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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 * This file should be used only for "library" routines that may have
10 * alternative implementations on specific architectures (generally
11 * found in <asm-xx/string.h>), or get overloaded by FORTIFY_SOURCE.
12 * (Specifically, this file is built with __NO_FORTIFY.)
13 *
14 * Other helper functions should live in string_helpers.c.
15 */
16
17#define __NO_FORTIFY
18#include <linux/types.h>
19#include <linux/string.h>
20#include <linux/ctype.h>
21#include <linux/kernel.h>
22#include <linux/export.h>
23#include <linux/bug.h>
24#include <linux/errno.h>
25#include <linux/slab.h>
26
27#include <asm/unaligned.h>
28#include <asm/byteorder.h>
29#include <asm/word-at-a-time.h>
30#include <asm/page.h>
31
32#ifndef __HAVE_ARCH_STRNCASECMP
33/**
34 * strncasecmp - Case insensitive, length-limited string comparison
35 * @s1: One string
36 * @s2: The other string
37 * @len: the maximum number of characters to compare
38 */
39int strncasecmp(const char *s1, const char *s2, size_t len)
40{
41 /* Yes, Virginia, it had better be unsigned */
42 unsigned char c1, c2;
43
44 if (!len)
45 return 0;
46
47 do {
48 c1 = *s1++;
49 c2 = *s2++;
50 if (!c1 || !c2)
51 break;
52 if (c1 == c2)
53 continue;
54 c1 = tolower(c1);
55 c2 = tolower(c2);
56 if (c1 != c2)
57 break;
58 } while (--len);
59 return (int)c1 - (int)c2;
60}
61EXPORT_SYMBOL(strncasecmp);
62#endif
63
64#ifndef __HAVE_ARCH_STRCASECMP
65int strcasecmp(const char *s1, const char *s2)
66{
67 int c1, c2;
68
69 do {
70 c1 = tolower(*s1++);
71 c2 = tolower(*s2++);
72 } while (c1 == c2 && c1 != 0);
73 return c1 - c2;
74}
75EXPORT_SYMBOL(strcasecmp);
76#endif
77
78#ifndef __HAVE_ARCH_STRCPY
79char *strcpy(char *dest, const char *src)
80{
81 char *tmp = dest;
82
83 while ((*dest++ = *src++) != '\0')
84 /* nothing */;
85 return tmp;
86}
87EXPORT_SYMBOL(strcpy);
88#endif
89
90#ifndef __HAVE_ARCH_STRNCPY
91char *strncpy(char *dest, const char *src, size_t count)
92{
93 char *tmp = dest;
94
95 while (count) {
96 if ((*tmp = *src) != 0)
97 src++;
98 tmp++;
99 count--;
100 }
101 return dest;
102}
103EXPORT_SYMBOL(strncpy);
104#endif
105
106#ifndef __HAVE_ARCH_STRSCPY
107ssize_t 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(src+res);
144 if (has_zero(c, &data, &constants)) {
145 data = prep_zero_mask(c, data, &constants);
146 data = create_zero_mask(data);
147 *(unsigned long *)(dest+res) = c & zero_bytemask(data);
148 return res + find_zero(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}
173EXPORT_SYMBOL(strscpy);
174#endif
175
176/**
177 * stpcpy - copy a string from src to dest returning a pointer to the new end
178 * of dest, including src's %NUL-terminator. May overrun dest.
179 * @dest: pointer to end of string being copied into. Must be large enough
180 * to receive copy.
181 * @src: pointer to the beginning of string being copied from. Must not overlap
182 * dest.
183 *
184 * stpcpy differs from strcpy in a key way: the return value is a pointer
185 * to the new %NUL-terminating character in @dest. (For strcpy, the return
186 * value is a pointer to the start of @dest). This interface is considered
187 * unsafe as it doesn't perform bounds checking of the inputs. As such it's
188 * not recommended for usage. Instead, its definition is provided in case
189 * the compiler lowers other libcalls to stpcpy.
