511 lines
19 KiB
Solidity
511 lines
19 KiB
Solidity
// SPDX-License-Identifier: Unlicense
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/*
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* @title Solidity Bytes Arrays Utils
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* @author Gonçalo Sá <goncalo.sa@consensys.net>
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*
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* @dev Bytes tightly packed arrays utility library for ethereum contracts written in Solidity.
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* The library lets you concatenate, slice and type cast bytes arrays both in memory and storage.
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*/
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pragma solidity >=0.8.0 <0.9.0;
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library BytesLib {
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function concat(
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bytes memory _preBytes,
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bytes memory _postBytes
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)
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internal
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pure
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returns (bytes memory)
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{
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bytes memory tempBytes;
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assembly {
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// Get a location of some free memory and store it in tempBytes as
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// Solidity does for memory variables.
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tempBytes := mload(0x40)
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// Store the length of the first bytes array at the beginning of
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// the memory for tempBytes.
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let length := mload(_preBytes)
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mstore(tempBytes, length)
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// Maintain a memory counter for the current write location in the
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// temp bytes array by adding the 32 bytes for the array length to
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// the starting location.
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let mc := add(tempBytes, 0x20)
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// Stop copying when the memory counter reaches the length of the
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// first bytes array.
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let end := add(mc, length)
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for {
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// Initialize a copy counter to the start of the _preBytes data,
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// 32 bytes into its memory.
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let cc := add(_preBytes, 0x20)
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} lt(mc, end) {
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// Increase both counters by 32 bytes each iteration.
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mc := add(mc, 0x20)
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cc := add(cc, 0x20)
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} {
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// Write the _preBytes data into the tempBytes memory 32 bytes
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// at a time.
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mstore(mc, mload(cc))
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}
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// Add the length of _postBytes to the current length of tempBytes
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// and store it as the new length in the first 32 bytes of the
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// tempBytes memory.
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length := mload(_postBytes)
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mstore(tempBytes, add(length, mload(tempBytes)))
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// Move the memory counter back from a multiple of 0x20 to the
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// actual end of the _preBytes data.
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mc := end
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// Stop copying when the memory counter reaches the new combined
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// length of the arrays.
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end := add(mc, length)
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for {
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let cc := add(_postBytes, 0x20)
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} lt(mc, end) {
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mc := add(mc, 0x20)
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cc := add(cc, 0x20)
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} {
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mstore(mc, mload(cc))
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}
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// Update the free-memory pointer by padding our last write location
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// to 32 bytes: add 31 bytes to the end of tempBytes to move to the
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// next 32 byte block, then round down to the nearest multiple of
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// 32. If the sum of the length of the two arrays is zero then add
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// one before rounding down to leave a blank 32 bytes (the length block with 0).
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mstore(0x40, and(
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add(add(end, iszero(add(length, mload(_preBytes)))), 31),
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not(31) // Round down to the nearest 32 bytes.
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))
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}
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return tempBytes;
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}
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function concatStorage(bytes storage _preBytes, bytes memory _postBytes) internal {
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assembly {
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// Read the first 32 bytes of _preBytes storage, which is the length
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// of the array. (We don't need to use the offset into the slot
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// because arrays use the entire slot.)
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let fslot := sload(_preBytes.slot)
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// Arrays of 31 bytes or less have an even value in their slot,
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// while longer arrays have an odd value. The actual length is
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// the slot divided by two for odd values, and the lowest order
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// byte divided by two for even values.
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// If the slot is even, bitwise and the slot with 255 and divide by
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// two to get the length. If the slot is odd, bitwise and the slot
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// with -1 and divide by two.
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let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
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let mlength := mload(_postBytes)
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let newlength := add(slength, mlength)
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// slength can contain both the length and contents of the array
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// if length < 32 bytes so let's prepare for that
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// v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
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switch add(lt(slength, 32), lt(newlength, 32))
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case 2 {
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// Since the new array still fits in the slot, we just need to
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// update the contents of the slot.
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// uint256(bytes_storage) = uint256(bytes_storage) + uint256(bytes_memory) + new_length
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sstore(
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_preBytes.slot,
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// all the modifications to the slot are inside this
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// next block
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add(
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// we can just add to the slot contents because the
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// bytes we want to change are the LSBs
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fslot,
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add(
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mul(
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div(
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// load the bytes from memory
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mload(add(_postBytes, 0x20)),
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// zero all bytes to the right
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exp(0x100, sub(32, mlength))
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),
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// and now shift left the number of bytes to
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// leave space for the length in the slot
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exp(0x100, sub(32, newlength))
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),
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// increase length by the double of the memory
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// bytes length
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mul(mlength, 2)
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)
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)
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)
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}
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case 1 {
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// The stored value fits in the slot, but the combined value
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// will exceed it.
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// get the keccak hash to get the contents of the array
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mstore(0x0, _preBytes.slot)
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let sc := add(keccak256(0x0, 0x20), div(slength, 32))
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// save new length
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sstore(_preBytes.slot, add(mul(newlength, 2), 1))
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// The contents of the _postBytes array start 32 bytes into
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// the structure. Our first read should obtain the `submod`
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// bytes that can fit into the unused space in the last word
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// of the stored array. To get this, we read 32 bytes starting
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// from `submod`, so the data we read overlaps with the array
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// contents by `submod` bytes. Masking the lowest-order
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// `submod` bytes allows us to add that value directly to the
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// stored value.
