Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * linux/lib/string.c
4 : *
5 : * Copyright (C) 1991, 1992 Linus Torvalds
6 : */
7 :
8 : /*
9 : * This file should be used only for "library" routines that may have
10 : * alternative implementations on specific architectures (generally
11 : * found in <asm-xx/string.h>), or get overloaded by FORTIFY_SOURCE.
12 : * (Specifically, this file is built with __NO_FORTIFY.)
13 : *
14 : * Other helper functions should live in string_helpers.c.
15 : */
16 :
17 : #define __NO_FORTIFY
18 : #include <linux/types.h>
19 : #include <linux/string.h>
20 : #include <linux/ctype.h>
21 : #include <linux/kernel.h>
22 : #include <linux/export.h>
23 : #include <linux/bug.h>
24 : #include <linux/errno.h>
25 : #include <linux/slab.h>
26 :
27 : #include <asm/unaligned.h>
28 : #include <asm/byteorder.h>
29 : #include <asm/word-at-a-time.h>
30 : #include <asm/page.h>
31 :
32 : #ifndef __HAVE_ARCH_STRNCASECMP
33 : /**
34 : * strncasecmp - Case insensitive, length-limited string comparison
35 : * @s1: One string
36 : * @s2: The other string
37 : * @len: the maximum number of characters to compare
38 : */
39 0 : int strncasecmp(const char *s1, const char *s2, size_t len)
40 : {
41 : /* Yes, Virginia, it had better be unsigned */
42 : unsigned char c1, c2;
43 :
44 0 : if (!len)
45 : return 0;
46 :
47 : do {
48 0 : c1 = *s1++;
49 0 : c2 = *s2++;
50 0 : if (!c1 || !c2)
51 : break;
52 0 : if (c1 == c2)
53 0 : continue;
54 0 : c1 = tolower(c1);
55 0 : c2 = tolower(c2);
56 0 : if (c1 != c2)
57 : break;
58 0 : } while (--len);
59 0 : return (int)c1 - (int)c2;
60 : }
61 : EXPORT_SYMBOL(strncasecmp);
62 : #endif
63 :
64 : #ifndef __HAVE_ARCH_STRCASECMP
65 0 : int strcasecmp(const char *s1, const char *s2)
66 : {
67 : int c1, c2;
68 :
69 : do {
70 0 : c1 = tolower(*s1++);
71 0 : c2 = tolower(*s2++);
72 0 : } while (c1 == c2 && c1 != 0);
73 0 : return c1 - c2;
74 : }
75 : EXPORT_SYMBOL(strcasecmp);
76 : #endif
77 :
78 : #ifndef __HAVE_ARCH_STRCPY
79 43 : char *strcpy(char *dest, const char *src)
80 : {
81 43 : char *tmp = dest;
82 :
83 43 : while ((*dest++ = *src++) != '\0')
84 : /* nothing */;
85 43 : return tmp;
86 : }
87 : EXPORT_SYMBOL(strcpy);
88 : #endif
89 :
90 : #ifndef __HAVE_ARCH_STRNCPY
91 1 : char *strncpy(char *dest, const char *src, size_t count)
92 : {
93 1 : char *tmp = dest;
94 :
95 21 : while (count) {
96 19 : if ((*tmp = *src) != 0)
97 3 : src++;
98 19 : tmp++;
99 19 : count--;
100 : }
101 1 : return dest;
102 : }
103 : EXPORT_SYMBOL(strncpy);
104 : #endif
105 :
106 : #ifndef __HAVE_ARCH_STRLCPY
107 3 : size_t strlcpy(char *dest, const char *src, size_t size)
108 : {
109 3 : size_t ret = strlen(src);
110 :
111 3 : if (size) {
112 3 : size_t len = (ret >= size) ? size - 1 : ret;
113 3 : __builtin_memcpy(dest, src, len);
114 3 : dest[len] = '\0';
115 : }
116 3 : return ret;
117 : }
118 : EXPORT_SYMBOL(strlcpy);
119 : #endif
120 :
121 : #ifndef __HAVE_ARCH_STRSCPY
122 529 : ssize_t strscpy(char *dest, const char *src, size_t count)
123 : {
124 529 : const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
125 529 : size_t max = count;
126 529 : long res = 0;
127 :
128 529 : if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
129 : return -E2BIG;
130 :
131 : #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
132 : /*
133 : * If src is unaligned, don't cross a page boundary,
134 : * since we don't know if the next page is mapped.
