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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  * stupid library routines.. The optimized versions should generally be found
10  * as inline code in <asm-xx/string.h>
11  *
12  * These are buggy as well..
13  *
14  * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
15  * -  Added strsep() which will replace strtok() soon (because strsep() is
16  *    reentrant and should be faster). Use only strsep() in new code, please.
17  *
18  * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
19  *                    Matthew Hawkins <matt@mh.dropbear.id.au>
20  * -  Kissed strtok() goodbye
21  */
22 
23 #include <linux/types.h>
24 #include <linux/string.h>
25 #include <linux/ctype.h>
26 #include <linux/kernel.h>
27 #include <linux/export.h>
28 #include <linux/bug.h>
29 #include <linux/errno.h>
30 #include <linux/slab.h>
31 
32 #include <asm/unaligned.h>
33 #include <asm/byteorder.h>
34 #include <asm/word-at-a-time.h>
35 #include <asm/page.h>
36 
37 #ifndef __HAVE_ARCH_STRNCASECMP
38 /**
39  * strncasecmp - Case insensitive, length-limited string comparison
40  * @s1: One string
41  * @s2: The other string
42  * @len: the maximum number of characters to compare
43  */
strncasecmp(const char * s1,const char * s2,size_t len)44 int strncasecmp(const char *s1, const char *s2, size_t len)
45 {
46 	/* Yes, Virginia, it had better be unsigned */
47 	unsigned char c1, c2;
48 
49 	if (!len)
50 		return 0;
51 
52 	do {
53 		c1 = *s1++;
54 		c2 = *s2++;
55 		if (!c1 || !c2)
56 			break;
57 		if (c1 == c2)
58 			continue;
59 		c1 = tolower(c1);
60 		c2 = tolower(c2);
61 		if (c1 != c2)
62 			break;
63 	} while (--len);
64 	return (int)c1 - (int)c2;
65 }
66 EXPORT_SYMBOL(strncasecmp);
67 #endif
68 
69 #ifndef __HAVE_ARCH_STRCASECMP
strcasecmp(const char * s1,const char * s2)70 int strcasecmp(const char *s1, const char *s2)
71 {
72 	int c1, c2;
73 
74 	do {
75 		c1 = tolower(*s1++);
76 		c2 = tolower(*s2++);
77 	} while (c1 == c2 && c1 != 0);
78 	return c1 - c2;
79 }
80 EXPORT_SYMBOL(strcasecmp);
81 #endif
82 
83 #ifndef __HAVE_ARCH_STRCPY
84 /**
85  * strcpy - Copy a %NUL terminated string
86  * @dest: Where to copy the string to
87  * @src: Where to copy the string from
88  */
strcpy(char * dest,const char * src)89 char *strcpy(char *dest, const char *src)
90 {
91 	char *tmp = dest;
92 
93 	while ((*dest++ = *src++) != '\0')
94 		/* nothing */;
95 	return tmp;
96 }
97 EXPORT_SYMBOL(strcpy);
98 #endif
99 
100 #ifndef __HAVE_ARCH_STRNCPY
101 /**
102  * strncpy - Copy a length-limited, C-string
103  * @dest: Where to copy the string to
104  * @src: Where to copy the string from
105  * @count: The maximum number of bytes to copy
106  *
107  * The result is not %NUL-terminated if the source exceeds
108  * @count bytes.
109  *
110  * In the case where the length of @src is less than  that  of
111  * count, the remainder of @dest will be padded with %NUL.
112  *
113  */
strncpy(char * dest,const char * src,size_t count)114 char *strncpy(char *dest, const char *src, size_t count)
115 {
116 	char *tmp = dest;
117 
118 	while (count) {
119 		if ((*tmp = *src) != 0)
120 			src++;
121 		tmp++;
122 		count--;
123 	}
124 	return dest;
125 }
126 EXPORT_SYMBOL(strncpy);
127 #endif
128 
129 #ifndef __HAVE_ARCH_STRLCPY
130 /**
131  * strlcpy - Copy a C-string into a sized buffer
132  * @dest: Where to copy the string to
133  * @src: Where to copy the string from
134  * @size: size of destination buffer
135  *
136  * Compatible with ``*BSD``: the result is always a valid
137  * NUL-terminated string that fits in the buffer (unless,
138  * of course, the buffer size is zero). It does not pad
139  * out the result like strncpy() does.
