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 */
strncasecmp(const char * s1,const char * s2,size_t len)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 */
strcasecmp(const char * s1,const char * s2)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 */
strcpy(char * dest,const char * src)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 */
strncpy(char * dest,const char * src,size_t count)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 */
strlcpy(char * dest,const char * src,size_t size)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 */
strcat(char * dest,const char * src)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 */
strncat(char * dest,const char * src,size_t count)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 */
strcmp(const char * cs,const char * ct)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 */
strncmp(const char * cs,const char * ct,size_t count)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 */
strchr(const char * s,int c)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
strchrnul(const char * s,int c)233 const char *strchrnul(const char *s, int c)
234 {
235 for (; *s != (char)c; ++s)
236 if (*s == '\0')
237 break;
238 return s;
239 }
240
241 #ifndef __HAVE_ARCH_STRRCHR
242 /**
243 * strrchr - Find the last occurrence of a character in a string
244 * @s: The string to be searched
245 * @c: The character to search for
246 */
strrchr(const char * s,int c)247 char * strrchr(const char * s, int c)
248 {
249 const char *p = s + strlen(s);
250 do {
251 if (*p == (char)c)
252 return (char *)p;
253 } while (--p >= s);
254 return NULL;
255 }
256 #endif
257
258 #ifndef __HAVE_ARCH_STRLEN
259 /**
260 * strlen - Find the length of a string
261 * @s: The string to be sized
262 */
strlen(const char * s)263 size_t strlen(const char * s)
264 {
265 const char *sc;
266
267 for (sc = s; *sc != '\0'; ++sc)
268 /* nothing */;
269 return sc - s;
270 }
271 #endif
272
273 #ifndef __HAVE_ARCH_STRNLEN
274 /**
275 * strnlen - Find the length of a length-limited string
276 * @s: The string to be sized
277 * @count: The maximum number of bytes to search
278 */
strnlen(const char * s,size_t count)279 size_t strnlen(const char * s, size_t count)
280 {
281 const char *sc;
282
283 for (sc = s; count-- && *sc != '\0'; ++sc)
284 /* nothing */;
285 return sc - s;
286 }
287 #endif
288
289 #ifndef __HAVE_ARCH_STRCSPN
290 /**
291 * strcspn - Calculate the length of the initial substring of @s which does
292 * not contain letters in @reject
293 * @s: The string to be searched
294 * @reject: The string to avoid
295 */
strcspn(const char * s,const char * reject)296 size_t strcspn(const char *s, const char *reject)
297 {
298 const char *p;
299 const char *r;
300 size_t count = 0;
301
302 for (p = s; *p != '\0'; ++p) {
303 for (r = reject; *r != '\0'; ++r) {
304 if (*p == *r)
305 return count;
306 }
307 ++count;
308 }
309 return count;
310 }
311 #endif
312
313 #ifndef __HAVE_ARCH_STRDUP
strdup(const char * s)314 char * strdup(const char *s)
315 {
316 char *new;
317
318 if ((s == NULL) ||
319 ((new = malloc (strlen(s) + 1)) == NULL) ) {
320 return NULL;
321 }
322
323 strcpy (new, s);
324 return new;
325 }
326 #endif
327
328 #ifndef __HAVE_ARCH_STRSPN
329 /**
330 * strspn - Calculate the length of the initial substring of @s which only
331 * contain letters in @accept
332 * @s: The string to be searched
333 * @accept: The string to search for
334 */
strspn(const char * s,const char * accept)335 size_t strspn(const char *s, const char *accept)
336 {
337 const char *p;
338 const char *a;
339 size_t count = 0;
340
341 for (p = s; *p != '\0'; ++p) {
342 for (a = accept; *a != '\0'; ++a) {
343 if (*p == *a)
344 break;
345 }
346 if (*a == '\0')
347 return count;
348 ++count;
349 }
350
351 return count;
352 }
353 #endif
354
355 #ifndef __HAVE_ARCH_STRPBRK
356 /**
357 * strpbrk - Find the first occurrence of a set of characters
358 * @cs: The string to be searched
359 * @ct: The characters to search for
360 */
strpbrk(const char * cs,const char * ct)361 char * strpbrk(const char * cs,const char * ct)
362 {
363 const char *sc1,*sc2;
364
365 for( sc1 = cs; *sc1 != '\0'; ++sc1) {
366 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
367 if (*sc1 == *sc2)
368 return (char *) sc1;
369 }
370 }
371 return NULL;
372 }
373 #endif
374
375 #ifndef __HAVE_ARCH_STRTOK
376 /**
377 * strtok - Split a string into tokens
378 * @s: The string to be searched
379 * @ct: The characters to search for
380 *
381 * WARNING: strtok is deprecated, use strsep instead.
