xref: /openbmc/linux/lib/string.c (revision b6dcefde)
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/module.h>
26 
27 #ifndef __HAVE_ARCH_STRNICMP
28 /**
29  * strnicmp - Case insensitive, length-limited string comparison
30  * @s1: One string
31  * @s2: The other string
32  * @len: the maximum number of characters to compare
33  */
34 int strnicmp(const char *s1, const char *s2, size_t len)
35 {
36 	/* Yes, Virginia, it had better be unsigned */
37 	unsigned char c1, c2;
38 
39 	c1 = c2 = 0;
40 	if (len) {
41 		do {
42 			c1 = *s1;
43 			c2 = *s2;
44 			s1++;
45 			s2++;
46 			if (!c1)
47 				break;
48 			if (!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 	}
58 	return (int)c1 - (int)c2;
59 }
60 EXPORT_SYMBOL(strnicmp);
61 #endif
62 
63 #ifndef __HAVE_ARCH_STRCASECMP
64 int strcasecmp(const char *s1, const char *s2)
65 {
66 	int c1, c2;
67 
68 	do {
69 		c1 = tolower(*s1++);
70 		c2 = tolower(*s2++);
71 	} while (c1 == c2 && c1 != 0);
72 	return c1 - c2;
73 }
74 EXPORT_SYMBOL(strcasecmp);
75 #endif
76 
77 #ifndef __HAVE_ARCH_STRNCASECMP
78 int strncasecmp(const char *s1, const char *s2, size_t n)
79 {
80 	int c1, c2;
81 
82 	do {
83 		c1 = tolower(*s1++);
84 		c2 = tolower(*s2++);
85 	} while ((--n > 0) && c1 == c2 && c1 != 0);
86 	return c1 - c2;
87 }
88 EXPORT_SYMBOL(strncasecmp);
89 #endif
90 
91 #ifndef __HAVE_ARCH_STRCPY
92 /**
93  * strcpy - Copy a %NUL terminated string
94  * @dest: Where to copy the string to
95  * @src: Where to copy the string from
96  */
97 #undef strcpy
98 char *strcpy(char *dest, const char *src)
99 {
100 	char *tmp = dest;
101 
102 	while ((*dest++ = *src++) != '\0')
103 		/* nothing */;
104 	return tmp;
105 }
106 EXPORT_SYMBOL(strcpy);
107 #endif
108 
109 #ifndef __HAVE_ARCH_STRNCPY
110 /**
111  * strncpy - Copy a length-limited, %NUL-terminated string
112  * @dest: Where to copy the string to
113  * @src: Where to copy the string from
114  * @count: The maximum number of bytes to copy
115  *
116  * The result is not %NUL-terminated if the source exceeds
117  * @count bytes.
118  *
119  * In the case where the length of @src is less than  that  of
120  * count, the remainder of @dest will be padded with %NUL.
121  *
122  */
123 char *strncpy(char *dest, const char *src, size_t count)
124 {
125 	char *tmp = dest;
126 
127 	while (count) {
128 		if ((*tmp = *src) != 0)
129 			src++;
130 		tmp++;
131 		count--;
132 	}
133 	return dest;
134 }
135 EXPORT_SYMBOL(strncpy);
136 #endif
137 
138 #ifndef __HAVE_ARCH_STRLCPY
139 /**
140  * strlcpy - Copy a %NUL terminated string into a sized buffer
141  * @dest: Where to copy the string to
142  * @src: Where to copy the string from
143  * @size: size of destination buffer
144  *
145  * Compatible with *BSD: the result is always a valid
146  * NUL-terminated string that fits in the buffer (unless,
147  * of course, the buffer size is zero). It does not pad
148  * out the result like strncpy() does.
