1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Taken from:
4 * linux/lib/string.c
5 *
6 * Copyright (C) 1991, 1992 Linus Torvalds
7 */
8
9 #include <linux/ctype.h>
10 #include <linux/kernel.h>
11 #include <linux/types.h>
12 #include <linux/string.h>
13
14 #ifndef __HAVE_ARCH_STRSTR
15 /**
16 * strstr - Find the first substring in a %NUL terminated string
17 * @s1: The string to be searched
18 * @s2: The string to search for
19 */
strstr(const char * s1,const char * s2)20 char *strstr(const char *s1, const char *s2)
21 {
22 size_t l1, l2;
23
24 l2 = strlen(s2);
25 if (!l2)
26 return (char *)s1;
27 l1 = strlen(s1);
28 while (l1 >= l2) {
29 l1--;
30 if (!memcmp(s1, s2, l2))
31 return (char *)s1;
32 s1++;
33 }
34 return NULL;
35 }
36 #endif
37
38 #ifndef __HAVE_ARCH_STRNCMP
39 /**
40 * strncmp - Compare two length-limited strings
41 * @cs: One string
42 * @ct: Another string
43 * @count: The maximum number of bytes to compare
44 */
strncmp(const char * cs,const char * ct,size_t count)45 int strncmp(const char *cs, const char *ct, size_t count)
46 {
47 unsigned char c1, c2;
48
49 while (count) {
50 c1 = *cs++;
51 c2 = *ct++;
52 if (c1 != c2)
53 return c1 < c2 ? -1 : 1;
54 if (!c1)
55 break;
56 count--;
57 }
58 return 0;
59 }
60 #endif
61
62 /* Works only for digits and letters, but small and fast */
63 #define TOLOWER(x) ((x) | 0x20)
64
simple_guess_base(const char * cp)65 static unsigned int simple_guess_base(const char *cp)
66 {
67 if (cp[0] == '0') {
68 if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
69 return 16;
70 else
71 return 8;
72 } else {
73 return 10;
74 }
75 }
76
77 /**
78 * simple_strtoull - convert a string to an unsigned long long
79 * @cp: The start of the string
80 * @endp: A pointer to the end of the parsed string will be placed here
81 * @base: The number base to use
82 */
83
simple_strtoull(const char * cp,char ** endp,unsigned int base)84 unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
85 {
86 unsigned long long result = 0;
87
88 if (!base)
89 base = simple_guess_base(cp);
90
91 if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
92 cp += 2;
93
94 while (isxdigit(*cp)) {
95 unsigned int value;
96
97 value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
98 if (value >= base)
99 break;
100 result = result * base + value;
101 cp++;
102 }
103 if (endp)
104 *endp = (char *)cp;
105
106 return result;
107 }
108
simple_strtol(const char * cp,char ** endp,unsigned int base)109 long simple_strtol(const char *cp, char **endp, unsigned int base)
110 {
111 if (*cp == '-')
112 return -simple_strtoull(cp + 1, endp, base);
113
114 return simple_strtoull(cp, endp, base);
115 }
116