-
Notifications
You must be signed in to change notification settings - Fork 8
/
safe_math_impl.h
2587 lines (2140 loc) · 59.7 KB
/
safe_math_impl.h
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
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
// Licensed under the MIT License.
// Copyright David LeBlanc - [email protected]
/*-----------------------------------------------------------------------------------------------------------
c_safe_math
Version 1.0 - 6/21/22
This header implements a set of functions that check for integer overflows in C code.
It is based on code and logic from SafeInt.hpp, but ported to C.
Portions copied from SafeInt.hpp are Licensed under the MIT License,
and are originally copyrighted to Microsoft.
*/
#ifndef C_SAFE_MATH_IMPL
#define C_SAFE_MATH_IMPL
#if defined _MSC_VER
// static inline expansion warnings
#pragma warning(disable:4710 4711)
#endif
#ifdef __cplusplus
extern "C"
{
#endif
// It is a bit tricky to sort out what compiler we are actually using,
// do this once here, and avoid cluttering the code
#define VISUAL_STUDIO_COMPILER 0
#define CLANG_COMPILER 1
#define GCC_COMPILER 2
#define UNKNOWN_COMPILER -1
// Clang will sometimes pretend to be Visual Studio
// and does pretend to be gcc. Check it first, as nothing else pretends to be clang
#if defined __clang__
#define SAFEINT_COMPILER CLANG_COMPILER
#elif defined __GNUC__
#define SAFEINT_COMPILER GCC_COMPILER
#elif defined _MSC_VER
#define SAFEINT_COMPILER VISUAL_STUDIO_COMPILER
#else
#define SAFEINT_COMPILER UNKNOWN_COMPILER
#endif
// Various defines to help make working with multiple compilers easier - from SafeInt.hpp
#if SAFEINT_COMPILER == GCC_COMPILER || SAFEINT_COMPILER == CLANG_COMPILER
#define SAFEINT_NORETURN __attribute__((noreturn))
#define SAFEINT_STDCALL
#define SAFEINT_VISIBLE __attribute__ ((__visibility__("default")))
#define SAFEINT_WEAK __attribute__ ((weak))
#else
#define SAFEINT_NORETURN __declspec(noreturn)
#define SAFEINT_STDCALL __stdcall
#define SAFEINT_VISIBLE
#define SAFEINT_WEAK
#endif
#if SAFEINT_COMPILER == VISUAL_STUDIO_COMPILER
// limits.h checks __STDC_WANT_SECURE_LIB__, but doesn't include what sets it
#if !defined __STDC_WANT_SECURE_LIB__
#define __STDC_WANT_SECURE_LIB__ 0
#endif
#endif
#include <stdint.h>
#include <stdbool.h>
#include <limits.h>
// Figure out if we should use intrinsics
// If the user has already decided, let that override
#define SAFEINT_MULTIPLY_MATH 0 // no intrinsics, no built in, no 128-bit
#define SAFEINT_MULTIPLY_INTRINSICS 1 // 64-bit Visual Studio
#define SAFEINT_MULTIPLY_BUILTIN 2 // gcc, clang
#define SAFEINT_MULTIPLY_INT128 3 // Best case
// We might have 128-bit int support, check for that, as it should work best
#if !defined SAFEINT_HAS_INT128
#if defined __SIZEOF_INT128__ && __SIZEOF_INT128__ == 16
#define SAFEINT_HAS_INT128 1
#else
#define SAFEINT_HAS_INT128 0
#endif
#endif
#if SAFEINT_HAS_INT128
#define SAFEINT_MULTIPLY_METHOD SAFEINT_MULTIPLY_INT128
#else
#if !defined SAFEINT_USE_INTRINSICS
// If it is the Visual Studio compiler, then it has to be 64-bit, and not ARM64EC
#if SAFEINT_COMPILER == VISUAL_STUDIO_COMPILER
#if defined _M_AMD64 && !defined _M_ARM64EC
#include <intrin.h>
#define SAFEINT_MULTIPLY_METHOD SAFEINT_MULTIPLY_INTRINSICS
#else
#define SAFEINT_MULTIPLY_METHOD SAFEINT_MULTIPLY_MATH
#endif
