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 <linux/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 | #ifdef __BIG_ENDIAN |
108 | # define ALLBUTLAST_BYTE_MASK (~255ul) |
109 | #else |
110 | # define ALLBUTLAST_BYTE_MASK (~0ul >> 8) |
111 | #endif |
112 | |
113 | ssize_t sized_strscpy(char *dest, const char *src, size_t count) |
114 | { |
115 | const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS; |
116 | size_t max = count; |
117 | long res = 0; |
118 | |
119 | if (count == 0 || WARN_ON_ONCE(count > INT_MAX)) |
120 | return -E2BIG; |
121 | |
122 | #ifndef CONFIG_DCACHE_WORD_ACCESS |
123 | #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS |
124 | /* |
125 | * If src is unaligned, don't cross a page boundary, |
126 | * since we don't know if the next page is mapped. |
127 | */ |
128 | if ((long)src & (sizeof(long) - 1)) { |
129 | size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1)); |
130 | if (limit < max) |
131 | max = limit; |
132 | } |
133 | #else |
134 | /* If src or dest is unaligned, don't do word-at-a-time. */ |
135 | if (((long) dest | (long) src) & (sizeof(long) - 1)) |
136 | max = 0; |
137 | #endif |
138 | #endif |
139 | |
140 | /* |
141 | * load_unaligned_zeropad() or read_word_at_a_time() below may read |
142 | * uninitialized bytes after the trailing zero and use them in |
143 | * comparisons. Disable this optimization under KMSAN to prevent |
144 | * false positive reports. |
145 | */ |
146 | if (IS_ENABLED(CONFIG_KMSAN)) |
147 | max = 0; |
148 | |
149 | while (max >= sizeof(unsigned long)) { |
150 | unsigned long c, data; |
151 | |
152 | #ifdef CONFIG_DCACHE_WORD_ACCESS |
153 | c = load_unaligned_zeropad(addr: src+res); |
154 | #else |
155 | c = read_word_at_a_time(src+res); |
156 | #endif |
157 | if (has_zero(a: c, bits: &data, c: &constants)) { |
158 | data = prep_zero_mask(a: c, bits: data, c: &constants); |
159 | data = create_zero_mask(data); |
160 | *(unsigned long *)(dest+res) = c & zero_bytemask(bits: data); |
161 | return res + find_zero(data); |
162 | } |
163 | count -= sizeof(unsigned long); |
164 | if (unlikely(!count)) { |
165 | c &= ALLBUTLAST_BYTE_MASK; |
166 | *(unsigned long *)(dest+res) = c; |
167 | return -E2BIG; |
168 | } |
169 | *(unsigned long *)(dest+res) = c; |
170 | res += sizeof(unsigned long); |
171 | max -= sizeof(unsigned long); |
172 | } |
173 | |
174 | while (count > 1) { |
175 | char c; |
176 | |
177 | c = src[res]; |
178 | dest[res] = c; |
179 | if (!c) |
180 | return res; |
181 | res++; |
182 | count--; |
183 | } |
184 | |
185 | /* Force NUL-termination. */ |
186 | dest[res] = '\0'; |
187 | |
188 | /* Return E2BIG if the source didn't stop */ |
189 | return src[res] ? -E2BIG : res; |
190 | } |
191 | EXPORT_SYMBOL(sized_strscpy); |
192 | |
193 | /** |
194 | * stpcpy - copy a string from src to dest returning a pointer to the new end |
195 | * of dest, including src's %NUL-terminator. May overrun dest. |
196 | * @dest: pointer to end of string being copied into. Must be large enough |
197 | * to receive copy. |
198 | * @src: pointer to the beginning of string being copied from. Must not overlap |
199 | * dest. |
200 | * |
201 | * stpcpy differs from strcpy in a key way: the return value is a pointer |
202 | * to the new %NUL-terminating character in @dest. (For strcpy, the return |
203 | * value is a pointer to the start of @dest). This interface is considered |
204 | * unsafe as it doesn't perform bounds checking of the inputs. As such it's |
205 | * not recommended for usage. Instead, its definition is provided in case |
206 | * the compiler lowers other libcalls to stpcpy. |
207 | */ |
208 | char *stpcpy(char *__restrict__ dest, const char *__restrict__ src); |
