projects/linux·blob v3.19 · refs

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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 <[email protected]>
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 <[email protected]>,
18 * Matthew Hawkins <[email protected]>
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_STRNCASECMP
31/**
32 * strncasecmp - 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 strncasecmp(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(strncasecmp);
60#endif
61#ifndef __HAVE_ARCH_STRNICMP
62#undef strnicmp
63int strnicmp(const char *s1, const char *s2, size_t len)
64{
65 return strncasecmp(s1, s2, len);
66}
67EXPORT_SYMBOL(strnicmp);
68#endif
69
70#ifndef __HAVE_ARCH_STRCASECMP
71int strcasecmp(const char *s1, const char *s2)
72{
73 int c1, c2;
74
75 do {
76 c1 = tolower(*s1++);
77 c2 = tolower(*s2++);
78 } while (c1 == c2 && c1 != 0);
79 return c1 - c2;
80}
81EXPORT_SYMBOL(strcasecmp);
82#endif
83
84#ifndef __HAVE_ARCH_STRCPY
85/**
86 * strcpy - Copy a %NUL terminated string
87 * @dest: Where to copy the string to
88 * @src: Where to copy the string from
89 */
90#undef strcpy
91char *strcpy(char *dest, const char *src)
92{
93 char *tmp = dest;
94
95 while ((*dest++ = *src++) != '\0')
96 /* nothing */;
97 return tmp;
98}
99EXPORT_SYMBOL(strcpy);
100#endif
101
102#ifndef __HAVE_ARCH_STRNCPY
103/**
104 * strncpy - Copy a length-limited, C-string
105 * @dest: Where to copy the string to
106 * @src: Where to copy the string from
107 * @count: The maximum number of bytes to copy
108 *
109 * The result is not %NUL-terminated if the source exceeds
110 * @count bytes.
111 *
112 * In the case where the length of @src is less than that of
113 * count, the remainder of @dest will be padded with %NUL.
114 *
115 */
116char *strncpy(char *dest, const char *src, size_t count)
117{
118 char *tmp = dest;
119
120 while (count) {
121 if ((*tmp = *src) != 0)
122 src++;
123 tmp++;
124 count--;
125 }
126 return dest;
127}
128EXPORT_SYMBOL(strncpy);
129#endif
130
131#ifndef __HAVE_ARCH_STRLCPY
132/**
133 * strlcpy - Copy a C-string into a sized buffer
134 * @dest: Where to copy the string to
135 * @src: Where to copy the string from
136 * @size: size of destination buffer
137 *
138 * Compatible with *BSD: the result is always a valid
139 * NUL-terminated string that fits in the buffer (unless,
140 * of course, the buffer size is zero). It does not pad
141 * out the result like strncpy() does.
142 */
143size_t strlcpy(char *dest, const char *src, size_t size)
144{
145 size_t ret = strlen(src);
146
147 if (size) {
148 size_t len = (ret >= size) ? size - 1 : ret;
149 memcpy(dest, src, len);
150 dest[len] = '\0';
151 }
152 return ret;
153}
154EXPORT_SYMBOL(strlcpy);
155#endif
156
157#ifndef __HAVE_ARCH_STRCAT
158/**
159 * strcat - Append one %NUL-terminated string to another
160 * @dest: The string to be appended to
161 * @src: The string to append to it
162 */
163#undef strcat
164char *strcat(char *dest, const char *src)
165{
166 char *tmp = dest;
167
168 while (*dest)
169 dest++;
170 while ((*dest++ = *src++) != '\0')
171 ;
172 return tmp;
173}
174EXPORT_SYMBOL(strcat);
175#endif
176
177#ifndef __HAVE_ARCH_STRNCAT
178/**
179 * strncat - Append a length-limited, C-string to another
180 * @dest: The string to be appended to
181 * @src: The string to append to it
182 * @count: The maximum numbers of bytes to copy
183 *
184 * Note that in contrast to strncpy(), strncat() ensures the result is
185 * terminated.
186 */
187char *strncat(char *dest, const char *src, size_t count)
188{
189 char *tmp = dest;
190
191 if (count) {
192 while (*dest)
193 dest++;
194 while ((*dest++ = *src++) != 0) {
195 if (--count == 0) {
196 *dest = '\0';
197 break;
198 }
199 }
200 }
201 return tmp;
202}
203EXPORT_SYMBOL(strncat);
204#endif
205
206#ifndef __HAVE_ARCH_STRLCAT
207/**
208 * strlcat - Append a length-limited, C-string to another
209 * @dest: The string to be appended to
210 * @src: The string to append to it
211 * @count: The size of the destination buffer.