149  */
150 size_t strlcpy(char *dest, const char *src, size_t size)
151 {
152 	size_t ret = strlen(src);
153 
154 	if (size) {
155 		size_t len = (ret >= size) ? size - 1 : ret;
156 		memcpy(dest, src, len);
157 		dest[len] = '\0';
158 	}
159 	return ret;
160 }
161 EXPORT_SYMBOL(strlcpy);
162 #endif
163 
164 #ifndef __HAVE_ARCH_STRCAT
165 /**
166  * strcat - Append one %NUL-terminated string to another
167  * @dest: The string to be appended to
168  * @src: The string to append to it
169  */
170 #undef strcat
171 char *strcat(char *dest, const char *src)
172 {
173 	char *tmp = dest;
174 
175 	while (*dest)
176 		dest++;
177 	while ((*dest++ = *src++) != '\0')
178 		;
179 	return tmp;
180 }
181 EXPORT_SYMBOL(strcat);
182 #endif
183 
184 #ifndef __HAVE_ARCH_STRNCAT
185 /**
186  * strncat - Append a length-limited, %NUL-terminated string to another
187  * @dest: The string to be appended to
188  * @src: The string to append to it
189  * @count: The maximum numbers of bytes to copy
190  *
191  * Note that in contrast to strncpy(), strncat() ensures the result is
192  * terminated.
193  */
194 char *strncat(char *dest, const char *src, size_t count)
195 {
196 	char *tmp = dest;
197 
198 	if (count) {
199 		while (*dest)
200 			dest++;
201 		while ((*dest++ = *src++) != 0) {
202 			if (--count == 0) {
203 				*dest = '\0';
204 				break;
205 			}
206 		}
207 	}
208 	return tmp;
209 }
210 EXPORT_SYMBOL(strncat);
211 #endif
212 
213 #ifndef __HAVE_ARCH_STRLCAT
214 /**
215  * strlcat - Append a length-limited, %NUL-terminated string to another
216  * @dest: The string to be appended to
217  * @src: The string to append to it
218  * @count: The size of the destination buffer.
219  */
220 size_t strlcat(char *dest, const char *src, size_t count)
221 {
222 	size_t dsize = strlen(dest);
223 	size_t len = strlen(src);
224 	size_t res = dsize + len;
225 
226 	/* This would be a bug */
227 	BUG_ON(dsize >= count);
228 
229 	dest += dsize;
230 	count -= dsize;
231 	if (len >= count)
232 		len = count-1;
233 	memcpy(dest, src, len);
234 	dest[len] = 0;
235 	return res;
236 }
237 EXPORT_SYMBOL(strlcat);
238 #endif
239 
240 #ifndef __HAVE_ARCH_STRCMP
241 /**
242  * strcmp - Compare two strings
243  * @cs: One string
244  * @ct: Another string
245  */
246 #undef strcmp
247 int strcmp(const char *cs, const char *ct)
248 {
249 	unsigned char c1, c2;
250 
251 	while (1) {
252 		c1 = *cs++;
253 		c2 = *ct++;
254 		if (c1 != c2)
255 			return c1 < c2 ? -1 : 1;
256 		if (!c1)
257 			break;
258 	}
259 	return 0;
260 }
261 EXPORT_SYMBOL(strcmp);
262 #endif
263 
264 #ifndef __HAVE_ARCH_STRNCMP
265 /**
266  * strncmp - Compare two length-limited strings
267  * @cs: One string
268  * @ct: Another string
269  * @count: The maximum number of bytes to compare
270  */
271 int strncmp(const char *cs, const char *ct, size_t count)
272 {
273 	unsigned char c1, c2;
274 
275 	while (count) {
276 		c1 = *cs++;
277 		c2 = *ct++;
278 		if (c1 != c2)
279 			return c1 < c2 ? -1 : 1;
280 		if (!c1)
281 			break;
282 		count--;
283 	}
284 	return 0;
285 }
286 EXPORT_SYMBOL(strncmp);
287 #endif
288 
289 #ifndef __HAVE_ARCH_STRCHR
290 /**
291  * strchr - Find the first occurrence of a character in a string
292  * @s: The string to be searched
293  * @c: The character to search for
294  */
295 char *strchr(const char *s, int c)
296 {
297 	for (; *s != (char)c; ++s)
298 		if (*s == '\0')
299 			return NULL;
300 	return (char *)s;
301 }
302 EXPORT_SYMBOL(strchr);
303 #endif
304 
305 #ifndef __HAVE_ARCH_STRRCHR
306 /**
307  * strrchr - Find the last occurrence of a character in a string
308  * @s: The string to be searched
309  * @c: The character to search for
310  */
311 char *strrchr(const char *s, int c)
312 {
313        const char *p = s + strlen(s);
314        do {
315            if (*p == (char)c)
316                return (char *)p;
317        } while (--p >= s);
318        return NULL;
319 }
320 EXPORT_SYMBOL(strrchr);
321 #endif
322 
323 #ifndef __HAVE_ARCH_STRNCHR
324 /**
325  * strnchr - Find a character in a length limited string
326  * @s: The string to be searched
327  * @count: The number of characters to be searched
328  * @c: The character to search for
329  */
330 char *strnchr(const char *s, size_t count, int c)
331 {
332 	for (; count-- && *s != '\0'; ++s)
333 		if (*s == (char)c)
334 			return (char *)s;
335 	return NULL;
336 }
337 EXPORT_SYMBOL(strnchr);
338 #endif
339 
340 /**
341  * skip_spaces - Removes leading whitespace from @str.