140  */
strlcpy(char * dest,const char * src,size_t size)141 size_t strlcpy(char *dest, const char *src, size_t size)
142 {
143 	size_t ret = strlen(src);
144 
145 	if (size) {
146 		size_t len = (ret >= size) ? size - 1 : ret;
147 		memcpy(dest, src, len);
148 		dest[len] = '\0';
149 	}
150 	return ret;
151 }
152 EXPORT_SYMBOL(strlcpy);
153 #endif
154 
155 #ifndef __HAVE_ARCH_STRSCPY
156 /**
157  * strscpy - Copy a C-string into a sized buffer
158  * @dest: Where to copy the string to
159  * @src: Where to copy the string from
160  * @count: Size of destination buffer
161  *
162  * Copy the string, or as much of it as fits, into the dest buffer.  The
163  * behavior is undefined if the string buffers overlap.  The destination
164  * buffer is always NUL terminated, unless it's zero-sized.
165  *
166  * Preferred to strlcpy() since the API doesn't require reading memory
167  * from the src string beyond the specified "count" bytes, and since
168  * the return value is easier to error-check than strlcpy()'s.
169  * In addition, the implementation is robust to the string changing out
170  * from underneath it, unlike the current strlcpy() implementation.
171  *
172  * Preferred to strncpy() since it always returns a valid string, and
173  * doesn't unnecessarily force the tail of the destination buffer to be
174  * zeroed.  If zeroing is desired please use strscpy_pad().
175  *
176  * Returns:
177  * * The number of characters copied (not including the trailing %NUL)
178  * * -E2BIG if count is 0 or @src was truncated.
179  */
strscpy(char * dest,const char * src,size_t count)180 ssize_t strscpy(char *dest, const char *src, size_t count)
181 {
182 	const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
183 	size_t max = count;
184 	long res = 0;
185 
186 	if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
187 		return -E2BIG;
188 
189 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
190 	/*
191 	 * If src is unaligned, don't cross a page boundary,
192 	 * since we don't know if the next page is mapped.
193 	 */
194 	if ((long)src & (sizeof(long) - 1)) {
195 		size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
196 		if (limit < max)
197 			max = limit;
198 	}
199 #else
200 	/* If src or dest is unaligned, don't do word-at-a-time. */
201 	if (((long) dest | (long) src) & (sizeof(long) - 1))
202 		max = 0;
203 #endif
204 
205 	while (max >= sizeof(unsigned long)) {
206 		unsigned long c, data;
207 
208 		c = read_word_at_a_time(src+res);
209 		if (has_zero(c, &data, &constants)) {
210 			data = prep_zero_mask(c, data, &constants);
211 			data = create_zero_mask(data);
212 			*(unsigned long *)(dest+res) = c & zero_bytemask(data);
213 			return res + find_zero(data);
214 		}
215 		*(unsigned long *)(dest+res) = c;
216 		res += sizeof(unsigned long);
217 		count -= sizeof(unsigned long);
218 		max -= sizeof(unsigned long);
219 	}
220 
221 	while (count) {
222 		char c;
223 
224 		c = src[res];
225 		dest[res] = c;
226 		if (!c)
227 			return res;
228 		res++;
229 		count--;
230 	}
231 
232 	/* Hit buffer length without finding a NUL; force NUL-termination. */
233 	if (res)
234 		dest[res-1] = '\0';
235 
236 	return -E2BIG;
237 }
238 EXPORT_SYMBOL(strscpy);
239 #endif
240 
241 /**
242  * strscpy_pad() - Copy a C-string into a sized buffer
243  * @dest: Where to copy the string to
244  * @src: Where to copy the string from
245  * @count: Size of destination buffer
246  *
247  * Copy the string, or as much of it as fits, into the dest buffer.  The
248  * behavior is undefined if the string buffers overlap.  The destination
249  * buffer is always %NUL terminated, unless it's zero-sized.
250  *
251  * If the source string is shorter than the destination buffer, zeros
252  * the tail of the destination buffer.
253  *
254  * For full explanation of why you may want to consider using the
255  * 'strscpy' functions please see the function docstring for strscpy().
256  *
257  * Returns:
258  * * The number of characters copied (not including the trailing %NUL)
259  * * -E2BIG if count is 0 or @src was truncated.
260  */
strscpy_pad(char * dest,const char * src,size_t count)261 ssize_t strscpy_pad(char *dest, const char *src, size_t count)
262 {
263 	ssize_t written;
264 
265 	written = strscpy(dest, src, count);
266 	if (written < 0 || written == count - 1)
267 		return written;
268 
269 	memset(dest + written + 1, 0, count - written - 1);
270 
271 	return written;
272 }
273 EXPORT_SYMBOL(strscpy_pad);
274 
275 /**
276  * stpcpy - copy a string from src to dest returning a pointer to the new end
277  *          of dest, including src's %NUL-terminator. May overrun dest.
278  * @dest: pointer to end of string being copied into. Must be large enough
279  *        to receive copy.
280  * @src: pointer to the beginning of string being copied from. Must not overlap
281  *       dest.