212 */
213size_t strlcat(char *dest, const char *src, size_t count)
214{
215 size_t dsize = strlen(dest);
216 size_t len = strlen(src);
217 size_t res = dsize + len;
218
219 /* This would be a bug */
220 BUG_ON(dsize >= count);
221
222 dest += dsize;
223 count -= dsize;
224 if (len >= count)
225 len = count-1;
226 memcpy(dest, src, len);
227 dest[len] = 0;
228 return res;
229}
230EXPORT_SYMBOL(strlcat);
231#endif
232
233#ifndef __HAVE_ARCH_STRCMP
234/**
235 * strcmp - Compare two strings
236 * @cs: One string
237 * @ct: Another string
238 */
239#undef strcmp
240int strcmp(const char *cs, const char *ct)
241{
242 unsigned char c1, c2;
243
244 while (1) {
245 c1 = *cs++;
246 c2 = *ct++;
247 if (c1 != c2)
248 return c1 < c2 ? -1 : 1;
249 if (!c1)
250 break;
251 }
252 return 0;
253}
254EXPORT_SYMBOL(strcmp);
255#endif
256
257#ifndef __HAVE_ARCH_STRNCMP
258/**
259 * strncmp - Compare two length-limited strings
260 * @cs: One string
261 * @ct: Another string
262 * @count: The maximum number of bytes to compare
263 */
264int strncmp(const char *cs, const char *ct, size_t count)
265{
266 unsigned char c1, c2;
267
268 while (count) {
269 c1 = *cs++;
270 c2 = *ct++;
271 if (c1 != c2)
272 return c1 < c2 ? -1 : 1;
273 if (!c1)
274 break;
275 count--;
276 }
277 return 0;
278}
279EXPORT_SYMBOL(strncmp);
280#endif
281
282#ifndef __HAVE_ARCH_STRCHR
283/**
284 * strchr - Find the first occurrence of a character in a string
285 * @s: The string to be searched
286 * @c: The character to search for
287 */
288char *strchr(const char *s, int c)
289{
290 for (; *s != (char)c; ++s)
291 if (*s == '\0')
292 return NULL;
293 return (char *)s;
294}
295EXPORT_SYMBOL(strchr);
296#endif
297
298#ifndef __HAVE_ARCH_STRCHRNUL
299/**
300 * strchrnul - Find and return a character in a string, or end of string
301 * @s: The string to be searched
302 * @c: The character to search for
303 *
304 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
305 * return a pointer to the null byte at the end of s.
306 */
307char *strchrnul(const char *s, int c)
308{
309 while (*s && *s != (char)c)
310 s++;
311 return (char *)s;
312}
313EXPORT_SYMBOL(strchrnul);
314#endif
315
316#ifndef __HAVE_ARCH_STRRCHR
317/**
318 * strrchr - Find the last occurrence of a character in a string
319 * @s: The string to be searched
320 * @c: The character to search for
321 */
322char *strrchr(const char *s, int c)
323{
324 const char *p = s + strlen(s);
325 do {
326 if (*p == (char)c)
327 return (char *)p;
328 } while (--p >= s);
329 return NULL;
330}
331EXPORT_SYMBOL(strrchr);
332#endif
333
334#ifndef __HAVE_ARCH_STRNCHR
335/**
336 * strnchr - Find a character in a length limited string
337 * @s: The string to be searched
338 * @count: The number of characters to be searched
339 * @c: The character to search for
340 */
341char *strnchr(const char *s, size_t count, int c)
342{
343 for (; count-- && *s != '\0'; ++s)
344 if (*s == (char)c)
345 return (char *)s;
346 return NULL;
347}
348EXPORT_SYMBOL(strnchr);
349#endif
350
351/**
352 * skip_spaces - Removes leading whitespace from @str.
353 * @str: The string to be stripped.
354 *
355 * Returns a pointer to the first non-whitespace character in @str.
356 */
357char *skip_spaces(const char *str)
358{
359 while (isspace(*str))
360 ++str;
361 return (char *)str;
362}
363EXPORT_SYMBOL(skip_spaces);
364
365/**
366 * strim - Removes leading and trailing whitespace from @s.
