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