#else // Not VISUAL_STUDIO_COMPILER
// Else for gcc and clang, we can use builtin functions
#if SAFEINT_COMPILER == CLANG_COMPILER || SAFEINT_COMPILER == GCC_COMPILER
#define SAFEINT_MULTIPLY_METHOD SAFEINT_MULTIPLY_BUILTIN
#else
#define SAFEINT_MULTIPLY_METHOD SAFEINT_MULTIPLY_MATH
#endif
#endif
#endif // SAFEINT_USE_INTRINSICS
#endif // SAFEINT_HAS_INT128
/*
To replace safe_math_fail, wrap this header,
implement safe_math_fail how you prefer,
and set SAFE_MATH_FAIL_DEFINED
*/
#if !defined SAFE_MATH_FAIL_DEFINED
#define SAFE_MATH_FAIL_DEFINED
#include <stdlib.h>
SAFEINT_NORETURN
static inline void safe_math_fail(const char* msg)
{
(void)msg;
abort();
}
#endif
#if !defined UINT64_MAX
#define INT8_MIN (-127i8 - 1)
#define INT16_MIN (-32767i16 - 1)
#define INT32_MIN (-2147483647i32 - 1)
#define INT64_MIN (-9223372036854775807i64 - 1)
#define INT8_MAX 127i8
#define INT16_MAX 32767i16
#define INT32_MAX 2147483647i32
#define INT64_MAX 9223372036854775807i64
#define UINT8_MAX 0xffui8
#define UINT16_MAX 0xffffui16
#define UINT32_MAX 0xffffffffui32
#define UINT64_MAX 0xffffffffffffffffui64
#endif
// Utility functions
// Purpose of this is to negate an int in a way
// where the compiler won't remove it if the input is a
// compile time constant MIN_INT
static inline int32_t negate32(int32_t in) { return (int32_t)(~(uint32_t)in + 1); }
static inline int64_t negate64(int64_t in) { return (int64_t)(~(uint64_t)in + 1); }
static inline uint32_t safe_abs32(int32_t in)
{
if (in < 0)
return ~(uint32_t)in + 1;
return (uint32_t)in;
}
static inline uint64_t safe_abs64(int64_t in)
{
if (in < 0)
return ~(uint64_t)in + 1;
return (uint64_t)in;
}
// Checked casting functions
// 0 if the cast is safe, non-zero if unsafe
static inline int check_cast_int8_int32(int32_t in) { return (in < INT8_MIN || in > INT8_MAX); }
static inline int check_cast_int8_uint32(uint32_t in) { return in > INT8_MAX; }
static inline int check_cast_int8_int64(int64_t in) { return in < INT8_MIN || in > INT8_MAX; }
static inline int check_cast_int8_uint64(uint64_t in) { return (in > INT8_MAX); }
static inline int check_cast_int16_int32(int32_t in) { return in < INT16_MIN || in > INT16_MAX; }
static inline int check_cast_int16_uint32(uint32_t in) { return (in > INT16_MAX); }
static inline int check_cast_int16_int64(int64_t in) { return (in < INT16_MIN || in > INT16_MAX); }
static inline int check_cast_int16_uint64(uint64_t in) { return (in > INT16_MAX); }
static inline int check_cast_int32_uint32(uint32_t in) { return (in > INT32_MAX); }
static inline int check_cast_int32_int64(int64_t in) { return (in < INT32_MIN || in > INT32_MAX); }
static inline int check_cast_int32_uint64(uint64_t in) { return (in > INT32_MAX); }
static inline int check_cast_int64_uint64(uint64_t in) { return (in > INT64_MAX); }
static inline int check_cast_uint8_int32(int32_t in) { return (in < 0 || in > UINT8_MAX); }
static inline int check_cast_uint8_uint32(uint32_t in) { return (in > UINT8_MAX); }
static inline int check_cast_uint8_int64(int64_t in) { return (in < 0 || in > UINT8_MAX); }
static inline int check_cast_uint8_uint64(uint64_t in) { return (in > UINT8_MAX); }
static inline int check_cast_uint16_int32(int32_t in) { return (in < 0 || in > UINT16_MAX); }
static inline int check_cast_uint16_uint32(uint32_t in) { return (in > UINT16_MAX); }