190 */
191char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
192char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
193{
194 while ((*dest++ = *src++) != '\0')
195 /* nothing */;
196 return --dest;
197}
198EXPORT_SYMBOL(stpcpy);
199
200#ifndef __HAVE_ARCH_STRCAT
201char *strcat(char *dest, const char *src)
202{
203 char *tmp = dest;
204
205 while (*dest)
206 dest++;
207 while ((*dest++ = *src++) != '\0')
208 ;
209 return tmp;
210}
211EXPORT_SYMBOL(strcat);
212#endif
213
214#ifndef __HAVE_ARCH_STRNCAT
215char *strncat(char *dest, const char *src, size_t count)
216{
217 char *tmp = dest;
218
219 if (count) {
220 while (*dest)
221 dest++;
222 while ((*dest++ = *src++) != 0) {
223 if (--count == 0) {
224 *dest = '\0';
225 break;
226 }
227 }
228 }
229 return tmp;
230}
231EXPORT_SYMBOL(strncat);
232#endif
233
234#ifndef __HAVE_ARCH_STRLCAT
235size_t strlcat(char *dest, const char *src, size_t count)
236{
237 size_t dsize = strlen(dest);
238 size_t len = strlen(src);
239 size_t res = dsize + len;
240
241 /* This would be a bug */
242 BUG_ON(dsize >= count);
243
244 dest += dsize;
245 count -= dsize;
246 if (len >= count)
247 len = count-1;
248 __builtin_memcpy(dest, src, len);
249 dest[len] = 0;
250 return res;
251}
252EXPORT_SYMBOL(strlcat);
253#endif
254
255#ifndef __HAVE_ARCH_STRCMP
256/**
257 * strcmp - Compare two strings
258 * @cs: One string
259 * @ct: Another string
260 */
261int strcmp(const char *cs, const char *ct)
262{
263 unsigned char c1, c2;
264
265 while (1) {
266 c1 = *cs++;
267 c2 = *ct++;
268 if (c1 != c2)
269 return c1 < c2 ? -1 : 1;
270 if (!c1)
271 break;
272 }
273 return 0;
274}
275EXPORT_SYMBOL(strcmp);
276#endif
277
278#ifndef __HAVE_ARCH_STRNCMP
279/**
280 * strncmp - Compare two length-limited strings
281 * @cs: One string
282 * @ct: Another string
283 * @count: The maximum number of bytes to compare
284 */
285int strncmp(const char *cs, const char *ct, size_t count)
286{
287 unsigned char c1, c2;
288
289 while (count) {
290 c1 = *cs++;
291 c2 = *ct++;
292 if (c1 != c2)
293 return c1 < c2 ? -1 : 1;
294 if (!c1)
295 break;
296 count--;
297 }
298 return 0;
299}
300EXPORT_SYMBOL(strncmp);
301#endif
302
303#ifndef __HAVE_ARCH_STRCHR
304/**
305 * strchr - Find the first occurrence of a character in a string
306 * @s: The string to be searched
307 * @c: The character to search for
308 *
309 * Note that the %NUL-terminator is considered part of the string, and can
310 * be searched for.
311 */
312char *strchr(const char *s, int c)
313{
314 for (; *s != (char)c; ++s)
315 if (*s == '\0')
316 return NULL;
317 return (char *)s;
318}
319EXPORT_SYMBOL(strchr);
320#endif
321
322#ifndef __HAVE_ARCH_STRCHRNUL
323/**
324 * strchrnul - Find and return a character in a string, or end of string
325 * @s: The string to be searched
326 * @c: The character to search for
327 *
328 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
329 * return a pointer to the null byte at the end of s.
330 */
331char *strchrnul(const char *s, int c)
332{
333 while (*s && *s != (char)c)
334 s++;
335 return (char *)s;
336}
337EXPORT_SYMBOL(strchrnul);
338#endif
339
340/**
341 * strnchrnul - Find and return a character in a length limited string,
342 * or end of 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 * Returns pointer to the first occurrence of 'c' in s. If c is not found,
348 * then return a pointer to the last character of the string.
349 */
350char *strnchrnul(const char *s, size_t count, int c)
351{
352 while (count-- && *s && *s != (char)c)
353 s++;
354 return (char *)s;
355}
356
357#ifndef __HAVE_ARCH_STRRCHR
358/**
359 * strrchr - Find the last occurrence of a character in a string
360 * @s: The string to be searched
361 * @c: The character to search for
362 */
363char *strrchr(const char *s, int c)
364{
365 const char *last = NULL;
366 do {
367 if (*s == (char)c)
368 last = s;
369 } while (*s++);
370 return (char *)last;
371}
372EXPORT_SYMBOL(strrchr);
373#endif
374
375#ifndef __HAVE_ARCH_STRNCHR
376/**
377 * strnchr - Find a character in a length limited string
378 * @s: The string to be searched
379 * @count: The number of characters to be searched
380 * @c: The character to search for
381 *
382 * Note that the %NUL-terminator is considered part of the string, and can
383 * be searched for.