367 * @s: The string to be stripped.
368 *
369 * Note that the first trailing whitespace is replaced with a %NUL-terminator
370 * in the given string @s. Returns a pointer to the first non-whitespace
371 * character in @s.
372 */
373char *strim(char *s)
374{
375 size_t size;
376 char *end;
377
378 size = strlen(s);
379 if (!size)
380 return s;
381
382 end = s + size - 1;
383 while (end >= s && isspace(*end))
384 end--;
385 *(end + 1) = '\0';
386
387 return skip_spaces(s);
388}
389EXPORT_SYMBOL(strim);
390
391#ifndef __HAVE_ARCH_STRLEN
392/**
393 * strlen - Find the length of a string
394 * @s: The string to be sized
395 */
396size_t strlen(const char *s)
397{
398 const char *sc;
399
400 for (sc = s; *sc != '\0'; ++sc)
401 /* nothing */;
402 return sc - s;
403}
404EXPORT_SYMBOL(strlen);
405#endif
406
407#ifndef __HAVE_ARCH_STRNLEN
408/**
409 * strnlen - Find the length of a length-limited string
410 * @s: The string to be sized
411 * @count: The maximum number of bytes to search
412 */
413size_t strnlen(const char *s, size_t count)
414{
415 const char *sc;
416
417 for (sc = s; count-- && *sc != '\0'; ++sc)
418 /* nothing */;
419 return sc - s;
420}
421EXPORT_SYMBOL(strnlen);
422#endif
423
424#ifndef __HAVE_ARCH_STRSPN
425/**
426 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
427 * @s: The string to be searched
428 * @accept: The string to search for
429 */
430size_t strspn(const char *s, const char *accept)
431{
432 const char *p;
433 const char *a;
434 size_t count = 0;
435
436 for (p = s; *p != '\0'; ++p) {
437 for (a = accept; *a != '\0'; ++a) {
438 if (*p == *a)
439 break;
440 }
441 if (*a == '\0')
442 return count;
443 ++count;
444 }
445 return count;
446}
447
448EXPORT_SYMBOL(strspn);
449#endif
450
451#ifndef __HAVE_ARCH_STRCSPN
452/**
453 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
454 * @s: The string to be searched
455 * @reject: The string to avoid
456 */
457size_t strcspn(const char *s, const char *reject)
458{
459 const char *p;
460 const char *r;
461 size_t count = 0;
462
463 for (p = s; *p != '\0'; ++p) {
464 for (r = reject; *r != '\0'; ++r) {
465 if (*p == *r)
466 return count;
467 }
468 ++count;
469 }
470 return count;
471}
472EXPORT_SYMBOL(strcspn);
473#endif
474
475#ifndef __HAVE_ARCH_STRPBRK
476/**
477 * strpbrk - Find the first occurrence of a set of characters
478 * @cs: The string to be searched
479 * @ct: The characters to search for
480 */
481char *strpbrk(const char *cs, const char *ct)
482{
483 const char *sc1, *sc2;
484
485 for (sc1 = cs; *sc1 != '\0'; ++sc1) {
486 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
487 if (*sc1 == *sc2)
488 return (char *)sc1;
489 }
490 }
491 return NULL;
492}
493EXPORT_SYMBOL(strpbrk);
494#endif
495
496#ifndef __HAVE_ARCH_STRSEP
497/**
498 * strsep - Split a string into tokens
499 * @s: The string to be searched
500 * @ct: The characters to search for
501 *
502 * strsep() updates @s to point after the token, ready for the next call.
503 *
504 * It returns empty tokens, too, behaving exactly like the libc function
505 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
506 * Same semantics, slimmer shape. ;)
507 */
508char *strsep(char **s, const char *ct)
509{
510 char *sbegin = *s;
511 char *end;
512
513 if (sbegin == NULL)
514 return NULL;
515
516 end = strpbrk(sbegin, ct);
517 if (end)
518 *end++ = '\0';
519 *s = end;
520 return sbegin;
521}
522EXPORT_SYMBOL(strsep);
523#endif
524
525/**
526 * sysfs_streq - return true if strings are equal, modulo trailing newline
527 * @s1: one string
528 * @s2: another string
529 *
530 * This routine returns true iff two strings are equal, treating both
531 * NUL and newline-then-NUL as equivalent string terminations. It's
532 * geared for use with sysfs input strings, which generally terminate
533 * with newlines but are compared against values without newlines.
