1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
|
/*
Copyright 2018 ZeroEx Intl.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
pragma solidity ^0.4.24;
library LibBytes {
using LibBytes for bytes;
// Revert reasons
string constant GREATER_THAN_ZERO_LENGTH_REQUIRED = "GREATER_THAN_ZERO_LENGTH_REQUIRED";
string constant GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED";
string constant GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED";
string constant GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED";
string constant GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED";
string constant GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED = "GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED";
string constant FROM_LESS_THAN_TO_REQUIRED = "FROM_LESS_THAN_TO_REQUIRED";
string constant TO_LESS_THAN_LENGTH_REQUIRED = "TO_LESS_THAN_LENGTH_REQUIRED";
/// @dev Gets the memory address for a byte array.
/// @param input Byte array to lookup.
/// @return memoryAddress Memory address of byte array. This
/// points to the header of the byte array which contains
/// the length.
function rawAddress(bytes memory input)
internal
pure
returns (uint256 memoryAddress)
{
assembly {
memoryAddress := input
}
return memoryAddress;
}
/// @dev Gets the memory address for the contents of a byte array.
/// @param input Byte array to lookup.
/// @return memoryAddress Memory address of the contents of the byte array.
function contentAddress(bytes memory input)
internal
pure
returns (uint256 memoryAddress)
{
assembly {
memoryAddress := add(input, 32)
}
return memoryAddress;
}
/// @dev Copies `length` bytes from memory location `source` to `dest`.
/// @param dest memory address to copy bytes to.
/// @param source memory address to copy bytes from.
/// @param length number of bytes to copy.
function memCopy(
uint256 dest,
uint256 source,
uint256 length
)
internal
pure
{
if (length < 32) {
// Handle a partial word by reading destination and masking
// off the bits we are interested in.
// This correctly handles overlap, zero lengths and source == dest
assembly {
let mask := sub(exp(256, sub(32, length)), 1)
let s := and(mload(source), not(mask))
let d := and(mload(dest), mask)
mstore(dest, or(s, d))
}
} else {
// Skip the O(length) loop when source == dest.
if (source == dest) {
return;
}
// For large copies we copy whole words at a time. The final
// word is aligned to the end of the range (instead of after the
// previous) to handle partial words. So a copy will look like this:
//
// ####
// ####
// ####
// ####
//
// We handle overlap in the source and destination range by
// changing the copying direction. This prevents us from
// overwriting parts of source that we still need to copy.
//
// This correctly handles source == dest
//
if (source > dest) {
assembly {
// We subtract 32 from `sEnd` and `dEnd` because it
// is easier to compare with in the loop, and these
// are also the addresses we need for copying the
// last bytes.
length := sub(length, 32)
let sEnd := add(source, length)
let dEnd := add(dest, length)
// Remember the last 32 bytes of source
// This needs to be done here and not after the loop
// because we may have overwritten the last bytes in
// source already due to overlap.
let last := mload(sEnd)
// Copy whole words front to back
// Note: the first check is always true,
// this could have been a do-while loop.
for {} lt(source, sEnd) {} {
mstore(dest, mload(source))
source := add(source, 32)
dest := add(dest, 32)
}
// Write the last 32 bytes
mstore(dEnd, last)
}
} else {
assembly {
// We subtract 32 from `sEnd` and `dEnd` because those
// are the starting points when copying a word at the end.
length := sub(length, 32)
let sEnd := add(source, length)
let dEnd := add(dest, length)
// Remember the first 32 bytes of source
// This needs to be done here and not after the loop
// because we may have overwritten the first bytes in
// source already due to overlap.
let first := mload(source)
// Copy whole words back to front
// We use a signed comparisson here to allow dEnd to become
// negative (happens when source and dest < 32). Valid
// addresses in local memory will never be larger than
// 2**255, so they can be safely re-interpreted as signed.
// Note: the first check is always true,
// this could have been a do-while loop.
for {} slt(dest, dEnd) {} {
mstore(dEnd, mload(sEnd))
sEnd := sub(sEnd, 32)
dEnd := sub(dEnd, 32)
}
// Write the first 32 bytes
mstore(dest, first)
}
}
}
}
/// @dev Returns a slices from a byte array.
/// @param b The byte array to take a slice from.
/// @param from The starting index for the slice (inclusive).
/// @param to The final index for the slice (exclusive).
/// @return result The slice containing bytes at indices [from, to)
function slice(bytes memory b, uint256 from, uint256 to)
internal
pure
returns (bytes memory result)
{
require(from <= to, FROM_LESS_THAN_TO_REQUIRED);
require(to < b.length, TO_LESS_THAN_LENGTH_REQUIRED);
// Create a new bytes structure and copy contents
result = new bytes(to - from);
memCopy(
result.contentAddress(),
b.contentAddress() + from,
result.length);
return result;
}
/// @dev Returns a slices from a byte array without preserving the input.