384 */
385char *strnchr(const char *s, size_t count, int c)
386{
387 while (count--) {
388 if (*s == (char)c)
389 return (char *)s;
390 if (*s++ == '\0')
391 break;
392 }
393 return NULL;
394}
395EXPORT_SYMBOL(strnchr);
396#endif
397
398#ifndef __HAVE_ARCH_STRLEN
399size_t strlen(const char *s)
400{
401 const char *sc;
402
403 for (sc = s; *sc != '\0'; ++sc)
404 /* nothing */;
405 return sc - s;
406}
407EXPORT_SYMBOL(strlen);
408#endif
409
410#ifndef __HAVE_ARCH_STRNLEN
411size_t strnlen(const char *s, size_t count)
412{
413 const char *sc;
414
415 for (sc = s; count-- && *sc != '\0'; ++sc)
416 /* nothing */;
417 return sc - s;
418}
419EXPORT_SYMBOL(strnlen);
420#endif
421
422#ifndef __HAVE_ARCH_STRSPN
423/**
424 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
425 * @s: The string to be searched
426 * @accept: The string to search for
427 */
428size_t strspn(const char *s, const char *accept)
429{
430 const char *p;
431
432 for (p = s; *p != '\0'; ++p) {
433 if (!strchr(accept, *p))
434 break;
435 }
436 return p - s;
437}
438EXPORT_SYMBOL(strspn);
439#endif
440
441#ifndef __HAVE_ARCH_STRCSPN
442/**
443 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
444 * @s: The string to be searched
445 * @reject: The string to avoid
446 */
447size_t strcspn(const char *s, const char *reject)
448{
449 const char *p;
450
451 for (p = s; *p != '\0'; ++p) {
452 if (strchr(reject, *p))
453 break;
454 }
455 return p - s;
456}
457EXPORT_SYMBOL(strcspn);
458#endif
459
460#ifndef __HAVE_ARCH_STRPBRK
461/**
462 * strpbrk - Find the first occurrence of a set of characters
463 * @cs: The string to be searched
464 * @ct: The characters to search for
465 */
466char *strpbrk(const char *cs, const char *ct)
467{
468 const char *sc;
469
470 for (sc = cs; *sc != '\0'; ++sc) {
471 if (strchr(ct, *sc))
472 return (char *)sc;
473 }
474 return NULL;
475}
476EXPORT_SYMBOL(strpbrk);
477#endif
478
479#ifndef __HAVE_ARCH_STRSEP
480/**
481 * strsep - Split a string into tokens
482 * @s: The string to be searched
483 * @ct: The characters to search for
484 *
485 * strsep() updates @s to point after the token, ready for the next call.
486 *
487 * It returns empty tokens, too, behaving exactly like the libc function
488 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
489 * Same semantics, slimmer shape. ;)
490 */
491char *strsep(char **s, const char *ct)
492{
493 char *sbegin = *s;
494 char *end;
495
496 if (sbegin == NULL)
497 return NULL;
498
499 end = strpbrk(sbegin, ct);
500 if (end)
501 *end++ = '\0';
502 *s = end;
503 return sbegin;
504}
505EXPORT_SYMBOL(strsep);
506#endif
507
508#ifndef __HAVE_ARCH_MEMSET
509/**
510 * memset - Fill a region of memory with the given value
511 * @s: Pointer to the start of the area.
512 * @c: The byte to fill the area with
513 * @count: The size of the area.
514 *
515 * Do not use memset() to access IO space, use memset_io() instead.
516 */
517void *memset(void *s, int c, size_t count)
518{
519 char *xs = s;
520
521 while (count--)
522 *xs++ = c;
523 return s;
524}
525EXPORT_SYMBOL(memset);
526#endif
527
528#ifndef __HAVE_ARCH_MEMSET16
529/**
530 * memset16() - Fill a memory area with a uint16_t
531 * @s: Pointer to the start of the area.
532 * @v: The value to fill the area with
533 * @count: The number of values to store
534 *
535 * Differs from memset() in that it fills with a uint16_t instead
536 * of a byte. Remember that @count is the number of uint16_ts to
537 * store, not the number of bytes.
538 */
539void *memset16(uint16_t *s, uint16_t v, size_t count)
540{
541 uint16_t *xs = s;
542
543 while (count--)
544 *xs++ = v;
545 return s;
546}
547EXPORT_SYMBOL(memset16);
548#endif
549
550#ifndef __HAVE_ARCH_MEMSET32
551/**
552 * memset32() - Fill a memory area with a uint32_t
553 * @s: Pointer to the start of the area.
554 * @v: The value to fill the area with
555 * @count: The number of values to store
556 *
557 * Differs from memset() in that it fills with a uint32_t instead
558 * of a byte. Remember that @count is the number of uint32_ts to
559 * store, not the number of bytes.
560 */
561void *memset32(uint32_t *s, uint32_t v, size_t count)
562{
563 uint32_t *xs = s;
564
565 while (count--)
566 *xs++ = v;
567 return s;
568}
569EXPORT_SYMBOL(memset32);
570#endif
571
572#ifndef __HAVE_ARCH_MEMSET64
573/**
574 * memset64() - Fill a memory area with a uint64_t
575 * @s: Pointer to the start of the area.