static inline int check_cast_uint16_int64(int64_t in) { return (in < 0 || in > UINT16_MAX); }
static inline int check_cast_uint16_uint64(uint64_t in) { return (in > UINT16_MAX); }
static inline int check_cast_uint32_int32(int32_t in) { return (in < 0); }
static inline int check_cast_uint32_int64(int64_t in) { return (in < 0 || in > UINT32_MAX); }
static inline int check_cast_uint32_uint64(uint64_t in) { return (in > UINT32_MAX); }
static inline int check_cast_uint64_int64(int64_t in) { return (in < 0); }
static inline int8_t safe_cast_int8_int32(int32_t in)
{
if (!check_cast_int8_int32(in))
safe_math_fail("safe_math_fail safe_cast_int8_int32");
return (int8_t)in;
}
static inline int8_t safe_cast_int8_uint32(uint32_t in)
{
if (check_cast_int8_uint32(in))
safe_math_fail("safe_math_fail safe_cast_int8_uint32");
return (int8_t)in;
}
static inline int8_t safe_cast_int8_int64(int64_t in)
{
if (check_cast_int8_int64(in))
safe_math_fail("safe_math_fail safe_cast_int8_int64");
return (int8_t)in;
}
static inline int8_t safe_cast_int8_uint64(uint64_t in)
{
if (check_cast_int8_uint64(in))
safe_math_fail("safe_math_fail safe_cast_int8_uint64");
return (int8_t)in;
}
static inline int16_t safe_cast_int16_int32(int32_t in)
{
if (check_cast_int16_int32(in))
safe_math_fail("safe_math_fail safe_cast_int16_int32");
return (int16_t)in;
}
static inline int16_t safe_cast_int16_uint32(uint32_t in)
{
if (check_cast_int16_uint32(in))
safe_math_fail("safe_math_fail safe_cast_int16_uint32");
return (int16_t)in;
}
static inline int16_t safe_cast_int16_int64(int64_t in)
{
if (check_cast_int16_int64(in))
safe_math_fail("safe_math_fail safe_cast_int16_int64");
return (int16_t)in;
}
static inline int16_t safe_cast_int16_uint64(uint64_t in)
{
if (in > INT16_MAX)
safe_math_fail("safe_math_fail safe_cast_int16_uint64");
return (int16_t)in;
}
static inline int32_t safe_cast_int32_uint32(uint32_t in)
{
if (check_cast_int32_uint32(in))
safe_math_fail("safe_math_fail safe_cast_int32_uint32");
return (int32_t)in;
}
static inline int32_t safe_cast_int32_int64(int64_t in)
{
if (check_cast_int32_int64(in))
safe_math_fail("safe_math_fail safe_cast_int32_int64");
return (int32_t)in;
}
static inline int32_t safe_cast_int32_uint64(uint64_t in)
{
if (check_cast_int32_uint64(in))
safe_math_fail("safe_math_fail safe_cast_int32_uint64");
return (int32_t)in;
}
static inline int64_t safe_cast_int64_uint64(uint64_t in)
{
if (check_cast_int64_uint64(in))
safe_math_fail("safe_math_fail safe_cast_int64_uint64");
return (int64_t)in;
}
static inline uint8_t safe_cast_uint8_int32(int32_t in)
{
if (check_cast_uint8_int32(in))
safe_math_fail("safe_math_fail safe_cast_uint8_int32");
return (uint8_t)in;
}
static inline uint8_t safe_cast_uint8_uint32(uint32_t in)
{
if (check_cast_uint8_uint32(in))
safe_math_fail("safe_math_fail safe_cast_uint8_uint32");
return (uint8_t)in;
}
static inline uint8_t safe_cast_uint8_int64(int64_t in)
{
if (check_cast_uint8_int64(in))
safe_math_fail("safe_math_fail safe_cast_uint8_int64");
return (uint8_t)in;
}
static inline uint8_t safe_cast_uint8_uint64(uint64_t in)
{
if (check_cast_uint8_uint64(in))
safe_math_fail("safe_math_fail safe_cast_uint8_uint64");
return (uint8_t)in;
}
static inline uint16_t safe_cast_uint16_int32(int32_t in)
{
if (check_cast_uint16_int32(in))
safe_math_fail("safe_math_fail safe_cast_uint16_int32");
return (uint16_t)in;