/// @param b The byte array to take a slice from. Will be destroyed in the process.
/// @param from The starting index for the slice (inclusive).
/// @param to The final index for the slice (exclusive).
/// @return result The slice containing bytes at indices [from, to)
/// @dev When `from == 0`, the original array will match the slice. In other cases it's state will be corrupted.
function sliceDestructive(bytes memory b, uint256 from, uint256 to)
internal
pure
returns (bytes memory result)
{
require(from <= to, FROM_LESS_THAN_TO_REQUIRED);
require(to < b.length, TO_LESS_THAN_LENGTH_REQUIRED);
// Create a new bytes structure around [from, to) in-place.
assembly {
result := add(b, from)
mstore(result, sub(to, from))
}
return result;
}
/// @dev Pops the last byte off of a byte array by modifying its length.
/// @param b Byte array that will be modified.
/// @return The byte that was popped off.
function popLastByte(bytes memory b)
internal
pure
returns (bytes1 result)
{
require(
b.length > 0,
GREATER_THAN_ZERO_LENGTH_REQUIRED
);
// Store last byte.
result = b[b.length - 1];
assembly {
// Decrement length of byte array.
let newLen := sub(mload(b), 1)
mstore(b, newLen)
}
return result;
}
/// @dev Pops the last 20 bytes off of a byte array by modifying its length.
/// @param b Byte array that will be modified.
/// @return The 20 byte address that was popped off.
function popLast20Bytes(bytes memory b)
internal
pure
returns (address result)
{
require(
b.length >= 20,
GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED
);
// Store last 20 bytes.
result = readAddress(b, b.length - 20);
assembly {
// Subtract 20 from byte array length.
let newLen := sub(mload(b), 20)
mstore(b, newLen)
}
return result;
}
/// @dev Tests equality of two byte arrays.
/// @param lhs First byte array to compare.
/// @param rhs Second byte array to compare.
/// @return True if arrays are the same. False otherwise.
function equals(
bytes memory lhs,
bytes memory rhs
)
internal
pure
returns (bool equal)
{
// Keccak gas cost is 30 + numWords * 6. This is a cheap way to compare.
// We early exit on unequal lengths, but keccak would also correctly
// handle this.
return lhs.length == rhs.length && keccak256(lhs) == keccak256(rhs);
}
/// @dev Reads an address from a position in a byte array.
/// @param b Byte array containing an address.
/// @param index Index in byte array of address.
/// @return address from byte array.
function readAddress(
bytes memory b,
uint256 index
)
internal
pure
returns (address result)
{
require(
b.length >= index + 20, // 20 is length of address
GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED
);
// Add offset to index:
// 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
// 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
index += 20;
// Read address from array memory
assembly {
// 1. Add index to address of bytes array
// 2. Load 32-byte word from memory
// 3. Apply 20-byte mask to obtain address
result := and(mload(add(b, index)), 0xffffffffffffffffffffffffffffffffffffffff)
}
return result;
}
/// @dev Writes an address into a specific position in a byte array.
/// @param b Byte array to insert address into.
/// @param index Index in byte array of address.
/// @param input Address to put into byte array.
function writeAddress(
bytes memory b,
uint256 index,
address input
)
internal
pure
{
require(
b.length >= index + 20, // 20 is length of address
GREATER_OR_EQUAL_TO_20_LENGTH_REQUIRED
);
// Add offset to index:
// 1. Arrays are prefixed by 32-byte length parameter (add 32 to index)
// 2. Account for size difference between address length and 32-byte storage word (subtract 12 from index)
index += 20;
// Store address into array memory
assembly {
// The address occupies 20 bytes and mstore stores 32 bytes.
// First fetch the 32-byte word where we'll be storing the address, then
// apply a mask so we have only the bytes in the word that the address will not occupy.
// Then combine these bytes with the address and store the 32 bytes back to memory with mstore.
// 1. Add index to address of bytes array
// 2. Load 32-byte word from memory
// 3. Apply 12-byte mask to obtain extra bytes occupying word of memory where we'll store the address
let neighbors := and(mload(add(b, index)), 0xffffffffffffffffffffffff0000000000000000000000000000000000000000)
// Store the neighbors and address into memory
mstore(add(b, index), xor(input, neighbors))
}
}
/// @dev Reads a bytes32 value from a position in a byte array.
/// @param b Byte array containing a bytes32 value.
/// @param index Index in byte array of bytes32 value.
/// @return bytes32 value from byte array.
function readBytes32(
bytes memory b,
uint256 index
)
internal
pure
returns (bytes32 result)
{
require(
b.length >= index + 32,
GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED
);
// Arrays are prefixed by a 256 bit length parameter
index += 32;
// Read the bytes32 from array memory
assembly {
result := mload(add(b, index))
}
return result;
}
/// @dev Writes a bytes32 into a specific position in a byte array.
