96 lines
2.8 KiB
Go
96 lines
2.8 KiB
Go
// Copyright 2014 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package vm
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import (
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"math"
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"github.com/ethereum/go-ethereum/common"
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"github.com/holiman/uint256"
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)
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// calcMemSize64 calculates the required memory size, and returns
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// the size and whether the result overflowed uint64
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func calcMemSize64(off, l *uint256.Int) (uint64, bool) {
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if !l.IsUint64() {
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return 0, true
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}
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return calcMemSize64WithUint(off, l.Uint64())
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}
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// calcMemSize64WithUint calculates the required memory size, and returns
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// the size and whether the result overflowed uint64
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// Identical to calcMemSize64, but length is a uint64
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func calcMemSize64WithUint(off *uint256.Int, length64 uint64) (uint64, bool) {
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// if length is zero, memsize is always zero, regardless of offset
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if length64 == 0 {
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return 0, false
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}
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// Check that offset doesn't overflow
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offset64, overflow := off.Uint64WithOverflow()
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if overflow {
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return 0, true
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}
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val := offset64 + length64
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// if value < either of it's parts, then it overflowed
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return val, val < offset64
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}
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// getData returns a slice from the data based on the start and size and pads
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// up to size with zero's. This function is overflow safe.
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func getData(data []byte, start uint64, size uint64) []byte {
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length := uint64(len(data))
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if start > length {
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start = length
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}
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end := start + size
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if end > length {
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end = length
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}
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return common.RightPadBytes(data[start:end], int(size))
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}
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func getDataAndAdjustedBounds(data []byte, start uint64, size uint64) (codeCopyPadded []byte, actualStart uint64, sizeNonPadded uint64) {
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length := uint64(len(data))
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if start > length {
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start = length
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}
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end := start + size
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if end > length {
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end = length
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}
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return common.RightPadBytes(data[start:end], int(size)), start, end - start
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}
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// toWordSize returns the ceiled word size required for memory expansion.
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func toWordSize(size uint64) uint64 {
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if size > math.MaxUint64-31 {
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return math.MaxUint64/32 + 1
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}
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return (size + 31) / 32
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}
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func allZero(b []byte) bool {
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for _, byte := range b {
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if byte != 0 {
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return false
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}
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}
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return true
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}
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