282  *
283  * stpcpy differs from strcpy in a key way: the return value is a pointer
284  * to the new %NUL-terminating character in @dest. (For strcpy, the return
285  * value is a pointer to the start of @dest). This interface is considered
286  * unsafe as it doesn't perform bounds checking of the inputs. As such it's
287  * not recommended for usage. Instead, its definition is provided in case
288  * the compiler lowers other libcalls to stpcpy.
289  */
290 char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
stpcpy(char * __restrict__ dest,const char * __restrict__ src)291 char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
292 {
293 	while ((*dest++ = *src++) != '\0')
294 		/* nothing */;
295 	return --dest;
296 }
297 EXPORT_SYMBOL(stpcpy);
298 
299 #ifndef __HAVE_ARCH_STRCAT
300 /**
301  * strcat - Append one %NUL-terminated string to another
302  * @dest: The string to be appended to
303  * @src: The string to append to it
304  */
strcat(char * dest,const char * src)305 char *strcat(char *dest, const char *src)
306 {
307 	char *tmp = dest;
308 
309 	while (*dest)
310 		dest++;
311 	while ((*dest++ = *src++) != '\0')
312 		;
313 	return tmp;
314 }
315 EXPORT_SYMBOL(strcat);
316 #endif
317 
318 #ifndef __HAVE_ARCH_STRNCAT
319 /**
320  * strncat - Append a length-limited, C-string to another
321  * @dest: The string to be appended to
322  * @src: The string to append to it
323  * @count: The maximum numbers of bytes to copy
324  *
325  * Note that in contrast to strncpy(), strncat() ensures the result is
326  * terminated.
327  */
strncat(char * dest,const char * src,size_t count)328 char *strncat(char *dest, const char *src, size_t count)
329 {
330 	char *tmp = dest;
331 
332 	if (count) {
333 		while (*dest)
334 			dest++;
335 		while ((*dest++ = *src++) != 0) {
336 			if (--count == 0) {
337 				*dest = '\0';
338 				break;
339 			}
340 		}
341 	}
342 	return tmp;
343 }
344 EXPORT_SYMBOL(strncat);
345 #endif
346 
347 #ifndef __HAVE_ARCH_STRLCAT
348 /**
349  * strlcat - Append a length-limited, C-string to another
350  * @dest: The string to be appended to
351  * @src: The string to append to it
352  * @count: The size of the destination buffer.
353  */
strlcat(char * dest,const char * src,size_t count)354 size_t strlcat(char *dest, const char *src, size_t count)
355 {
356 	size_t dsize = strlen(dest);
357 	size_t len = strlen(src);
358 	size_t res = dsize + len;
359 
360 	/* This would be a bug */
361 	BUG_ON(dsize >= count);
362 
363 	dest += dsize;
364 	count -= dsize;
365 	if (len >= count)
366 		len = count-1;
367 	memcpy(dest, src, len);
368 	dest[len] = 0;
369 	return res;
370 }
371 EXPORT_SYMBOL(strlcat);
372 #endif
373 
374 #ifndef __HAVE_ARCH_STRCMP
375 /**
376  * strcmp - Compare two strings
377  * @cs: One string
378  * @ct: Another string
379  */
strcmp(const char * cs,const char * ct)380 int strcmp(const char *cs, const char *ct)
381 {
382 	unsigned char c1, c2;
383 
384 	while (1) {
385 		c1 = *cs++;
386 		c2 = *ct++;
387 		if (c1 != c2)
388 			return c1 < c2 ? -1 : 1;
389 		if (!c1)
390 			break;
391 	}
392 	return 0;
393 }
394 EXPORT_SYMBOL(strcmp);
395 #endif
396 
397 #ifndef __HAVE_ARCH_STRNCMP
398 /**
399  * strncmp - Compare two length-limited strings
400  * @cs: One string
401  * @ct: Another string
402  * @count: The maximum number of bytes to compare
403  */
strncmp(const char * cs,const char * ct,size_t count)404 int strncmp(const char *cs, const char *ct, size_t count)
405 {
406 	unsigned char c1, c2;
407 
408 	while (count) {
409 		c1 = *cs++;
410 		c2 = *ct++;
411 		if (c1 != c2)
412 			return c1 < c2 ? -1 : 1;
413 		if (!c1)
414 			break;
415 		count--;
416 	}
417 	return 0;
418 }
419 EXPORT_SYMBOL(strncmp);
420 #endif
421 
422 #ifndef __HAVE_ARCH_STRCHR
423 /**
424  * strchr - Find the first occurrence of a character in a string
425  * @s: The string to be searched
426  * @c: The character to search for
427  *
428  * Note that the %NUL-terminator is considered part of the string, and can
429  * be searched for.