135 : */
136 : if ((long)src & (sizeof(long) - 1)) {
137 : size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
138 : if (limit < max)
139 : max = limit;
140 : }
141 : #else
142 : /* If src or dest is unaligned, don't do word-at-a-time. */
143 529 : if (((long) dest | (long) src) & (sizeof(long) - 1))
144 285 : max = 0;
145 : #endif
146 :
147 : /*
148 : * read_word_at_a_time() below may read uninitialized bytes after the
149 : * trailing zero and use them in comparisons. Disable this optimization
150 : * under KMSAN to prevent false positive reports.
151 : */
152 : if (IS_ENABLED(CONFIG_KMSAN))
153 : max = 0;
154 :
155 941 : while (max >= sizeof(unsigned long)) {
156 : unsigned long c, data;
157 :
158 858 : c = read_word_at_a_time(src+res);
159 429 : if (has_zero(c, &data, &constants)) {
160 17 : data = prep_zero_mask(c, data, &constants);
161 34 : data = create_zero_mask(data);
162 17 : *(unsigned long *)(dest+res) = c & zero_bytemask(data);
163 34 : return res + find_zero(data);
164 : }
165 412 : *(unsigned long *)(dest+res) = c;
166 412 : res += sizeof(unsigned long);
167 412 : count -= sizeof(unsigned long);
168 412 : max -= sizeof(unsigned long);
169 : }
170 :
171 3714 : while (count) {
172 : char c;
173 :
174 3511 : c = src[res];
175 3511 : dest[res] = c;
176 3511 : if (!c)
177 : return res;
178 3202 : res++;
179 3202 : count--;
180 : }
181 :
182 : /* Hit buffer length without finding a NUL; force NUL-termination. */
183 203 : if (res)
184 203 : dest[res-1] = '\0';
185 :
186 : return -E2BIG;
187 : }
188 : EXPORT_SYMBOL(strscpy);
189 : #endif
190 :
191 : /**
192 : * stpcpy - copy a string from src to dest returning a pointer to the new end
193 : * of dest, including src's %NUL-terminator. May overrun dest.
194 : * @dest: pointer to end of string being copied into. Must be large enough
195 : * to receive copy.
196 : * @src: pointer to the beginning of string being copied from. Must not overlap
197 : * dest.
198 : *
199 : * stpcpy differs from strcpy in a key way: the return value is a pointer
200 : * to the new %NUL-terminating character in @dest. (For strcpy, the return
201 : * value is a pointer to the start of @dest). This interface is considered
202 : * unsafe as it doesn't perform bounds checking of the inputs. As such it's
203 : * not recommended for usage. Instead, its definition is provided in case
204 : * the compiler lowers other libcalls to stpcpy.