/// @param b Byte array to insert <input> into.
/// @param index Index in byte array of <input>.
/// @param input bytes32 to put into byte array.
function writeBytes32(
bytes memory b,
uint256 index,
bytes32 input
)
internal
pure
{
require(
b.length >= index + 32,
GREATER_OR_EQUAL_TO_32_LENGTH_REQUIRED
);
// Arrays are prefixed by a 256 bit length parameter
index += 32;
// Read the bytes32 from array memory
assembly {
mstore(add(b, index), input)
}
}
/// @dev Reads a uint256 value from a position in a byte array.
/// @param b Byte array containing a uint256 value.
/// @param index Index in byte array of uint256 value.
/// @return uint256 value from byte array.
function readUint256(
bytes memory b,
uint256 index
)
internal
pure
returns (uint256 result)
{
return uint256(readBytes32(b, index));
}
/// @dev Writes a uint256 into a specific position in a byte array.
/// @param b Byte array to insert <input> into.
/// @param index Index in byte array of <input>.
/// @param input uint256 to put into byte array.
function writeUint256(
bytes memory b,
uint256 index,
uint256 input
)
internal
pure
{
writeBytes32(b, index, bytes32(input));
}
/// @dev Reads an unpadded bytes4 value from a position in a byte array.
/// @param b Byte array containing a bytes4 value.
/// @param index Index in byte array of bytes4 value.
/// @return bytes4 value from byte array.
function readBytes4(
bytes memory b,
uint256 index)
internal
pure
returns (bytes4 result)
{
require(
b.length >= index + 4,
GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED
);
assembly {
result := mload(add(b, 32))
}
return result;
}
/// @dev Reads nested bytes from a specific position.
/// @param b Byte array containing nested bytes.
/// @param index Index of nested bytes.
/// @return result Nested bytes.
function readBytesWithLength(
bytes memory b,
uint256 index
)
internal
pure
returns (bytes memory result)
{
// Read length of nested bytes
uint256 nestedBytesLength = readUint256(b, index);
index += 32;
// Assert length of <b> is valid, given
// length of nested bytes
require(
b.length >= index + nestedBytesLength,
GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED
);
// Allocate memory and copy value to result
result = new bytes(nestedBytesLength);
memCopy(
result.contentAddress(),
b.contentAddress() + index,
nestedBytesLength
);
return result;
}
/// @dev Inserts bytes at a specific position in a byte array.
/// @param b Byte array to insert <input> into.
/// @param index Index in byte array of <input>.
/// @param input bytes to insert.
function writeBytesWithLength(
bytes memory b,
uint256 index,
bytes memory input
)
internal
pure
{
// Assert length of <b> is valid, given
// length of input
require(
b.length >= index + 32 /* 32 bytes to store length */ + input.length,
GREATER_OR_EQUAL_TO_NESTED_BYTES_LENGTH_REQUIRED
);
// Copy <input> into <b>
memCopy(
b.contentAddress() + index,
input.rawAddress(), // includes length of <input>
input.length + 32 // +32 bytes to store <input> length
);
}
/// @dev Tests equality of two byte arrays.
/// @param lhs First byte array to compare.
/// @param rhs Second byte array to compare.
/// @return True if arrays are the same. False otherwise.
function areBytesEqual(
bytes memory lhs,
bytes memory rhs
)
internal
pure
returns (bool equal)
{
assembly {
// Get the number of words occupied by <lhs>
let lenFullWords := div(add(mload(lhs), 0x1F), 0x20)
// Add 1 to the number of words, to account for the length field
lenFullWords := add(lenFullWords, 0x1)
// Test equality word-by-word.
// Terminates early if there is a mismatch.
for {let i := 0} lt(i, lenFullWords) {i := add(i, 1)} {
let lhsWord := mload(add(lhs, mul(i, 0x20)))
let rhsWord := mload(add(rhs, mul(i, 0x20)))
equal := eq(lhsWord, rhsWord)
if eq(equal, 0) {
// Break
i := lenFullWords
}
}
}
return equal;
}
/// @dev Performs a deep copy of a byte array onto another byte array of greater than or equal length.
/// @param dest Byte array that will be overwritten with source bytes.
/// @param source Byte array to copy onto dest bytes.
function deepCopyBytes(
bytes memory dest,
bytes memory source
)
internal
pure
{
uint256 sourceLen = source.length;
// Dest length must be >= source length, or some bytes would not be copied.
require(
dest.length >= sourceLen,
GREATER_OR_EQUAL_TO_SOURCE_BYTES_LENGTH_REQUIRED
);
memCopy(
getMemAddress(dest) + 32, // +32 to skip length of <dest>
getMemAddress(source) + 32, // +32 to skip length of <source>
sourceLen
);
}
}
|