430  */
strchr(const char * s,int c)431 char *strchr(const char *s, int c)
432 {
433 	for (; *s != (char)c; ++s)
434 		if (*s == '\0')
435 			return NULL;
436 	return (char *)s;
437 }
438 EXPORT_SYMBOL(strchr);
439 #endif
440 
441 #ifndef __HAVE_ARCH_STRCHRNUL
442 /**
443  * strchrnul - Find and return a character in a string, or end of string
444  * @s: The string to be searched
445  * @c: The character to search for
446  *
447  * Returns pointer to first occurrence of 'c' in s. If c is not found, then
448  * return a pointer to the null byte at the end of s.
449  */
strchrnul(const char * s,int c)450 char *strchrnul(const char *s, int c)
451 {
452 	while (*s && *s != (char)c)
453 		s++;
454 	return (char *)s;
455 }
456 EXPORT_SYMBOL(strchrnul);
457 #endif
458 
459 /**
460  * strnchrnul - Find and return a character in a length limited string,
461  * or end of string
462  * @s: The string to be searched
463  * @count: The number of characters to be searched
464  * @c: The character to search for
465  *
466  * Returns pointer to the first occurrence of 'c' in s. If c is not found,
467  * then return a pointer to the last character of the string.
468  */
strnchrnul(const char * s,size_t count,int c)469 char *strnchrnul(const char *s, size_t count, int c)
470 {
471 	while (count-- && *s && *s != (char)c)
472 		s++;
473 	return (char *)s;
474 }
475 
476 #ifndef __HAVE_ARCH_STRRCHR
477 /**
478  * strrchr - Find the last occurrence of a character in a string
479  * @s: The string to be searched
480  * @c: The character to search for
481  */
strrchr(const char * s,int c)482 char *strrchr(const char *s, int c)
483 {
484 	const char *last = NULL;
485 	do {
486 		if (*s == (char)c)
487 			last = s;
488 	} while (*s++);
489 	return (char *)last;
490 }
491 EXPORT_SYMBOL(strrchr);
492 #endif
493 
494 #ifndef __HAVE_ARCH_STRNCHR
495 /**
496  * strnchr - Find a character in a length limited string
497  * @s: The string to be searched
498  * @count: The number of characters to be searched
499  * @c: The character to search for
500  *
501  * Note that the %NUL-terminator is considered part of the string, and can
502  * be searched for.
503  */
strnchr(const char * s,size_t count,int c)504 char *strnchr(const char *s, size_t count, int c)
505 {
506 	while (count--) {
507 		if (*s == (char)c)
508 			return (char *)s;
509 		if (*s++ == '\0')
510 			break;
511 	}
512 	return NULL;
513 }
514 EXPORT_SYMBOL(strnchr);
515 #endif
516 
517 /**
518  * skip_spaces - Removes leading whitespace from @str.
519  * @str: The string to be stripped.
520  *
521  * Returns a pointer to the first non-whitespace character in @str.
522  */
skip_spaces(const char * str)523 char *skip_spaces(const char *str)
524 {
525 	while (isspace(*str))
526 		++str;
527 	return (char *)str;
528 }
529 EXPORT_SYMBOL(skip_spaces);
530 
531 /**
532  * strim - Removes leading and trailing whitespace from @s.
533  * @s: The string to be stripped.
534  *
535  * Note that the first trailing whitespace is replaced with a %NUL-terminator
536  * in the given string @s. Returns a pointer to the first non-whitespace
537  * character in @s.
