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1/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
2/*
3 * string function definitions for NOLIBC
4 * Copyright (C) 2017-2021 Willy Tarreau <w@1wt.eu>
5 */
6
7#ifndef _NOLIBC_STRING_H
8#define _NOLIBC_STRING_H
9
10#include "std.h"
11
12static void *malloc(size_t len);
13
14/*
15 * As much as possible, please keep functions alphabetically sorted.
16 */
17
18static __attribute__((unused))
19int memcmp(const void *s1, const void *s2, size_t n)
20{
21 size_t ofs = 0;
22 int c1 = 0;
23
24 while (ofs < n && !(c1 = ((unsigned char *)s1)[ofs] - ((unsigned char *)s2)[ofs])) {
25 ofs++;
26 }
27 return c1;
28}
29
30#ifndef NOLIBC_ARCH_HAS_MEMMOVE
31/* might be ignored by the compiler without -ffreestanding, then found as
32 * missing.
33 */
34__attribute__((weak,unused,section(".text.nolibc_memmove")))
35void *memmove(void *dst, const void *src, size_t len)
36{
37 size_t dir, pos;
38
39 pos = len;
40 dir = -1;
41
42 if (dst < src) {
43 pos = -1;
44 dir = 1;
45 }
46
47 while (len) {
48 pos += dir;
49 ((char *)dst)[pos] = ((const char *)src)[pos];
50 len--;
51 }
52 return dst;
53}
54#endif /* #ifndef NOLIBC_ARCH_HAS_MEMMOVE */
55
56#ifndef NOLIBC_ARCH_HAS_MEMCPY
57/* must be exported, as it's used by libgcc on ARM */
58__attribute__((weak,unused,section(".text.nolibc_memcpy")))
59void *memcpy(void *dst, const void *src, size_t len)
60{
61 size_t pos = 0;
62
63 while (pos < len) {
64 ((char *)dst)[pos] = ((const char *)src)[pos];
65 pos++;
66 }
67 return dst;
68}
69#endif /* #ifndef NOLIBC_ARCH_HAS_MEMCPY */
70
71#ifndef NOLIBC_ARCH_HAS_MEMSET
72/* might be ignored by the compiler without -ffreestanding, then found as
73 * missing.
74 */
75__attribute__((weak,unused,section(".text.nolibc_memset")))
76void *memset(void *dst, int b, size_t len)
77{
78 char *p = dst;
79
80 while (len--) {
81 /* prevent gcc from recognizing memset() here */
82 __asm__ volatile("");
83 *(p++) = b;
84 }
85 return dst;
86}
87#endif /* #ifndef NOLIBC_ARCH_HAS_MEMSET */
88
89static __attribute__((unused))
90char *strchr(const char *s, int c)
91{
92 while (*s) {
93 if (*s == (char)c)
94 return (char *)s;
95 s++;
96 }
97 return NULL;
98}
99
100static __attribute__((unused))
101int strcmp(const char *a, const char *b)
102{
103 unsigned int c;
104 int diff;
105
106 while (!(diff = (unsigned char)*a++ - (c = (unsigned char)*b++)) && c)
107 ;
108 return diff;
109}
110
111static __attribute__((unused))
112char *strcpy(char *dst, const char *src)
113{
114 char *ret = dst;
115
116 while ((*dst++ = *src++));
117 return ret;
118}
119
120/* this function is only used with arguments that are not constants or when
121 * it's not known because optimizations are disabled. Note that gcc 12
122 * recognizes an strlen() pattern and replaces it with a jump to strlen(),
123 * thus itself, hence the asm() statement below that's meant to disable this
124 * confusing practice.
125 */
126static __attribute__((unused))
127size_t strlen(const char *str)
128{
129 size_t len;
130
131 for (len = 0; str[len]; len++)
132 __asm__("");
133 return len;
134}
135
136/* do not trust __builtin_constant_p() at -O0, as clang will emit a test and
137 * the two branches, then will rely on an external definition of strlen().
138 */
139#if defined(__OPTIMIZE__)
140#define nolibc_strlen(x) strlen(x)
141#define strlen(str) ({ \
142 __builtin_constant_p((str)) ? \
143 __builtin_strlen((str)) : \
144 nolibc_strlen((str)); \
145})
146#endif
147
148static __attribute__((unused))
149size_t strnlen(const char *str, size_t maxlen)
150{
151 size_t len;
152
153 for (len = 0; (len < maxlen) && str[len]; len++);
154 return len;
155}
156
157static __attribute__((unused))
158char *strdup(const char *str)
159{
160 size_t len;
161 char *ret;
162
163 len = strlen(str);
164 ret = malloc(len + 1);
165 if (__builtin_expect(ret != NULL, 1))
166 memcpy(ret, str, len + 1);
167
168 return ret;
169}
170
171static __attribute__((unused))
172char *strndup(const char *str, size_t maxlen)
173{
174 size_t len;
175 char *ret;
176
177 len = strnlen(str, maxlen);
178 ret = malloc(len + 1);
179 if (__builtin_expect(ret != NULL, 1)) {
180 memcpy(ret, str, len);
181 ret[len] = '\0';
182 }
183
184 return ret;
185}
186
187static __attribute__((unused))
188size_t strlcat(char *dst, const char *src, size_t size)
189{
190 size_t len;
191 char c;
192
193 for (len = 0; dst[len]; len++)
194 ;
195
196 for (;;) {
197 c = *src;
198 if (len < size)
199 dst[len] = c;
200 if (!c)
201 break;
202 len++;
203 src++;
204 }
205
206 return len;
207}
208
209static __attribute__((unused))
210size_t strlcpy(char *dst, const char *src, size_t size)
211{
212 size_t len;
213 char c;
214
215 for (len = 0;;) {
216 c = src[len];
217 if (len < size)
218 dst[len] = c;
219 if (!c)
220 break;
221 len++;
222 }
223 return len;
224}
225
226static __attribute__((unused))
227char *strncat(char *dst, const char *src, size_t size)
228{
229 char *orig = dst;
230
231 while (*dst)
232 dst++;
233
234 while (size && (*dst = *src)) {
235 src++;
236 dst++;
237 size--;
238 }
239
240 *dst = 0;
241 return orig;
242}
243
244static __attribute__((unused))
245int strncmp(const char *a, const char *b, size_t size)
246{
247 unsigned int c;
248 int diff = 0;
249
250 while (size-- &&
251 !(diff = (unsigned char)*a++ - (c = (unsigned char)*b++)) && c)
252 ;
253
254 return diff;
255}
256
257static __attribute__((unused))
258char *strncpy(char *dst, const char *src, size_t size)
259{
260 size_t len;
261
262 for (len = 0; len < size; len++)
263 if ((dst[len] = *src))
264 src++;
265 return dst;
266}
267
268static __attribute__((unused))
269char *strrchr(const char *s, int c)
270{
271 const char *ret = NULL;
272
273 while (*s) {
274 if (*s == (char)c)
275 ret = s;
276 s++;
277 }
278 return (char *)ret;
279}
280
281/* make sure to include all global symbols */
282#include "nolibc.h"
283
284#endif /* _NOLIBC_STRING_H */
285

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source code of linux/tools/include/nolibc/string.h