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let submod := sub(32, slength)
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let mc := add(_postBytes, submod)
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let end := add(_postBytes, mlength)
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let mask := sub(exp(0x100, submod), 1)
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sstore(
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sc,
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add(
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and(
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fslot,
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0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff00
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),
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and(mload(mc), mask)
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)
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)
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for {
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mc := add(mc, 0x20)
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sc := add(sc, 1)
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} lt(mc, end) {
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sc := add(sc, 1)
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mc := add(mc, 0x20)
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} {
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sstore(sc, mload(mc))
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}
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mask := exp(0x100, sub(mc, end))
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sstore(sc, mul(div(mload(mc), mask), mask))
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}
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default {
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// get the keccak hash to get the contents of the array
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mstore(0x0, _preBytes.slot)
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// Start copying to the last used word of the stored array.
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let sc := add(keccak256(0x0, 0x20), div(slength, 32))
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// save new length
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sstore(_preBytes.slot, add(mul(newlength, 2), 1))
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// Copy over the first `submod` bytes of the new data as in
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// case 1 above.
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let slengthmod := mod(slength, 32)
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let mlengthmod := mod(mlength, 32)
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let submod := sub(32, slengthmod)
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let mc := add(_postBytes, submod)
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let end := add(_postBytes, mlength)
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let mask := sub(exp(0x100, submod), 1)
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sstore(sc, add(sload(sc), and(mload(mc), mask)))
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for {
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sc := add(sc, 1)
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mc := add(mc, 0x20)
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} lt(mc, end) {
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sc := add(sc, 1)
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mc := add(mc, 0x20)
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} {
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sstore(sc, mload(mc))
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}
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mask := exp(0x100, sub(mc, end))
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sstore(sc, mul(div(mload(mc), mask), mask))
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}
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}
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}
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function slice(
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bytes memory _bytes,
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uint256 _start,
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uint256 _length
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)
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internal
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pure
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returns (bytes memory)
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{
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require(_length + 31 >= _length, "slice_overflow");
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require(_bytes.length >= _start + _length, "slice_outOfBounds");
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bytes memory tempBytes;
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assembly {
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switch iszero(_length)
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case 0 {
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// Get a location of some free memory and store it in tempBytes as
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// Solidity does for memory variables.
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tempBytes := mload(0x40)
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// The first word of the slice result is potentially a partial
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// word read from the original array. To read it, we calculate
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// the length of that partial word and start copying that many
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// bytes into the array. The first word we copy will start with
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// data we don't care about, but the last `lengthmod` bytes will
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// land at the beginning of the contents of the new array. When
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// we're done copying, we overwrite the full first word with
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// the actual length of the slice.
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let lengthmod := and(_length, 31)
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// The multiplication in the next line is necessary
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// because when slicing multiples of 32 bytes (lengthmod == 0)
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// the following copy loop was copying the origin's length
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// and then ending prematurely not copying everything it should.
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let mc := add(add(tempBytes, lengthmod), mul(0x20, iszero(lengthmod)))
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let end := add(mc, _length)
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for {
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// The multiplication in the next line has the same exact purpose
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// as the one above.
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let cc := add(add(add(_bytes, lengthmod), mul(0x20, iszero(lengthmod))), _start)
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} lt(mc, end) {
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mc := add(mc, 0x20)
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cc := add(cc, 0x20)
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} {
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mstore(mc, mload(cc))
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}
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mstore(tempBytes, _length)
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//update free-memory pointer
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//allocating the array padded to 32 bytes like the compiler does now
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mstore(0x40, and(add(mc, 31), not(31)))
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}
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//if we want a zero-length slice let's just return a zero-length array
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default {
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tempBytes := mload(0x40)
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//zero out the 32 bytes slice we are about to return
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//we need to do it because Solidity does not garbage collect
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mstore(tempBytes, 0)
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mstore(0x40, add(tempBytes, 0x20))
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}
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}
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return tempBytes;
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}
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function toAddress(bytes memory _bytes, uint256 _start) internal pure returns (address) {
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require(_bytes.length >= _start + 20, "toAddress_outOfBounds");
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address tempAddress;
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assembly {
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tempAddress := div(mload(add(add(_bytes, 0x20), _start)), 0x1000000000000000000000000)
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}
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return tempAddress;
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}
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function toUint8(bytes memory _bytes, uint256 _start) internal pure returns (uint8) {
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require(_bytes.length >= _start + 1 , "toUint8_outOfBounds");
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uint8 tempUint;
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assembly {
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tempUint := mload(add(add(_bytes, 0x1), _start))
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}
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return tempUint;
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}
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function toUint16(bytes memory _bytes, uint256 _start) internal pure returns (uint16) {
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require(_bytes.length >= _start + 2, "toUint16_outOfBounds");
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uint16 tempUint;
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assembly {
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tempUint := mload(add(add(_bytes, 0x2), _start))
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}
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return tempUint;
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}
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function toUint32(bytes memory _bytes, uint256 _start) internal pure returns (uint32) {
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require(_bytes.length >= _start + 4, "toUint32_outOfBounds");