}
static inline uint16_t safe_cast_uint16_uint32(uint32_t in)
{
if (check_cast_uint16_uint32(in))
safe_math_fail("safe_math_fail safe_cast_uint16_uint32");
return (uint16_t)in;
}
static inline uint16_t safe_cast_uint16_int64(int64_t in)
{
if (check_cast_uint16_int64(in))
safe_math_fail("safe_math_fail safe_cast_uint16_int64");
return (uint16_t)in;
}
static inline uint16_t safe_cast_uint16_uint64(uint64_t in)
{
if (check_cast_uint16_uint64(in))
safe_math_fail("safe_math_fail safe_cast_int16_uint64");
return (uint16_t)in;
}
static inline uint32_t safe_cast_uint32_int32(int32_t in)
{
if (check_cast_uint32_int32(in))
safe_math_fail("safe_math_fail safe_cast_uint32_int32");
return (uint32_t)in;
}
static inline uint32_t safe_cast_uint32_int64(int64_t in)
{
if (check_cast_uint32_int64(in))
safe_math_fail("safe_math_fail safe_cast_int32_int64");
return (uint32_t)in;
}
static inline uint32_t safe_cast_uint32_uint64(uint64_t in)
{
if (check_cast_uint32_uint64(in))
safe_math_fail("safe_math_fail safe_cast_uint32_uint64");
return (uint32_t)in;
}
static inline uint64_t safe_cast_uint64_int64(int64_t in)
{
if (check_cast_uint64_int64(in))
safe_math_fail("safe_math_fail safe_cast_int64_uint64");
return (uint64_t)in;
}
// Addition
/*
For addition and multiplication, there will be checks for the following matrix:
- int32
- uint32
- int64
- uint64
If you want to add smaller types, then do it inside the appropriate safe_cast function,
or if adding one of the above and a smaller type, pass it into one that takes a larger
size of the same type, for example, uint16 -> uint32.
*/
static inline int32_t safe_add_int32_int32(int32_t a, int32_t b)
{
return safe_cast_int32_int64((int64_t)a + b);
}
static inline bool check_add_int32_int32(int32_t a, int32_t b, int32_t* ret)
{
int64_t tmp = (int64_t)a + b;
*ret = (int32_t)tmp;
return check_cast_int32_int64(tmp) == 0;
}
static inline int32_t safe_add_int32_uint32(int32_t a, uint32_t b)
{
return safe_cast_int32_int64((int64_t)a + b);
}
static inline bool check_add_int32_uint32(int32_t a, uint32_t b, int32_t* ret)
{
int64_t tmp = (int64_t)a + b;
*ret = (int32_t)tmp;
return check_cast_int32_int64(tmp) == 0;
}
static inline int32_t safe_add_int32_int64(int32_t a, int64_t b)
{
int64_t tmp = (int64_t)((uint64_t)a + (uint64_t)b);
if (a >= 0)
{
// mixed sign cannot overflow
if (b >= 0 && tmp < a)
safe_math_fail("safe_math_fail safe_add_int32_int64");
}
else
{
// lhs negative
if (b < 0 && tmp > a)
safe_math_fail("safe_math_fail safe_add_int32_int64");
}
return safe_cast_int32_int64(tmp);
}
static inline bool check_add_int32_int64(int32_t a, int64_t b, int32_t* ret)
{
int64_t tmp = (int64_t)((uint64_t)a + (uint64_t)b);
*ret = (int32_t)tmp;
if (a >= 0)
{
// mixed sign cannot overflow
if (b >= 0 && tmp < a)
return false;
}
else
{
// lhs negative
if (b < 0 && tmp > a)
return false;
}
return check_cast_int32_int64(tmp) == 0;
}
static inline int32_t safe_add_int32_uint64(int32_t a, uint64_t b)
{
if ((uint32_t)(b >> 32) == 0)
{
// Now it just happens to work out that the standard behavior does what we want
// Adding explicit casts to show exactly what's happening here
uint32_t tmp = (uint32_t)a + (uint32_t)b;
if ((int32_t)tmp >= a)
{
return (int32_t)tmp;
}
}
safe_math_fail("safe_math_fail safe_add_int32_uint64");
}
static inline bool check_add_int32_uint64(int32_t a, uint64_t b, int32_t* ret)
