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1 /*
2 * linux/lib/string.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7 /*
8 * stupid library routines.. The optimized versions should generally be found
9 * as inline code in <asm-xx/string.h>
10 *
11 * These are buggy as well..
12 *
13 * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
14 * - Added strsep() which will replace strtok() soon (because strsep() is
15 * reentrant and should be faster). Use only strsep() in new code, please.
16 *
17 * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
18 * Matthew Hawkins <matt@mh.dropbear.id.au>
19 * - Kissed strtok() goodbye
20 */
21
22 #include <linux/types.h>
23 #include <linux/string.h>
24 #include <linux/ctype.h>
25 #include <linux/kernel.h>
26 #include <linux/export.h>
27 #include <linux/bug.h>
28 #include <linux/errno.h>
29
30 #ifndef __HAVE_ARCH_STRNICMP
31 /**
32 * strnicmp - Case insensitive, length-limited string comparison
33 * @s1: One string
34 * @s2: The other string
35 * @len: the maximum number of characters to compare
36 */
37 int strnicmp(const char *s1, const char *s2, size_t len)
38 {
39 /* Yes, Virginia, it had better be unsigned */
40 unsigned char c1, c2;
41
42 if (!len)
43 return 0;
44
45 do {
46 c1 = *s1++;
47 c2 = *s2++;
48 if (!c1 || !c2)
49 break;
50 if (c1 == c2)
51 continue;
52 c1 = tolower(c1);
53 c2 = tolower(c2);
54 if (c1 != c2)
55 break;
56 } while (--len);
57 return (int)c1 - (int)c2;
58 }
59 EXPORT_SYMBOL(strnicmp);
60 #endif
61
62 #ifndef __HAVE_ARCH_STRCASECMP
63 int strcasecmp(const char *s1, const char *s2)
64 {
65 int c1, c2;
66
67 do {
68 c1 = tolower(*s1++);
69 c2 = tolower(*s2++);
70 } while (c1 == c2 && c1 != 0);
71 return c1 - c2;
72 }
73 EXPORT_SYMBOL(strcasecmp);
74 #endif
75
76 #ifndef __HAVE_ARCH_STRNCASECMP
77 int strncasecmp(const char *s1, const char *s2, size_t n)
78 {
79 int c1, c2;
80
81 do {
82 c1 = tolower(*s1++);
83 c2 = tolower(*s2++);
84 } while ((--n > 0) && c1 == c2 && c1 != 0);
85 return c1 - c2;
86 }
87 EXPORT_SYMBOL(strncasecmp);
88 #endif
89
90 #ifndef __HAVE_ARCH_STRCPY
91 /**
92 * strcpy - Copy a %NUL terminated string
93 * @dest: Where to copy the string to
94 * @src: Where to copy the string from
95 */
96 #undef strcpy
97 char *strcpy(char *dest, const char *src)
98 {
99 char *tmp = dest;
100
101 while ((*dest++ = *src++) != '\0')
102 /* nothing */;
103 return tmp;
104 }
105 EXPORT_SYMBOL(strcpy);
106 #endif
107
108 #ifndef __HAVE_ARCH_STRNCPY
109 /**
110 * strncpy - Copy a length-limited, C-string
111 * @dest: Where to copy the string to
112 * @src: Where to copy the string from
113 * @count: The maximum number of bytes to copy
114 *
115 * The result is not %NUL-terminated if the source exceeds
116 * @count bytes.
117 *
118 * In the case where the length of @src is less than that of
119 * count, the remainder of @dest will be padded with %NUL.
