1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * linux/tools/lib/string.c
4 *
5 * Copied from linux/lib/string.c, where it is:
6 *
7 * Copyright (C) 1991, 1992 Linus Torvalds
8 *
9 * More specifically, the first copied function was strtobool, which
10 * was introduced by:
11 *
12 * d0f1fed29e6e ("Add a strtobool function matching semantics of existing in kernel equivalents")
13 * Author: Jonathan Cameron <jic23@cam.ac.uk>
14 */
15
16 #include <stdlib.h>
17 #include <string.h>
18 #include <errno.h>
19 #include <linux/string.h>
20 #include <linux/ctype.h>
21 #include <linux/compiler.h>
22
23 /**
24 * memdup - duplicate region of memory
25 *
26 * @src: memory region to duplicate
27 * @len: memory region length
28 */
29 void *memdup(const void *src, size_t len)
30 {
31 void *p = malloc(len);
32
33 if (p)
34 memcpy(p, src, len);
35
36 return p;
37 }
38
39 /**
40 * strtobool - convert common user inputs into boolean values
41 * @s: input string
42 * @res: result
43 *
44 * This routine returns 0 iff the first character is one of 'Yy1Nn0', or
45 * [oO][NnFf] for "on" and "off". Otherwise it will return -EINVAL. Value
46 * pointed to by res is updated upon finding a match.
47 */
48 int strtobool(const char *s, bool *res)
49 {
50 if (!s)
51 return -EINVAL;
52
53 switch (s[0]) {
54 case 'y':
55 case 'Y':
56 case '1':
57 *res = true;
58 return 0;
59 case 'n':
60 case 'N':
61 case '':
62 *res = false;
63 return 0;
64 case 'o':
65 case 'O':
66 switch (s[1]) {
67 case 'n':
68 case 'N':
69 *res = true;
70 return 0;
71 case 'f':
72 case 'F':
73 *res = false;
74 return 0;
75 default:
76 break;
77 }
78 default:
79 break;
80 }
81
82 return -EINVAL;
83 }
84
85 /**
86 * strlcpy - Copy a C-string into a sized buffer
87 * @dest: Where to copy the string to
88 * @src: Where to copy the string from
89 * @size: size of destination buffer
90 *
91 * Compatible with *BSD: the result is always a valid
92 * NUL-terminated string that fits in the buffer (unless,
93 * of course, the buffer size is zero). It does not pad
94 * out the result like strncpy() does.
95 *
96 * If libc has strlcpy() then that version will override this
97 * implementation:
98 */
99 #ifdef __clang__
100 #pragma clang diagnostic push
101 #pragma clang diagnostic ignored "-Wignored-attributes"
102 #endif
103 size_t __weak strlcpy(char *dest, const char *src, size_t size)
104 {
105 size_t ret = strlen(src);
106
107 if (size) {
108 size_t len = (ret >= size) ? size - 1 : ret;
109 memcpy(dest, src, len);
110 dest[len] = '\0';
111 }
112 return ret;
113 }
114 #ifdef __clang__
115 #pragma clang diagnostic pop
116 #endif
117
118 /**
119 * skip_spaces - Removes leading whitespace from @str.
120 * @str: The string to be stripped.
121 *
122 * Returns a pointer to the first non-whitespace character in @str.
123 */
124 char *skip_spaces(const char *str)
125 {
126 while (isspace(*str))
127 ++str;
128 return (char *)str;
129 }
130
131 /**
132 * strim - Removes leading and trailing whitespace from @s.
133 * @s: The string to be stripped.
134 *
135 * Note that the first trailing whitespace is replaced with a %NUL-terminator
136 * in the given string @s. Returns a pointer to the first non-whitespace
137 * character in @s.
138 */
139 char *strim(char *s)
140 {
141 size_t size;
142 char *end;
143
144 size = strlen(s);
145 if (!size)
146 return s;
147
148 end = s + size - 1;
149 while (end >= s && isspace(*end))
150 end--;
151 *(end + 1) = '\0';
152
153 return skip_spaces(s);
154 }
155
156 /**
157 * strreplace - Replace all occurrences of character in string.
158 * @s: The string to operate on.
159 * @old: The character being replaced.
160 * @new: The character @old is replaced with.
161 *
162 * Returns pointer to the nul byte at the end of @s.
163 */
164 char *strreplace(char *s, char old, char new)
165 {
166 for (; *s; ++s)
167 if (*s == old)
168 *s = new;
169 return s;
170 }
171
172 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
173 {
174 while (bytes) {
175 if (*start != value)
176 return (void *)start;
177 start++;
178 bytes--;
179 }
180 return NULL;
181 }
182
183 /**
184 * memchr_inv - Find an unmatching character in an area of memory.
185 * @start: The memory area
186 * @c: Find a character other than c
187 * @bytes: The size of the area.
188 *
189 * returns the address of the first character other than @c, or %NULL
190 * if the whole buffer contains just @c.
191 */
192 void *memchr_inv(const void *start, int c, size_t bytes)
193 {
194 u8 value = c;
195 u64 value64;
196 unsigned int words, prefix;
197
198 if (bytes <= 16)
199 return check_bytes8(start, value, bytes);
200
201 value64 = value;
202 value64 |= value64 << 8;
203 value64 |= value64 << 16;
204 value64 |= value64 << 32;
205
206 prefix = (unsigned long)start % 8;
207 if (prefix) {
208 u8 *r;
209
210 prefix = 8 - prefix;
211 r = check_bytes8(start, value, prefix);
212 if (r)
213 return r;
214 start += prefix;
215 bytes -= prefix;
216 }
217
218 words = bytes / 8;
219
220 while (words) {
221 if (*(u64 *)start != value64)
222 return check_bytes8(start, value, 8);
223 start += 8;
224 words--;
225 }
226
227 return check_bytes8(start, value, bytes % 8);
228 }
229
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