209 | char *stpcpy(char *__restrict__ dest, const char *__restrict__ src) |
210 | { |
211 | while ((*dest++ = *src++) != '\0') |
212 | /* nothing */; |
213 | return --dest; |
214 | } |
215 | EXPORT_SYMBOL(stpcpy); |
216 | |
217 | #ifndef __HAVE_ARCH_STRCAT |
218 | char *strcat(char *dest, const char *src) |
219 | { |
220 | char *tmp = dest; |
221 | |
222 | while (*dest) |
223 | dest++; |
224 | while ((*dest++ = *src++) != '\0') |
225 | ; |
226 | return tmp; |
227 | } |
228 | EXPORT_SYMBOL(strcat); |
229 | #endif |
230 | |
231 | #ifndef __HAVE_ARCH_STRNCAT |
232 | char *strncat(char *dest, const char *src, size_t count) |
233 | { |
234 | char *tmp = dest; |
235 | |
236 | if (count) { |
237 | while (*dest) |
238 | dest++; |
239 | while ((*dest++ = *src++) != 0) { |
240 | if (--count == 0) { |
241 | *dest = '\0'; |
242 | break; |
243 | } |
244 | } |
245 | } |
246 | return tmp; |
247 | } |
248 | EXPORT_SYMBOL(strncat); |
249 | #endif |
250 | |
251 | #ifndef __HAVE_ARCH_STRLCAT |
252 | size_t strlcat(char *dest, const char *src, size_t count) |
253 | { |
254 | size_t dsize = strlen(dest); |
255 | size_t len = strlen(src); |
256 | size_t res = dsize + len; |
257 | |
258 | /* This would be a bug */ |
259 | BUG_ON(dsize >= count); |
260 | |
261 | dest += dsize; |
262 | count -= dsize; |
263 | if (len >= count) |
264 | len = count-1; |
265 | __builtin_memcpy(dest, src, len); |
266 | dest[len] = 0; |
267 | return res; |
268 | } |
269 | EXPORT_SYMBOL(strlcat); |
270 | #endif |
271 | |
272 | #ifndef __HAVE_ARCH_STRCMP |
273 | /** |
274 | * strcmp - Compare two strings |
275 | * @cs: One string |
276 | * @ct: Another string |
277 | */ |
278 | int strcmp(const char *cs, const char *ct) |
279 | { |
280 | unsigned char c1, c2; |
281 | |
282 | while (1) { |
283 | c1 = *cs++; |
284 | c2 = *ct++; |
285 | if (c1 != c2) |
286 | return c1 < c2 ? -1 : 1; |
287 | if (!c1) |
288 | break; |
289 | } |
290 | return 0; |
291 | } |
292 | EXPORT_SYMBOL(strcmp); |
293 | #endif |
294 | |
295 | #ifndef __HAVE_ARCH_STRNCMP |
296 | /** |
297 | * strncmp - Compare two length-limited strings |
298 | * @cs: One string |
299 | * @ct: Another string |
300 | * @count: The maximum number of bytes to compare |
301 | */ |
302 | int strncmp(const char *cs, const char *ct, size_t count) |
303 | { |
304 | unsigned char c1, c2; |
305 | |
306 | while (count) { |
307 | c1 = *cs++; |
308 | c2 = *ct++; |
309 | if (c1 != c2) |
310 | return c1 < c2 ? -1 : 1; |
311 | if (!c1) |
312 | break; |
313 | count--; |
314 | } |
315 | return 0; |
316 | } |
317 | EXPORT_SYMBOL(strncmp); |
318 | #endif |
319 | |
320 | #ifndef __HAVE_ARCH_STRCHR |
321 | /** |
322 | * strchr - Find the first occurrence of a character in a string |
323 | * @s: The string to be searched |
324 | * @c: The character to search for |
325 | * |
326 | * Note that the %NUL-terminator is considered part of the string, and can |
327 | * be searched for. |
328 | */ |
329 | char *strchr(const char *s, int c) |
330 | { |
331 | for (; *s != (char)c; ++s) |
332 | if (*s == '\0') |
333 | return NULL; |
334 | return (char *)s; |
335 | } |
336 | EXPORT_SYMBOL(strchr); |
337 | #endif |
338 | |
339 | #ifndef __HAVE_ARCH_STRCHRNUL |
340 | /** |
341 | * strchrnul - Find and return a character in a string, or end of string |
342 | * @s: The string to be searched |
343 | * @c: The character to search for |
344 | * |
345 | * Returns pointer to first occurrence of 'c' in s. If c is not found, then |
346 | * return a pointer to the null byte at the end of s. |
347 | */ |
348 | char *strchrnul(const char *s, int c) |
349 | { |
350 | while (*s && *s != (char)c) |
351 | s++; |
352 | return (char *)s; |
353 | } |
354 | EXPORT_SYMBOL(strchrnul); |
355 | #endif |
