abi tag in '%s' is empty", structFieldName)
}
// check which argument field matches with the abi tag.
found := false
for _, abiField := range args.NonIndexed() {
if abiField.Name == tagName {
if abi2struct[abiField.Name] != "" {
return nil, fmt.Errorf("struct: abi tag in '%s' already mapped", structFieldName)
}
// pair them
abi2struct[abiField.Name] = structFieldName
struct2abi[structFieldName] = abiField.Name
found = true
}
}
// check if this tag has been mapped.
if !found {
return nil, fmt.Errorf("struct: abi tag '%s' defined but not found in abi", tagName)
}
}
// second round ~~~
for _, arg := range args {
abiFieldName := arg.Name
structFieldName := capitalise(abiFieldName)
if structFieldName == "" {
return nil, fmt.Errorf("abi: purely underscored output cannot unpack to struct")
}
// this abi has already been paired, skip it... unless there exists another, yet unassigned
// struct field with the same field name. If so, raise an error:
// abi: [ { "name": "value" } ]
// struct { Value *big.Int , Value1 *big.Int `abi:"value"`}
if abi2struct[abiFieldName] != "" {
if abi2struct[abiFieldName] != structFieldName &&
struct2abi[structFieldName] == "" &&
value.FieldByName(structFieldName).IsValid() {
return nil, fmt.Errorf("abi: multiple variables maps to the same abi field '%s'", abiFieldName)
}
continue
}
// return an error if this struct field has already been paired.
if struct2abi[structFieldName] != "" {
return nil, fmt.Errorf("abi: multiple outputs mapping to the same struct field '%s'", structFieldName)
}
if value.FieldByName(structFieldName).IsValid() {
// pair them
abi2struct[abiFieldName] = structFieldName
struct2abi[structFieldName] = abiFieldName
} else {
// not paired, but annotate as used, to detect cases like
// abi : [ { "name": "value" }, { "name": "_value" } ]
// struct { Value *big.Int }
struct2abi[structFieldName] = abiFieldName
}
}
return abi2struct, nil
}
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