534 */
535bool sysfs_streq(const char *s1, const char *s2)
536{
537 while (*s1 && *s1 == *s2) {
538 s1++;
539 s2++;
540 }
541
542 if (*s1 == *s2)
543 return true;
544 if (!*s1 && *s2 == '\n' && !s2[1])
545 return true;
546 if (*s1 == '\n' && !s1[1] && !*s2)
547 return true;
548 return false;
549}
550EXPORT_SYMBOL(sysfs_streq);
551
552/**
553 * strtobool - convert common user inputs into boolean values
554 * @s: input string
555 * @res: result
556 *
557 * This routine returns 0 iff the first character is one of 'Yy1Nn0'.
558 * Otherwise it will return -EINVAL. Value pointed to by res is
559 * updated upon finding a match.
560 */
561int strtobool(const char *s, bool *res)
562{
563 switch (s[0]) {
564 case 'y':
565 case 'Y':
566 case '1':
567 *res = true;
568 break;
569 case 'n':
570 case 'N':
571 case '0':
572 *res = false;
573 break;
574 default:
575 return -EINVAL;
576 }
577 return 0;
578}
579EXPORT_SYMBOL(strtobool);
580
581#ifndef __HAVE_ARCH_MEMSET
582/**
583 * memset - Fill a region of memory with the given value
584 * @s: Pointer to the start of the area.
585 * @c: The byte to fill the area with
586 * @count: The size of the area.
587 *
588 * Do not use memset() to access IO space, use memset_io() instead.
589 */
590void *memset(void *s, int c, size_t count)
591{
592 char *xs = s;
593
594 while (count--)
595 *xs++ = c;
596 return s;
597}
598EXPORT_SYMBOL(memset);
599#endif
600
601/**
602 * memzero_explicit - Fill a region of memory (e.g. sensitive
603 * keying data) with 0s.
604 * @s: Pointer to the start of the area.
605 * @count: The size of the area.
606 *
607 * memzero_explicit() doesn't need an arch-specific version as
608 * it just invokes the one of memset() implicitly.
609 */
610void memzero_explicit(void *s, size_t count)
611{
612 memset(s, 0, count);
613 OPTIMIZER_HIDE_VAR(s);
614}
615EXPORT_SYMBOL(memzero_explicit);
616
617#ifndef __HAVE_ARCH_MEMCPY
618/**
619 * memcpy - Copy one area of memory to another
620 * @dest: Where to copy to
621 * @src: Where to copy from
622 * @count: The size of the area.
623 *
624 * You should not use this function to access IO space, use memcpy_toio()
625 * or memcpy_fromio() instead.
626 */
627void *memcpy(void *dest, const void *src, size_t count)
628{
629 char *tmp = dest;
630 const char *s = src;
631
632 while (count--)
633 *tmp++ = *s++;
634 return dest;
635}
636EXPORT_SYMBOL(memcpy);
637#endif
638
639#ifndef __HAVE_ARCH_MEMMOVE
640/**
641 * memmove - Copy one area of memory to another
642 * @dest: Where to copy to
643 * @src: Where to copy from
644 * @count: The size of the area.
645 *
646 * Unlike memcpy(), memmove() copes with overlapping areas.
647 */
648void *memmove(void *dest, const void *src, size_t count)
649{
650 char *tmp;
651 const char *s;
652
653 if (dest <= src) {
654 tmp = dest;
655 s = src;
656 while (count--)
657 *tmp++ = *s++;
658 } else {
659 tmp = dest;
660 tmp += count;
661 s = src;
662 s += count;
663 while (count--)
664 *--tmp = *--s;
665 }
666 return dest;
667}
668EXPORT_SYMBOL(memmove);
669#endif
670
671#ifndef __HAVE_ARCH_MEMCMP
672/**
673 * memcmp - Compare two areas of memory
674 * @cs: One area of memory
675 * @ct: Another area of memory
676 * @count: The size of the area.
677 */
678#undef memcmp
679__visible int memcmp(const void *cs, const void *ct, size_t count)
680{
681 const unsigned char *su1, *su2;
682 int res = 0;
683
684 for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
685 if ((res = *su1 - *su2) != 0)
686 break;
687 return res;
688}
689EXPORT_SYMBOL(memcmp);
690#endif
691
692#ifndef __HAVE_ARCH_MEMSCAN
693/**
694 * memscan - Find a character in an area of memory.
