summaryrefslogtreecommitdiff
path: root/src/util.c
blob: d173f776face48ce64c33932b41fa80c28899267 (plain)
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
/*
 * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "fmacros.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <limits.h>
#include <math.h>
#include <unistd.h>
#include <sys/time.h>
#include <float.h>
#include <stdint.h>
#include <errno.h>
#include <time.h>

#include "util.h"
#include "sha256.h"

/* Glob-style pattern matching. */
int stringmatchlen(const char *pattern, int patternLen,
        const char *string, int stringLen, int nocase)
{
    while(patternLen && stringLen) {
        switch(pattern[0]) {
        case '*':
            while (pattern[1] == '*') {
                pattern++;
                patternLen--;
            }
            if (patternLen == 1)
                return 1; /* match */
            while(stringLen) {
                if (stringmatchlen(pattern+1, patternLen-1,
                            string, stringLen, nocase))
                    return 1; /* match */
                string++;
                stringLen--;
            }
            return 0; /* no match */
            break;
        case '?':
            if (stringLen == 0)
                return 0; /* no match */
            string++;
            stringLen--;
            break;
        case '[':
        {
            int not, match;

            pattern++;
            patternLen--;
            not = pattern[0] == '^';
            if (not) {
                pattern++;
                patternLen--;
            }
            match = 0;
            while(1) {
                if (pattern[0] == '\\' && patternLen >= 2) {
                    pattern++;
                    patternLen--;
                    if (pattern[0] == string[0])
                        match = 1;
                } else if (pattern[0] == ']') {
                    break;
                } else if (patternLen == 0) {
                    pattern--;
                    patternLen++;
                    break;
                } else if (pattern[1] == '-' && patternLen >= 3) {
                    int start = pattern[0];
                    int end = pattern[2];
                    int c = string[0];
                    if (start > end) {
                        int t = start;
                        start = end;
                        end = t;
                    }
                    if (nocase) {
                        start = tolower(start);
                        end = tolower(end);
                        c = tolower(c);
                    }
                    pattern += 2;
                    patternLen -= 2;
                    if (c >= start && c <= end)
                        match = 1;
                } else {
                    if (!nocase) {
                        if (pattern[0] == string[0])
                            match = 1;
                    } else {
                        if (tolower((int)pattern[0]) == tolower((int)string[0]))
                            match = 1;
                    }
                }
                pattern++;
                patternLen--;
            }
            if (not)
                match = !match;
            if (!match)
                return 0; /* no match */
            string++;
            stringLen--;
            break;
        }
        case '\\':
            if (patternLen >= 2) {
                pattern++;
                patternLen--;
            }
            /* fall through */
        default:
            if (!nocase) {
                if (pattern[0] != string[0])
                    return 0; /* no match */
            } else {
                if (tolower((int)pattern[0]) != tolower((int)string[0]))
                    return 0; /* no match */
            }
            string++;
            stringLen--;
            break;
        }
        pattern++;
        patternLen--;
        if (stringLen == 0) {
            while(*pattern == '*') {
                pattern++;
                patternLen--;
            }
            break;
        }
    }
    if (patternLen == 0 && stringLen == 0)
        return 1;
    return 0;
}

int stringmatch(const char *pattern, const char *string, int nocase) {
    return stringmatchlen(pattern,strlen(pattern),string,strlen(string),nocase);
}

/* Fuzz stringmatchlen() trying to crash it with bad input. */
int stringmatchlen_fuzz_test(void) {
    char str[32];
    char pat[32];
    int cycles = 10000000;
    int total_matches = 0;
    while(cycles--) {
        int strlen = rand() % sizeof(str);
        int patlen = rand() % sizeof(pat);
        for (int j = 0; j < strlen; j++) str[j] = rand() % 128;
        for (int j = 0; j < patlen; j++) pat[j] = rand() % 128;
        total_matches += stringmatchlen(pat, patlen, str, strlen, 0);
    }
    return total_matches;
}

