Root/lib/string.c

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 */
34int 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    if (!len)
40        return 0;
41
42    do {
43        c1 = *s1++;
44        c2 = *s2++;
45        if (!c1 || !c2)
46            break;
47        if (c1 == c2)
48            continue;
49        c1 = tolower(c1);
50        c2 = tolower(c2);
51        if (c1 != c2)
52            break;
53    } while (--len);
54    return (int)c1 - (int)c2;
55}
56EXPORT_SYMBOL(strnicmp);
57#endif
58
59#ifndef __HAVE_ARCH_STRCASECMP
60int strcasecmp(const char *s1, const char *s2)
61{
62    int c1, c2;
63
64    do {
65        c1 = tolower(*s1++);
66        c2 = tolower(*s2++);
67    } while (c1 == c2 && c1 != 0);
68    return c1 - c2;
69}
70EXPORT_SYMBOL(strcasecmp);
71#endif
72
73#ifndef __HAVE_ARCH_STRNCASECMP
74int strncasecmp(const char *s1, const char *s2, size_t n)
75{
76    int c1, c2;
77
78    do {
79        c1 = tolower(*s1++);
80        c2 = tolower(*s2++);
81    } while ((--n > 0) && c1 == c2 && c1 != 0);
82    return c1 - c2;
83}
84EXPORT_SYMBOL(strncasecmp);
85#endif
86
87#ifndef __HAVE_ARCH_STRCPY
88/**
89 * strcpy - Copy a %NUL terminated string
90 * @dest: Where to copy the string to
91 * @src: Where to copy the string from
92 */
93#undef strcpy
94char *strcpy(char *dest, const char *src)
95{
96    char *tmp = dest;
97
98    while ((*dest++ = *src++) != '\0')
99        /* nothing */;
100    return tmp;
101}
102EXPORT_SYMBOL(strcpy);
103#endif
104
105#ifndef __HAVE_ARCH_STRNCPY
106/**
107 * strncpy - Copy a length-limited, %NUL-terminated string
108 * @dest: Where to copy the string to
109 * @src: Where to copy the string from
110 * @count: The maximum number of bytes to copy
111 *
112 * The result is not %NUL-terminated if the source exceeds
113 * @count bytes.
114 *
115 * In the case where the length of @src is less than that of
116 * count, the remainder of @dest will be padded with %NUL.
117 *
118 */
119char *strncpy(char *dest, const char *src, size_t count)
120{
121    char *tmp = dest;
122
123    while (count) {
124        if ((*tmp = *src) != 0)
125            src++;
126        tmp++;
127        count--;
128    }
129    return dest;
130}
131EXPORT_SYMBOL(strncpy);
132#endif
133
134#ifndef __HAVE_ARCH_STRLCPY
135/**
136 * strlcpy - Copy a %NUL terminated string into a sized buffer
137 * @dest: Where to copy the string to
138 * @src: Where to copy the string from
139 * @size: size of destination buffer
140 *
141 * Compatible with *BSD: the result is always a valid
142 * NUL-terminated string that fits in the buffer (unless,
143 * of course, the buffer size is zero). It does not pad
144 * out the result like strncpy() does.
145 */
146size_t strlcpy(char *dest, const char *src, size_t size)
147{
148    size_t ret = strlen(src);
149
150    if (size) {
151        size_t len = (ret >= size) ? size - 1 : ret;
152        memcpy(dest, src, len);
153        dest[len] = '\0';
154    }
155    return ret;
156}
157EXPORT_SYMBOL(strlcpy);
158#endif
159
160#ifndef __HAVE_ARCH_STRCAT
161/**
162 * strcat - Append one %NUL-terminated string to another
163 * @dest: The string to be appended to
164 * @src: The string to append to it
165 */
166#undef strcat
167char *strcat(char *dest, const char *src)
168{
169    char *tmp = dest;
170
171    while (*dest)
172        dest++;
173    while ((*dest++ = *src++) != '\0')
174        ;
175    return tmp;
176}
177EXPORT_SYMBOL(strcat);
178#endif
179
180#ifndef __HAVE_ARCH_STRNCAT
181/**
182 * strncat - Append a length-limited, %NUL-terminated string to another
183 * @dest: The string to be appended to
184 * @src: The string to append to it
185 * @count: The maximum numbers of bytes to copy
186 *
187 * Note that in contrast to strncpy(), strncat() ensures the result is
188 * terminated.