576 * @v: The value to fill the area with
577 * @count: The number of values to store
578 *
579 * Differs from memset() in that it fills with a uint64_t instead
580 * of a byte. Remember that @count is the number of uint64_ts to
581 * store, not the number of bytes.
582 */
583void *memset64(uint64_t *s, uint64_t v, size_t count)
584{
585 uint64_t *xs = s;
586
587 while (count--)
588 *xs++ = v;
589 return s;
590}
591EXPORT_SYMBOL(memset64);
592#endif
593
594#ifndef __HAVE_ARCH_MEMCPY
595/**
596 * memcpy - Copy one area of memory to another
597 * @dest: Where to copy to
598 * @src: Where to copy from
599 * @count: The size of the area.
600 *
601 * You should not use this function to access IO space, use memcpy_toio()
602 * or memcpy_fromio() instead.
603 */
604void *memcpy(void *dest, const void *src, size_t count)
605{
606 char *tmp = dest;
607 const char *s = src;
608
609 while (count--)
610 *tmp++ = *s++;
611 return dest;
612}
613EXPORT_SYMBOL(memcpy);
614#endif
615
616#ifndef __HAVE_ARCH_MEMMOVE
617/**
618 * memmove - Copy one area of memory to another
619 * @dest: Where to copy to
620 * @src: Where to copy from
621 * @count: The size of the area.
622 *
623 * Unlike memcpy(), memmove() copes with overlapping areas.
624 */
625void *memmove(void *dest, const void *src, size_t count)
626{
627 char *tmp;
628 const char *s;
629
630 if (dest <= src) {
631 tmp = dest;
632 s = src;
633 while (count--)
634 *tmp++ = *s++;
635 } else {
636 tmp = dest;
637 tmp += count;
638 s = src;
639 s += count;
640 while (count--)
641 *--tmp = *--s;
642 }
643 return dest;
644}
645EXPORT_SYMBOL(memmove);
646#endif
647
648#ifndef __HAVE_ARCH_MEMCMP
649/**
650 * memcmp - Compare two areas of memory
651 * @cs: One area of memory
652 * @ct: Another area of memory
653 * @count: The size of the area.
654 */
655#undef memcmp
656__visible int memcmp(const void *cs, const void *ct, size_t count)
657{
658 const unsigned char *su1, *su2;
659 int res = 0;
660
661#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
662 if (count >= sizeof(unsigned long)) {
663 const unsigned long *u1 = cs;
664 const unsigned long *u2 = ct;
665 do {
666 if (get_unaligned(u1) != get_unaligned(u2))
667 break;
668 u1++;
669 u2++;
670 count -= sizeof(unsigned long);
671 } while (count >= sizeof(unsigned long));
672 cs = u1;
673 ct = u2;
674 }
675#endif
676 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
677 if ((res = *su1 - *su2) != 0)
678 break;
679 return res;
680}
681EXPORT_SYMBOL(memcmp);
682#endif
683
684#ifndef __HAVE_ARCH_BCMP
685/**
686 * bcmp - returns 0 if and only if the buffers have identical contents.
687 * @a: pointer to first buffer.
688 * @b: pointer to second buffer.
689 * @len: size of buffers.
690 *
691 * The sign or magnitude of a non-zero return value has no particular
692 * meaning, and architectures may implement their own more efficient bcmp(). So
693 * while this particular implementation is a simple (tail) call to memcmp, do
694 * not rely on anything but whether the return value is zero or non-zero.
695 */
696int bcmp(const void *a, const void *b, size_t len)
697{
698 return memcmp(a, b, len);
699}
700EXPORT_SYMBOL(bcmp);
701#endif
702
703#ifndef __HAVE_ARCH_MEMSCAN
704/**
705 * memscan - Find a character in an area of memory.
706 * @addr: The memory area
707 * @c: The byte to search for
708 * @size: The size of the area.
