Loading...
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
651int 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);