120 *
121 */
122 char *strncpy(char *dest, const char *src, size_t count)
123 {
124 char *tmp = dest;
125
126 while (count) {
127 if ((*tmp = *src) != 0)
128 src++;
129 tmp++;
130 count--;
131 }
132 return dest;
133 }
134 EXPORT_SYMBOL(strncpy);
135 #endif
136
137 #ifndef __HAVE_ARCH_STRLCPY
138 /**
139 * strlcpy - Copy a C-string into a sized buffer
140 * @dest: Where to copy the string to
141 * @src: Where to copy the string from
142 * @size: size of destination buffer
143 *
144 * Compatible with *BSD: the result is always a valid
145 * NUL-terminated string that fits in the buffer (unless,
146 * of course, the buffer size is zero). It does not pad
147 * out the result like strncpy() does.
148 */
149 size_t strlcpy(char *dest, const char *src, size_t size)
150 {
151 size_t ret = strlen(src);
152
153 if (size) {
154 size_t len = (ret >= size) ? size - 1 : ret;
155 memcpy(dest, src, len);
156 dest[len] = '\0';
157 }
158 return ret;
159 }
160 EXPORT_SYMBOL(strlcpy);
161 #endif
162
163 #ifndef __HAVE_ARCH_STRCAT
164 /**
165 * strcat - Append one %NUL-terminated string to another
166 * @dest: The string to be appended to
167 * @src: The string to append to it
168 */
169 #undef strcat
170 char *strcat(char *dest, const char *src)
171 {
172 char *tmp = dest;
173
174 while (*dest)
175 dest++;
176 while ((*dest++ = *src++) != '\0')
177 ;
178 return tmp;
179 }
180 EXPORT_SYMBOL(strcat);
181 #endif
182
183 #ifndef __HAVE_ARCH_STRNCAT
184 /**
185 * strncat - Append a length-limited, C-string to another
186 * @dest: The string to be appended to
187 * @src: The string to append to it
188 * @count: The maximum numbers of bytes to copy
189 *
190 * Note that in contrast to strncpy(), strncat() ensures the result is
191 * terminated.
192 */
193 char *strncat(char *dest, const char *src, size_t count)
194 {
195 char *tmp = dest;
196
197 if (count) {
198 while (*dest)
199 dest++;
200 while ((*dest++ = *src++) != 0) {
201 if (--count == 0) {
202 *dest = '\0';
203 break;
204 }
205 }
206 }
207 return tmp;
208 }
209 EXPORT_SYMBOL(strncat);
210 #endif
211
212 #ifndef __HAVE_ARCH_STRLCAT
213 /**
214 * strlcat - Append a length-limited, C-string to another
215 * @dest: The string to be appended to
216 * @src: The string to append to it
217 * @count: The size of the destination buffer.
218 */
219 size_t strlcat(char *dest, const char *src, size_t count)
220 {
221 size_t dsize = strlen(dest);
222 size_t len = strlen(src);
223 size_t res = dsize + len;
224
225 /* This would be a bug */
226 BUG_ON(dsize >= count);
227
228 dest += dsize;
229 count -= dsize;
230 if (len >= count)
231 len = count-1;
232 memcpy(dest, src, len);
233 dest[len] = 0;
234 return res;
235 }
236 EXPORT_SYMBOL(strlcat);
237 #endif
238
239 #ifndef __HAVE_ARCH_STRCMP
240 /**
241 * strcmp - Compare two strings
242 * @cs: One string
243 * @ct: Another string
244 */
245 #undef strcmp
246 int strcmp(const char *cs, const char *ct)
247 {
248 unsigned char c1, c2;
249
250 while (1) {
251 c1 = *cs++;
252 c2 = *ct++;
253 if (c1 != c2)
254 return c1 < c2 ? -1 : 1;
255 if (!c1)
256 break;
257 }
258 return 0;
259 }
260 EXPORT_SYMBOL(strcmp);
261 #endif
262
263 #ifndef __HAVE_ARCH_STRNCMP
264 /**
265 * strncmp - Compare two length-limited strings
266 * @cs: One string
267 * @ct: Another string
268 * @count: The maximum number of bytes to compare
269 */
270 int strncmp(const char *cs, const char *ct, size_t count)
271 {
272 unsigned char c1, c2;
273
274 while (count) {
275 c1 = *cs++;
276 c2 = *ct++;
277 if (c1 != c2)
278 return c1 < c2 ? -1 : 1;
279 if (!c1)
280 break;
281 count--;
282 }
283 return 0;
284 }
285 EXPORT_SYMBOL(strncmp);
286 #endif
287
288 #ifndef __HAVE_ARCH_STRCHR
289 /**
290 * strchr - Find the first occurrence of a character in a string
291 * @s: The string to be searched
292 * @c: The character to search for
293 */
294 char *strchr(const char *s, int c)
295 {
296 for (; *s != (char)c; ++s)
297 if (*s == '\0')
298 return NULL;
299 return (char *)s;
300 }
301 EXPORT_SYMBOL(strchr);
302 #endif
303
304 #ifndef __HAVE_ARCH_STRCHRNUL
305 /**
306 * strchrnul - Find and return a character in a string, or end of string
307 * @s: The string to be searched
308 * @c: The character to search for
309 *
310 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
311 * return a pointer to the null byte at the end of s.