/* Convert a string representing an amount of memory into the number of
 * bytes, so for instance memtoll("1Gb") will return 1073741824 that is
 * (1024*1024*1024).
 *
 * On parsing error, if *err is not NULL, it's set to 1, otherwise it's
 * set to 0. On error the function return value is 0, regardless of the
 * fact 'err' is NULL or not. */
long long memtoll(const char *p, int *err) {
    const char *u;
    char buf[128];
    long mul; /* unit multiplier */
    long long val;
    unsigned int digits;

    if (err) *err = 0;

    /* Search the first non digit character. */
    u = p;
    if (*u == '-') u++;
    while(*u && isdigit(*u)) u++;
    if (*u == '\0' || !strcasecmp(u,"b")) {
        mul = 1;
    } else if (!strcasecmp(u,"k")) {
        mul = 1000;
    } else if (!strcasecmp(u,"kb")) {
        mul = 1024;
    } else if (!strcasecmp(u,"m")) {
        mul = 1000*1000;
    } else if (!strcasecmp(u,"mb")) {
        mul = 1024*1024;
    } else if (!strcasecmp(u,"g")) {
        mul = 1000L*1000*1000;
    } else if (!strcasecmp(u,"gb")) {
        mul = 1024L*1024*1024;
    } else {
        if (err) *err = 1;
        return 0;
    }

    /* Copy the digits into a buffer, we'll use strtoll() to convert
     * the digit (without the unit) into a number. */
    digits = u-p;
    if (digits >= sizeof(buf)) {
        if (err) *err = 1;
        return 0;
    }
    memcpy(buf,p,digits);
    buf[digits] = '\0';

    char *endptr;
    errno = 0;
    val = strtoll(buf,&endptr,10);
    if ((val == 0 && errno == EINVAL) || *endptr != '\0') {
        if (err) *err = 1;
        return 0;
    }
    return val*mul;
}

/* Return the number of digits of 'v' when converted to string in radix 10.
 * See ll2string() for more information. */
uint32_t digits10(uint64_t v) {
    if (v < 10) return 1;
    if (v < 100) return 2;
    if (v < 1000) return 3;
    if (v < 1000000000000UL) {
        if (v < 100000000UL) {
            if (v < 1000000) {
                if (v < 10000) return 4;
                return 5 + (v >= 100000);
            }
            return 7 + (v >= 10000000UL);
        }
        if (v < 10000000000UL) {
            return 9 + (v >= 1000000000UL);
        }
        return 11 + (v >= 100000000000UL);
    }
    return 12 + digits10(v / 1000000000000UL);
}

/* Like digits10() but for signed values. */
uint32_t sdigits10(int64_t v) {
    if (v < 0) {
        /* Abs value of LLONG_MIN requires special handling. */
        uint64_t uv = (v != LLONG_MIN) ?
                      (uint64_t)-v : ((uint64_t) LLONG_MAX)+1;
        return digits10(uv)+1; /* +1 for the minus. */
    } else {
        return digits10(v);
    }
}

/* Convert a long long into a string. Returns the number of
 * characters needed to represent the number.
 * If the buffer is not big enough to store the string, 0 is returned.
 *
 * Based on the following article (that apparently does not provide a
 * novel approach but only publicizes an already used technique):
 *
 * https://www.facebook.com/notes/facebook-engineering/three-optimization-tips-for-c/10151361643253920
 *
 * Modified in order to handle signed integers since the original code was
 * designed for unsigned integers. */
int ll2string(char *dst, size_t dstlen, long long svalue) {
    static const char digits[201] =
        "0001020304050607080910111213141516171819"
        "2021222324252627282930313233343536373839"
        "4041424344454647484950515253545556575859"
        "6061626364656667686970717273747576777879"
        "8081828384858687888990919293949596979899";
    int negative;
    unsigned long long value;

    /* The main loop works with 64bit unsigned integers for simplicity, so
     * we convert the number here and remember if it is negative. */
    if (svalue < 0) {
        if (svalue != LLONG_MIN) {
            value = -svalue;
        } else {
            value = ((unsigned long long) LLONG_MAX)+1;
        }
        negative = 1;
    } else {
        value = svalue;
        negative = 0;
    }

    /* Check length. */
    uint32_t const length = digits10(value)+negative;
    if (length >= dstlen) return 0;