189 */
190char *strncat(char *dest, const char *src, size_t count)
191{
192    char *tmp = dest;
193
194    if (count) {
195        while (*dest)
196            dest++;
197        while ((*dest++ = *src++) != 0) {
198            if (--count == 0) {
199                *dest = '\0';
200                break;
201            }
202        }
203    }
204    return tmp;
205}
206EXPORT_SYMBOL(strncat);
207#endif
208
209#ifndef __HAVE_ARCH_STRLCAT
210/**
211 * strlcat - Append a length-limited, %NUL-terminated string to another
212 * @dest: The string to be appended to
213 * @src: The string to append to it
214 * @count: The size of the destination buffer.
215 */
216size_t strlcat(char *dest, const char *src, size_t count)
217{
218    size_t dsize = strlen(dest);
219    size_t len = strlen(src);
220    size_t res = dsize + len;
221
222    /* This would be a bug */
223    BUG_ON(dsize >= count);
224
225    dest += dsize;
226    count -= dsize;
227    if (len >= count)
228        len = count-1;
229    memcpy(dest, src, len);
230    dest[len] = 0;
231    return res;
232}
233EXPORT_SYMBOL(strlcat);
234#endif
235
236#ifndef __HAVE_ARCH_STRCMP
237/**
238 * strcmp - Compare two strings
239 * @cs: One string
240 * @ct: Another string
241 */
242#undef strcmp
243int strcmp(const char *cs, const char *ct)
244{
245    unsigned char c1, c2;
246
247    while (1) {
248        c1 = *cs++;
249        c2 = *ct++;
250        if (c1 != c2)
251            return c1 < c2 ? -1 : 1;
252        if (!c1)
253            break;
254    }
255    return 0;
256}
257EXPORT_SYMBOL(strcmp);
258#endif
259
260#ifndef __HAVE_ARCH_STRNCMP
261/**
262 * strncmp - Compare two length-limited strings
263 * @cs: One string
264 * @ct: Another string
265 * @count: The maximum number of bytes to compare
266 */
267int strncmp(const char *cs, const char *ct, size_t count)
268{
269    unsigned char c1, c2;
270
271    while (count) {
272        c1 = *cs++;
273        c2 = *ct++;
274        if (c1 != c2)
275            return c1 < c2 ? -1 : 1;
276        if (!c1)
277            break;
278        count--;
279    }
280    return 0;
281}
282EXPORT_SYMBOL(strncmp);
283#endif
284
285#ifndef __HAVE_ARCH_STRCHR
286/**
287 * strchr - Find the first occurrence of a character in a string
288 * @s: The string to be searched
289 * @c: The character to search for
290 */
291char *strchr(const char *s, int c)
292{
293    for (; *s != (char)c; ++s)
294        if (*s == '\0')
295            return NULL;
296    return (char *)s;
297}
298EXPORT_SYMBOL(strchr);
299#endif
300
301#ifndef __HAVE_ARCH_STRRCHR
302/**
303 * strrchr - Find the last occurrence of a character in a string
304 * @s: The string to be searched
305 * @c: The character to search for
306 */
307char *strrchr(const char *s, int c)
308{
309       const char *p = s + strlen(s);
310       do {
311           if (*p == (char)c)
312               return (char *)p;
313       } while (--p >= s);
314       return NULL;
315}
316EXPORT_SYMBOL(strrchr);
317#endif
318
319#ifndef __HAVE_ARCH_STRNCHR
320/**
321 * strnchr - Find a character in a length limited string
322 * @s: The string to be searched
323 * @count: The number of characters to be searched
324 * @c: The character to search for
325 */
326char *strnchr(const char *s, size_t count, int c)
327{
328    for (; count-- && *s != '\0'; ++s)
329        if (*s == (char)c)
330            return (char *)s;
331    return NULL;
332}
333EXPORT_SYMBOL(strnchr);
334#endif
335
336/**
337 * skip_spaces - Removes leading whitespace from @str.
338 * @str: The string to be stripped.
339 *
340 * Returns a pointer to the first non-whitespace character in @str.
341 */
342char *skip_spaces(const char *str)
343{
344    while (isspace(*str))
345        ++str;
346    return (char *)str;
347}
348EXPORT_SYMBOL(skip_spaces);
349
350/**
351 * strim - Removes leading and trailing whitespace from @s.
352 * @s: The string to be stripped.
353 *
354 * Note that the first trailing whitespace is replaced with a %NUL-terminator
355 * in the given string @s. Returns a pointer to the first non-whitespace
356 * character in @s.