356 | |
357 | /** |
358 | * strnchrnul - Find and return a character in a length limited string, |
359 | * or end of string |
360 | * @s: The string to be searched |
361 | * @count: The number of characters to be searched |
362 | * @c: The character to search for |
363 | * |
364 | * Returns pointer to the first occurrence of 'c' in s. If c is not found, |
365 | * then return a pointer to the last character of the string. |
366 | */ |
367 | char *strnchrnul(const char *s, size_t count, int c) |
368 | { |
369 | while (count-- && *s && *s != (char)c) |
370 | s++; |
371 | return (char *)s; |
372 | } |
373 | |
374 | #ifndef __HAVE_ARCH_STRRCHR |
375 | /** |
376 | * strrchr - Find the last occurrence of a character in a string |
377 | * @s: The string to be searched |
378 | * @c: The character to search for |
379 | */ |
380 | char *strrchr(const char *s, int c) |
381 | { |
382 | const char *last = NULL; |
383 | do { |
384 | if (*s == (char)c) |
385 | last = s; |
386 | } while (*s++); |
387 | return (char *)last; |
388 | } |
389 | EXPORT_SYMBOL(strrchr); |
390 | #endif |
391 | |
392 | #ifndef __HAVE_ARCH_STRNCHR |
393 | /** |
394 | * strnchr - Find a character in a length limited string |
395 | * @s: The string to be searched |
396 | * @count: The number of characters to be searched |
397 | * @c: The character to search for |
398 | * |
399 | * Note that the %NUL-terminator is considered part of the string, and can |
400 | * be searched for. |
401 | */ |
402 | char *strnchr(const char *s, size_t count, int c) |
403 | { |
404 | while (count--) { |
405 | if (*s == (char)c) |
406 | return (char *)s; |
407 | if (*s++ == '\0') |
408 | break; |
409 | } |
410 | return NULL; |
411 | } |
412 | EXPORT_SYMBOL(strnchr); |
413 | #endif |
414 | |
415 | #ifndef __HAVE_ARCH_STRLEN |
416 | size_t strlen(const char *s) |
417 | { |
418 | const char *sc; |
419 | |
420 | for (sc = s; *sc != '\0'; ++sc) |
421 | /* nothing */; |
422 | return sc - s; |
423 | } |
424 | EXPORT_SYMBOL(strlen); |
425 | #endif |
426 | |
427 | #ifndef __HAVE_ARCH_STRNLEN |
428 | size_t strnlen(const char *s, size_t count) |
429 | { |
430 | const char *sc; |
431 | |
432 | for (sc = s; count-- && *sc != '\0'; ++sc) |
433 | /* nothing */; |
434 | return sc - s; |
435 | } |
436 | EXPORT_SYMBOL(strnlen); |
437 | #endif |
438 | |
439 | #ifndef __HAVE_ARCH_STRSPN |
440 | /** |
441 | * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept |
442 | * @s: The string to be searched |
443 | * @accept: The string to search for |
444 | */ |
445 | size_t strspn(const char *s, const char *accept) |
446 | { |
447 | const char *p; |
448 | |
449 | for (p = s; *p != '\0'; ++p) { |
450 | if (!strchr(accept, *p)) |
451 | break; |
452 | } |
453 | return p - s; |
454 | } |
455 | EXPORT_SYMBOL(strspn); |
456 | #endif |
457 | |
458 | #ifndef __HAVE_ARCH_STRCSPN |
459 | /** |
460 | * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject |
461 | * @s: The string to be searched |
462 | * @reject: The string to avoid |
463 | */ |
464 | size_t strcspn(const char *s, const char *reject) |
465 | { |
466 | const char *p; |
467 | |
468 | for (p = s; *p != '\0'; ++p) { |
469 | if (strchr(reject, *p)) |
470 | break; |
471 | } |
472 | return p - s; |
473 | } |
474 | EXPORT_SYMBOL(strcspn); |
475 | #endif |
476 | |
477 | #ifndef __HAVE_ARCH_STRPBRK |
478 | /** |
479 | * strpbrk - Find the first occurrence of a set of characters |
480 | * @cs: The string to be searched |
481 | * @ct: The characters to search for |
482 | */ |
483 | char *strpbrk(const char *cs, const char *ct) |
484 | { |
485 | const char *sc; |
486 | |
487 | for (sc = cs; *sc != '\0'; ++sc) { |
488 | if (strchr(ct, *sc)) |
489 | return (char *)sc; |
490 | } |