{
if ((uint32_t)(b >> 32) == 0)
{
// Now it just happens to work out that the standard behavior does what we want
// Adding explicit casts to show exactly what's happening here
uint32_t tmp = (uint32_t)a + (uint32_t)b;
*ret = (int32_t)tmp;
if ((int32_t)tmp >= a)
{
return true;
}
}
return false;
}
static inline uint32_t safe_add_uint32_int32(uint32_t a, int32_t b)
{
return safe_cast_uint32_int64((int64_t)a + b);
}
static inline bool check_add_uint32_int32(uint32_t a, int32_t b, uint32_t* ret)
{
int64_t tmp = (int64_t)a + b;
*ret = (uint32_t)tmp;
return check_cast_uint32_int64(tmp) == 0;
}
static inline uint32_t safe_add_uint32_uint32(uint32_t a, uint32_t b)
{
uint32_t tmp = a + b;
if (tmp < a)
{
safe_math_fail("safe_math_fail safe_add_uint32_uint32");
}
return tmp;
}
static inline bool check_add_uint32_uint32(uint32_t a, uint32_t b, uint32_t* ret)
{
uint32_t tmp = a + b;
*ret = tmp;
return tmp >= a;
}
static inline uint32_t safe_add_uint32_int64(uint32_t a, int64_t b)
{
if (b < 0)
{
if (a >= safe_abs64(b)) //negation is safe, since rhs is 64-bit
{
return (uint32_t)(a + b);
}
}
else
{
// now we know that rhs can be safely cast into an std::uint64_t
uint64_t tmp = (uint64_t)a + (uint64_t)b;
// special case - rhs cannot be larger than 0x7fffffffffffffff, lhs cannot be larger than 0xffffffff
// it is not possible for the operation above to overflow, so just check max
return safe_cast_uint32_uint64(tmp);
}
safe_math_fail("safe_math_fail safe_add_uint32_int64");
}
static inline bool check_add_uint32_int64(uint32_t a, int64_t b, uint32_t* ret)
{
if (b < 0)
{
if (a >= safe_abs64(b)) //negation is safe, since rhs is 64-bit
{
*ret = (uint32_t)(a + b);
return true;
}
}
else
{
// now we know that rhs can be safely cast into an std::uint64_t
uint64_t tmp = (uint64_t)a + (uint64_t)b;
// special case - rhs cannot be larger than 0x7fffffffffffffff, lhs cannot be larger than 0xffffffff
// it is not possible for the operation above to overflow, so just check max
*ret = (uint32_t)tmp;
return check_cast_uint32_uint64(tmp) == 0;
}
return false;
}
static inline uint32_t safe_add_uint32_uint64(uint32_t a, uint64_t b)
{
uint64_t tmp = (uint64_t)a + b;
if (tmp >= a && tmp <= UINT32_MAX)
{
return (uint32_t)tmp;
}
safe_math_fail("safe_math_fail safe_add_uint32_uint64");
}
static inline bool check_add_uint32_uint64(uint32_t a, uint64_t b, uint32_t* ret)
{
uint64_t tmp = (uint64_t)a + b;
*ret = (uint32_t)tmp;
return (tmp >= a && tmp <= UINT32_MAX);
}
static inline int64_t safe_add_int64_int32(int64_t a, int32_t b)
{
int64_t tmp = (int64_t)((uint64_t)a + (uint64_t)b);
if (a >= 0)
{
// mixed sign cannot overflow
if (b >= 0 && tmp < a)
safe_math_fail("safe_math_fail safe_add_int64_int32");
}
else
{
// lhs negative
if (b < 0 && tmp > a)
safe_math_fail("safe_math_fail safe_add_int64_int32");
}
return tmp;
}
static inline bool check_add_int64_int32(int64_t a, int32_t b, int64_t* ret)
{
int64_t tmp = (int64_t)((uint64_t)a + (uint64_t)b);
*ret = tmp;
if (a >= 0)
{
// mixed sign cannot overflow
if (b >= 0 && tmp < a)
return false;
}
else
{
// lhs negative
if (b < 0 && tmp > a)
return false;
}
return true;
}
static inline int64_t safe_add_int64_uint32(int64_t a, uint32_t b)
{
uint64_t tmp = (uint64_t)a + (uint64_t)b;
if ((int64_t)tmp >= a)
{
return (int64_t)tmp;
}
safe_math_fail("safe_math_fail safe_add_int64_uint32");