709 *
710 * returns the address of the first occurrence of @c, or 1 byte past
711 * the area if @c is not found
712 */
713void *memscan(void *addr, int c, size_t size)
714{
715 unsigned char *p = addr;
716
717 while (size) {
718 if (*p == (unsigned char)c)
719 return (void *)p;
720 p++;
721 size--;
722 }
723 return (void *)p;
724}
725EXPORT_SYMBOL(memscan);
726#endif
727
728#ifndef __HAVE_ARCH_STRSTR
729/**
730 * strstr - Find the first substring in a %NUL terminated string
731 * @s1: The string to be searched
732 * @s2: The string to search for
733 */
734char *strstr(const char *s1, const char *s2)
735{
736 size_t l1, l2;
737
738 l2 = strlen(s2);
739 if (!l2)
740 return (char *)s1;
741 l1 = strlen(s1);
742 while (l1 >= l2) {
743 l1--;
744 if (!memcmp(s1, s2, l2))
745 return (char *)s1;
746 s1++;
747 }
748 return NULL;
749}
750EXPORT_SYMBOL(strstr);
751#endif
752
753#ifndef __HAVE_ARCH_STRNSTR
754/**
755 * strnstr - Find the first substring in a length-limited string
756 * @s1: The string to be searched
757 * @s2: The string to search for
758 * @len: the maximum number of characters to search
759 */
760char *strnstr(const char *s1, const char *s2, size_t len)
761{
762 size_t l2;
763
764 l2 = strlen(s2);
765 if (!l2)
766 return (char *)s1;
767 while (len >= l2) {
768 len--;
769 if (!memcmp(s1, s2, l2))
770 return (char *)s1;
771 s1++;
772 }
773 return NULL;
774}
775EXPORT_SYMBOL(strnstr);
776#endif
777
778#ifndef __HAVE_ARCH_MEMCHR
779/**
780 * memchr - Find a character in an area of memory.
781 * @s: The memory area
782 * @c: The byte to search for
783 * @n: The size of the area.
784 *
785 * returns the address of the first occurrence of @c, or %NULL
786 * if @c is not found
787 */
788void *memchr(const void *s, int c, size_t n)
789{
790 const unsigned char *p = s;
791 while (n-- != 0) {
792 if ((unsigned char)c == *p++) {
793 return (void *)(p - 1);
794 }
795 }
796 return NULL;
797}
798EXPORT_SYMBOL(memchr);
799#endif
800
801static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
802{
803 while (bytes) {
804 if (*start != value)
805 return (void *)start;
806 start++;
807 bytes--;
808 }
809 return NULL;
810}
811
812/**
813 * memchr_inv - Find an unmatching character in an area of memory.
814 * @start: The memory area
815 * @c: Find a character other than c
816 * @bytes: The size of the area.
817 *
818 * returns the address of the first character other than @c, or %NULL
819 * if the whole buffer contains just @c.
820 */
821void *memchr_inv(const void *start, int c, size_t bytes)
822{
823 u8 value = c;
824 u64 value64;
825 unsigned int words, prefix;
826
827 if (bytes <= 16)
828 return check_bytes8(start, value, bytes);
829
830 value64 = value;
831#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
832 value64 *= 0x0101010101010101ULL;
833#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
834 value64 *= 0x01010101;
835 value64 |= value64 << 32;
836#else
837 value64 |= value64 << 8;
838 value64 |= value64 << 16;
839 value64 |= value64 << 32;
840#endif
841
842 prefix = (unsigned long)start % 8;
843 if (prefix) {
844 u8 *r;
845
846 prefix = 8 - prefix;
847 r = check_bytes8(start, value, prefix);
848 if (r)
849 return r;
850 start += prefix;
851 bytes -= prefix;
852 }
853
854 words = bytes / 8;
855
856 while (words) {
857 if (*(u64 *)start != value64)
858 return check_bytes8(start, value, 8);
859 start += 8;
860 words--;
861 }
862
863 return check_bytes8(start, value, bytes % 8);
864}
865EXPORT_SYMBOL(memchr_inv);
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 */
37int 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}
59EXPORT_SYMBOL(strnicmp);
60#endif
61
62#ifndef __HAVE_ARCH_STRCASECMP
63int 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}
73EXPORT_SYMBOL(strcasecmp);
74#endif
75
76#ifndef __HAVE_ARCH_STRNCASECMP
77int 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}
87EXPORT_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
97char *strcpy(char *dest, const char *src)
98{
99 char *tmp = dest;
100
101 while ((*dest++ = *src++) != '\0')
102 /* nothing */;
103 return tmp;
104}
105EXPORT_SYMBOL(strcpy);
106#endif
107
108#ifndef __HAVE_ARCH_STRNCPY
109/**
110 * strncpy - Copy a length-limited, %NUL-terminated 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 */
122char *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}
134EXPORT_SYMBOL(strncpy);
135#endif
136
137#ifndef __HAVE_ARCH_STRLCPY
138/**
139 * strlcpy - Copy a %NUL terminated 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 */
149size_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}
160EXPORT_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
170char *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}
180EXPORT_SYMBOL(strcat);
181#endif
182
183#ifndef __HAVE_ARCH_STRNCAT
184/**
185 * strncat - Append a length-limited, %NUL-terminated 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 */
193char *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}
