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1 /*
2 * linux/lib/string.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7 /*
8 * stupid library routines.. The optimized versions should generally be found
9 * as inline code in <asm-xx/string.h>
10 *
11 * These are buggy as well..
12 *
13 * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
14 * - Added strsep() which will replace strtok() soon (because strsep() is
15 * reentrant and should be faster). Use only strsep() in new code, please.
16 */
17
18 #include <linux/types.h>
19 #include <linux/string.h>
20 #include <linux/ctype.h>
21 #include <malloc.h>
22
23
24 /**
25 * strncasecmp - Case insensitive, length-limited string comparison
26 * @s1: One string
27 * @s2: The other string
28 * @len: the maximum number of characters to compare
29 */
30 int strncasecmp(const char *s1, const char *s2, size_t len)
31 {
32 /* Yes, Virginia, it had better be unsigned */
33 unsigned char c1, c2;
34
35 c1 = 0; c2 = 0;
36 if (len) {
37 do {
38 c1 = *s1; c2 = *s2;
39 s1++; s2++;
40 if (!c1)
41 break;
42 if (!c2)
43 break;
44 if (c1 == c2)
45 continue;
46 c1 = tolower(c1);
47 c2 = tolower(c2);
48 if (c1 != c2)
49 break;
50 } while (--len);
51 }
52 return (int)c1 - (int)c2;
53 }
54
55 /**
56 * strcasecmp - Case insensitive string comparison
57 * @s1: One string
58 * @s2: The other string
59 */
60 int strcasecmp(const char *s1, const char *s2)
61 {
62 return strncasecmp(s1, s2, -1U);
63 }
64
65 char * ___strtok;
66
67 #ifndef __HAVE_ARCH_STRCPY
68 /**
69 * strcpy - Copy a %NUL terminated string
70 * @dest: Where to copy the string to
71 * @src: Where to copy the string from
72 */
73 char * strcpy(char * dest,const char *src)
74 {
75 char *tmp = dest;
76
77 while ((*dest++ = *src++) != '\0')
78 /* nothing */;
79 return tmp;
80 }
81 #endif
82
83 #ifndef __HAVE_ARCH_STRNCPY
84 /**
85 * strncpy - Copy a length-limited, %NUL-terminated string
86 * @dest: Where to copy the string to
87 * @src: Where to copy the string from
88 * @count: The maximum number of bytes to copy
89 *
90 * Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
91 * However, the result is not %NUL-terminated if the source exceeds
92 * @count bytes.
93 */
94 char * strncpy(char * dest,const char *src,size_t count)
95 {
96 char *tmp = dest;
97
98 while (count-- && (*dest++ = *src++) != '\0')
99 /* nothing */;
100
101 return tmp;
102 }
103 #endif
104
105 #ifndef __HAVE_ARCH_STRLCPY
106 /**
107 * strlcpy - Copy a C-string into a sized buffer
108 * @dest: Where to copy the string to
109 * @src: Where to copy the string from
110 * @size: size of destination buffer
111 *
112 * Compatible with *BSD: the result is always a valid
113 * NUL-terminated string that fits in the buffer (unless,
114 * of course, the buffer size is zero). It does not pad
115 * out the result like strncpy() does.
116 */
117 size_t strlcpy(char *dest, const char *src, size_t size)
118 {
119 size_t ret = strlen(src);
120
121 if (size) {
122 size_t len = (ret >= size) ? size - 1 : ret;
123 memcpy(dest, src, len);
124 dest[len] = '\0';
125 }
126 return ret;
127 }
128 #endif
129
130 #ifndef __HAVE_ARCH_STRCAT
131 /**
132 * strcat - Append one %NUL-terminated string to another
133 * @dest: The string to be appended to
134 * @src: The string to append to it
135 */
136 char * strcat(char * dest, const char * src)
137 {
138 char *tmp = dest;
139
140 while (*dest)
141 dest++;
142 while ((*dest++ = *src++) != '\0')
143 ;
144
145 return tmp;
146 }
147 #endif
148
149 #ifndef __HAVE_ARCH_STRNCAT
150 /**
151 * strncat - Append a length-limited, %NUL-terminated string to another
152 * @dest: The string to be appended to
153 * @src: The string to append to it
154 * @count: The maximum numbers of bytes to copy
155 *
156 * Note that in contrast to strncpy, strncat ensures the result is
157 * terminated.