    /* Null term. */
    uint32_t next = length;
    dst[next] = '\0';
    next--;
    while (value >= 100) {
        int const i = (value % 100) * 2;
        value /= 100;
        dst[next] = digits[i + 1];
        dst[next - 1] = digits[i];
        next -= 2;
    }

    /* Handle last 1-2 digits. */
    if (value < 10) {
        dst[next] = '0' + (uint32_t) value;
    } else {
        int i = (uint32_t) value * 2;
        dst[next] = digits[i + 1];
        dst[next - 1] = digits[i];
    }

    /* Add sign. */
    if (negative) dst[0] = '-';
    return length;
}

/* Convert a string into a long long. Returns 1 if the string could be parsed
 * into a (non-overflowing) long long, 0 otherwise. The value will be set to
 * the parsed value when appropriate.
 *
 * Note that this function demands that the string strictly represents
 * a long long: no spaces or other characters before or after the string
 * representing the number are accepted, nor zeroes at the start if not
 * for the string "0" representing the zero number.
 *
 * Because of its strictness, it is safe to use this function to check if
 * you can convert a string into a long long, and obtain back the string
 * from the number without any loss in the string representation. */
int string2ll(const char *s, size_t slen, long long *value) {
    const char *p = s;
    size_t plen = 0;
    int negative = 0;
    unsigned long long v;

    /* A zero length string is not a valid number. */
    if (plen == slen)
        return 0;

    /* Special case: first and only digit is 0. */
    if (slen == 1 && p[0] == '0') {
        if (value != NULL) *value = 0;
        return 1;
    }

    /* Handle negative numbers: just set a flag and continue like if it
     * was a positive number. Later convert into negative. */
    if (p[0] == '-') {
        negative = 1;
        p++; plen++;

        /* Abort on only a negative sign. */
        if (plen == slen)
            return 0;
    }

    /* First digit should be 1-9, otherwise the string should just be 0. */
    if (p[0] >= '1' && p[0] <= '9') {
        v = p[0]-'0';
        p++; plen++;
    } else {
        return 0;
    }

    /* Parse all the other digits, checking for overflow at every step. */
    while (plen < slen && p[0] >= '0' && p[0] <= '9') {
        if (v > (ULLONG_MAX / 10)) /* Overflow. */
            return 0;
        v *= 10;

        if (v > (ULLONG_MAX - (p[0]-'0'))) /* Overflow. */
            return 0;
        v += p[0]-'0';

        p++; plen++;
    }

    /* Return if not all bytes were used. */
    if (plen < slen)
        return 0;

    /* Convert to negative if needed, and do the final overflow check when
     * converting from unsigned long long to long long. */
    if (negative) {
        if (v > ((unsigned long long)(-(LLONG_MIN+1))+1)) /* Overflow. */
            return 0;
        if (value != NULL) *value = -v;
    } else {
        if (v > LLONG_MAX) /* Overflow. */
            return 0;
        if (value != NULL) *value = v;
    }
    return 1;
}

/* Helper function to convert a string to an unsigned long long value.
 * The function attempts to use the faster string2ll() function inside
 * Redis: if it fails, strtoull() is used instead. The function returns
 * 1 if the conversion happened successfully or 0 if the number is
 * invalid or out of range. */
int string2ull(const char *s, unsigned long long *value) {
    long long ll;
    if (string2ll(s,strlen(s),&ll)) {
        if (ll < 0) return 0; /* Negative values are out of range. */
        *value = ll;
        return 1;
    }
    errno = 0;
    char *endptr = NULL;
    *value = strtoull(s,&endptr,10);
    if (errno == EINVAL || errno == ERANGE || !(*s != '\0' && *endptr == '\0'))
        return 0; /* strtoull() failed. */
    return 1; /* Conversion done! */
}

/* Convert a string into a long. Returns 1 if the string could be parsed into a
 * (non-overflowing) long, 0 otherwise. The value will be set to the parsed
 * value when appropriate. */
int string2l(const char *s, size_t slen, long *lval) {
    long long llval;

    if (!string2ll(s,slen,&llval))
        return 0;

    if (llval < LONG_MIN || llval > LONG_MAX)
        return 0;