209EXPORT_SYMBOL(strncat);
210#endif
211
212#ifndef __HAVE_ARCH_STRLCAT
213/**
214 * strlcat - Append a length-limited, %NUL-terminated 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 */
219size_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}
236EXPORT_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
246int 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}
260EXPORT_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 */
270int 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}
285EXPORT_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 */
294char *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}
301EXPORT_SYMBOL(strchr);
302#endif
303
304#ifndef __HAVE_ARCH_STRRCHR
305/**
306 * strrchr - Find the last occurrence of a character in a string
307 * @s: The string to be searched
308 * @c: The character to search for
309 */
310char *strrchr(const char *s, int c)
311{
312 const char *p = s + strlen(s);
313 do {
314 if (*p == (char)c)
315 return (char *)p;
316 } while (--p >= s);
317 return NULL;
318}
319EXPORT_SYMBOL(strrchr);
320#endif
321
322#ifndef __HAVE_ARCH_STRNCHR
323/**
324 * strnchr - Find a character in a length limited string
325 * @s: The string to be searched
326 * @count: The number of characters to be searched
327 * @c: The character to search for
328 */
329char *strnchr(const char *s, size_t count, int c)
330{
331 for (; count-- && *s != '\0'; ++s)
332 if (*s == (char)c)
333 return (char *)s;
334 return NULL;
335}
336EXPORT_SYMBOL(strnchr);
337#endif
338
339/**
340 * skip_spaces - Removes leading whitespace from @str.
341 * @str: The string to be stripped.
342 *
343 * Returns a pointer to the first non-whitespace character in @str.
344 */
345char *skip_spaces(const char *str)
346{
347 while (isspace(*str))
348 ++str;
349 return (char *)str;
350}
351EXPORT_SYMBOL(skip_spaces);
352
353/**
354 * strim - Removes leading and trailing whitespace from @s.
355 * @s: The string to be stripped.
356 *
357 * Note that the first trailing whitespace is replaced with a %NUL-terminator
358 * in the given string @s. Returns a pointer to the first non-whitespace
359 * character in @s.
360 */
361char *strim(char *s)
362{
363 size_t size;
364 char *end;
365
366 size = strlen(s);
367 if (!size)
368 return s;
369
370 end = s + size - 1;
371 while (end >= s && isspace(*end))
372 end--;
373 *(end + 1) = '\0';
374
375 return skip_spaces(s);
376}
377EXPORT_SYMBOL(strim);
378
379#ifndef __HAVE_ARCH_STRLEN
380/**
381 * strlen - Find the length of a string
382 * @s: The string to be sized
383 */
384size_t strlen(const char *s)
385{
386 const char *sc;
387
388 for (sc = s; *sc != '\0'; ++sc)
389 /* nothing */;
390 return sc - s;
391}
392EXPORT_SYMBOL(strlen);
393#endif
394
395#ifndef __HAVE_ARCH_STRNLEN
396/**
397 * strnlen - Find the length of a length-limited string
398 * @s: The string to be sized
399 * @count: The maximum number of bytes to search
400 */
401size_t strnlen(const char *s, size_t count)
402{
403 const char *sc;
404
405 for (sc = s; count-- && *sc != '\0'; ++sc)
406 /* nothing */;
407 return sc - s;
408}
409EXPORT_SYMBOL(strnlen);
410#endif
411
412#ifndef __HAVE_ARCH_STRSPN
413/**
414 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
415 * @s: The string to be searched
416 * @accept: The string to search for
417 */
418size_t strspn(const char *s, const char *accept)
419{
420 const char *p;
421 const char *a;
422 size_t count = 0;
423
424 for (p = s; *p != '\0'; ++p) {
425 for (a = accept; *a != '\0'; ++a) {
426 if (*p == *a)
427 break;
428 }
429 if (*a == '\0')
430 return count;
431 ++count;
432 }
433 return count;
434}
435
436EXPORT_SYMBOL(strspn);
437#endif
438
439#ifndef __HAVE_ARCH_STRCSPN
440/**
441 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
442 * @s: The string to be searched
443 * @reject: The string to avoid
444 */
445size_t strcspn(const char *s, const char *reject)
446{
447 const char *p;
448 const char *r;
449 size_t count = 0;
450
451 for (p = s; *p != '\0'; ++p) {
452 for (r = reject; *r != '\0'; ++r) {
453 if (*p == *r)
454 return count;
455 }
456 ++count;
457 }
458 return count;
459}
460EXPORT_SYMBOL(strcspn);
461#endif
462
463#ifndef __HAVE_ARCH_STRPBRK
464/**
465 * strpbrk - Find the first occurrence of a set of characters
466 * @cs: The string to be searched
467 * @ct: The characters to search for
468 */
469char *strpbrk(const char *cs, const char *ct)
470{
471 const char *sc1, *sc2;
472
473 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
474 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
475 if (*sc1 == *sc2)
476 return (char *)sc1;
477 }
478 }
479 return NULL;
480}
481EXPORT_SYMBOL(strpbrk);
482#endif
483
484#ifndef __HAVE_ARCH_STRSEP
485/**
486 * strsep - Split a string into tokens
487 * @s: The string to be searched
488 * @ct: The characters to search for
489 *
490 * strsep() updates @s to point after the token, ready for the next call.