538  */
strim(char * s)539 char *strim(char *s)
540 {
541 	size_t size;
542 	char *end;
543 
544 	size = strlen(s);
545 	if (!size)
546 		return s;
547 
548 	end = s + size - 1;
549 	while (end >= s && isspace(*end))
550 		end--;
551 	*(end + 1) = '\0';
552 
553 	return skip_spaces(s);
554 }
555 EXPORT_SYMBOL(strim);
556 
557 #ifndef __HAVE_ARCH_STRLEN
558 /**
559  * strlen - Find the length of a string
560  * @s: The string to be sized
561  */
strlen(const char * s)562 size_t strlen(const char *s)
563 {
564 	const char *sc;
565 
566 	for (sc = s; *sc != '\0'; ++sc)
567 		/* nothing */;
568 	return sc - s;
569 }
570 EXPORT_SYMBOL(strlen);
571 #endif
572 
573 #ifndef __HAVE_ARCH_STRNLEN
574 /**
575  * strnlen - Find the length of a length-limited string
576  * @s: The string to be sized
577  * @count: The maximum number of bytes to search
578  */
strnlen(const char * s,size_t count)579 size_t strnlen(const char *s, size_t count)
580 {
581 	const char *sc;
582 
583 	for (sc = s; count-- && *sc != '\0'; ++sc)
584 		/* nothing */;
585 	return sc - s;
586 }
587 EXPORT_SYMBOL(strnlen);
588 #endif
589 
590 #ifndef __HAVE_ARCH_STRSPN
591 /**
592  * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
593  * @s: The string to be searched
594  * @accept: The string to search for
595  */
strspn(const char * s,const char * accept)596 size_t strspn(const char *s, const char *accept)
597 {
598 	const char *p;
599 	const char *a;
600 	size_t count = 0;
601 
602 	for (p = s; *p != '\0'; ++p) {
603 		for (a = accept; *a != '\0'; ++a) {
604 			if (*p == *a)
605 				break;
606 		}
607 		if (*a == '\0')
608 			return count;
609 		++count;
610 	}
611 	return count;
612 }
613 
614 EXPORT_SYMBOL(strspn);
615 #endif
616 
617 #ifndef __HAVE_ARCH_STRCSPN
618 /**
619  * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
620  * @s: The string to be searched
621  * @reject: The string to avoid
622  */
strcspn(const char * s,const char * reject)623 size_t strcspn(const char *s, const char *reject)
624 {
625 	const char *p;
626 	const char *r;
627 	size_t count = 0;
628 
629 	for (p = s; *p != '\0'; ++p) {
630 		for (r = reject; *r != '\0'; ++r) {
631 			if (*p == *r)
632 				return count;
633 		}
634 		++count;
635 	}
636 	return count;
637 }
638 EXPORT_SYMBOL(strcspn);
639 #endif
640 
641 #ifndef __HAVE_ARCH_STRPBRK
642 /**
643  * strpbrk - Find the first occurrence of a set of characters
644  * @cs: The string to be searched
645  * @ct: The characters to search for
646  */
strpbrk(const char * cs,const char * ct)647 char *strpbrk(const char *cs, const char *ct)
648 {
649 	const char *sc1, *sc2;
650 
651 	for (sc1 = cs; *sc1 != '\0'; ++sc1) {
652 		for (sc2 = ct; *sc2 != '\0'; ++sc2) {
653 			if (*sc1 == *sc2)
654 				return (char *)sc1;
655 		}
656 	}
657 	return NULL;
658 }
659 EXPORT_SYMBOL(strpbrk);
660 #endif
661 
662 #ifndef __HAVE_ARCH_STRSEP
663 /**
664  * strsep - Split a string into tokens
665  * @s: The string to be searched
666  * @ct: The characters to search for
667  *
668  * strsep() updates @s to point after the token, ready for the next call.
669  *
670  * It returns empty tokens, too, behaving exactly like the libc function
671  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
672  * Same semantics, slimmer shape. ;)
673  */
strsep(char ** s,const char * ct)674 char *strsep(char **s, const char *ct)
675 {
676 	char *sbegin = *s;
677 	char *end;
678 
679 	if (sbegin == NULL)
680 		return NULL;
681 
682 	end = strpbrk(sbegin, ct);
683 	if (end)
684 		*end++ = '\0';
685 	*s = end;
686 	return sbegin;
687 }
688 EXPORT_SYMBOL(strsep);
689 #endif
690 
691 /**
692  * sysfs_streq - return true if strings are equal, modulo trailing newline
693  * @s1: one string
694  * @s2: another string
695  *
696  * This routine returns true iff two strings are equal, treating both
697  * NUL and newline-then-NUL as equivalent string terminations.  It's
698  * geared for use with sysfs input strings, which generally terminate
699  * with newlines but are compared against values without newlines.
700  */
sysfs_streq(const char * s1,const char * s2)701 bool sysfs_streq(const char *s1, const char *s2)
702 {
703 	while (*s1 && *s1 == *s2) {
704 		s1++;
705 		s2++;
706 	}
707 
708 	if (*s1 == *s2)
709 		return true;
710 	if (!*s1 && *s2 == '\n' && !s2[1])
711 		return true;
712 	if (*s1 == '\n' && !s1[1] && !*s2)
713 		return true;
714 	return false;
715 }
716 EXPORT_SYMBOL(sysfs_streq);
717 
718 /**
719  * match_string - matches given string in an array
720  * @array:	array of strings
721  * @n:		number of strings in the array or -1 for NULL terminated arrays
722  * @string:	string to match with
723  *
724  * This routine will look for a string in an array of strings up to the
725  * n-th element in the array or until the first NULL element.
726  *
727  * Historically the value of -1 for @n, was used to search in arrays that
728  * are NULL terminated. However, the function does not make a distinction
729  * when finishing the search: either @n elements have been compared OR
730  * the first NULL element was found.
731  *
732  * Return:
733  * index of a @string in the @array if matches, or %-EINVAL otherwise.