    *lval = (long)llval;
    return 1;
}

/* Convert a string into a double. Returns 1 if the string could be parsed
 * into a (non-overflowing) double, 0 otherwise. The value will be set to
 * the parsed value when appropriate.
 *
 * Note that this function demands that the string strictly represents
 * a double: no spaces or other characters before or after the string
 * representing the number are accepted. */
int string2ld(const char *s, size_t slen, long double *dp) {
    char buf[MAX_LONG_DOUBLE_CHARS];
    long double value;
    char *eptr;

    if (slen == 0 || slen >= sizeof(buf)) return 0;
    memcpy(buf,s,slen);
    buf[slen] = '\0';

    errno = 0;
    value = strtold(buf, &eptr);
    if (isspace(buf[0]) || eptr[0] != '\0' ||
        (size_t)(eptr-buf) != slen ||
        (errno == ERANGE &&
            (value == HUGE_VAL || value == -HUGE_VAL || value == 0)) ||
        errno == EINVAL ||
        isnan(value))
        return 0;

    if (dp) *dp = value;
    return 1;
}

/* Convert a string into a double. Returns 1 if the string could be parsed
 * into a (non-overflowing) double, 0 otherwise. The value will be set to
 * the parsed value when appropriate.
 *
 * Note that this function demands that the string strictly represents
 * a double: no spaces or other characters before or after the string
 * representing the number are accepted. */
int string2d(const char *s, size_t slen, double *dp) {
    errno = 0;
    char *eptr;
    *dp = strtod(s, &eptr);
    if (slen == 0 ||
        isspace(((const char*)s)[0]) ||
        (size_t)(eptr-(char*)s) != slen ||
        (errno == ERANGE &&
            (*dp == HUGE_VAL || *dp == -HUGE_VAL || *dp == 0)) ||
        isnan(*dp))
        return 0;
    return 1;
}

/* Convert a double to a string representation. Returns the number of bytes
 * required. The representation should always be parsable by strtod(3).
 * This function does not support human-friendly formatting like ld2string
 * does. It is intended mainly to be used inside t_zset.c when writing scores
 * into a ziplist representing a sorted set. */
int d2string(char *buf, size_t len, double value) {
    if (isnan(value)) {
        len = snprintf(buf,len,"nan");
    } else if (isinf(value)) {
        if (value < 0)
            len = snprintf(buf,len,"-inf");
        else
            len = snprintf(buf,len,"inf");
    } else if (value == 0) {
        /* See: http://en.wikipedia.org/wiki/Signed_zero, "Comparisons". */
        if (1.0/value < 0)
            len = snprintf(buf,len,"-0");
        else
            len = snprintf(buf,len,"0");
    } else {
#if (DBL_MANT_DIG >= 52) && (LLONG_MAX == 0x7fffffffffffffffLL)
        /* Check if the float is in a safe range to be casted into a
         * long long. We are assuming that long long is 64 bit here.
         * Also we are assuming that there are no implementations around where
         * double has precision < 52 bit.
         *
         * Under this assumptions we test if a double is inside an interval
         * where casting to long long is safe. Then using two castings we
         * make sure the decimal part is zero. If all this is true we use
         * integer printing function that is much faster. */
        double min = -4503599627370495; /* (2^52)-1 */
        double max = 4503599627370496; /* -(2^52) */
        if (value > min && value < max && value == ((double)((long long)value)))
            len = ll2string(buf,len,(long long)value);
        else
#endif
            len = snprintf(buf,len,"%.17g",value);
    }

    return len;
}

/* Create a string object from a long double.
 * If mode is humanfriendly it does not use exponential format and trims trailing
 * zeroes at the end (may result in loss of precision).
 * If mode is default exp format is used and the output of snprintf()
 * is not modified (may result in loss of precision).
 * If mode is hex hexadecimal format is used (no loss of precision)
 *
 * The function returns the length of the string or zero if there was not
 * enough buffer room to store it. */
int ld2string(char *buf, size_t len, long double value, ld2string_mode mode) {
    size_t l = 0;