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uint32 tempUint;
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assembly {
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tempUint := mload(add(add(_bytes, 0x4), _start))
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}
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return tempUint;
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}
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function toUint64(bytes memory _bytes, uint256 _start) internal pure returns (uint64) {
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require(_bytes.length >= _start + 8, "toUint64_outOfBounds");
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uint64 tempUint;
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assembly {
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tempUint := mload(add(add(_bytes, 0x8), _start))
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}
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return tempUint;
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}
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function toUint96(bytes memory _bytes, uint256 _start) internal pure returns (uint96) {
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require(_bytes.length >= _start + 12, "toUint96_outOfBounds");
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uint96 tempUint;
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assembly {
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tempUint := mload(add(add(_bytes, 0xc), _start))
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}
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return tempUint;
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}
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function toUint128(bytes memory _bytes, uint256 _start) internal pure returns (uint128) {
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require(_bytes.length >= _start + 16, "toUint128_outOfBounds");
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uint128 tempUint;
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assembly {
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tempUint := mload(add(add(_bytes, 0x10), _start))
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}
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return tempUint;
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}
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function toUint256(bytes memory _bytes, uint256 _start) internal pure returns (uint256) {
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require(_bytes.length >= _start + 32, "toUint256_outOfBounds");
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uint256 tempUint;
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assembly {
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tempUint := mload(add(add(_bytes, 0x20), _start))
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}
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return tempUint;
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}
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function toBytes32(bytes memory _bytes, uint256 _start) internal pure returns (bytes32) {
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require(_bytes.length >= _start + 32, "toBytes32_outOfBounds");
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bytes32 tempBytes32;
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assembly {
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tempBytes32 := mload(add(add(_bytes, 0x20), _start))
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}
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return tempBytes32;
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}
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function equal(bytes memory _preBytes, bytes memory _postBytes) internal pure returns (bool) {
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bool success = true;
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assembly {
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let length := mload(_preBytes)
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// if lengths don't match the arrays are not equal
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switch eq(length, mload(_postBytes))
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case 1 {
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// cb is a circuit breaker in the for loop since there's
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// no said feature for inline assembly loops
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// cb = 1 - don't breaker
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// cb = 0 - break
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let cb := 1
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let mc := add(_preBytes, 0x20)
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let end := add(mc, length)
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for {
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let cc := add(_postBytes, 0x20)
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// the next line is the loop condition:
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// while(uint256(mc < end) + cb == 2)
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} eq(add(lt(mc, end), cb), 2) {
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mc := add(mc, 0x20)
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cc := add(cc, 0x20)
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} {
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// if any of these checks fails then arrays are not equal
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if iszero(eq(mload(mc), mload(cc))) {
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// unsuccess:
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success := 0
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cb := 0
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}
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}
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}
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default {
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// unsuccess:
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success := 0
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}
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}
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return success;
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}
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function equalStorage(
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bytes storage _preBytes,
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bytes memory _postBytes
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)
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internal
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view
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returns (bool)
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{
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bool success = true;
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assembly {
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// we know _preBytes_offset is 0
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let fslot := sload(_preBytes.slot)
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// Decode the length of the stored array like in concatStorage().
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let slength := div(and(fslot, sub(mul(0x100, iszero(and(fslot, 1))), 1)), 2)
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let mlength := mload(_postBytes)
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// if lengths don't match the arrays are not equal
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switch eq(slength, mlength)
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case 1 {
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// slength can contain both the length and contents of the array
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// if length < 32 bytes so let's prepare for that
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// v. http://solidity.readthedocs.io/en/latest/miscellaneous.html#layout-of-state-variables-in-storage
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if iszero(iszero(slength)) {
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switch lt(slength, 32)
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case 1 {
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// blank the last byte which is the length
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fslot := mul(div(fslot, 0x100), 0x100)
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if iszero(eq(fslot, mload(add(_postBytes, 0x20)))) {
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// unsuccess:
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success := 0
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}
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}
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default {
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// cb is a circuit breaker in the for loop since there's
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// no said feature for inline assembly loops
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// cb = 1 - don't breaker
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// cb = 0 - break
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let cb := 1
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// get the keccak hash to get the contents of the array
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mstore(0x0, _preBytes.slot)
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let sc := keccak256(0x0, 0x20)
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let mc := add(_postBytes, 0x20)
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let end := add(mc, mlength)
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// the next line is the loop condition:
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// while(uint256(mc < end) + cb == 2)
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for {} eq(add(lt(mc, end), cb), 2) {
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sc := add(sc, 1)
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mc := add(mc, 0x20)
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} {
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if iszero(eq(sload(sc), mload(mc))) {
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// unsuccess:
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success := 0
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cb := 0
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}
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}
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}
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}
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}
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default {
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// unsuccess:
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success := 0
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}
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}
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return success;
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}
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}
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