734  */
match_string(const char * const * array,size_t n,const char * string)735 int match_string(const char * const *array, size_t n, const char *string)
736 {
737 	int index;
738 	const char *item;
739 
740 	for (index = 0; index < n; index++) {
741 		item = array[index];
742 		if (!item)
743 			break;
744 		if (!strcmp(item, string))
745 			return index;
746 	}
747 
748 	return -EINVAL;
749 }
750 EXPORT_SYMBOL(match_string);
751 
752 /**
753  * __sysfs_match_string - matches given string in an array
754  * @array: array of strings
755  * @n: number of strings in the array or -1 for NULL terminated arrays
756  * @str: string to match with
757  *
758  * Returns index of @str in the @array or -EINVAL, just like match_string().
759  * Uses sysfs_streq instead of strcmp for matching.
760  *
761  * This routine will look for a string in an array of strings up to the
762  * n-th element in the array or until the first NULL element.
763  *
764  * Historically the value of -1 for @n, was used to search in arrays that
765  * are NULL terminated. However, the function does not make a distinction
766  * when finishing the search: either @n elements have been compared OR
767  * the first NULL element was found.
768  */
__sysfs_match_string(const char * const * array,size_t n,const char * str)769 int __sysfs_match_string(const char * const *array, size_t n, const char *str)
770 {
771 	const char *item;
772 	int index;
773 
774 	for (index = 0; index < n; index++) {
775 		item = array[index];
776 		if (!item)
777 			break;
778 		if (sysfs_streq(item, str))
779 			return index;
780 	}
781 
782 	return -EINVAL;
783 }
784 EXPORT_SYMBOL(__sysfs_match_string);
785 
786 #ifndef __HAVE_ARCH_MEMSET
787 /**
788  * memset - Fill a region of memory with the given value
789  * @s: Pointer to the start of the area.
790  * @c: The byte to fill the area with
791  * @count: The size of the area.
792  *
793  * Do not use memset() to access IO space, use memset_io() instead.
794  */
memset(void * s,int c,size_t count)795 void *memset(void *s, int c, size_t count)
796 {
797 	char *xs = s;
798 
799 	while (count--)
800 		*xs++ = c;
801 	return s;
802 }
803 EXPORT_SYMBOL(memset);
804 #endif
805 
806 #ifndef __HAVE_ARCH_MEMSET16
807 /**
808  * memset16() - Fill a memory area with a uint16_t
809  * @s: Pointer to the start of the area.
810  * @v: The value to fill the area with
811  * @count: The number of values to store
812  *
813  * Differs from memset() in that it fills with a uint16_t instead
814  * of a byte.  Remember that @count is the number of uint16_ts to
815  * store, not the number of bytes.
816  */
memset16(uint16_t * s,uint16_t v,size_t count)817 void *memset16(uint16_t *s, uint16_t v, size_t count)
818 {
819 	uint16_t *xs = s;
820 
821 	while (count--)
822 		*xs++ = v;
823 	return s;
824 }
825 EXPORT_SYMBOL(memset16);
826 #endif
827 
828 #ifndef __HAVE_ARCH_MEMSET32
829 /**
830  * memset32() - Fill a memory area with a uint32_t
831  * @s: Pointer to the start of the area.
832  * @v: The value to fill the area with
833  * @count: The number of values to store
834  *
835  * Differs from memset() in that it fills with a uint32_t instead
836  * of a byte.  Remember that @count is the number of uint32_ts to
837  * store, not the number of bytes.
838  */
memset32(uint32_t * s,uint32_t v,size_t count)839 void *memset32(uint32_t *s, uint32_t v, size_t count)
840 {
841 	uint32_t *xs = s;
842 
843 	while (count--)
844 		*xs++ = v;
845 	return s;
846 }
847 EXPORT_SYMBOL(memset32);
848 #endif
849 
850 #ifndef __HAVE_ARCH_MEMSET64
851 /**
852  * memset64() - Fill a memory area with a uint64_t
853  * @s: Pointer to the start of the area.
854  * @v: The value to fill the area with
855  * @count: The number of values to store
856  *
857  * Differs from memset() in that it fills with a uint64_t instead
858  * of a byte.  Remember that @count is the number of uint64_ts to
859  * store, not the number of bytes.
860  */
memset64(uint64_t * s,uint64_t v,size_t count)861 void *memset64(uint64_t *s, uint64_t v, size_t count)
862 {
863 	uint64_t *xs = s;
864 
865 	while (count--)
866 		*xs++ = v;
867 	return s;
868 }
869 EXPORT_SYMBOL(memset64);
870 #endif
871 
872 #ifndef __HAVE_ARCH_MEMCPY
873 /**
874  * memcpy - Copy one area of memory to another
875  * @dest: Where to copy to
876  * @src: Where to copy from
877  * @count: The size of the area.
