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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/* make sure to include all global symbols */
8#include "nolibc.h"
9
10#ifndef _NOLIBC_STRING_H
11#define _NOLIBC_STRING_H
12
13#include "arch.h"
14#include "std.h"
15
16static void *malloc(size_t len);
17
18/*
19 * As much as possible, please keep functions alphabetically sorted.
20 */
21
22static __attribute__((unused))
23int memcmp(const void *s1, const void *s2, size_t n)
24{
25 size_t ofs = 0;
26 int c1 = 0;
27
28 while (ofs < n && !(c1 = ((unsigned char *)s1)[ofs] - ((unsigned char *)s2)[ofs])) {
29 ofs++;
30 }
31 return c1;
32}
33
34#ifndef NOLIBC_ARCH_HAS_MEMMOVE
35/* might be ignored by the compiler without -ffreestanding, then found as
36 * missing.
37 */
38void *memmove(void *dst, const void *src, size_t len);
39__attribute__((weak,unused,section(".text.nolibc_memmove")))
40void *memmove(void *dst, const void *src, size_t len)
41{
42 size_t dir, pos;
43
44 pos = len;
45 dir = -1;
46
47 if (dst < src) {
48 pos = -1;
49 dir = 1;
50 }
51
52 while (len) {
53 pos += dir;
54 ((char *)dst)[pos] = ((const char *)src)[pos];
55 len--;
56 }
57 return dst;
58}
59#endif /* #ifndef NOLIBC_ARCH_HAS_MEMMOVE */
60
61#ifndef NOLIBC_ARCH_HAS_MEMCPY
62/* must be exported, as it's used by libgcc on ARM */
63void *memcpy(void *dst, const void *src, size_t len);
64__attribute__((weak,unused,section(".text.nolibc_memcpy")))
65void *memcpy(void *dst, const void *src, size_t len)
66{
67 size_t pos = 0;
68
69 while (pos < len) {
70 ((char *)dst)[pos] = ((const char *)src)[pos];
71 pos++;
72 }
73 return dst;
74}
75#endif /* #ifndef NOLIBC_ARCH_HAS_MEMCPY */
76
77#ifndef NOLIBC_ARCH_HAS_MEMSET
78/* might be ignored by the compiler without -ffreestanding, then found as
79 * missing.
80 */
81void *memset(void *dst, int b, size_t len);
82__attribute__((weak,unused,section(".text.nolibc_memset")))
83void *memset(void *dst, int b, size_t len)
84{
85 char *p = dst;
86
87 while (len--) {
88 /* prevent gcc from recognizing memset() here */
89 __asm__ volatile("");
90 *(p++) = b;
91 }
92 return dst;
93}
94#endif /* #ifndef NOLIBC_ARCH_HAS_MEMSET */
95
96#ifndef NOLIBC_ARCH_HAS_MEMCHR
97static __attribute__((unused))
98void *memchr(const void *s, int c, size_t len)
99{
100 char *p = (char *)s;
101
102 while (len--) {
103 if (*p == (char)c)
104 return p;
105 p++;
106 }
107 return NULL;
108}
109#endif /* #ifndef NOLIBC_ARCH_HAS_MEMCHR */
110
111static __attribute__((unused))
112char *strchr(const char *s, int c)
113{
114 while (*s) {
115 if (*s == (char)c)
116 return (char *)s;
117 s++;
118 }
119 return NULL;
120}
121
122static __attribute__((unused))
123int strcmp(const char *a, const char *b)
124{
125 unsigned int c;
126 int diff;
127
128 while (!(diff = (unsigned char)*a++ - (c = (unsigned char)*b++)) && c)
129 ;
130 return diff;
131}
132
133static __attribute__((unused))
134char *strcpy(char *dst, const char *src)
135{
136 char *ret = dst;
137
138 while ((*dst++ = *src++));
139 return ret;
140}
141
142/* this function is only used with arguments that are not constants or when
143 * it's not known because optimizations are disabled. Note that gcc 12
144 * recognizes an strlen() pattern and replaces it with a jump to strlen(),
145 * thus itself, hence the asm() statement below that's meant to disable this
146 * confusing practice.
147 */
148size_t strlen(const char *str);
149__attribute__((weak,unused,section(".text.nolibc_strlen")))
150size_t strlen(const char *str)
151{
152 size_t len;
153
154 for (len = 0; str[len]; len++)
155 __asm__("");
156 return len;
157}
158
159/* do not trust __builtin_constant_p() at -O0, as clang will emit a test and
160 * the two branches, then will rely on an external definition of strlen().