205 : */
206 : char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
207 0 : char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
208 : {
209 0 : while ((*dest++ = *src++) != '\0')
210 : /* nothing */;
211 0 : return --dest;
212 : }
213 : EXPORT_SYMBOL(stpcpy);
214 :
215 : #ifndef __HAVE_ARCH_STRCAT
216 0 : char *strcat(char *dest, const char *src)
217 : {
218 0 : char *tmp = dest;
219 :
220 0 : while (*dest)
221 0 : dest++;
222 0 : while ((*dest++ = *src++) != '\0')
223 : ;
224 0 : return tmp;
225 : }
226 : EXPORT_SYMBOL(strcat);
227 : #endif
228 :
229 : #ifndef __HAVE_ARCH_STRNCAT
230 0 : char *strncat(char *dest, const char *src, size_t count)
231 : {
232 0 : char *tmp = dest;
233 :
234 0 : if (count) {
235 0 : while (*dest)
236 0 : dest++;
237 0 : while ((*dest++ = *src++) != 0) {
238 0 : if (--count == 0) {
239 0 : *dest = '\0';
240 0 : break;
241 : }
242 : }
243 : }
244 0 : return tmp;
245 : }
246 : EXPORT_SYMBOL(strncat);
247 : #endif
248 :
249 : #ifndef __HAVE_ARCH_STRLCAT
250 2 : size_t strlcat(char *dest, const char *src, size_t count)
251 : {
252 2 : size_t dsize = strlen(dest);
253 2 : size_t len = strlen(src);
254 2 : size_t res = dsize + len;
255 :
256 : /* This would be a bug */
257 2 : BUG_ON(dsize >= count);
258 :
259 2 : dest += dsize;
260 2 : count -= dsize;
261 2 : if (len >= count)
262 0 : len = count-1;
263 2 : __builtin_memcpy(dest, src, len);
264 2 : dest[len] = 0;
265 2 : return res;
266 : }
267 : EXPORT_SYMBOL(strlcat);
268 : #endif
269 :
270 : #ifndef __HAVE_ARCH_STRCMP
271 : /**
272 : * strcmp - Compare two strings
273 : * @cs: One string
274 : * @ct: Another string
275 : */
276 2819 : int strcmp(const char *cs, const char *ct)
277 : {
278 : unsigned char c1, c2;
279 :
280 : while (1) {
281 10631 : c1 = *cs++;
282 10631 : c2 = *ct++;
283 10631 : if (c1 != c2)
284 1218 : return c1 < c2 ? -1 : 1;
285 9413 : if (!c1)
286 : break;
287 : }
288 : return 0;
289 : }
290 : EXPORT_SYMBOL(strcmp);
291 : #endif
292 :
293 : #ifndef __HAVE_ARCH_STRNCMP
294 : /**
295 : * strncmp - Compare two length-limited strings
296 : * @cs: One string
297 : * @ct: Another string
298 : * @count: The maximum number of bytes to compare
299 : */
300 480 : int strncmp(const char *cs, const char *ct, size_t count)
301 : {
302 : unsigned char c1, c2;
303 :
304 1154 : while (count) {
305 640 : c1 = *cs++;
306 640 : c2 = *ct++;
307 640 : if (c1 != c2)
308 446 : return c1 < c2 ? -1 : 1;
309 194 : if (!c1)
310 : break;
311 194 : count--;
312 : }
313 : return 0;
314 : }
315 : EXPORT_SYMBOL(strncmp);
316 : #endif
317 :
318 : #ifndef __HAVE_ARCH_STRCHR
319 : /**
320 : * strchr - Find the first occurrence of a character in a string
321 : * @s: The string to be searched
322 : * @c: The character to search for
323 : *
324 : * Note that the %NUL-terminator is considered part of the string, and can
325 : * be searched for.
326 : */
327 2256 : char *strchr(const char *s, int c)
328 : {
329 10903 : for (; *s != (char)c; ++s)
330 10145 : if (*s == '\0')
331 : return NULL;
332 : return (char *)s;
333 : }
334 : EXPORT_SYMBOL(strchr);
335 : #endif
336 :
337 : #ifndef __HAVE_ARCH_STRCHRNUL
338 : /**
339 : * strchrnul - Find and return a character in a string, or end of string
340 : * @s: The string to be searched
341 : * @c: The character to search for
342 : *
343 : * Returns pointer to first occurrence of 'c' in s. If c is not found, then
344 : * return a pointer to the null byte at the end of s.
345 : */
346 0 : char *strchrnul(const char *s, int c)
347 : {
348 0 : while (*s && *s != (char)c)
349 0 : s++;
350 0 : return (char *)s;
351 : }
352 : EXPORT_SYMBOL(strchrnul);
353 : #endif
354 :
355 : /**
356 : * strnchrnul - Find and return a character in a length limited string,
357 : * or end of string
358 : * @s: The string to be searched
359 : * @count: The number of characters to be searched
360 : * @c: The character to search for
361 : *
362 : * Returns pointer to the first occurrence of 'c' in s. If c is not found,
363 : * then return a pointer to the last character of the string.