878  *
879  * You should not use this function to access IO space, use memcpy_toio()
880  * or memcpy_fromio() instead.
881  */
memcpy(void * dest,const void * src,size_t count)882 void *memcpy(void *dest, const void *src, size_t count)
883 {
884 	char *tmp = dest;
885 	const char *s = src;
886 
887 	while (count--)
888 		*tmp++ = *s++;
889 	return dest;
890 }
891 EXPORT_SYMBOL(memcpy);
892 #endif
893 
894 #ifndef __HAVE_ARCH_MEMMOVE
895 /**
896  * memmove - Copy one area of memory to another
897  * @dest: Where to copy to
898  * @src: Where to copy from
899  * @count: The size of the area.
900  *
901  * Unlike memcpy(), memmove() copes with overlapping areas.
902  */
memmove(void * dest,const void * src,size_t count)903 void *memmove(void *dest, const void *src, size_t count)
904 {
905 	char *tmp;
906 	const char *s;
907 
908 	if (dest <= src) {
909 		tmp = dest;
910 		s = src;
911 		while (count--)
912 			*tmp++ = *s++;
913 	} else {
914 		tmp = dest;
915 		tmp += count;
916 		s = src;
917 		s += count;
918 		while (count--)
919 			*--tmp = *--s;
920 	}
921 	return dest;
922 }
923 EXPORT_SYMBOL(memmove);
924 #endif
925 
926 #ifndef __HAVE_ARCH_MEMCMP
927 /**
928  * memcmp - Compare two areas of memory
929  * @cs: One area of memory
930  * @ct: Another area of memory
931  * @count: The size of the area.
932  */
933 #undef memcmp
memcmp(const void * cs,const void * ct,size_t count)934 __visible int memcmp(const void *cs, const void *ct, size_t count)
935 {
936 	const unsigned char *su1, *su2;
937 	int res = 0;
938 
939 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
940 	if (count >= sizeof(unsigned long)) {
941 		const unsigned long *u1 = cs;
942 		const unsigned long *u2 = ct;
943 		do {
944 			if (get_unaligned(u1) != get_unaligned(u2))
945 				break;
946 			u1++;
947 			u2++;
948 			count -= sizeof(unsigned long);
949 		} while (count >= sizeof(unsigned long));
950 		cs = u1;
951 		ct = u2;
952 	}
953 #endif
954 	for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
955 		if ((res = *su1 - *su2) != 0)
956 			break;
957 	return res;
958 }
959 EXPORT_SYMBOL(memcmp);
960 #endif
961 
962 #ifndef __HAVE_ARCH_BCMP
963 /**
964  * bcmp - returns 0 if and only if the buffers have identical contents.
965  * @a: pointer to first buffer.
966  * @b: pointer to second buffer.
967  * @len: size of buffers.
968  *
969  * The sign or magnitude of a non-zero return value has no particular
970  * meaning, and architectures may implement their own more efficient bcmp(). So
971  * while this particular implementation is a simple (tail) call to memcmp, do
972  * not rely on anything but whether the return value is zero or non-zero.
973  */
bcmp(const void * a,const void * b,size_t len)974 int bcmp(const void *a, const void *b, size_t len)
975 {
976 	return memcmp(a, b, len);
977 }
978 EXPORT_SYMBOL(bcmp);
979 #endif
980 
981 #ifndef __HAVE_ARCH_MEMSCAN
982 /**
983  * memscan - Find a character in an area of memory.
984  * @addr: The memory area
985  * @c: The byte to search for
986  * @size: The size of the area.