}
static inline bool check_add_int64_uint32(int64_t a, uint32_t b, int64_t* ret)
{
uint64_t tmp = (uint64_t)a + (uint64_t)b;
*ret = (int64_t)tmp;
return ((int64_t)tmp >= a);
}
static inline int64_t safe_add_int64_int64(int64_t a, int64_t b)
{
int64_t tmp = (int64_t)((uint64_t)a + (uint64_t)b);
if (a >= 0)
{
// mixed sign cannot overflow
if (b >= 0 && tmp < a)
safe_math_fail("safe_math_fail safe_add_int64_int64");
}
else
{
// lhs negative
if (b < 0 && tmp > a)
safe_math_fail("safe_math_fail safe_add_int64_int64");
}
return tmp;
}
static inline bool check_add_int64_int64(int64_t a, int64_t b, int64_t* ret)
{
int64_t tmp = (int64_t)((uint64_t)a + (uint64_t)b);
*ret = tmp;
if (a >= 0)
{
// mixed sign cannot overflow
if (b >= 0 && tmp < a)
return false;
}
else
{
// lhs negative
if (b < 0 && tmp > a)
return false;
}
return true;
}
static inline int64_t safe_add_int64_uint64(int64_t a, uint64_t b)
{
uint64_t tmp = (uint64_t)a + b;
if ((int64_t)tmp >= a)
{
return (int64_t)tmp;
}
safe_math_fail("safe_math_fail safe_add_int64_uint64");
}
static inline bool check_add_int64_uint64(int64_t a, uint64_t b, int64_t* ret)
{
uint64_t tmp = (uint64_t)a + b;
*ret = (int64_t)tmp;
return ((int64_t)tmp >= a);
}
static inline uint64_t safe_add_uint64_int32(uint64_t a, int32_t b)
{
uint64_t tmp = 0;
if (b < 0)
{
// So we're effectively subtracting
tmp = safe_abs32(b);
if (tmp <= a)
{
return a - tmp;
}
}
else
{
// now we know that rhs can be safely cast into an std::uint64_t
tmp = (uint64_t)a + (uint64_t)b;
// We added and it did not become smaller
if (tmp >= a)
{
return tmp;
}
}
safe_math_fail("safe_math_fail safe_add_uint64_int32");
}
static inline bool check_add_uint64_int32(uint64_t a, int32_t b, uint64_t* ret)
{
uint64_t tmp = 0;
if (b < 0)
{
// So we're effectively subtracting
tmp = safe_abs32(b);
if (tmp <= a)
{
*ret = a - tmp;
return true;
}
}
else
{
// now we know that rhs can be safely cast into an std::uint64_t
tmp = (uint64_t)a + (uint64_t)b;
// We added and it did not become smaller
if (tmp >= a)
{
*ret = tmp;
return true;
}
}
return false;
}
static inline uint64_t safe_add_uint64_uint32(uint64_t a, uint32_t b)
{
uint64_t tmp = (uint64_t)a + (uint64_t)b;
// We added and it didn't get smaller
if (tmp >= a)
{
return tmp;
}
safe_math_fail("safe_math_fail safe_add_uint64_uint32");
}
static inline bool check_add_uint64_uint32(uint64_t a, uint32_t b, uint64_t* ret)
{
uint64_t tmp = (uint64_t)a + (uint64_t)b;
*ret = tmp;
// We added and it didn't get smaller
return (tmp >= a);
}
static inline uint64_t safe_add_uint64_int64(uint64_t a, int64_t b)
{
uint64_t tmp = 0;
if (b < 0)
{
// So we're effectively subtracting
tmp = safe_abs64(b);
if (tmp <= a)
{
return a - tmp;
}
}
else
{
// now we know that rhs can be safely cast into an std::uint64_t
tmp = (uint64_t)a + (uint64_t)b;
// We added and it did not become smaller
if (tmp >= a)
{
return tmp;
}
}
safe_math_fail("safe_math_fail safe_add_uint64_int64");
}
static inline bool check_add_uint64_int64(uint64_t a, int64_t b, uint64_t* ret)
{
uint64_t tmp = 0;
if (b < 0)
{
// So we're effectively subtracting
tmp = safe_abs64(b);
if (tmp <= a)
{
*ret = a - tmp;
return true;
}
}
else
{
// now we know that rhs can be safely cast into an std::uint64_t
tmp = (uint64_t)a + (uint64_t)b;
// We added and it did not become smaller
if (tmp >= a)