    if (isinf(value)) {
        /* Libc in odd systems (Hi Solaris!) will format infinite in a
         * different way, so better to handle it in an explicit way. */
        if (len < 5) return 0; /* No room. 5 is "-inf\0" */
        if (value > 0) {
            memcpy(buf,"inf",3);
            l = 3;
        } else {
            memcpy(buf,"-inf",4);
            l = 4;
        }
    } else {
        switch (mode) {
        case LD_STR_AUTO:
            l = snprintf(buf,len,"%.17Lg",value);
            if (l+1 > len) return 0; /* No room. */
            break;
        case LD_STR_HEX:
            l = snprintf(buf,len,"%La",value);
            if (l+1 > len) return 0; /* No room. */
            break;
        case LD_STR_HUMAN:
            /* We use 17 digits precision since with 128 bit floats that precision
             * after rounding is able to represent most small decimal numbers in a
             * way that is "non surprising" for the user (that is, most small
             * decimal numbers will be represented in a way that when converted
             * back into a string are exactly the same as what the user typed.) */
            l = snprintf(buf,len,"%.17Lf",value);
            if (l+1 > len) return 0; /* No room. */
            /* Now remove trailing zeroes after the '.' */
            if (strchr(buf,'.') != NULL) {
                char *p = buf+l-1;
                while(*p == '0') {
                    p--;
                    l--;
                }
                if (*p == '.') l--;
            }
            if (l == 2 && buf[0] == '-' && buf[1] == '0') {
                buf[0] = '0';
                l = 1;
            }
            break;
        default: return 0; /* Invalid mode. */
        }
    }
    buf[l] = '\0';
    return l;
}

/* Get random bytes, attempts to get an initial seed from /dev/urandom and
 * the uses a one way hash function in counter mode to generate a random
 * stream. However if /dev/urandom is not available, a weaker seed is used.
 *
 * This function is not thread safe, since the state is global. */
void getRandomBytes(unsigned char *p, size_t len) {
    /* Global state. */
    static int seed_initialized = 0;
    static unsigned char seed[64]; /* 512 bit internal block size. */
    static uint64_t counter = 0; /* The counter we hash with the seed. */

    if (!seed_initialized) {
        /* Initialize a seed and use SHA1 in counter mode, where we hash
         * the same seed with a progressive counter. For the goals of this
         * function we just need non-colliding strings, there are no
         * cryptographic security needs. */
        FILE *fp = fopen("/dev/urandom","r");
        if (fp == NULL || fread(seed,sizeof(seed),1,fp) != 1) {
            /* Revert to a weaker seed, and in this case reseed again
             * at every call.*/
            for (unsigned int j = 0; j < sizeof(seed); j++) {
                struct timeval tv;
                gettimeofday(&tv,NULL);
                pid_t pid = getpid();
                seed[j] = tv.tv_sec ^ tv.tv_usec ^ pid ^ (long)fp;
            }
        } else {
            seed_initialized = 1;
        }
        if (fp) fclose(fp);
    }

    while(len) {
        /* This implements SHA256-HMAC. */
        unsigned char digest[SHA256_BLOCK_SIZE];
        unsigned char kxor[64];
        unsigned int copylen =
            len > SHA256_BLOCK_SIZE ? SHA256_BLOCK_SIZE : len;

        /* IKEY: key xored with 0x36. */
        memcpy(kxor,seed,sizeof(kxor));
        for (unsigned int i = 0; i < sizeof(kxor); i++) kxor[i] ^= 0x36;

        /* Obtain HASH(IKEY||MESSAGE). */
        SHA256_CTX ctx;
        sha256_init(&ctx);
        sha256_update(&ctx,kxor,sizeof(kxor));
        sha256_update(&ctx,(unsigned char*)&counter,sizeof(counter));
        sha256_final(&ctx,digest);

        /* OKEY: key xored with 0x5c. */
        memcpy(kxor,seed,sizeof(kxor));
        for (unsigned int i = 0; i < sizeof(kxor); i++) kxor[i] ^= 0x5C;