312 */
313 char *strchrnul(const char *s, int c)
314 {
315 while (*s && *s != (char)c)
316 s++;
317 return (char *)s;
318 }
319 EXPORT_SYMBOL(strchrnul);
320 #endif
321
322 #ifndef __HAVE_ARCH_STRRCHR
323 /**
324 * strrchr - Find the last occurrence of a character in a string
325 * @s: The string to be searched
326 * @c: The character to search for
327 */
328 char *strrchr(const char *s, int c)
329 {
330 const char *p = s + strlen(s);
331 do {
332 if (*p == (char)c)
333 return (char *)p;
334 } while (--p >= s);
335 return NULL;
336 }
337 EXPORT_SYMBOL(strrchr);
338 #endif
339
340 #ifndef __HAVE_ARCH_STRNCHR
341 /**
342 * strnchr - Find a character in a length limited string
343 * @s: The string to be searched
344 * @count: The number of characters to be searched
345 * @c: The character to search for
346 */
347 char *strnchr(const char *s, size_t count, int c)
348 {
349 for (; count-- && *s != '\0'; ++s)
350 if (*s == (char)c)
351 return (char *)s;
352 return NULL;
353 }
354 EXPORT_SYMBOL(strnchr);
355 #endif
356
357 /**
358 * skip_spaces - Removes leading whitespace from @str.
359 * @str: The string to be stripped.
360 *
361 * Returns a pointer to the first non-whitespace character in @str.
362 */
363 char *skip_spaces(const char *str)
364 {
365 while (isspace(*str))
366 ++str;
367 return (char *)str;
368 }
369 EXPORT_SYMBOL(skip_spaces);
370
371 /**
372 * strim - Removes leading and trailing whitespace from @s.
373 * @s: The string to be stripped.
374 *
375 * Note that the first trailing whitespace is replaced with a %NUL-terminator
376 * in the given string @s. Returns a pointer to the first non-whitespace
377 * character in @s.