364 : */
365 0 : char *strnchrnul(const char *s, size_t count, int c)
366 : {
367 0 : while (count-- && *s && *s != (char)c)
368 0 : s++;
369 0 : return (char *)s;
370 : }
371 :
372 : #ifndef __HAVE_ARCH_STRRCHR
373 : /**
374 : * strrchr - Find the last occurrence of a character in a string
375 : * @s: The string to be searched
376 : * @c: The character to search for
377 : */
378 0 : char *strrchr(const char *s, int c)
379 : {
380 0 : const char *last = NULL;
381 : do {
382 0 : if (*s == (char)c)
383 0 : last = s;
384 0 : } while (*s++);
385 0 : return (char *)last;
386 : }
387 : EXPORT_SYMBOL(strrchr);
388 : #endif
389 :
390 : #ifndef __HAVE_ARCH_STRNCHR
391 : /**
392 : * strnchr - Find a character in a length limited string
393 : * @s: The string to be searched
394 : * @count: The number of characters to be searched
395 : * @c: The character to search for
396 : *
397 : * Note that the %NUL-terminator is considered part of the string, and can
398 : * be searched for.
399 : */
400 1 : char *strnchr(const char *s, size_t count, int c)
401 : {
402 5 : while (count--) {
403 3 : if (*s == (char)c)
404 : return (char *)s;
405 3 : if (*s++ == '\0')
406 : break;
407 : }
408 : return NULL;
409 : }
410 : EXPORT_SYMBOL(strnchr);
411 : #endif
412 :
413 : #ifndef __HAVE_ARCH_STRLEN
414 24150 : size_t strlen(const char *s)
415 : {
416 : const char *sc;
417 :
418 286295 : for (sc = s; *sc != '\0'; ++sc)
419 : /* nothing */;
420 25361 : return sc - s;
421 : }
422 : EXPORT_SYMBOL(strlen);
423 : #endif
424 :
425 : #ifndef __HAVE_ARCH_STRNLEN
426 234 : size_t strnlen(const char *s, size_t count)
427 : {
428 : const char *sc;
429 :
430 234 : for (sc = s; count-- && *sc != '\0'; ++sc)
431 : /* nothing */;
432 234 : return sc - s;
433 : }
434 : EXPORT_SYMBOL(strnlen);
435 : #endif
436 :
437 : #ifndef __HAVE_ARCH_STRSPN
438 : /**
439 : * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
440 : * @s: The string to be searched
441 : * @accept: The string to search for
442 : */
443 0 : size_t strspn(const char *s, const char *accept)
444 : {
445 : const char *p;
446 :
447 0 : for (p = s; *p != '\0'; ++p) {
448 0 : if (!strchr(accept, *p))
449 : break;
450 : }
451 0 : return p - s;
452 : }
453 : EXPORT_SYMBOL(strspn);
454 : #endif
455 :
456 : #ifndef __HAVE_ARCH_STRCSPN
457 : /**
458 : * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
459 : * @s: The string to be searched
460 : * @reject: The string to avoid
461 : */
462 1 : size_t strcspn(const char *s, const char *reject)
463 : {
464 : const char *p;
465 :
466 3 : for (p = s; *p != '\0'; ++p) {
467 3 : if (strchr(reject, *p))
468 : break;
469 : }
470 1 : return p - s;
471 : }
472 : EXPORT_SYMBOL(strcspn);
473 : #endif
474 :
475 : #ifndef __HAVE_ARCH_STRPBRK
476 : /**
477 : * strpbrk - Find the first occurrence of a set of characters
478 : * @cs: The string to be searched
479 : * @ct: The characters to search for
480 : */
481 0 : char *strpbrk(const char *cs, const char *ct)
482 : {
483 : const char *sc;
484 :
485 0 : for (sc = cs; *sc != '\0'; ++sc) {
486 0 : if (strchr(ct, *sc))
487 : return (char *)sc;
488 : }
489 : return NULL;
490 : }
491 : EXPORT_SYMBOL(strpbrk);
492 : #endif
493 :
494 : #ifndef __HAVE_ARCH_STRSEP
495 : /**
496 : * strsep - Split a string into tokens
497 : * @s: The string to be searched
498 : * @ct: The characters to search for
499 : *
500 : * strsep() updates @s to point after the token, ready for the next call.
