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 */
29void *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 */
48int 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 '0':
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
103size_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 */
124char *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 */
139char *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 */
164char *strreplace(char *s, char old, char new)
165{
166	for (; *s; ++s)
167		if (*s == old)
168			*s = new;
169	return s;
170}
171
172static 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 */
192void *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