378 */
379 char *strim(char *s)
380 {
381 size_t size;
382 char *end;
383
384 size = strlen(s);
385 if (!size)
386 return s;
387
388 end = s + size - 1;
389 while (end >= s && isspace(*end))
390 end--;
391 *(end + 1) = '\0';
392
393 return skip_spaces(s);
394 }
395 EXPORT_SYMBOL(strim);
396
397 #ifndef __HAVE_ARCH_STRLEN
398 /**
399 * strlen - Find the length of a string
400 * @s: The string to be sized
401 */
402 size_t strlen(const char *s)
403 {
404 const char *sc;
405
406 for (sc = s; *sc != '\0'; ++sc)
407 /* nothing */;
408 return sc - s;
409 }
410 EXPORT_SYMBOL(strlen);
411 #endif
412
413 #ifndef __HAVE_ARCH_STRNLEN
414 /**
415 * strnlen - Find the length of a length-limited string
416 * @s: The string to be sized
417 * @count: The maximum number of bytes to search
418 */
419 size_t strnlen(const char *s, size_t count)
420 {
421 const char *sc;
422
423 for (sc = s; count-- && *sc != '\0'; ++sc)
424 /* nothing */;
425 return sc - s;
426 }
427 EXPORT_SYMBOL(strnlen);
428 #endif
429
430 #ifndef __HAVE_ARCH_STRSPN
431 /**
432 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
433 * @s: The string to be searched
434 * @accept: The string to search for
435 */
436 size_t strspn(const char *s, const char *accept)
437 {
438 const char *p;
439 const char *a;
440 size_t count = 0;
441
442 for (p = s; *p != '\0'; ++p) {
443 for (a = accept; *a != '\0'; ++a) {
444 if (*p == *a)
445 break;
446 }
447 if (*a == '\0')
448 return count;
449 ++count;
450 }
451 return count;
452 }
453
454 EXPORT_SYMBOL(strspn);
455 #endif
456
457 #ifndef __HAVE_ARCH_STRCSPN
458 /**
459 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
460 * @s: The string to be searched
461 * @reject: The string to avoid
462 */
463 size_t strcspn(const char *s, const char *reject)
464 {
465 const char *p;
466 const char *r;
467 size_t count = 0;
468
469 for (p = s; *p != '\0'; ++p) {
470 for (r = reject; *r != '\0'; ++r) {
471 if (*p == *r)
472 return count;
473 }
474 ++count;
475 }
476 return count;
477 }
478 EXPORT_SYMBOL(strcspn);
479 #endif
480
481 #ifndef __HAVE_ARCH_STRPBRK
482 /**
483 * strpbrk - Find the first occurrence of a set of characters
484 * @cs: The string to be searched
485 * @ct: The characters to search for
486 */
487 char *strpbrk(const char *cs, const char *ct)
488 {
489 const char *sc1, *sc2;
490
491 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
492 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
493 if (*sc1 == *sc2)
494 return (char *)sc1;
495 }
496 }
497 return NULL;
498 }
499 EXPORT_SYMBOL(strpbrk);
500 #endif
501
502 #ifndef __HAVE_ARCH_STRSEP
503 /**
504 * strsep - Split a string into tokens
505 * @s: The string to be searched
506 * @ct: The characters to search for
507 *
508 * strsep() updates @s to point after the token, ready for the next call.
509 *
510 * It returns empty tokens, too, behaving exactly like the libc function
511 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
512 * Same semantics, slimmer shape. ;)
513 */
514 char *strsep(char **s, const char *ct)
515 {
516 char *sbegin = *s;
517 char *end;
518
519 if (sbegin == NULL)
520 return NULL;
521
522 end = strpbrk(sbegin, ct);
523 if (end)
524 *end++ = '\0';
525 *s = end;
526 return sbegin;
527 }
528 EXPORT_SYMBOL(strsep);
529 #endif
530
531 /**
532 * sysfs_streq - return true if strings are equal, modulo trailing newline
533 * @s1: one string
534 * @s2: another string
535 *
536 * This routine returns true iff two strings are equal, treating both
537 * NUL and newline-then-NUL as equivalent string terminations. It's
538 * geared for use with sysfs input strings, which generally terminate
539 * with newlines but are compared against values without newlines.
540 */
541 bool sysfs_streq(const char *s1, const char *s2)
542 {
543 while (*s1 && *s1 == *s2) {
544 s1++;
545 s2++;
546 }
547
548 if (*s1 == *s2)
549 return true;
550 if (!*s1 && *s2 == '\n' && !s2[1])
551 return true;
552 if (*s1 == '\n' && !s1[1] && !*s2)
553 return true;
554 return false;
555 }
556 EXPORT_SYMBOL(sysfs_streq);
557
558 /**
559 * strtobool - convert common user inputs into boolean values
560 * @s: input string
561 * @res: result
562 *
563 * This routine returns 0 iff the first character is one of 'Yy1Nn0'.