382 */
strtok(char * s,const char * ct)383 char * strtok(char * s,const char * ct)
384 {
385 char *sbegin, *send;
386
387 sbegin = s ? s : ___strtok;
388 if (!sbegin) {
389 return NULL;
390 }
391 sbegin += strspn(sbegin,ct);
392 if (*sbegin == '\0') {
393 ___strtok = NULL;
394 return( NULL );
395 }
396 send = strpbrk( sbegin, ct);
397 if (send && *send != '\0')
398 *send++ = '\0';
399 ___strtok = send;
400 return (sbegin);
401 }
402 #endif
403
404 #ifndef __HAVE_ARCH_STRSEP
405 /**
406 * strsep - Split a string into tokens
407 * @s: The string to be searched
408 * @ct: The characters to search for
409 *
410 * strsep() updates @s to point after the token, ready for the next call.
411 *
412 * It returns empty tokens, too, behaving exactly like the libc function
413 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
414 * Same semantics, slimmer shape. ;)
415 */
strsep(char ** s,const char * ct)416 char * strsep(char **s, const char *ct)
417 {
418 char *sbegin = *s, *end;
419
420 if (sbegin == NULL)
421 return NULL;
422
423 end = strpbrk(sbegin, ct);
424 if (end)
425 *end++ = '\0';
426 *s = end;
427
428 return sbegin;
429 }
430 #endif
431
432 #ifndef __HAVE_ARCH_STRSWAB
433 /**
434 * strswab - swap adjacent even and odd bytes in %NUL-terminated string
435 * s: address of the string
436 *
437 * returns the address of the swapped string or NULL on error. If
438 * string length is odd, last byte is untouched.
439 */
strswab(const char * s)440 char *strswab(const char *s)
441 {
442 char *p, *q;
443
444 if ((NULL == s) || ('\0' == *s)) {
445 return (NULL);
446 }
447
448 for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
449 char tmp;
450
451 tmp = *p;
452 *p = *q;
453 *q = tmp;
454 }
455
456 return (char *) s;
457 }
458 #endif
459
460 #ifndef __HAVE_ARCH_MEMSET
461 /**
462 * memset - Fill a region of memory with the given value
463 * @s: Pointer to the start of the area.
464 * @c: The byte to fill the area with
465 * @count: The size of the area.
466 *
467 * Do not use memset() to access IO space, use memset_io() instead.
468 */
memset(void * s,int c,size_t count)469 void * memset(void * s,int c,size_t count)
470 {
471 unsigned long *sl = (unsigned long *) s;
472 char *s8;
473
474 #if !CONFIG_IS_ENABLED(TINY_MEMSET)
475 unsigned long cl = 0;
476 int i;
477
478 /* do it one word at a time (32 bits or 64 bits) while possible */
479 if ( ((ulong)s & (sizeof(*sl) - 1)) == 0) {
480 for (i = 0; i < sizeof(*sl); i++) {
481 cl <<= 8;
482 cl |= c & 0xff;
483 }
484 while (count >= sizeof(*sl)) {
485 *sl++ = cl;
486 count -= sizeof(*sl);
487 }
488 }
489 #endif /* fill 8 bits at a time */
490 s8 = (char *)sl;
491 while (count--)
492 *s8++ = c;
493
494 return s;
495 }
496 #endif
497
498 #ifndef __HAVE_ARCH_MEMCPY
499 /**
500 * memcpy - Copy one area of memory to another
501 * @dest: Where to copy to
502 * @src: Where to copy from
503 * @count: The size of the area.
504 *
505 * You should not use this function to access IO space, use memcpy_toio()
506 * or memcpy_fromio() instead.
507 */
memcpy(void * dest,const void * src,size_t count)508 void * memcpy(void *dest, const void *src, size_t count)
509 {
510 unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
511 char *d8, *s8;
512
513 if (src == dest)
514 return dest;
515
516 /* while all data is aligned (common case), copy a word at a time */
517 if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) {
518 while (count >= sizeof(*dl)) {
519 *dl++ = *sl++;
520 count -= sizeof(*dl);
521 }
522 }
523 /* copy the reset one byte at a time */
524 d8 = (char *)dl;
525 s8 = (char *)sl;
526 while (count--)
527 *d8++ = *s8++;
528
529 return dest;
530 }
531 #endif
532
533 #ifndef __HAVE_ARCH_MEMMOVE
534 /**
535 * memmove - Copy one area of memory to another
536 * @dest: Where to copy to
537 * @src: Where to copy from
538 * @count: The size of the area.