342  * @str: The string to be stripped.
343  *
344  * Returns a pointer to the first non-whitespace character in @str.
345  */
346 char *skip_spaces(const char *str)
347 {
348 	while (isspace(*str))
349 		++str;
350 	return (char *)str;
351 }
352 EXPORT_SYMBOL(skip_spaces);
353 
354 /**
355  * strim - Removes leading and trailing whitespace from @s.
356  * @s: The string to be stripped.
357  *
358  * Note that the first trailing whitespace is replaced with a %NUL-terminator
359  * in the given string @s. Returns a pointer to the first non-whitespace
360  * character in @s.
361  */
362 char *strim(char *s)
363 {
364 	size_t size;
365 	char *end;
366 
367 	s = skip_spaces(s);
368 	size = strlen(s);
369 	if (!size)
370 		return s;
371 
372 	end = s + size - 1;
373 	while (end >= s && isspace(*end))
374 		end--;
375 	*(end + 1) = '\0';
376 
377 	return s;
378 }
379 EXPORT_SYMBOL(strim);
380 
381 #ifndef __HAVE_ARCH_STRLEN
382 /**
383  * strlen - Find the length of a string
384  * @s: The string to be sized
385  */
386 size_t strlen(const char *s)
387 {
388 	const char *sc;
389 
390 	for (sc = s; *sc != '\0'; ++sc)
391 		/* nothing */;
392 	return sc - s;
393 }
394 EXPORT_SYMBOL(strlen);
395 #endif
396 
397 #ifndef __HAVE_ARCH_STRNLEN
398 /**
399  * strnlen - Find the length of a length-limited string
400  * @s: The string to be sized
401  * @count: The maximum number of bytes to search
402  */
403 size_t strnlen(const char *s, size_t count)
404 {
405 	const char *sc;
406 
407 	for (sc = s; count-- && *sc != '\0'; ++sc)
408 		/* nothing */;
409 	return sc - s;
410 }
411 EXPORT_SYMBOL(strnlen);
412 #endif
413 
414 #ifndef __HAVE_ARCH_STRSPN
415 /**
416  * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
417  * @s: The string to be searched
418  * @accept: The string to search for
419  */
420 size_t strspn(const char *s, const char *accept)
421 {
422 	const char *p;
423 	const char *a;
424 	size_t count = 0;
425 
426 	for (p = s; *p != '\0'; ++p) {
427 		for (a = accept; *a != '\0'; ++a) {
428 			if (*p == *a)
429 				break;
430 		}
431 		if (*a == '\0')
432 			return count;
433 		++count;
434 	}
435 	return count;
436 }
437 
438 EXPORT_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  */
447 size_t strcspn(const char *s, const char *reject)
448 {
449 	const char *p;
450 	const char *r;
451 	size_t count = 0;
452 
453 	for (p = s; *p != '\0'; ++p) {
454 		for (r = reject; *r != '\0'; ++r) {
455 			if (*p == *r)
456 				return count;
457 		}
458 		++count;
459 	}
460 	return count;
461 }
462 EXPORT_SYMBOL(strcspn);
463 #endif
464 
465 #ifndef __HAVE_ARCH_STRPBRK
466 /**
467  * strpbrk - Find the first occurrence of a set of characters
468  * @cs: The string to be searched
469  * @ct: The characters to search for
470  */
471 char *strpbrk(const char *cs, const char *ct)
472 {
473 	const char *sc1, *sc2;
474 
475 	for (sc1 = cs; *sc1 != '\0'; ++sc1) {
476 		for (sc2 = ct; *sc2 != '\0'; ++sc2) {
477 			if (*sc1 == *sc2)
478 				return (char *)sc1;
479 		}
480 	}
481 	return NULL;
482 }
483 EXPORT_SYMBOL(strpbrk);
484 #endif
485 
486 #ifndef __HAVE_ARCH_STRSEP
487 /**
488  * strsep - Split a string into tokens
489  * @s: The string to be searched
490  * @ct: The characters to search for
491  *
492  * strsep() updates @s to point after the token, ready for the next call.