491 *
492 * It returns empty tokens, too, behaving exactly like the libc function
493 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
494 * Same semantics, slimmer shape. ;)
495 */
496char *strsep(char **s, const char *ct)
497{
498 char *sbegin = *s;
499 char *end;
500
501 if (sbegin == NULL)
502 return NULL;
503
504 end = strpbrk(sbegin, ct);
505 if (end)
506 *end++ = '\0';
507 *s = end;
508 return sbegin;
509}
510EXPORT_SYMBOL(strsep);
511#endif
512
513/**
514 * sysfs_streq - return true if strings are equal, modulo trailing newline
515 * @s1: one string
516 * @s2: another string
517 *
518 * This routine returns true iff two strings are equal, treating both
519 * NUL and newline-then-NUL as equivalent string terminations. It's
520 * geared for use with sysfs input strings, which generally terminate
521 * with newlines but are compared against values without newlines.
522 */
523bool sysfs_streq(const char *s1, const char *s2)
524{
525 while (*s1 && *s1 == *s2) {
526 s1++;
527 s2++;
528 }
529
530 if (*s1 == *s2)
531 return true;
532 if (!*s1 && *s2 == '\n' && !s2[1])
533 return true;
534 if (*s1 == '\n' && !s1[1] && !*s2)
535 return true;
536 return false;
537}
538EXPORT_SYMBOL(sysfs_streq);
539
540/**
541 * strtobool - convert common user inputs into boolean values
542 * @s: input string
543 * @res: result
544 *
545 * This routine returns 0 iff the first character is one of 'Yy1Nn0'.
546 * Otherwise it will return -EINVAL. Value pointed to by res is
547 * updated upon finding a match.
548 */
549int strtobool(const char *s, bool *res)
550{
551 switch (s[0]) {
552 case 'y':
553 case 'Y':
554 case '1':
555 *res = true;
556 break;
557 case 'n':
558 case 'N':
559 case '0':
560 *res = false;
561 break;
562 default:
563 return -EINVAL;
564 }
565 return 0;
566}
567EXPORT_SYMBOL(strtobool);
568
569#ifndef __HAVE_ARCH_MEMSET
570/**
571 * memset - Fill a region of memory with the given value
572 * @s: Pointer to the start of the area.
573 * @c: The byte to fill the area with
574 * @count: The size of the area.
575 *
576 * Do not use memset() to access IO space, use memset_io() instead.
577 */
578void *memset(void *s, int c, size_t count)
579{
580 char *xs = s;
581
582 while (count--)
583 *xs++ = c;
584 return s;
585}
586EXPORT_SYMBOL(memset);
587#endif
588
589#ifndef __HAVE_ARCH_MEMCPY
590/**
591 * memcpy - Copy one area of memory to another
592 * @dest: Where to copy to
593 * @src: Where to copy from
594 * @count: The size of the area.
595 *
596 * You should not use this function to access IO space, use memcpy_toio()
597 * or memcpy_fromio() instead.
598 */
599void *memcpy(void *dest, const void *src, size_t count)
600{
601 char *tmp = dest;
602 const char *s = src;
603
604 while (count--)
605 *tmp++ = *s++;
606 return dest;
607}
608EXPORT_SYMBOL(memcpy);
609#endif
610
611#ifndef __HAVE_ARCH_MEMMOVE
612/**
613 * memmove - 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 * Unlike memcpy(), memmove() copes with overlapping areas.
619 */
620void *memmove(void *dest, const void *src, size_t count)
621{
622 char *tmp;
623 const char *s;
624
625 if (dest <= src) {
626 tmp = dest;
627 s = src;
628 while (count--)
629 *tmp++ = *s++;
630 } else {
631 tmp = dest;
632 tmp += count;
633 s = src;
634 s += count;
635 while (count--)
636 *--tmp = *--s;
637 }
638 return dest;
639}
640EXPORT_SYMBOL(memmove);
641#endif
642
643#ifndef __HAVE_ARCH_MEMCMP
644/**
645 * memcmp - Compare two areas of memory
646 * @cs: One area of memory
647 * @ct: Another area of memory
648 * @count: The size of the area.