161 */
162#if defined(__OPTIMIZE__)
163#define nolibc_strlen(x) strlen(x)
164#define strlen(str) ({ \
165 __builtin_constant_p((str)) ? \
166 __builtin_strlen((str)) : \
167 nolibc_strlen((str)); \
168})
169#endif
170
171static __attribute__((unused))
172size_t strnlen(const char *str, size_t maxlen)
173{
174 size_t len;
175
176 for (len = 0; (len < maxlen) && str[len]; len++);
177 return len;
178}
179
180static __attribute__((unused))
181char *strdup(const char *str)
182{
183 size_t len;
184 char *ret;
185
186 len = strlen(str);
187 ret = malloc(len: len + 1);
188 if (__builtin_expect(ret != NULL, 1))
189 memcpy(dst: ret, src: str, len: len + 1);
190
191 return ret;
192}
193
194static __attribute__((unused))
195char *strndup(const char *str, size_t maxlen)
196{
197 size_t len;
198 char *ret;
199
200 len = strnlen(str, maxlen);
201 ret = malloc(len: len + 1);
202 if (__builtin_expect(ret != NULL, 1)) {
203 memcpy(dst: ret, src: str, len);
204 ret[len] = '\0';
205 }
206
207 return ret;
208}
209
210static __attribute__((unused))
211size_t strlcat(char *dst, const char *src, size_t size)
212{
213 size_t len = strnlen(str: dst, maxlen: size);
214
215 /*
216 * We want len < size-1. But as size is unsigned and can wrap
217 * around, we use len + 1 instead.
218 */
219 while (len + 1 < size) {
220 dst[len] = *src;
221 if (*src == '\0')
222 break;
223 len++;
224 src++;
225 }
226
227 if (len < size)
228 dst[len] = '\0';
229
230 while (*src++)
231 len++;
232
233 return len;
234}
235
236static __attribute__((unused))
237size_t strlcpy(char *dst, const char *src, size_t size)
238{
239 size_t len;
240
241 for (len = 0; len < size; len++) {
242 dst[len] = src[len];
243 if (!dst[len])
244 return len;
245 }
246 if (size)
247 dst[size-1] = '\0';
248
249 while (src[len])
250 len++;
251
252 return len;
253}
254
255static __attribute__((unused))
256char *strncat(char *dst, const char *src, size_t size)
257{
258 char *orig = dst;
259
260 while (*dst)
261 dst++;
262
263 while (size && (*dst = *src)) {
264 src++;
265 dst++;
266 size--;
267 }
268
269 *dst = 0;
270 return orig;
271}
272
273static __attribute__((unused))
274int strncmp(const char *a, const char *b, size_t size)
275{
276 unsigned int c;
277 int diff = 0;
278
279 while (size-- &&
280 !(diff = (unsigned char)*a++ - (c = (unsigned char)*b++)) && c)
281 ;
282
283 return diff;
284}
285
286static __attribute__((unused))
287char *strncpy(char *dst, const char *src, size_t size)
288{
289 size_t len;
290
291 for (len = 0; len < size; len++)
292 if ((dst[len] = *src))
293 src++;
294 return dst;
295}
296
297static __attribute__((unused))
298char *strrchr(const char *s, int c)
299{
300 const char *ret = NULL;
301
302 while (*s) {
303 if (*s == (char)c)
304 ret = s;
305 s++;
306 }
307 return (char *)ret;
308}
309
310static __attribute__((unused))
311char *strstr(const char *haystack, const char *needle)
312{
313 size_t len_haystack, len_needle;
314
315 len_needle = strlen(str: needle);
316 if (!len_needle)
317 return NULL;
318
319 len_haystack = strlen(str: haystack);
320 while (len_haystack >= len_needle) {
321 if (!memcmp(s1: haystack, s2: needle, n: len_needle))
322 return (char *)haystack;
323 haystack++;
324 len_haystack--;
325 }
326
327 return NULL;
328}
329
330static __attribute__((unused))
331int tolower(int c)
332{
333 if (c >= 'A' && c <= 'Z')
334 return c - 'A' + 'a';
335 return c;
336}
337
338static __attribute__((unused))
339int toupper(int c)
340{
341 if (c >= 'a' && c <= 'z')
342 return c - 'a' + 'A';
343 return c;
344}
345
346#endif /* _NOLIBC_STRING_H */
347

Warning: That file was not part of the compilation database. It may have many parsing errors.

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