        /* Obtain HASH(OKEY || HASH(IKEY||MESSAGE)). */
        sha256_init(&ctx);
        sha256_update(&ctx,kxor,sizeof(kxor));
        sha256_update(&ctx,digest,SHA256_BLOCK_SIZE);
        sha256_final(&ctx,digest);

        /* Increment the counter for the next iteration. */
        counter++;

        memcpy(p,digest,copylen);
        len -= copylen;
        p += copylen;
    }
}

/* Generate the Redis "Run ID", a SHA1-sized random number that identifies a
 * given execution of Redis, so that if you are talking with an instance
 * having run_id == A, and you reconnect and it has run_id == B, you can be
 * sure that it is either a different instance or it was restarted. */
void getRandomHexChars(char *p, size_t len) {
    char *charset = "0123456789abcdef";
    size_t j;

    getRandomBytes((unsigned char*)p,len);
    for (j = 0; j < len; j++) p[j] = charset[p[j] & 0x0F];
}

/* Given the filename, return the absolute path as an SDS string, or NULL
 * if it fails for some reason. Note that "filename" may be an absolute path
 * already, this will be detected and handled correctly.
 *
 * The function does not try to normalize everything, but only the obvious
 * case of one or more "../" appearing at the start of "filename"
 * relative path. */
sds getAbsolutePath(char *filename) {
    char cwd[1024];
    sds abspath;
    sds relpath = sdsnew(filename);

    relpath = sdstrim(relpath," \r\n\t");
    if (relpath[0] == '/') return relpath; /* Path is already absolute. */

    /* If path is relative, join cwd and relative path. */
    if (getcwd(cwd,sizeof(cwd)) == NULL) {
        sdsfree(relpath);
        return NULL;
    }
    abspath = sdsnew(cwd);
    if (sdslen(abspath) && abspath[sdslen(abspath)-1] != '/')
        abspath = sdscat(abspath,"/");

    /* At this point we have the current path always ending with "/", and
     * the trimmed relative path. Try to normalize the obvious case of
     * trailing ../ elements at the start of the path.
     *
     * For every "../" we find in the filename, we remove it and also remove
     * the last element of the cwd, unless the current cwd is "/". */
    while (sdslen(relpath) >= 3 &&
           relpath[0] == '.' && relpath[1] == '.' && relpath[2] == '/')
    {
        sdsrange(relpath,3,-1);
        if (sdslen(abspath) > 1) {
            char *p = abspath + sdslen(abspath)-2;
            int trimlen = 1;

            while(*p != '/') {
                p--;
                trimlen++;
            }
            sdsrange(abspath,0,-(trimlen+1));
        }
    }

    /* Finally glue the two parts together. */
    abspath = sdscatsds(abspath,relpath);
    sdsfree(relpath);
    return abspath;
}

/*
 * Gets the proper timezone in a more portable fashion
 * i.e timezone variables are linux specific.
 */

unsigned long getTimeZone(void) {
#ifdef __linux__
    return timezone;
#else
    struct timeval tv;
    struct timezone tz;

    gettimeofday(&tv, &tz);

    return tz.tz_minuteswest * 60UL;
#endif
}

/* Return true if the specified path is just a file basename without any
 * relative or absolute path. This function just checks that no / or \
 * character exists inside the specified path, that's enough in the
 * environments where Redis runs. */
int pathIsBaseName(char *path) {
    return strchr(path,'/') == NULL && strchr(path,'\\') == NULL;
}

#ifdef REDIS_TEST
#include <assert.h>

static void test_string2ll(void) {
    char buf[32];
    long long v;

    /* May not start with +. */
    strcpy(buf,"+1");
    assert(string2ll(buf,strlen(buf),&v) == 0);

    /* Leading space. */
    strcpy(buf," 1");
    assert(string2ll(buf,strlen(buf),&v) == 0);

    /* Trailing space. */
    strcpy(buf,"1 ");
    assert(string2ll(buf,strlen(buf),&v) == 0);