649 */
650#undef memcmp
651__visible int memcmp(const void *cs, const void *ct, size_t count)
652{
653 const unsigned char *su1, *su2;
654 int res = 0;
655
656 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
657 if ((res = *su1 - *su2) != 0)
658 break;
659 return res;
660}
661EXPORT_SYMBOL(memcmp);
662#endif
663
664#ifndef __HAVE_ARCH_MEMSCAN
665/**
666 * memscan - Find a character in an area of memory.
667 * @addr: The memory area
668 * @c: The byte to search for
669 * @size: The size of the area.
670 *
671 * returns the address of the first occurrence of @c, or 1 byte past
672 * the area if @c is not found
673 */
674void *memscan(void *addr, int c, size_t size)
675{
676 unsigned char *p = addr;
677
678 while (size) {
679 if (*p == c)
680 return (void *)p;
681 p++;
682 size--;
683 }
684 return (void *)p;
685}
686EXPORT_SYMBOL(memscan);
687#endif
688
689#ifndef __HAVE_ARCH_STRSTR
690/**
691 * strstr - Find the first substring in a %NUL terminated string
692 * @s1: The string to be searched
693 * @s2: The string to search for
694 */
695char *strstr(const char *s1, const char *s2)
696{
697 size_t l1, l2;
698
699 l2 = strlen(s2);
700 if (!l2)
701 return (char *)s1;
702 l1 = strlen(s1);
703 while (l1 >= l2) {
704 l1--;
705 if (!memcmp(s1, s2, l2))
706 return (char *)s1;
707 s1++;
708 }
709 return NULL;
710}
711EXPORT_SYMBOL(strstr);
712#endif
713
714#ifndef __HAVE_ARCH_STRNSTR
715/**
716 * strnstr - Find the first substring in a length-limited string
717 * @s1: The string to be searched
718 * @s2: The string to search for
719 * @len: the maximum number of characters to search
720 */
721char *strnstr(const char *s1, const char *s2, size_t len)
722{
723 size_t l2;
724
725 l2 = strlen(s2);
726 if (!l2)
727 return (char *)s1;
728 while (len >= l2) {
729 len--;
730 if (!memcmp(s1, s2, l2))
731 return (char *)s1;
732 s1++;
733 }
734 return NULL;
735}
736EXPORT_SYMBOL(strnstr);
737#endif
738
739#ifndef __HAVE_ARCH_MEMCHR
740/**
741 * memchr - Find a character in an area of memory.
742 * @s: The memory area
743 * @c: The byte to search for
744 * @n: The size of the area.
745 *
746 * returns the address of the first occurrence of @c, or %NULL
747 * if @c is not found
748 */
749void *memchr(const void *s, int c, size_t n)
750{
751 const unsigned char *p = s;
752 while (n-- != 0) {
753 if ((unsigned char)c == *p++) {
754 return (void *)(p - 1);
755 }
756 }
757 return NULL;
758}
759EXPORT_SYMBOL(memchr);
760#endif
761
762static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
763{
764 while (bytes) {
765 if (*start != value)
766 return (void *)start;
767 start++;
768 bytes--;
769 }
770 return NULL;
771}
772
773/**
774 * memchr_inv - Find an unmatching character in an area of memory.
775 * @start: The memory area
776 * @c: Find a character other than c
777 * @bytes: The size of the area.
778 *
779 * returns the address of the first character other than @c, or %NULL
780 * if the whole buffer contains just @c.
781 */
782void *memchr_inv(const void *start, int c, size_t bytes)
783{
784 u8 value = c;
785 u64 value64;
786 unsigned int words, prefix;
787
788 if (bytes <= 16)
789 return check_bytes8(start, value, bytes);
790
791 value64 = value;
792#if defined(ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
793 value64 *= 0x0101010101010101;
794#elif defined(ARCH_HAS_FAST_MULTIPLIER)
795 value64 *= 0x01010101;
796 value64 |= value64 << 32;
797#else
798 value64 |= value64 << 8;
799 value64 |= value64 << 16;
800 value64 |= value64 << 32;
801#endif
802
803 prefix = (unsigned long)start % 8;
804 if (prefix) {
805 u8 *r;
806
807 prefix = 8 - prefix;
808 r = check_bytes8(start, value, prefix);
809 if (r)
810 return r;
811 start += prefix;
812 bytes -= prefix;
813 }
814
815 words = bytes / 8;
816
817 while (words) {
818 if (*(u64 *)start != value64)
819 return check_bytes8(start, value, 8);
820 start += 8;
821 words--;
822 }
823
824 return check_bytes8(start, value, bytes % 8);
825}
826EXPORT_SYMBOL(memchr_inv);