158 */
159 char * strncat(char *dest, const char *src, size_t count)
160 {
161 char *tmp = dest;
162
163 if (count) {
164 while (*dest)
165 dest++;
166 while ((*dest++ = *src++)) {
167 if (--count == 0) {
168 *dest = '\0';
169 break;
170 }
171 }
172 }
173
174 return tmp;
175 }
176 #endif
177
178 #ifndef __HAVE_ARCH_STRCMP
179 /**
180 * strcmp - Compare two strings
181 * @cs: One string
182 * @ct: Another string
183 */
184 int strcmp(const char * cs,const char * ct)
185 {
186 register signed char __res;
187
188 while (1) {
189 if ((__res = *cs - *ct++) != 0 || !*cs++)
190 break;
191 }
192
193 return __res;
194 }
195 #endif
196
197 #ifndef __HAVE_ARCH_STRNCMP
198 /**
199 * strncmp - Compare two length-limited strings
200 * @cs: One string
201 * @ct: Another string
202 * @count: The maximum number of bytes to compare
203 */
204 int strncmp(const char * cs,const char * ct,size_t count)
205 {
206 register signed char __res = 0;
207
208 while (count) {
209 if ((__res = *cs - *ct++) != 0 || !*cs++)
210 break;
211 count--;
212 }
213
214 return __res;
215 }
216 #endif
217
218 #ifndef __HAVE_ARCH_STRCHR
219 /**
220 * strchr - Find the first occurrence of a character in a string
221 * @s: The string to be searched
222 * @c: The character to search for
223 */
224 char * strchr(const char * s, int c)
225 {
226 for(; *s != (char) c; ++s)
227 if (*s == '\0')
228 return NULL;
229 return (char *) s;
230 }
231 #endif
232
233 #ifndef __HAVE_ARCH_STRRCHR
234 /**
235 * strrchr - Find the last occurrence of a character in a string
236 * @s: The string to be searched
237 * @c: The character to search for
238 */
239 char * strrchr(const char * s, int c)
240 {
241 const char *p = s + strlen(s);
242 do {
243 if (*p == (char)c)
244 return (char *)p;
245 } while (--p >= s);
246 return NULL;
247 }
248 #endif
249
250 #ifndef __HAVE_ARCH_STRLEN
251 /**
252 * strlen - Find the length of a string
253 * @s: The string to be sized
254 */
255 size_t strlen(const char * s)
256 {
257 const char *sc;
258
259 for (sc = s; *sc != '\0'; ++sc)
260 /* nothing */;
261 return sc - s;
262 }
263 #endif
264
265 #ifndef __HAVE_ARCH_STRNLEN
266 /**
267 * strnlen - Find the length of a length-limited string
268 * @s: The string to be sized
269 * @count: The maximum number of bytes to search
270 */
271 size_t strnlen(const char * s, size_t count)
272 {
273 const char *sc;
274
275 for (sc = s; count-- && *sc != '\0'; ++sc)
276 /* nothing */;
277 return sc - s;
278 }
279 #endif
280
281 #ifndef __HAVE_ARCH_STRDUP
282 char * strdup(const char *s)
283 {
284 char *new;
285
286 if ((s == NULL) ||
287 ((new = malloc (strlen(s) + 1)) == NULL) ) {
288 return NULL;
289 }
290
291 strcpy (new, s);
292 return new;
293 }
294 #endif
295
296 #ifndef __HAVE_ARCH_STRSPN
297 /**
298 * strspn - Calculate the length of the initial substring of @s which only
299 * contain letters in @accept
300 * @s: The string to be searched
301 * @accept: The string to search for
302 */
303 size_t strspn(const char *s, const char *accept)
304 {
305 const char *p;
306 const char *a;
307 size_t count = 0;
308
309 for (p = s; *p != '\0'; ++p) {
310 for (a = accept; *a != '\0'; ++a) {
311 if (*p == *a)
312 break;
313 }
314 if (*a == '\0')
315 return count;
316 ++count;
317 }
318
319 return count;
320 }
321 #endif
322
323 #ifndef __HAVE_ARCH_STRPBRK
324 /**
325 * strpbrk - Find the first occurrence of a set of characters
326 * @cs: The string to be searched
327 * @ct: The characters to search for
328 */
329 char * strpbrk(const char * cs,const char * ct)
330 {
331 const char *sc1,*sc2;
332
333 for( sc1 = cs; *sc1 != '\0'; ++sc1) {
334 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
335 if (*sc1 == *sc2)
336 return (char *) sc1;
337 }
338 }
339 return NULL;
340 }
341 #endif
342
343 #ifndef __HAVE_ARCH_STRTOK
344 /**
345 * strtok - Split a string into tokens
346 * @s: The string to be searched
347 * @ct: The characters to search for
348 *
349 * WARNING: strtok is deprecated, use strsep instead.
