// Copyright 2014 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 vm import ( "math/big" "github.com/ava-labs/go-ethereum/common" "github.com/ava-labs/go-ethereum/common/math" ) // calcMemSize64 calculates the required memory size, and returns // the size and whether the result overflowed uint64 func calcMemSize64(off, l *big.Int) (uint64, bool) { if !l.IsUint64() { return 0, true } return calcMemSize64WithUint(off, l.Uint64()) } // calcMemSize64WithUint calculates the required memory size, and returns // the size and whether the result overflowed uint64 // Identical to calcMemSize64, but length is a uint64 func calcMemSize64WithUint(off *big.Int, length64 uint64) (uint64, bool) { // if length is zero, memsize is always zero, regardless of offset if length64 == 0 { return 0, false } // Check that offset doesn't overflow if !off.IsUint64() { return 0, true } offset64 := off.Uint64() val := offset64 + length64 // if value < either of it's parts, then it overflowed return val, val < offset64 } // getData returns a slice from the data based on the start and size and pads // up to size with zero's. This function is overflow safe. func getData(data []byte, start uint64, size uint64) []byte { length := uint64(len(data)) if start > length { start = length } end := start + size if end > length { end = length } return common.RightPadBytes(data[start:end], int(size)) } // getDataBig returns a slice from the data based on the start and size and pads // up to size with zero's. This function is overflow safe. func getDataBig(data []byte, start *big.Int, size *big.Int) []byte { dlen := big.NewInt(int64(len(data))) s := math.BigMin(start, dlen) e := math.BigMin(new(big.Int).Add(s, size), dlen) return common.RightPadBytes(data[s.Uint64():e.Uint64()], int(size.Uint64())) } // bigUint64 returns the integer casted to a uint64 and returns whether it // overflowed in the process. func bigUint64(v *big.Int) (uint64, bool) { return v.Uint64(), !v.IsUint64() } // toWordSize returns the ceiled word size required for memory expansion. func toWordSize(size uint64) uint64 { if size > math.MaxUint64-31 { return math.MaxUint64/32 + 1 } return (size + 31) / 32 } func allZero(b []byte) bool { for _, byte := range b { if byte != 0 { return false } } return true }