493  *
494  * It returns empty tokens, too, behaving exactly like the libc function
495  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
496  * Same semantics, slimmer shape. ;)
497  */
498 char *strsep(char **s, const char *ct)
499 {
500 	char *sbegin = *s;
501 	char *end;
502 
503 	if (sbegin == NULL)
504 		return NULL;
505 
506 	end = strpbrk(sbegin, ct);
507 	if (end)
508 		*end++ = '\0';
509 	*s = end;
510 	return sbegin;
511 }
512 EXPORT_SYMBOL(strsep);
513 #endif
514 
515 /**
516  * sysfs_streq - return true if strings are equal, modulo trailing newline
517  * @s1: one string
518  * @s2: another string
519  *
520  * This routine returns true iff two strings are equal, treating both
521  * NUL and newline-then-NUL as equivalent string terminations.  It's
522  * geared for use with sysfs input strings, which generally terminate
523  * with newlines but are compared against values without newlines.
524  */
525 bool sysfs_streq(const char *s1, const char *s2)
526 {
527 	while (*s1 && *s1 == *s2) {
528 		s1++;
529 		s2++;
530 	}
531 
532 	if (*s1 == *s2)
533 		return true;
534 	if (!*s1 && *s2 == '\n' && !s2[1])
535 		return true;
536 	if (*s1 == '\n' && !s1[1] && !*s2)
537 		return true;
538 	return false;
539 }
540 EXPORT_SYMBOL(sysfs_streq);
541 
542 #ifndef __HAVE_ARCH_MEMSET
543 /**
544  * memset - Fill a region of memory with the given value
545  * @s: Pointer to the start of the area.
546  * @c: The byte to fill the area with
547  * @count: The size of the area.
548  *
549  * Do not use memset() to access IO space, use memset_io() instead.
550  */
551 void *memset(void *s, int c, size_t count)
552 {
553 	char *xs = s;
554 
555 	while (count--)
556 		*xs++ = c;
557 	return s;
558 }
559 EXPORT_SYMBOL(memset);
560 #endif
561 
562 #ifndef __HAVE_ARCH_MEMCPY
563 /**
564  * memcpy - Copy one area of memory to another
565  * @dest: Where to copy to
566  * @src: Where to copy from
567  * @count: The size of the area.
568  *
569  * You should not use this function to access IO space, use memcpy_toio()
570  * or memcpy_fromio() instead.
571  */
572 void *memcpy(void *dest, const void *src, size_t count)
573 {
574 	char *tmp = dest;
575 	const char *s = src;
576 
577 	while (count--)
578 		*tmp++ = *s++;
579 	return dest;
580 }
581 EXPORT_SYMBOL(memcpy);
582 #endif
583 
584 #ifndef __HAVE_ARCH_MEMMOVE
585 /**
586  * memmove - Copy one area of memory to another
587  * @dest: Where to copy to
588  * @src: Where to copy from
589  * @count: The size of the area.
