1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 * Copyright (c) 2022 Aymeric Wibo <obiwac@gmail.com>
4 */
5
6 #include <ctype.h>
7 #include <stddef.h>
8
9 int
strverscmp(const char * s1,const char * s2)10 strverscmp(const char *s1, const char *s2)
11 {
12 size_t digit_count_1, digit_count_2;
13 size_t zeros_count_1, zeros_count_2;
14 const unsigned char *num_1, *num_2;
15 const unsigned char *u1 = __DECONST(const unsigned char *, s1);
16 const unsigned char *u2 = __DECONST(const unsigned char *, s2);
17
18 /*
19 * If pointers are the same, no need to go through to process of
20 * comparing them.
21 */
22 if (s1 == s2)
23 return (0);
24
25 while (*u1 != '\0' && *u2 != '\0') {
26 /* If either character is not a digit, act like strcmp(3). */
27
28 if (!isdigit(*u1) || !isdigit(*u2)) {
29 if (*u1 != *u2)
30 return (*u1 - *u2);
31 u1++;
32 u2++;
33 continue;
34 }
35 if (*u1 == '0' || *u2 == '0') {
36 /*
37 * Treat leading zeros as if they were the fractional
38 * part of a number, i.e. as if they had a decimal point
39 * in front. First, count the leading zeros (more zeros
40 * == smaller number).
41 */
42 zeros_count_1 = 0;
43 zeros_count_2 = 0;
44 for (; *u1 == '0'; u1++)
45 zeros_count_1++;
46 for (; *u2 == '0'; u2++)
47 zeros_count_2++;
48 if (zeros_count_1 != zeros_count_2)
49 return (zeros_count_2 - zeros_count_1);
50
51 /* Handle the case where 0 < 09. */
52 if (!isdigit(*u1) && isdigit(*u2))
53 return (1);
54 if (!isdigit(*u2) && isdigit(*u1))
55 return (-1);
56 } else {
57 /*
58 * No leading zeros; we're simply comparing two numbers.
59 * It is necessary to first count how many digits there
60 * are before going back to compare each digit, so that
61 * e.g. 7 is not considered larger than 60.
62 */
63 num_1 = u1;
64 num_2 = u2;
65
66 /* Count digits (more digits == larger number). */
67 for (; isdigit(*u1); u1++)
68 ;
69 for (; isdigit(*u2); u2++)
70 ;
71 digit_count_1 = u1 - num_1;
72 digit_count_2 = u2 - num_2;
73 if (digit_count_1 != digit_count_2)
74 return (digit_count_1 - digit_count_2);
75
76 /*
77 * If there are the same number of digits, go back to
78 * the start of the number.
79 */
80 u1 = num_1;
81 u2 = num_2;
82 }
83
84 /* Compare each digit until there are none left. */
85 for (; isdigit(*u1) && isdigit(*u2); u1++, u2++) {
86 if (*u1 != *u2)
87 return (*u1 - *u2);
88 }
89 }
90 return (*u1 - *u2);
91 }
92