695 * @addr: The memory area
696 * @c: The byte to search for
697 * @size: The size of the area.
698 *
699 * returns the address of the first occurrence of @c, or 1 byte past
700 * the area if @c is not found
701 */
702void *memscan(void *addr, int c, size_t size)
703{
704 unsigned char *p = addr;
705
706 while (size) {
707 if (*p == c)
708 return (void *)p;
709 p++;
710 size--;
711 }
712 return (void *)p;
713}
714EXPORT_SYMBOL(memscan);
715#endif
716
717#ifndef __HAVE_ARCH_STRSTR
718/**
719 * strstr - Find the first substring in a %NUL terminated string
720 * @s1: The string to be searched
721 * @s2: The string to search for
722 */
723char *strstr(const char *s1, const char *s2)
724{
725 size_t l1, l2;
726
727 l2 = strlen(s2);
728 if (!l2)
729 return (char *)s1;
730 l1 = strlen(s1);
731 while (l1 >= l2) {
732 l1--;
733 if (!memcmp(s1, s2, l2))
734 return (char *)s1;
735 s1++;
736 }
737 return NULL;
738}
739EXPORT_SYMBOL(strstr);
740#endif
741
742#ifndef __HAVE_ARCH_STRNSTR
743/**
744 * strnstr - Find the first substring in a length-limited string
745 * @s1: The string to be searched
746 * @s2: The string to search for
747 * @len: the maximum number of characters to search
748 */
749char *strnstr(const char *s1, const char *s2, size_t len)
750{
751 size_t l2;
752
753 l2 = strlen(s2);
754 if (!l2)
755 return (char *)s1;
756 while (len >= l2) {
757 len--;
758 if (!memcmp(s1, s2, l2))
759 return (char *)s1;
760 s1++;
761 }
762 return NULL;
763}
764EXPORT_SYMBOL(strnstr);
765#endif
766
767#ifndef __HAVE_ARCH_MEMCHR
768/**
769 * memchr - Find a character in an area of memory.
770 * @s: The memory area
771 * @c: The byte to search for
772 * @n: The size of the area.
773 *
774 * returns the address of the first occurrence of @c, or %NULL
775 * if @c is not found
776 */
777void *memchr(const void *s, int c, size_t n)
778{
779 const unsigned char *p = s;
780 while (n-- != 0) {
781 if ((unsigned char)c == *p++) {
782 return (void *)(p - 1);
783 }
784 }
785 return NULL;
786}
787EXPORT_SYMBOL(memchr);
788#endif
789
790static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
791{
792 while (bytes) {
793 if (*start != value)
794 return (void *)start;
795 start++;
796 bytes--;
797 }
798 return NULL;
799}
800
801/**
802 * memchr_inv - Find an unmatching character in an area of memory.
803 * @start: The memory area
804 * @c: Find a character other than c
805 * @bytes: The size of the area.
806 *
807 * returns the address of the first character other than @c, or %NULL
808 * if the whole buffer contains just @c.
809 */
810void *memchr_inv(const void *start, int c, size_t bytes)
811{
812 u8 value = c;
813 u64 value64;
814 unsigned int words, prefix;
815
816 if (bytes <= 16)
817 return check_bytes8(start, value, bytes);
818
819 value64 = value;
820#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
821 value64 *= 0x0101010101010101;
822#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
823 value64 *= 0x01010101;
824 value64 |= value64 << 32;
825#else
826 value64 |= value64 << 8;
827 value64 |= value64 << 16;
828 value64 |= value64 << 32;
829#endif
830
831 prefix = (unsigned long)start % 8;
832 if (prefix) {
833 u8 *r;
834
835 prefix = 8 - prefix;
836 r = check_bytes8(start, value, prefix);
837 if (r)
838 return r;
839 start += prefix;
840 bytes -= prefix;
841 }
842
843 words = bytes / 8;
844
845 while (words) {
846 if (*(u64 *)start != value64)
847 return check_bytes8(start, value, 8);
848 start += 8;
849 words--;
850 }
851
852 return check_bytes8(start, value, bytes % 8);
853}
854EXPORT_SYMBOL(memchr_inv);