590  *
591  * Unlike memcpy(), memmove() copes with overlapping areas.
592  */
593 void *memmove(void *dest, const void *src, size_t count)
594 {
595 	char *tmp;
596 	const char *s;
597 
598 	if (dest <= src) {
599 		tmp = dest;
600 		s = src;
601 		while (count--)
602 			*tmp++ = *s++;
603 	} else {
604 		tmp = dest;
605 		tmp += count;
606 		s = src;
607 		s += count;
608 		while (count--)
609 			*--tmp = *--s;
610 	}
611 	return dest;
612 }
613 EXPORT_SYMBOL(memmove);
614 #endif
615 
616 #ifndef __HAVE_ARCH_MEMCMP
617 /**
618  * memcmp - Compare two areas of memory
619  * @cs: One area of memory
620  * @ct: Another area of memory
621  * @count: The size of the area.
622  */
623 #undef memcmp
624 int memcmp(const void *cs, const void *ct, size_t count)
625 {
626 	const unsigned char *su1, *su2;
627 	int res = 0;
628 
629 	for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
630 		if ((res = *su1 - *su2) != 0)
631 			break;
632 	return res;
633 }
634 EXPORT_SYMBOL(memcmp);
635 #endif
636 
637 #ifndef __HAVE_ARCH_MEMSCAN
638 /**
639  * memscan - Find a character in an area of memory.
640  * @addr: The memory area
641  * @c: The byte to search for
642  * @size: The size of the area.
643  *
644  * returns the address of the first occurrence of @c, or 1 byte past
645  * the area if @c is not found
646  */
647 void *memscan(void *addr, int c, size_t size)
648 {
649 	unsigned char *p = addr;
650 
651 	while (size) {
652 		if (*p == c)
653 			return (void *)p;
654 		p++;
655 		size--;
656 	}
657   	return (void *)p;
658 }
659 EXPORT_SYMBOL(memscan);
660 #endif
661 
662 #ifndef __HAVE_ARCH_STRSTR
663 /**
664  * strstr - Find the first substring in a %NUL terminated string
665  * @s1: The string to be searched
666  * @s2: The string to search for
667  */
668 char *strstr(const char *s1, const char *s2)
669 {
670 	size_t l1, l2;
671 
672 	l2 = strlen(s2);
673 	if (!l2)
674 		return (char *)s1;
675 	l1 = strlen(s1);
676 	while (l1 >= l2) {
677 		l1--;
678 		if (!memcmp(s1, s2, l2))
679 			return (char *)s1;
680 		s1++;
681 	}
682 	return NULL;
683 }
684 EXPORT_SYMBOL(strstr);
685 #endif
686 
687 #ifndef __HAVE_ARCH_STRNSTR
688 /**
689  * strnstr - Find the first substring in a length-limited string
690  * @s1: The string to be searched
691  * @s2: The string to search for
692  * @len: the maximum number of characters to search
693  */
694 char *strnstr(const char *s1, const char *s2, size_t len)
695 {
696 	size_t l1 = len, l2;
697 
698 	l2 = strlen(s2);
699 	if (!l2)
700 		return (char *)s1;
701 	while (l1 >= l2) {
702 		l1--;
703 		if (!memcmp(s1, s2, l2))
704 			return (char *)s1;
705 		s1++;
706 	}
707 	return NULL;
708 }
709 EXPORT_SYMBOL(strnstr);
710 #endif
711 
712 #ifndef __HAVE_ARCH_MEMCHR
713 /**
714  * memchr - Find a character in an area of memory.
715  * @s: The memory area
716  * @c: The byte to search for
717  * @n: The size of the area.
718  *
719  * returns the address of the first occurrence of @c, or %NULL
720  * if @c is not found
721  */
722 void *memchr(const void *s, int c, size_t n)
723 {
724 	const unsigned char *p = s;
725 	while (n-- != 0) {
726         	if ((unsigned char)c == *p++) {
727 			return (void *)(p - 1);
728 		}
729 	}
730 	return NULL;
731 }
732 EXPORT_SYMBOL(memchr);
733 #endif
734