491 | return NULL; |
492 | } |
493 | EXPORT_SYMBOL(strpbrk); |
494 | #endif |
495 | |
496 | #ifndef __HAVE_ARCH_STRSEP |
497 | /** |
498 | * strsep - Split a string into tokens |
499 | * @s: The string to be searched |
500 | * @ct: The characters to search for |
501 | * |
502 | * strsep() updates @s to point after the token, ready for the next call. |
503 | * |
504 | * It returns empty tokens, too, behaving exactly like the libc function |
505 | * of that name. In fact, it was stolen from glibc2 and de-fancy-fied. |
506 | * Same semantics, slimmer shape. ;) |
507 | */ |
508 | char *strsep(char **s, const char *ct) |
509 | { |
510 | char *sbegin = *s; |
511 | char *end; |
512 | |
513 | if (sbegin == NULL) |
514 | return NULL; |
515 | |
516 | end = strpbrk(sbegin, ct); |
517 | if (end) |
518 | *end++ = '\0'; |
519 | *s = end; |
520 | return sbegin; |
521 | } |
522 | EXPORT_SYMBOL(strsep); |
523 | #endif |
524 | |
525 | #ifndef __HAVE_ARCH_MEMSET |
526 | /** |
527 | * memset - Fill a region of memory with the given value |
528 | * @s: Pointer to the start of the area. |
529 | * @c: The byte to fill the area with |
530 | * @count: The size of the area. |
531 | * |
532 | * Do not use memset() to access IO space, use memset_io() instead. |
533 | */ |
534 | void *memset(void *s, int c, size_t count) |
535 | { |
536 | char *xs = s; |
537 | |
538 | while (count--) |
539 | *xs++ = c; |
540 | return s; |
541 | } |
542 | EXPORT_SYMBOL(memset); |
543 | #endif |
544 | |
545 | #ifndef __HAVE_ARCH_MEMSET16 |
546 | /** |
547 | * memset16() - Fill a memory area with a uint16_t |
548 | * @s: Pointer to the start of the area. |
549 | * @v: The value to fill the area with |
550 | * @count: The number of values to store |
551 | * |
552 | * Differs from memset() in that it fills with a uint16_t instead |
553 | * of a byte. Remember that @count is the number of uint16_ts to |
554 | * store, not the number of bytes. |
555 | */ |
556 | void *memset16(uint16_t *s, uint16_t v, size_t count) |
557 | { |
558 | uint16_t *xs = s; |
559 | |
560 | while (count--) |
561 | *xs++ = v; |
562 | return s; |
563 | } |
564 | EXPORT_SYMBOL(memset16); |
565 | #endif |
566 | |
567 | #ifndef __HAVE_ARCH_MEMSET32 |
568 | /** |
569 | * memset32() - Fill a memory area with a uint32_t |
570 | * @s: Pointer to the start of the area. |
571 | * @v: The value to fill the area with |
572 | * @count: The number of values to store |
573 | * |
574 | * Differs from memset() in that it fills with a uint32_t instead |
575 | * of a byte. Remember that @count is the number of uint32_ts to |
576 | * store, not the number of bytes. |
577 | */ |
578 | void *memset32(uint32_t *s, uint32_t v, size_t count) |
579 | { |
580 | uint32_t *xs = s; |
581 | |
582 | while (count--) |
583 | *xs++ = v; |
584 | return s; |
585 | } |
586 | EXPORT_SYMBOL(memset32); |
587 | #endif |
588 | |
589 | #ifndef __HAVE_ARCH_MEMSET64 |
590 | /** |
591 | * memset64() - Fill a memory area with a uint64_t |
592 | * @s: Pointer to the start of the area. |
593 | * @v: The value to fill the area with |
594 | * @count: The number of values to store |
595 | * |
596 | * Differs from memset() in that it fills with a uint64_t instead |
597 | * of a byte. Remember that @count is the number of uint64_ts to |
598 | * store, not the number of bytes. |
599 | */ |
600 | void *memset64(uint64_t *s, uint64_t v, size_t count) |
601 | { |
602 | uint64_t *xs = s; |
603 | |
604 | while (count--) |
605 | *xs++ = v; |
606 | return s; |
607 | } |
608 | EXPORT_SYMBOL(memset64); |
609 | #endif |
610 | |
611 | #ifndef __HAVE_ARCH_MEMCPY |
612 | /** |
613 | * memcpy - Copy one area of memory to another |
614 | * @dest: Where to copy to |
615 | * @src: Where to copy from |