987  *
988  * returns the address of the first occurrence of @c, or 1 byte past
989  * the area if @c is not found
990  */
memscan(void * addr,int c,size_t size)991 void *memscan(void *addr, int c, size_t size)
992 {
993 	unsigned char *p = addr;
994 
995 	while (size) {
996 		if (*p == (unsigned char)c)
997 			return (void *)p;
998 		p++;
999 		size--;
1000 	}
1001   	return (void *)p;
1002 }
1003 EXPORT_SYMBOL(memscan);
1004 #endif
1005 
1006 #ifndef __HAVE_ARCH_STRSTR
1007 /**
1008  * strstr - Find the first substring in a %NUL terminated string
1009  * @s1: The string to be searched
1010  * @s2: The string to search for
1011  */
strstr(const char * s1,const char * s2)1012 char *strstr(const char *s1, const char *s2)
1013 {
1014 	size_t l1, l2;
1015 
1016 	l2 = strlen(s2);
1017 	if (!l2)
1018 		return (char *)s1;
1019 	l1 = strlen(s1);
1020 	while (l1 >= l2) {
1021 		l1--;
1022 		if (!memcmp(s1, s2, l2))
1023 			return (char *)s1;
1024 		s1++;
1025 	}
1026 	return NULL;
1027 }
1028 EXPORT_SYMBOL(strstr);
1029 #endif
1030 
1031 #ifndef __HAVE_ARCH_STRNSTR
1032 /**
1033  * strnstr - Find the first substring in a length-limited string
1034  * @s1: The string to be searched
1035  * @s2: The string to search for
1036  * @len: the maximum number of characters to search
1037  */
strnstr(const char * s1,const char * s2,size_t len)1038 char *strnstr(const char *s1, const char *s2, size_t len)
1039 {
1040 	size_t l2;
1041 
1042 	l2 = strlen(s2);
1043 	if (!l2)
1044 		return (char *)s1;
1045 	while (len >= l2) {
1046 		len--;
1047 		if (!memcmp(s1, s2, l2))
1048 			return (char *)s1;
1049 		s1++;
1050 	}
1051 	return NULL;
1052 }
1053 EXPORT_SYMBOL(strnstr);
1054 #endif
1055 
1056 #ifndef __HAVE_ARCH_MEMCHR
1057 /**
1058  * memchr - Find a character in an area of memory.
1059  * @s: The memory area
1060  * @c: The byte to search for
1061  * @n: The size of the area.
1062  *
1063  * returns the address of the first occurrence of @c, or %NULL
1064  * if @c is not found
1065  */
memchr(const void * s,int c,size_t n)1066 void *memchr(const void *s, int c, size_t n)
1067 {
1068 	const unsigned char *p = s;
1069 	while (n-- != 0) {
1070         	if ((unsigned char)c == *p++) {
1071 			return (void *)(p - 1);
1072 		}
1073 	}
1074 	return NULL;
1075 }
1076 EXPORT_SYMBOL(memchr);
1077 #endif
1078 
check_bytes8(const u8 * start,u8 value,unsigned int bytes)1079 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1080 {
1081 	while (bytes) {
1082 		if (*start != value)
1083 			return (void *)start;
1084 		start++;
1085 		bytes--;
1086 	}
1087 	return NULL;
1088 }
1089 
1090 /**
1091  * memchr_inv - Find an unmatching character in an area of memory.
1092  * @start: The memory area
1093  * @c: Find a character other than c
1094  * @bytes: The size of the area.
1095  *
1096  * returns the address of the first character other than @c, or %NULL
1097  * if the whole buffer contains just @c.
1098  */
memchr_inv(const void * start,int c,size_t bytes)1099 void *memchr_inv(const void *start, int c, size_t bytes)
1100 {
1101 	u8 value = c;
1102 	u64 value64;
1103 	unsigned int words, prefix;
1104 
1105 	if (bytes <= 16)
1106 		return check_bytes8(start, value, bytes);
1107 
1108 	value64 = value;
1109 #if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1110 	value64 *= 0x0101010101010101ULL;
1111 #elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1112 	value64 *= 0x01010101;
1113 	value64 |= value64 << 32;
1114 #else
1115 	value64 |= value64 << 8;
1116 	value64 |= value64 << 16;
1117 	value64 |= value64 << 32;
1118 #endif
1119 
1120 	prefix = (unsigned long)start % 8;
1121 	if (prefix) {
1122 		u8 *r;
1123 
1124 		prefix = 8 - prefix;
1125 		r = check_bytes8(start, value, prefix);
1126 		if (r)
1127 			return r;
1128 		start += prefix;
1129 		bytes -= prefix;
1130 	}
1131 
1132 	words = bytes / 8;
1133 
1134 	while (words) {
1135 		if (*(u64 *)start != value64)
1136 			return check_bytes8(start, value, 8);
1137 		start += 8;
1138 		words--;
1139 	}
1140 
1141 	return check_bytes8(start, value, bytes % 8);
1142 }
1143 EXPORT_SYMBOL(memchr_inv);
1144 
1145 /**
1146  * strreplace - Replace all occurrences of character in string.
1147  * @s: The string to operate on.
1148  * @old: The character being replaced.
1149  * @new: The character @old is replaced with.
1150  *
1151  * Returns pointer to the nul byte at the end of @s.
1152  */
strreplace(char * s,char old,char new)1153 char *strreplace(char *s, char old, char new)
1154 {
1155 	for (; *s; ++s)
1156 		if (*s == old)
1157 			*s = new;
1158 	return s;
1159 }
1160 EXPORT_SYMBOL(strreplace);
1161 
fortify_panic(const char * name)1162 void fortify_panic(const char *name)
1163 {
1164 	pr_emerg("detected buffer overflow in %s\n", name);
1165 	BUG();
1166 }
1167 EXPORT_SYMBOL(fortify_panic);
1168