564 * Otherwise it will return -EINVAL. Value pointed to by res is
565 * updated upon finding a match.
566 */
567 int strtobool(const char *s, bool *res)
568 {
569 switch (s[0]) {
570 case 'y':
571 case 'Y':
572 case '1':
573 *res = true;
574 break;
575 case 'n':
576 case 'N':
577 case '0':
578 *res = false;
579 break;
580 default:
581 return -EINVAL;
582 }
583 return 0;
584 }
585 EXPORT_SYMBOL(strtobool);
586
587 #ifndef __HAVE_ARCH_MEMSET
588 /**
589 * memset - Fill a region of memory with the given value
590 * @s: Pointer to the start of the area.
591 * @c: The byte to fill the area with
592 * @count: The size of the area.
593 *
594 * Do not use memset() to access IO space, use memset_io() instead.
595 */
596 void *memset(void *s, int c, size_t count)
597 {
598 char *xs = s;
599
600 while (count--)
601 *xs++ = c;
602 return s;
603 }
604 EXPORT_SYMBOL(memset);
605 #endif
606
607 #ifndef __HAVE_ARCH_MEMCPY
608 /**
609 * memcpy - Copy one area of memory to another
610 * @dest: Where to copy to
611 * @src: Where to copy from
612 * @count: The size of the area.
613 *
614 * You should not use this function to access IO space, use memcpy_toio()
615 * or memcpy_fromio() instead.
616 */
617 void *memcpy(void *dest, const void *src, size_t count)
618 {
619 char *tmp = dest;
620 const char *s = src;
621
622 while (count--)
623 *tmp++ = *s++;
624 return dest;
625 }
626 EXPORT_SYMBOL(memcpy);
627 #endif
628
629 #ifndef __HAVE_ARCH_MEMMOVE
630 /**
631 * memmove - Copy one area of memory to another
632 * @dest: Where to copy to
633 * @src: Where to copy from
634 * @count: The size of the area.
635 *
636 * Unlike memcpy(), memmove() copes with overlapping areas.
637 */
638 void *memmove(void *dest, const void *src, size_t count)
639 {
640 char *tmp;
641 const char *s;
642
643 if (dest <= src) {
644 tmp = dest;
645 s = src;
646 while (count--)
647 *tmp++ = *s++;
648 } else {
649 tmp = dest;
650 tmp += count;
651 s = src;
652 s += count;
653 while (count--)
654 *--tmp = *--s;
655 }
656 return dest;
657 }
658 EXPORT_SYMBOL(memmove);
659 #endif
660
661 #ifndef __HAVE_ARCH_MEMCMP
662 /**
663 * memcmp - Compare two areas of memory
664 * @cs: One area of memory
665 * @ct: Another area of memory
666 * @count: The size of the area.
667 */
668 #undef memcmp
669 __visible int memcmp(const void *cs, const void *ct, size_t count)
670 {
671 const unsigned char *su1, *su2;
672 int res = 0;
673
674 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
675 if ((res = *su1 - *su2) != 0)
676 break;
677 return res;
678 }
679 EXPORT_SYMBOL(memcmp);
680 #endif
681
682 #ifndef __HAVE_ARCH_MEMSCAN
683 /**
684 * memscan - Find a character in an area of memory.
685 * @addr: The memory area
686 * @c: The byte to search for
687 * @size: The size of the area.