616 | * @count: The size of the area. |
617 | * |
618 | * You should not use this function to access IO space, use memcpy_toio() |
619 | * or memcpy_fromio() instead. |
620 | */ |
621 | void *memcpy(void *dest, const void *src, size_t count) |
622 | { |
623 | char *tmp = dest; |
624 | const char *s = src; |
625 | |
626 | while (count--) |
627 | *tmp++ = *s++; |
628 | return dest; |
629 | } |
630 | EXPORT_SYMBOL(memcpy); |
631 | #endif |
632 | |
633 | #ifndef __HAVE_ARCH_MEMMOVE |
634 | /** |
635 | * memmove - Copy one area of memory to another |
636 | * @dest: Where to copy to |
637 | * @src: Where to copy from |
638 | * @count: The size of the area. |
639 | * |
640 | * Unlike memcpy(), memmove() copes with overlapping areas. |
641 | */ |
642 | void *memmove(void *dest, const void *src, size_t count) |
643 | { |
644 | char *tmp; |
645 | const char *s; |
646 | |
647 | if (dest <= src) { |
648 | tmp = dest; |
649 | s = src; |
650 | while (count--) |
651 | *tmp++ = *s++; |
652 | } else { |
653 | tmp = dest; |
654 | tmp += count; |
655 | s = src; |
656 | s += count; |
657 | while (count--) |
658 | *--tmp = *--s; |
659 | } |
660 | return dest; |
661 | } |
662 | EXPORT_SYMBOL(memmove); |
663 | #endif |
664 | |
665 | #ifndef __HAVE_ARCH_MEMCMP |
666 | /** |
667 | * memcmp - Compare two areas of memory |
668 | * @cs: One area of memory |
669 | * @ct: Another area of memory |
670 | * @count: The size of the area. |
671 | */ |
672 | #undef memcmp |
673 | __visible int memcmp(const void *cs, const void *ct, size_t count) |
674 | { |
675 | const unsigned char *su1, *su2; |
676 | int res = 0; |
677 | |
678 | #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS |
679 | if (count >= sizeof(unsigned long)) { |
680 | const unsigned long *u1 = cs; |
681 | const unsigned long *u2 = ct; |
682 | do { |
683 | if (get_unaligned(u1) != get_unaligned(u2)) |
684 | break; |
685 | u1++; |
686 | u2++; |
687 | count -= sizeof(unsigned long); |
688 | } while (count >= sizeof(unsigned long)); |
689 | cs = u1; |
690 | ct = u2; |
691 | } |
692 | #endif |
693 | for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--) |
694 | if ((res = *su1 - *su2) != 0) |
695 | break; |
696 | return res; |
697 | } |
698 | EXPORT_SYMBOL(memcmp); |
699 | #endif |
700 | |
701 | #ifndef __HAVE_ARCH_BCMP |
702 | /** |
703 | * bcmp - returns 0 if and only if the buffers have identical contents. |
704 | * @a: pointer to first buffer. |
705 | * @b: pointer to second buffer. |
706 | * @len: size of buffers. |
707 | * |
708 | * The sign or magnitude of a non-zero return value has no particular |
709 | * meaning, and architectures may implement their own more efficient bcmp(). So |
710 | * while this particular implementation is a simple (tail) call to memcmp, do |
711 | * not rely on anything but whether the return value is zero or non-zero. |
712 | */ |
713 | int bcmp(const void *a, const void *b, size_t len) |
714 | { |
715 | return memcmp(a, b, len); |
716 | } |
717 | EXPORT_SYMBOL(bcmp); |
718 | #endif |
719 | |
720 | #ifndef __HAVE_ARCH_MEMSCAN |
721 | /** |
722 | * memscan - Find a character in an area of memory. |
723 | * @addr: The memory area |
724 | * @c: The byte to search for |
725 | * @size: The size of the area. |
726 | * |
727 | * returns the address of the first occurrence of @c, or 1 byte past |
728 | * the area if @c is not found |
729 | */ |
730 | void *memscan(void *addr, int c, size_t size) |
731 | { |
732 | unsigned char *p = addr; |
733 | |
734 | while (size) { |
735 | if (*p == (unsigned char)c) |
736 | return (void *)p; |
737 | p++; |
738 | size--; |
739 | } |
740 | return (void *)p; |
741 | } |
742 | EXPORT_SYMBOL(memscan); |
743 | #endif |
744 | |
745 | #ifndef __HAVE_ARCH_STRSTR |