    /* May not start with 0. */
    strcpy(buf,"01");
    assert(string2ll(buf,strlen(buf),&v) == 0);

    strcpy(buf,"-1");
    assert(string2ll(buf,strlen(buf),&v) == 1);
    assert(v == -1);

    strcpy(buf,"0");
    assert(string2ll(buf,strlen(buf),&v) == 1);
    assert(v == 0);

    strcpy(buf,"1");
    assert(string2ll(buf,strlen(buf),&v) == 1);
    assert(v == 1);

    strcpy(buf,"99");
    assert(string2ll(buf,strlen(buf),&v) == 1);
    assert(v == 99);

    strcpy(buf,"-99");
    assert(string2ll(buf,strlen(buf),&v) == 1);
    assert(v == -99);

    strcpy(buf,"-9223372036854775808");
    assert(string2ll(buf,strlen(buf),&v) == 1);
    assert(v == LLONG_MIN);

    strcpy(buf,"-9223372036854775809"); /* overflow */
    assert(string2ll(buf,strlen(buf),&v) == 0);

    strcpy(buf,"9223372036854775807");
    assert(string2ll(buf,strlen(buf),&v) == 1);
    assert(v == LLONG_MAX);

    strcpy(buf,"9223372036854775808"); /* overflow */
    assert(string2ll(buf,strlen(buf),&v) == 0);
}

static void test_string2l(void) {
    char buf[32];
    long v;

    /* May not start with +. */
    strcpy(buf,"+1");
    assert(string2l(buf,strlen(buf),&v) == 0);

    /* May not start with 0. */
    strcpy(buf,"01");
    assert(string2l(buf,strlen(buf),&v) == 0);

    strcpy(buf,"-1");
    assert(string2l(buf,strlen(buf),&v) == 1);
    assert(v == -1);

    strcpy(buf,"0");
    assert(string2l(buf,strlen(buf),&v) == 1);
    assert(v == 0);

    strcpy(buf,"1");
    assert(string2l(buf,strlen(buf),&v) == 1);
    assert(v == 1);

    strcpy(buf,"99");
    assert(string2l(buf,strlen(buf),&v) == 1);
    assert(v == 99);

    strcpy(buf,"-99");
    assert(string2l(buf,strlen(buf),&v) == 1);
    assert(v == -99);

#if LONG_MAX != LLONG_MAX
    strcpy(buf,"-2147483648");
    assert(string2l(buf,strlen(buf),&v) == 1);
    assert(v == LONG_MIN);

    strcpy(buf,"-2147483649"); /* overflow */
    assert(string2l(buf,strlen(buf),&v) == 0);

    strcpy(buf,"2147483647");
    assert(string2l(buf,strlen(buf),&v) == 1);
    assert(v == LONG_MAX);

    strcpy(buf,"2147483648"); /* overflow */
    assert(string2l(buf,strlen(buf),&v) == 0);
#endif
}

static void test_ll2string(void) {
    char buf[32];
    long long v;
    int sz;

    v = 0;
    sz = ll2string(buf, sizeof buf, v);
    assert(sz == 1);
    assert(!strcmp(buf, "0"));

    v = -1;
    sz = ll2string(buf, sizeof buf, v);
    assert(sz == 2);
    assert(!strcmp(buf, "-1"));

    v = 99;
    sz = ll2string(buf, sizeof buf, v);
    assert(sz == 2);
    assert(!strcmp(buf, "99"));

    v = -99;
    sz = ll2string(buf, sizeof buf, v);
    assert(sz == 3);
    assert(!strcmp(buf, "-99"));

    v = -2147483648;
    sz = ll2string(buf, sizeof buf, v);
    assert(sz == 11);
    assert(!strcmp(buf, "-2147483648"));

    v = LLONG_MIN;
    sz = ll2string(buf, sizeof buf, v);
    assert(sz == 20);
    assert(!strcmp(buf, "-9223372036854775808"));

    v = LLONG_MAX;
    sz = ll2string(buf, sizeof buf, v);
    assert(sz == 19);
    assert(!strcmp(buf, "9223372036854775807"));
}

#define UNUSED(x) (void)(x)
int utilTest(int argc, char **argv) {
    UNUSED(argc);
    UNUSED(argv);

    test_string2ll();
    test_string2l();
    test_ll2string();
    return 0;
}
#endif