357 */
358char *strim(char *s)
359{
360    size_t size;
361    char *end;
362
363    s = skip_spaces(s);
364    size = strlen(s);
365    if (!size)
366        return s;
367
368    end = s + size - 1;
369    while (end >= s && isspace(*end))
370        end--;
371    *(end + 1) = '\0';
372
373    return s;
374}
375EXPORT_SYMBOL(strim);
376
377#ifndef __HAVE_ARCH_STRLEN
378/**
379 * strlen - Find the length of a string
380 * @s: The string to be sized
381 */
382size_t strlen(const char *s)
383{
384    const char *sc;
385
386    for (sc = s; *sc != '\0'; ++sc)
387        /* nothing */;
388    return sc - s;
389}
390EXPORT_SYMBOL(strlen);
391#endif
392
393#ifndef __HAVE_ARCH_STRNLEN
394/**
395 * strnlen - Find the length of a length-limited string
396 * @s: The string to be sized
397 * @count: The maximum number of bytes to search
398 */
399size_t strnlen(const char *s, size_t count)
400{
401    const char *sc;
402
403    for (sc = s; count-- && *sc != '\0'; ++sc)
404        /* nothing */;
405    return sc - s;
406}
407EXPORT_SYMBOL(strnlen);
408#endif
409
410#ifndef __HAVE_ARCH_STRSPN
411/**
412 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
413 * @s: The string to be searched
414 * @accept: The string to search for
415 */
416size_t strspn(const char *s, const char *accept)
417{
418    const char *p;
419    const char *a;
420    size_t count = 0;
421
422    for (p = s; *p != '\0'; ++p) {
423        for (a = accept; *a != '\0'; ++a) {
424            if (*p == *a)
425                break;
426        }
427        if (*a == '\0')
428            return count;
429        ++count;
430    }
431    return count;
432}
433
434EXPORT_SYMBOL(strspn);
435#endif
436
437#ifndef __HAVE_ARCH_STRCSPN
438/**
439 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
440 * @s: The string to be searched
441 * @reject: The string to avoid
442 */
443size_t strcspn(const char *s, const char *reject)
444{
445    const char *p;
446    const char *r;
447    size_t count = 0;
448
449    for (p = s; *p != '\0'; ++p) {
450        for (r = reject; *r != '\0'; ++r) {
451            if (*p == *r)
452                return count;
453        }
454        ++count;
455    }
456    return count;
457}
458EXPORT_SYMBOL(strcspn);
459#endif
460
461#ifndef __HAVE_ARCH_STRPBRK
462/**
463 * strpbrk - Find the first occurrence of a set of characters
464 * @cs: The string to be searched
465 * @ct: The characters to search for
466 */
467char *strpbrk(const char *cs, const char *ct)
468{
469    const char *sc1, *sc2;
470
471    for (sc1 = cs; *sc1 != '\0'; ++sc1) {
472        for (sc2 = ct; *sc2 != '\0'; ++sc2) {
473            if (*sc1 == *sc2)
474                return (char *)sc1;
475        }
476    }
477    return NULL;
478}
479EXPORT_SYMBOL(strpbrk);
480#endif
481
482#ifndef __HAVE_ARCH_STRSEP
483/**
484 * strsep - Split a string into tokens
485 * @s: The string to be searched
486 * @ct: The characters to search for
487 *
488 * strsep() updates @s to point after the token, ready for the next call.
489 *
490 * It returns empty tokens, too, behaving exactly like the libc function
491 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
492 * Same semantics, slimmer shape. ;)
493 */
494char *strsep(char **s, const char *ct)
495{
496    char *sbegin = *s;
497    char *end;
498
499    if (sbegin == NULL)
500        return NULL;
501
502    end = strpbrk(sbegin, ct);
503    if (end)
504        *end++ = '\0';
505    *s = end;
506    return sbegin;
507}
508EXPORT_SYMBOL(strsep);
509#endif
510
511/**
512 * sysfs_streq - return true if strings are equal, modulo trailing newline
513 * @s1: one string
514 * @s2: another string
515 *
516 * This routine returns true iff two strings are equal, treating both
517 * NUL and newline-then-NUL as equivalent string terminations. It's
518 * geared for use with sysfs input strings, which generally terminate
519 * with newlines but are compared against values without newlines.
520 */
521bool sysfs_streq(const char *s1, const char *s2)
522{
523    while (*s1 && *s1 == *s2) {
524        s1++;
525        s2++;
526    }
527
528    if (*s1 == *s2)
529        return true;
530    if (!*s1 && *s2 == '\n' && !s2[1])
531        return true;
532    if (*s1 == '\n' && !s1[1] && !*s2)
533        return true;
534    return false;
535}
536EXPORT_SYMBOL(sysfs_streq);
537
538#ifndef __HAVE_ARCH_MEMSET
539/**
540 * memset - Fill a region of memory with the given value
541 * @s: Pointer to the start of the area.
542 * @c: The byte to fill the area with
543 * @count: The size of the area.
544 *
545 * Do not use memset() to access IO space, use memset_io() instead.
