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 EFI_HAVE_STRLEN
15 /**
16  * strlen - Find the length of a string
17  * @s: The string to be sized
18  */
19 size_t strlen(const char *s)
20 {
21 	const char *sc;
22 
23 	for (sc = s; *sc != '\0'; ++sc)
24 		/* nothing */;
25 	return sc - s;
26 }
27 #endif
28 
29 #ifndef EFI_HAVE_STRNLEN
30 /**
31  * strnlen - Find the length of a length-limited string
32  * @s: The string to be sized
33  * @count: The maximum number of bytes to search
34  */
35 size_t strnlen(const char *s, size_t count)
36 {
37 	const char *sc;
38 
39 	for (sc = s; count-- && *sc != '\0'; ++sc)
40 		/* nothing */;
41 	return sc - s;
42 }
43 #endif
44 
45 /**
46  * strstr - Find the first substring in a %NUL terminated string
47  * @s1: The string to be searched
48  * @s2: The string to search for
49  */
50 char *strstr(const char *s1, const char *s2)
51 {
52 	size_t l1, l2;
53 
54 	l2 = strlen(s2);
55 	if (!l2)
56 		return (char *)s1;
57 	l1 = strlen(s1);
58 	while (l1 >= l2) {
59 		l1--;
60 		if (!memcmp(s1, s2, l2))
61 			return (char *)s1;
62 		s1++;
63 	}
64 	return NULL;
65 }
66 
67 #ifndef EFI_HAVE_STRCMP
68 /**
69  * strcmp - Compare two strings
70  * @cs: One string
71  * @ct: Another string
72  */
73 int strcmp(const char *cs, const char *ct)
74 {
75 	unsigned char c1, c2;
76 
77 	while (1) {
78 		c1 = *cs++;
79 		c2 = *ct++;
80 		if (c1 != c2)
81 			return c1 < c2 ? -1 : 1;
82 		if (!c1)
83 			break;
84 	}
85 	return 0;
86 }
87 #endif
88 
89 /**
90  * strncmp - Compare two length-limited strings
91  * @cs: One string
92  * @ct: Another string
93  * @count: The maximum number of bytes to compare
94  */
95 int strncmp(const char *cs, const char *ct, size_t count)
96 {
97 	unsigned char c1, c2;
98 
99 	while (count) {
100 		c1 = *cs++;
101 		c2 = *ct++;
102 		if (c1 != c2)
103 			return c1 < c2 ? -1 : 1;
104 		if (!c1)
105 			break;
106 		count--;
107 	}
108 	return 0;
109 }
110 
111 /* Works only for digits and letters, but small and fast */
112 #define TOLOWER(x) ((x) | 0x20)
113 
114 static unsigned int simple_guess_base(const char *cp)
115 {
116 	if (cp[0] == '0') {
117 		if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2]))
118 			return 16;
119 		else
120 			return 8;
121 	} else {
122 		return 10;
123 	}
124 }
125 
126 /**
127  * simple_strtoull - convert a string to an unsigned long long
128  * @cp: The start of the string
129  * @endp: A pointer to the end of the parsed string will be placed here
130  * @base: The number base to use
131  */
132 
133 unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base)
134 {
135 	unsigned long long result = 0;
136 
137 	if (!base)
138 		base = simple_guess_base(cp);
139 
140 	if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x')
141 		cp += 2;
142 
143 	while (isxdigit(*cp)) {
144 		unsigned int value;
145 
146 		value = isdigit(*cp) ? *cp - '0' : TOLOWER(*cp) - 'a' + 10;
147 		if (value >= base)
148 			break;
149 		result = result * base + value;
150 		cp++;
151 	}
152 	if (endp)
153 		*endp = (char *)cp;
154 
155 	return result;
156 }
157 
158 long simple_strtol(const char *cp, char **endp, unsigned int base)
159 {
160 	if (*cp == '-')
161 		return -simple_strtoull(cp + 1, endp, base);
162 
163 	return simple_strtoull(cp, endp, base);
164 }
165 
166 #ifdef CONFIG_EFI_PARAMS_FROM_FDT
167 #ifndef EFI_HAVE_STRRCHR
168 /**
169  * strrchr - Find the last occurrence of a character in a string
170  * @s: The string to be searched
171  * @c: The character to search for
172  */
173 char *strrchr(const char *s, int c)
174 {
175 	const char *last = NULL;
176 	do {
177 		if (*s == (char)c)
178 			last = s;
179 	} while (*s++);
180 	return (char *)last;
181 }
182 #endif
183 #ifndef EFI_HAVE_MEMCHR
184 /**
185  * memchr - Find a character in an area of memory.
186  * @s: The memory area
187  * @c: The byte to search for
188  * @n: The size of the area.
189  *
190  * returns the address of the first occurrence of @c, or %NULL
191  * if @c is not found
192  */
193 void *memchr(const void *s, int c, size_t n)
194 {
195 	const unsigned char *p = s;
196 	while (n-- != 0) {
197 		if ((unsigned char)c == *p++) {
198 			return (void *)(p - 1);
199 		}
200 	}
201 	return NULL;
202 }
203 #endif
204 #endif
205