539 *
540 * Unlike memcpy(), memmove() copes with overlapping areas.
541 */
memmove(void * dest,const void * src,size_t count)542 void * memmove(void * dest,const void *src,size_t count)
543 {
544 char *tmp, *s;
545
546 if (dest <= src) {
547 memcpy(dest, src, count);
548 } else {
549 tmp = (char *) dest + count;
550 s = (char *) src + count;
551 while (count--)
552 *--tmp = *--s;
553 }
554
555 return dest;
556 }
557 #endif
558
559 #ifndef __HAVE_ARCH_MEMCMP
560 /**
561 * memcmp - Compare two areas of memory
562 * @cs: One area of memory
563 * @ct: Another area of memory
564 * @count: The size of the area.
565 */
memcmp(const void * cs,const void * ct,size_t count)566 int memcmp(const void * cs,const void * ct,size_t count)
567 {
568 const unsigned char *su1, *su2;
569 int res = 0;
570
571 for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
572 if ((res = *su1 - *su2) != 0)
573 break;
574 return res;
575 }
576 #endif
577
578 #ifndef __HAVE_ARCH_MEMSCAN
579 /**
580 * memscan - Find a character in an area of memory.
581 * @addr: The memory area
582 * @c: The byte to search for
583 * @size: The size of the area.
584 *
585 * returns the address of the first occurrence of @c, or 1 byte past
586 * the area if @c is not found
587 */
memscan(void * addr,int c,size_t size)588 void * memscan(void * addr, int c, size_t size)
589 {
590 unsigned char * p = (unsigned char *) addr;
591
592 while (size) {
593 if (*p == c)
594 return (void *) p;
595 p++;
596 size--;
597 }
598 return (void *) p;
599 }
600 #endif
601
602 #ifndef __HAVE_ARCH_STRSTR
603 /**
604 * strstr - Find the first substring in a %NUL terminated string
605 * @s1: The string to be searched
606 * @s2: The string to search for
607 */
strstr(const char * s1,const char * s2)608 char * strstr(const char * s1,const char * s2)
609 {
610 int l1, l2;
611
612 l2 = strlen(s2);
613 if (!l2)
614 return (char *) s1;
615 l1 = strlen(s1);
616 while (l1 >= l2) {
617 l1--;
618 if (!memcmp(s1,s2,l2))
619 return (char *) s1;
620 s1++;
621 }
622 return NULL;
623 }
624 #endif
625
626 #ifndef __HAVE_ARCH_MEMCHR
627 /**
628 * memchr - Find a character in an area of memory.
629 * @s: The memory area
630 * @c: The byte to search for
631 * @n: The size of the area.
632 *
633 * returns the address of the first occurrence of @c, or %NULL
634 * if @c is not found
635 */
memchr(const void * s,int c,size_t n)636 void *memchr(const void *s, int c, size_t n)
637 {
638 const unsigned char *p = s;
639 while (n-- != 0) {
640 if ((unsigned char)c == *p++) {
641 return (void *)(p-1);
642 }
643 }
644 return NULL;
645 }
646
647 #endif
648 #ifndef __HAVE_ARCH_MEMCHR_INV
check_bytes8(const u8 * start,u8 value,unsigned int bytes)649 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
650 {
651 while (bytes) {
652 if (*start != value)
653 return (void *)start;
654 start++;
655 bytes--;
656 }
657 return NULL;
658 }
659 /**
660 * memchr_inv - Find an unmatching character in an area of memory.
661 * @start: The memory area
662 * @c: Find a character other than c
663 * @bytes: The size of the area.
664 *
665 * returns the address of the first character other than @c, or %NULL
666 * if the whole buffer contains just @c.
667 */
memchr_inv(const void * start,int c,size_t bytes)668 void *memchr_inv(const void *start, int c, size_t bytes)
669 {
670 u8 value = c;
671 u64 value64;
672 unsigned int words, prefix;
673
674 if (bytes <= 16)
675 return check_bytes8(start, value, bytes);
676
677 value64 = value;
678 value64 |= value64 << 8;
679 value64 |= value64 << 16;
680 value64 |= value64 << 32;
681
682 prefix = (unsigned long)start % 8;
683 if (prefix) {
684 u8 *r;
685
686 prefix = 8 - prefix;
687 r = check_bytes8(start, value, prefix);
688 if (r)
689 return r;
690 start += prefix;
691 bytes -= prefix;
692 }
693
694 words = bytes / 8;
695
696 while (words) {
697 if (*(u64 *)start != value64)
698 return check_bytes8(start, value, 8);
699 start += 8;
700 words--;
701 }
702
703 return check_bytes8(start, value, bytes % 8);
704 }
705 #endif
706