546 */
547void *memset(void *s, int c, size_t count)
548{
549    char *xs = s;
550
551    while (count--)
552        *xs++ = c;
553    return s;
554}
555EXPORT_SYMBOL(memset);
556#endif
557
558#ifndef __HAVE_ARCH_MEMCPY
559/**
560 * memcpy - Copy one area of memory to another
561 * @dest: Where to copy to
562 * @src: Where to copy from
563 * @count: The size of the area.
564 *
565 * You should not use this function to access IO space, use memcpy_toio()
566 * or memcpy_fromio() instead.
567 */
568void *memcpy(void *dest, const void *src, size_t count)
569{
570    char *tmp = dest;
571    const char *s = src;
572
573    while (count--)
574        *tmp++ = *s++;
575    return dest;
576}
577EXPORT_SYMBOL(memcpy);
578#endif
579
580#ifndef __HAVE_ARCH_MEMMOVE
581/**
582 * memmove - Copy one area of memory to another
583 * @dest: Where to copy to
584 * @src: Where to copy from
585 * @count: The size of the area.
586 *
587 * Unlike memcpy(), memmove() copes with overlapping areas.
588 */
589void *memmove(void *dest, const void *src, size_t count)
590{
591    char *tmp;
592    const char *s;
593
594    if (dest <= src) {
595        tmp = dest;
596        s = src;
597        while (count--)
598            *tmp++ = *s++;
599    } else {
600        tmp = dest;
601        tmp += count;
602        s = src;
603        s += count;
604        while (count--)
605            *--tmp = *--s;
606    }
607    return dest;
608}
609EXPORT_SYMBOL(memmove);
610#endif
611
612#ifndef __HAVE_ARCH_MEMCMP
613/**
614 * memcmp - Compare two areas of memory
615 * @cs: One area of memory
616 * @ct: Another area of memory
617 * @count: The size of the area.
618 */
619#undef memcmp
620int memcmp(const void *cs, const void *ct, size_t count)
621{
622    const unsigned char *su1, *su2;
623    int res = 0;
624
625    for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
626        if ((res = *su1 - *su2) != 0)
627            break;
628    return res;
629}
630EXPORT_SYMBOL(memcmp);
631#endif
632
633#ifndef __HAVE_ARCH_MEMSCAN
634/**
635 * memscan - Find a character in an area of memory.
636 * @addr: The memory area
637 * @c: The byte to search for
638 * @size: The size of the area.
639 *
640 * returns the address of the first occurrence of @c, or 1 byte past
641 * the area if @c is not found
642 */
643void *memscan(void *addr, int c, size_t size)
644{
645    unsigned char *p = addr;
646
647    while (size) {
648        if (*p == c)
649            return (void *)p;
650        p++;
651        size--;
652    }
653      return (void *)p;
654}
655EXPORT_SYMBOL(memscan);
656#endif
657
658#ifndef __HAVE_ARCH_STRSTR
659/**
660 * strstr - Find the first substring in a %NUL terminated string
661 * @s1: The string to be searched
662 * @s2: The string to search for
663 */
664char *strstr(const char *s1, const char *s2)
665{
666    size_t l1, l2;
667
668    l2 = strlen(s2);
669    if (!l2)
670        return (char *)s1;
671    l1 = strlen(s1);
672    while (l1 >= l2) {
673        l1--;
674        if (!memcmp(s1, s2, l2))
675            return (char *)s1;
676        s1++;
677    }
678    return NULL;
679}
680EXPORT_SYMBOL(strstr);
681#endif
682
683#ifndef __HAVE_ARCH_STRNSTR
684/**
685 * strnstr - Find the first substring in a length-limited string
686 * @s1: The string to be searched
687 * @s2: The string to search for
688 * @len: the maximum number of characters to search
689 */
690char *strnstr(const char *s1, const char *s2, size_t len)
691{
692    size_t l2;
693
694    l2 = strlen(s2);
695    if (!l2)
696        return (char *)s1;
697    while (len >= l2) {
698        len--;
699        if (!memcmp(s1, s2, l2))
700            return (char *)s1;
701        s1++;
702    }
703    return NULL;
704}
705EXPORT_SYMBOL(strnstr);
706#endif
707
708#ifndef __HAVE_ARCH_MEMCHR
709/**
710 * memchr - Find a character in an area of memory.
711 * @s: The memory area
712 * @c: The byte to search for
713 * @n: The size of the area.
714 *
715 * returns the address of the first occurrence of @c, or %NULL
716 * if @c is not found
717 */
718void *memchr(const void *s, int c, size_t n)
719{
720    const unsigned char *p = s;
721    while (n-- != 0) {
722            if ((unsigned char)c == *p++) {
723            return (void *)(p - 1);
724        }
725    }
726    return NULL;
727}
728EXPORT_SYMBOL(memchr);
729#endif
730

Archive Download this file



interactive