688 *
689 * returns the address of the first occurrence of @c, or 1 byte past
690 * the area if @c is not found
691 */
692 void *memscan(void *addr, int c, size_t size)
693 {
694 unsigned char *p = addr;
695
696 while (size) {
697 if (*p == c)
698 return (void *)p;
699 p++;
700 size--;
701 }
702 return (void *)p;
703 }
704 EXPORT_SYMBOL(memscan);
705 #endif
706
707 #ifndef __HAVE_ARCH_STRSTR
708 /**
709 * strstr - Find the first substring in a %NUL terminated string
710 * @s1: The string to be searched
711 * @s2: The string to search for
712 */
713 char *strstr(const char *s1, const char *s2)
714 {
715 size_t l1, l2;
716
717 l2 = strlen(s2);
718 if (!l2)
719 return (char *)s1;
720 l1 = strlen(s1);
721 while (l1 >= l2) {
722 l1--;
723 if (!memcmp(s1, s2, l2))
724 return (char *)s1;
725 s1++;
726 }
727 return NULL;
728 }
729 EXPORT_SYMBOL(strstr);
730 #endif
731
732 #ifndef __HAVE_ARCH_STRNSTR
733 /**
734 * strnstr - Find the first substring in a length-limited string
735 * @s1: The string to be searched
736 * @s2: The string to search for
737 * @len: the maximum number of characters to search
738 */
739 char *strnstr(const char *s1, const char *s2, size_t len)
740 {
741 size_t l2;
742
743 l2 = strlen(s2);
744 if (!l2)
745 return (char *)s1;
746 while (len >= l2) {
747 len--;
748 if (!memcmp(s1, s2, l2))
749 return (char *)s1;
750 s1++;
751 }
752 return NULL;
753 }
754 EXPORT_SYMBOL(strnstr);
755 #endif
756
757 #ifndef __HAVE_ARCH_MEMCHR
758 /**
759 * memchr - Find a character in an area of memory.
760 * @s: The memory area
761 * @c: The byte to search for
762 * @n: The size of the area.
763 *
764 * returns the address of the first occurrence of @c, or %NULL
765 * if @c is not found
766 */
767 void *memchr(const void *s, int c, size_t n)
768 {
769 const unsigned char *p = s;
770 while (n-- != 0) {
771 if ((unsigned char)c == *p++) {
772 return (void *)(p - 1);
773 }
774 }
775 return NULL;
776 }
777 EXPORT_SYMBOL(memchr);
778 #endif
779
780 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
781 {
782 while (bytes) {
783 if (*start != value)
784 return (void *)start;
785 start++;
786 bytes--;
787 }
788 return NULL;
789 }
790
791 /**
792 * memchr_inv - Find an unmatching character in an area of memory.
793 * @start: The memory area
794 * @c: Find a character other than c
795 * @bytes: The size of the area.
796 *
797 * returns the address of the first character other than @c, or %NULL
798 * if the whole buffer contains just @c.
799 */
800 void *memchr_inv(const void *start, int c, size_t bytes)
801 {
802 u8 value = c;
803 u64 value64;
804 unsigned int words, prefix;
805
806 if (bytes <= 16)
807 return check_bytes8(start, value, bytes);
808
809 value64 = value;
810 #if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
811 value64 *= 0x0101010101010101;
812 #elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
813 value64 *= 0x01010101;
814 value64 |= value64 << 32;
815 #else
816 value64 |= value64 << 8;
817 value64 |= value64 << 16;
818 value64 |= value64 << 32;
819 #endif
820
821 prefix = (unsigned long)start % 8;
822 if (prefix) {
823 u8 *r;
824
825 prefix = 8 - prefix;
826 r = check_bytes8(start, value, prefix);
827 if (r)
828 return r;
829 start += prefix;
830 bytes -= prefix;
831 }
832
833 words = bytes / 8;
834
835 while (words) {
836 if (*(u64 *)start != value64)
837 return check_bytes8(start, value, 8);
838 start += 8;
839 words--;
840 }
841
842 return check_bytes8(start, value, bytes % 8);
843 }
844 EXPORT_SYMBOL(memchr_inv);