{
*ret = tmp;
return true;
}
}
return false;
}
static inline uint64_t safe_add_uint64_uint64(uint64_t a, uint64_t b)
{
uint64_t tmp = a + b;
if(tmp < a)
safe_math_fail("safe_math_fail safe_add_uint64_uint64");
return tmp;
}
static inline bool check_add_uint64_uint64(uint64_t a, uint64_t b, uint64_t* ret)
{
uint64_t tmp = a + b;
*ret = tmp;
return (tmp >= a);
}
// As we're working in C, use defines
// It would be nice to use an enum, but the compiler
// will complain that it isn't a proper C++ enum
#define SAFE_INT_MUL_FAIL 0
#define SAFE_INT_MUL_SUCCESS 1
// Multiplication primatives
#if SAFEINT_MULTIPLY_METHOD == SAFEINT_MULTIPLY_INT128
static inline int MultiplyUint64(uint64_t a, uint64_t b, uint64_t* pRet)
{
unsigned __int128 tmp = (unsigned __int128)a * (unsigned __int128)b;
if ((tmp >> 64) == 0)
{
*pRet = (uint64_t)tmp;
return SAFE_INT_MUL_SUCCESS;
}
return SAFE_INT_MUL_FAIL;
}
static inline int MultiplyInt64(int64_t a, int64_t b, int64_t* pRet)
{
__int128 tmp = (__int128)a * (__int128)b;
int64_t tmp_high = (int64_t)((unsigned __int128)tmp >> 64);
*pRet = (int64_t)tmp;
// If only one input is negative, result must be negative, or zero
if ((a ^ b) < 0)
{
if ((tmp_high == -1 && *pRet < 0) ||
(tmp_high == 0 && *pRet == 0))
{
return SAFE_INT_MUL_SUCCESS;
}
}
else
{
if (tmp_high == 0 && (uint64_t)*pRet <= (uint64_t)INT64_MAX)
{
return SAFE_INT_MUL_SUCCESS;
}
}
return SAFE_INT_MUL_FAIL;
}
#elif SAFEINT_MULTIPLY_METHOD == SAFEINT_MULTIPLY_INTRINSICS // Implies Visual Studio compiler
// As usual, unsigned is easy
static inline int MultiplyUint64(uint64_t a, uint64_t b, uint64_t * pRet)
{
uint64_t ulHigh = 0;
*pRet = _umul128(a, b, &ulHigh);
return ulHigh == 0 ? SAFE_INT_MUL_SUCCESS : SAFE_INT_MUL_FAIL;
}
// Signed, is not so easy
static inline int MultiplyInt64(int64_t a, int64_t b, int64_t* pRet)
{
int64_t llHigh = 0;
*pRet = _mul128(a, b, &llHigh);
// Now we need to figure out what we expect
// If llHigh is 0, then treat *pRet as unsigned
// If llHigh is < 0, then treat *pRet as signed
if ((a ^ b) < 0)
{
// Negative (or zero) result expected
if (llHigh == -1 && *pRet < 0 ||
llHigh == 0 && *pRet == 0)
{
// Everything is within range
return SAFE_INT_MUL_SUCCESS;
}
}
else
{
// Result should be positive
// Check for overflow
if (llHigh == 0 && (uint64_t)*pRet <= (uint64_t)INT64_MAX)
return SAFE_INT_MUL_SUCCESS;
}
return SAFE_INT_MUL_FAIL;
}
#elif SAFEINT_MULTIPLY_METHOD == SAFEINT_MULTIPLY_BUILTIN // Implies gcc or clang
static inline int MultiplyUint64(uint64_t a, uint64_t b, uint64_t* pRet)
{
return !__builtin_umulll_overflow(a, b, (unsigned long long*)pRet) ? SAFE_INT_MUL_SUCCESS : SAFE_INT_MUL_FAIL;
}
static inline int MultiplyInt64(int64_t a, int64_t b, int64_t* pRet)
{
return !__builtin_smulll_overflow(a, b, (long long*)pRet) ? SAFE_INT_MUL_SUCCESS : SAFE_INT_MUL_FAIL;
}
#elif SAFEINT_MULTIPLY_METHOD == SAFEINT_MULTIPLY_MATH // Just going to have to do the math...
static inline int MultiplyUint64(uint64_t a, uint64_t b, uint64_t* pRet)
{
uint32_t a_high = a >> 32;
uint32_t a_low = (uint32_t)a;
uint32_t b_high = b >> 32;
uint32_t b_low = (uint32_t)b;
uint64_t tmp = 0;
uint64_t tmp2 = 0;
/*
* Now we have the equivalent of (a_high * 2^32 + a_low) * (b_high * 2^32 + b_low)
* Expanding:
* result = a_high * b_high * 2^64 + a_high * b_low * 2^32 + b_high * a_low * 2^32 + a_low * b_low