501 : *
502 : * It returns empty tokens, too, behaving exactly like the libc function
503 : * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
504 : * Same semantics, slimmer shape. ;)
505 : */
506 0 : char *strsep(char **s, const char *ct)
507 : {
508 0 : char *sbegin = *s;
509 : char *end;
510 :
511 0 : if (sbegin == NULL)
512 : return NULL;
513 :
514 0 : end = strpbrk(sbegin, ct);
515 0 : if (end)
516 0 : *end++ = '\0';
517 0 : *s = end;
518 0 : return sbegin;
519 : }
520 : EXPORT_SYMBOL(strsep);
521 : #endif
522 :
523 : #ifndef __HAVE_ARCH_MEMSET
524 : /**
525 : * memset - Fill a region of memory with the given value
526 : * @s: Pointer to the start of the area.
527 : * @c: The byte to fill the area with
528 : * @count: The size of the area.
529 : *
530 : * Do not use memset() to access IO space, use memset_io() instead.
531 : */
532 : void *memset(void *s, int c, size_t count)
533 : {
534 : char *xs = s;
535 :
536 : while (count--)
537 : *xs++ = c;
538 : return s;
539 : }
540 : EXPORT_SYMBOL(memset);
541 : #endif
542 :
543 : #ifndef __HAVE_ARCH_MEMSET16
544 : /**
545 : * memset16() - Fill a memory area with a uint16_t
546 : * @s: Pointer to the start of the area.
547 : * @v: The value to fill the area with
548 : * @count: The number of values to store
549 : *
550 : * Differs from memset() in that it fills with a uint16_t instead
551 : * of a byte. Remember that @count is the number of uint16_ts to
552 : * store, not the number of bytes.
553 : */
554 : void *memset16(uint16_t *s, uint16_t v, size_t count)
555 : {
556 : uint16_t *xs = s;
557 :
558 : while (count--)
559 : *xs++ = v;
560 : return s;
561 : }
562 : EXPORT_SYMBOL(memset16);
563 : #endif
564 :
565 : #ifndef __HAVE_ARCH_MEMSET32
566 : /**
567 : * memset32() - Fill a memory area with a uint32_t
568 : * @s: Pointer to the start of the area.
569 : * @v: The value to fill the area with
570 : * @count: The number of values to store
571 : *
572 : * Differs from memset() in that it fills with a uint32_t instead
573 : * of a byte. Remember that @count is the number of uint32_ts to
574 : * store, not the number of bytes.
575 : */
576 : void *memset32(uint32_t *s, uint32_t v, size_t count)
577 : {
578 : uint32_t *xs = s;
579 :
580 : while (count--)
581 : *xs++ = v;
582 : return s;
583 : }
584 : EXPORT_SYMBOL(memset32);
585 : #endif
586 :
587 : #ifndef __HAVE_ARCH_MEMSET64
588 : /**
589 : * memset64() - Fill a memory area with a uint64_t
590 : * @s: Pointer to the start of the area.
591 : * @v: The value to fill the area with
592 : * @count: The number of values to store
593 : *
594 : * Differs from memset() in that it fills with a uint64_t instead
595 : * of a byte. Remember that @count is the number of uint64_ts to
596 : * store, not the number of bytes.
597 : */
598 : void *memset64(uint64_t *s, uint64_t v, size_t count)
599 : {
600 : uint64_t *xs = s;
601 :
602 : while (count--)
603 : *xs++ = v;
604 : return s;
605 : }
606 : EXPORT_SYMBOL(memset64);
607 : #endif
608 :
609 : #ifndef __HAVE_ARCH_MEMCPY
610 : /**
611 : * memcpy - Copy one area of memory to another
612 : * @dest: Where to copy to
613 : * @src: Where to copy from
614 : * @count: The size of the area.
615 : *
616 : * You should not use this function to access IO space, use memcpy_toio()
617 : * or memcpy_fromio() instead.