350 */
351 char * strtok(char * s,const char * ct)
352 {
353 char *sbegin, *send;
354
355 sbegin = s ? s : ___strtok;
356 if (!sbegin) {
357 return NULL;
358 }
359 sbegin += strspn(sbegin,ct);
360 if (*sbegin == '\0') {
361 ___strtok = NULL;
362 return( NULL );
363 }
364 send = strpbrk( sbegin, ct);
365 if (send && *send != '\0')
366 *send++ = '\0';
367 ___strtok = send;
368 return (sbegin);
369 }
370 #endif
371
372 #ifndef __HAVE_ARCH_STRSEP
373 /**
374 * strsep - Split a string into tokens
375 * @s: The string to be searched
376 * @ct: The characters to search for
377 *
378 * strsep() updates @s to point after the token, ready for the next call.
379 *
380 * It returns empty tokens, too, behaving exactly like the libc function
381 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
382 * Same semantics, slimmer shape. ;)
383 */
384 char * strsep(char **s, const char *ct)
385 {
386 char *sbegin = *s, *end;
387
388 if (sbegin == NULL)
389 return NULL;
390
391 end = strpbrk(sbegin, ct);
392 if (end)
393 *end++ = '\0';
394 *s = end;
395
396 return sbegin;
397 }
398 #endif
399
400 #ifndef __HAVE_ARCH_STRSWAB
401 /**
402 * strswab - swap adjacent even and odd bytes in %NUL-terminated string
403 * s: address of the string
404 *
405 * returns the address of the swapped string or NULL on error. If
406 * string length is odd, last byte is untouched.
407 */
408 char *strswab(const char *s)
409 {
410 char *p, *q;
411
412 if ((NULL == s) || ('\0' == *s)) {
413 return (NULL);
414 }
415
416 for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
417 char tmp;
418
419 tmp = *p;
420 *p = *q;
421 *q = tmp;
422 }
423
424 return (char *) s;
425 }
426 #endif
427
428 #ifndef __HAVE_ARCH_MEMSET
429 /**
430 * memset - Fill a region of memory with the given value
431 * @s: Pointer to the start of the area.
432 * @c: The byte to fill the area with
433 * @count: The size of the area.
434 *
435 * Do not use memset() to access IO space, use memset_io() instead.
436 */
437 void * memset(void * s,int c,size_t count)
438 {
439 unsigned long *sl = (unsigned long *) s;
440 char *s8;
441
442 #if !CONFIG_IS_ENABLED(TINY_MEMSET)
443 unsigned long cl = 0;
444 int i;
445
446 /* do it one word at a time (32 bits or 64 bits) while possible */
447 if ( ((ulong)s & (sizeof(*sl) - 1)) == 0) {
448 for (i = 0; i < sizeof(*sl); i++) {
449 cl <<= 8;
450 cl |= c & 0xff;
451 }
452 while (count >= sizeof(*sl)) {
453 *sl++ = cl;
454 count -= sizeof(*sl);
455 }
456 }
457 #endif /* fill 8 bits at a time */
458 s8 = (char *)sl;
459 while (count--)
460 *s8++ = c;
461
462 return s;
463 }
464 #endif
465
466 #ifndef __HAVE_ARCH_MEMCPY
467 /**
468 * memcpy - Copy one area of memory to another
469 * @dest: Where to copy to
470 * @src: Where to copy from
471 * @count: The size of the area.
472 *
473 * You should not use this function to access IO space, use memcpy_toio()
474 * or memcpy_fromio() instead.
475 */
476 void * memcpy(void *dest, const void *src, size_t count)
477 {
478 unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
479 char *d8, *s8;
480
481 if (src == dest)
482 return dest;
483
484 /* while all data is aligned (common case), copy a word at a time */
485 if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) {
486 while (count >= sizeof(*dl)) {
487 *dl++ = *sl++;
488 count -= sizeof(*dl);
489 }
490 }
491 /* copy the reset one byte at a time */
492 d8 = (char *)dl;
493 s8 = (char *)sl;
494 while (count--)
495 *d8++ = *s8++;
496
497 return dest;
498 }
499 #endif
500
501 #ifndef __HAVE_ARCH_MEMMOVE
502 /**
503 * memmove - Copy one area of memory to another
504 * @dest: Where to copy to
505 * @src: Where to copy from
506 * @count: The size of the area.