746 | /** |
747 | * strstr - Find the first substring in a %NUL terminated string |
748 | * @s1: The string to be searched |
749 | * @s2: The string to search for |
750 | */ |
751 | char *strstr(const char *s1, const char *s2) |
752 | { |
753 | size_t l1, l2; |
754 | |
755 | l2 = strlen(s2); |
756 | if (!l2) |
757 | return (char *)s1; |
758 | l1 = strlen(s1); |
759 | while (l1 >= l2) { |
760 | l1--; |
761 | if (!memcmp(s1, s2, l2)) |
762 | return (char *)s1; |
763 | s1++; |
764 | } |
765 | return NULL; |
766 | } |
767 | EXPORT_SYMBOL(strstr); |
768 | #endif |
769 | |
770 | #ifndef __HAVE_ARCH_STRNSTR |
771 | /** |
772 | * strnstr - Find the first substring in a length-limited string |
773 | * @s1: The string to be searched |
774 | * @s2: The string to search for |
775 | * @len: the maximum number of characters to search |
776 | */ |
777 | char *strnstr(const char *s1, const char *s2, size_t len) |
778 | { |
779 | size_t l2; |
780 | |
781 | l2 = strlen(s2); |
782 | if (!l2) |
783 | return (char *)s1; |
784 | while (len >= l2) { |
785 | len--; |
786 | if (!memcmp(s1, s2, l2)) |
787 | return (char *)s1; |
788 | s1++; |
789 | } |
790 | return NULL; |
791 | } |
792 | EXPORT_SYMBOL(strnstr); |
793 | #endif |
794 | |
795 | #ifndef __HAVE_ARCH_MEMCHR |
796 | /** |
797 | * memchr - Find a character in an area of memory. |
798 | * @s: The memory area |
799 | * @c: The byte to search for |
800 | * @n: The size of the area. |
801 | * |
802 | * returns the address of the first occurrence of @c, or %NULL |
803 | * if @c is not found |
804 | */ |
805 | void *memchr(const void *s, int c, size_t n) |
806 | { |
807 | const unsigned char *p = s; |
808 | while (n-- != 0) { |
809 | if ((unsigned char)c == *p++) { |
810 | return (void *)(p - 1); |
811 | } |
812 | } |
813 | return NULL; |
814 | } |
815 | EXPORT_SYMBOL(memchr); |
816 | #endif |
817 | |
818 | static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes) |
819 | { |
820 | while (bytes) { |
821 | if (*start != value) |
822 | return (void *)start; |
823 | start++; |
824 | bytes--; |
825 | } |
826 | return NULL; |
827 | } |
828 | |
829 | /** |
830 | * memchr_inv - Find an unmatching character in an area of memory. |
831 | * @start: The memory area |
832 | * @c: Find a character other than c |
833 | * @bytes: The size of the area. |
834 | * |
835 | * returns the address of the first character other than @c, or %NULL |
836 | * if the whole buffer contains just @c. |
837 | */ |
838 | void *memchr_inv(const void *start, int c, size_t bytes) |
839 | { |
840 | u8 value = c; |
841 | u64 value64; |
842 | unsigned int words, prefix; |
843 | |
844 | if (bytes <= 16) |
845 | return check_bytes8(start, value, bytes); |
846 | |
847 | value64 = value; |
848 | #if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64 |
849 | value64 *= 0x0101010101010101ULL; |
850 | #elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) |
851 | value64 *= 0x01010101; |
852 | value64 |= value64 << 32; |
853 | #else |
854 | value64 |= value64 << 8; |
855 | value64 |= value64 << 16; |
856 | value64 |= value64 << 32; |
857 | #endif |
858 | |
859 | prefix = (unsigned long)start % 8; |
860 | if (prefix) { |
861 | u8 *r; |
862 | |
863 | prefix = 8 - prefix; |
864 | r = check_bytes8(start, value, bytes: prefix); |
865 | if (r) |
866 | return r; |
867 | start += prefix; |
868 | bytes -= prefix; |
869 | } |
870 | |
871 | words = bytes / 8; |
872 | |
873 | while (words) { |
874 | if (*(u64 *)start != value64) |
875 | return check_bytes8(start, value, bytes: 8); |
876 | start += 8; |
877 | words--; |
878 | } |
879 | |
880 | return check_bytes8(start, value, bytes: bytes % 8); |
881 | } |
882 | EXPORT_SYMBOL(memchr_inv); |
883 | |