618 : */
619 : void *memcpy(void *dest, const void *src, size_t count)
620 : {
621 : char *tmp = dest;
622 : const char *s = src;
623 :
624 : while (count--)
625 : *tmp++ = *s++;
626 : return dest;
627 : }
628 : EXPORT_SYMBOL(memcpy);
629 : #endif
630 :
631 : #ifndef __HAVE_ARCH_MEMMOVE
632 : /**
633 : * memmove - Copy one area of memory to another
634 : * @dest: Where to copy to
635 : * @src: Where to copy from
636 : * @count: The size of the area.
637 : *
638 : * Unlike memcpy(), memmove() copes with overlapping areas.
639 : */
640 : void *memmove(void *dest, const void *src, size_t count)
641 : {
642 : char *tmp;
643 : const char *s;
644 :
645 : if (dest <= src) {
646 : tmp = dest;
647 : s = src;
648 : while (count--)
649 : *tmp++ = *s++;
650 : } else {
651 : tmp = dest;
652 : tmp += count;
653 : s = src;
654 : s += count;
655 : while (count--)
656 : *--tmp = *--s;
657 : }
658 : return dest;
659 : }
660 : EXPORT_SYMBOL(memmove);
661 : #endif
662 :
663 : #ifndef __HAVE_ARCH_MEMCMP
664 : /**
665 : * memcmp - Compare two areas of memory
666 : * @cs: One area of memory
667 : * @ct: Another area of memory
668 : * @count: The size of the area.
669 : */
670 : #undef memcmp
671 2255 : __visible int memcmp(const void *cs, const void *ct, size_t count)
672 : {
673 : const unsigned char *su1, *su2;
674 207760 : int res = 0;
675 :
676 : #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
677 : if (count >= sizeof(unsigned long)) {
678 : const unsigned long *u1 = cs;
679 : const unsigned long *u2 = ct;
680 : do {
681 : if (get_unaligned(u1) != get_unaligned(u2))
682 : break;
683 : u1++;
684 : u2++;
685 : count -= sizeof(unsigned long);
686 : } while (count >= sizeof(unsigned long));
687 : cs = u1;
688 : ct = u2;
689 : }
690 : #endif
691 288230 : for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
692 286893 : if ((res = *su1 - *su2) != 0)
693 : break;
694 2255 : return res;
695 : }
696 : EXPORT_SYMBOL(memcmp);
697 : #endif
698 :
699 : #ifndef __HAVE_ARCH_BCMP
700 : /**
701 : * bcmp - returns 0 if and only if the buffers have identical contents.
702 : * @a: pointer to first buffer.
703 : * @b: pointer to second buffer.
704 : * @len: size of buffers.
705 : *
706 : * The sign or magnitude of a non-zero return value has no particular
707 : * meaning, and architectures may implement their own more efficient bcmp(). So
708 : * while this particular implementation is a simple (tail) call to memcmp, do
709 : * not rely on anything but whether the return value is zero or non-zero.
710 : */
711 0 : int bcmp(const void *a, const void *b, size_t len)
712 : {
713 0 : return memcmp(a, b, len);
714 : }
715 : EXPORT_SYMBOL(bcmp);
716 : #endif
717 :
718 : #ifndef __HAVE_ARCH_MEMSCAN
719 : /**
720 : * memscan - Find a character in an area of memory.
721 : * @addr: The memory area
722 : * @c: The byte to search for
723 : * @size: The size of the area.