507 *
508 * Unlike memcpy(), memmove() copes with overlapping areas.
509 */
510 void * memmove(void * dest,const void *src,size_t count)
511 {
512 char *tmp, *s;
513
514 if (src == dest)
515 return dest;
516
517 if (dest <= src) {
518 tmp = (char *) dest;
519 s = (char *) src;
520 while (count--)
521 *tmp++ = *s++;
522 }
523 else {
524 tmp = (char *) dest + count;
525 s = (char *) src + count;
526 while (count--)
527 *--tmp = *--s;
528 }
529
530 return dest;
531 }
532 #endif
533
534 #ifndef __HAVE_ARCH_MEMCMP
535 /**
536 * memcmp - Compare two areas of memory
537 * @cs: One area of memory
538 * @ct: Another area of memory
539 * @count: The size of the area.
540 */
541 int memcmp(const void * cs,const void * ct,size_t count)
542 {
543 const unsigned char *su1, *su2;
544 int res = 0;
545
546 for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
547 if ((res = *su1 - *su2) != 0)
548 break;
549 return res;
550 }
551 #endif
552
553 #ifndef __HAVE_ARCH_MEMSCAN
554 /**
555 * memscan - Find a character in an area of memory.
556 * @addr: The memory area
557 * @c: The byte to search for
558 * @size: The size of the area.
559 *
560 * returns the address of the first occurrence of @c, or 1 byte past
561 * the area if @c is not found
562 */
563 void * memscan(void * addr, int c, size_t size)
564 {
565 unsigned char * p = (unsigned char *) addr;
566
567 while (size) {
568 if (*p == c)
569 return (void *) p;
570 p++;
571 size--;
572 }
573 return (void *) p;
574 }
575 #endif
576
577 #ifndef __HAVE_ARCH_STRSTR
578 /**
579 * strstr - Find the first substring in a %NUL terminated string
580 * @s1: The string to be searched
581 * @s2: The string to search for
582 */
583 char * strstr(const char * s1,const char * s2)
584 {
585 int l1, l2;
586
587 l2 = strlen(s2);
588 if (!l2)
589 return (char *) s1;
590 l1 = strlen(s1);
591 while (l1 >= l2) {
592 l1--;
593 if (!memcmp(s1,s2,l2))
594 return (char *) s1;
595 s1++;
596 }
597 return NULL;
598 }
599 #endif
600
601 #ifndef __HAVE_ARCH_MEMCHR
602 /**
603 * memchr - Find a character in an area of memory.
604 * @s: The memory area
605 * @c: The byte to search for
606 * @n: The size of the area.
607 *
608 * returns the address of the first occurrence of @c, or %NULL
609 * if @c is not found
610 */
611 void *memchr(const void *s, int c, size_t n)
612 {
613 const unsigned char *p = s;
614 while (n-- != 0) {
615 if ((unsigned char)c == *p++) {
616 return (void *)(p-1);
617 }
618 }
619 return NULL;
620 }
621
622 #endif
623 #ifndef __HAVE_ARCH_MEMCHR_INV
624 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
625 {
626 while (bytes) {
627 if (*start != value)
628 return (void *)start;
629 start++;
630 bytes--;
631 }
632 return NULL;
633 }
634 /**
635 * memchr_inv - Find an unmatching character in an area of memory.
636 * @start: The memory area
637 * @c: Find a character other than c
638 * @bytes: The size of the area.
639 *
640 * returns the address of the first character other than @c, or %NULL
641 * if the whole buffer contains just @c.
642 */
643 void *memchr_inv(const void *start, int c, size_t bytes)
644 {
645 u8 value = c;
646 u64 value64;
647 unsigned int words, prefix;
648
649 if (bytes <= 16)
650 return check_bytes8(start, value, bytes);
651
652 value64 = value;
653 value64 |= value64 << 8;
654 value64 |= value64 << 16;
655 value64 |= value64 << 32;
656
657 prefix = (unsigned long)start % 8;
658 if (prefix) {
659 u8 *r;
660
661 prefix = 8 - prefix;
662 r = check_bytes8(start, value, prefix);
663 if (r)
664 return r;
665 start += prefix;
666 bytes -= prefix;
667 }
668
669 words = bytes / 8;
670
671 while (words) {
672 if (*(u64 *)start != value64)
673 return check_bytes8(start, value, 8);
674 start += 8;
675 words--;
676 }
677
678 return check_bytes8(start, value, bytes % 8);
679 }
680 #endif