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