724 : *
725 : * returns the address of the first occurrence of @c, or 1 byte past
726 : * the area if @c is not found
727 : */
728 0 : void *memscan(void *addr, int c, size_t size)
729 : {
730 0 : unsigned char *p = addr;
731 :
732 0 : while (size) {
733 0 : if (*p == (unsigned char)c)
734 : return (void *)p;
735 0 : p++;
736 0 : size--;
737 : }
738 : return (void *)p;
739 : }
740 : EXPORT_SYMBOL(memscan);
741 : #endif
742 :
743 : #ifndef __HAVE_ARCH_STRSTR
744 : /**
745 : * strstr - Find the first substring in a %NUL terminated string
746 : * @s1: The string to be searched
747 : * @s2: The string to search for
748 : */
749 602 : char *strstr(const char *s1, const char *s2)
750 : {
751 : size_t l1, l2;
752 :
753 602 : l2 = strlen(s2);
754 602 : if (!l2)
755 : return (char *)s1;
756 602 : l1 = strlen(s1);
757 206572 : while (l1 >= l2) {
758 205505 : l1--;
759 205505 : if (!memcmp(s1, s2, l2))
760 : return (char *)s1;
761 205368 : s1++;
762 : }
763 : return NULL;
764 : }
765 : EXPORT_SYMBOL(strstr);
766 : #endif
767 :
768 : #ifndef __HAVE_ARCH_STRNSTR
769 : /**
770 : * strnstr - Find the first substring in a length-limited string
771 : * @s1: The string to be searched
772 : * @s2: The string to search for
773 : * @len: the maximum number of characters to search
774 : */
775 0 : char *strnstr(const char *s1, const char *s2, size_t len)
776 : {
777 : size_t l2;
778 :
779 0 : l2 = strlen(s2);
780 0 : if (!l2)
781 : return (char *)s1;
782 0 : while (len >= l2) {
783 0 : len--;
784 0 : if (!memcmp(s1, s2, l2))
785 : return (char *)s1;
786 0 : s1++;
787 : }
788 : return NULL;
789 : }
790 : EXPORT_SYMBOL(strnstr);
791 : #endif
792 :
793 : #ifndef __HAVE_ARCH_MEMCHR
794 : /**
795 : * memchr - Find a character in an area of memory.
796 : * @s: The memory area
797 : * @c: The byte to search for
798 : * @n: The size of the area.
799 : *
800 : * returns the address of the first occurrence of @c, or %NULL
801 : * if @c is not found
802 : */
803 421 : void *memchr(const void *s, int c, size_t n)
804 : {
805 421 : const unsigned char *p = s;
806 18809 : while (n-- != 0) {
807 17967 : if ((unsigned char)c == *p++) {
808 : return (void *)(p - 1);
809 : }
810 : }
811 : return NULL;
812 : }
813 : EXPORT_SYMBOL(memchr);
814 : #endif
815 :
816 : static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
817 : {
818 0 : while (bytes) {
819 0 : if (*start != value)
820 : return (void *)start;
821 0 : start++;
822 0 : bytes--;
823 : }
824 : return NULL;
825 : }
826 :
827 : /**
828 : * memchr_inv - Find an unmatching character in an area of memory.
829 : * @start: The memory area
830 : * @c: Find a character other than c
831 : * @bytes: The size of the area.
832 : *
833 : * returns the address of the first character other than @c, or %NULL
834 : * if the whole buffer contains just @c.
835 : */
836 0 : void *memchr_inv(const void *start, int c, size_t bytes)
837 : {
838 0 : u8 value = c;
839 : u64 value64;
840 : unsigned int words, prefix;
841 :
842 0 : if (bytes <= 16)
843 0 : return check_bytes8(start, value, bytes);
844 :
845 0 : value64 = value;
846 : #if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
847 : value64 *= 0x0101010101010101ULL;
848 : #elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
849 : value64 *= 0x01010101;
850 : value64 |= value64 << 32;
851 : #else
852 0 : value64 |= value64 << 8;
853 0 : value64 |= value64 << 16;
854 0 : value64 |= value64 << 32;
855 : #endif
856 :
857 0 : prefix = (unsigned long)start % 8;
858 0 : if (prefix) {
859 : u8 *r;
860 :
861 0 : prefix = 8 - prefix;
862 0 : r = check_bytes8(start, value, prefix);
863 0 : if (r)
864 : return r;
865 0 : start += prefix;
866 0 : bytes -= prefix;
867 : }
868 :
869 0 : words = bytes / 8;
870 :
871 0 : while (words) {
872 0 : if (*(u64 *)start != value64)
873 : return check_bytes8(start, value, 8);
874 0 : start += 8;
875 0 : words--;
876 : }
877 :
878 0 : return check_bytes8(start, value, bytes % 8);
879 : }
880 : EXPORT_SYMBOL(memchr_inv);
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