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/kernel.h>
26#include <linux/export.h>
27#include <linux/bug.h>
28#include <linux/errno.h>
29
30#ifndef __HAVE_ARCH_STRNICMP
31/**
32 * strnicmp - 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 strnicmp(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(strnicmp);
60#endif
61
62#ifndef __HAVE_ARCH_STRCASECMP
63int strcasecmp(const char *s1, const char *s2)
64{
65    int c1, c2;
66
67    do {
68        c1 = tolower(*s1++);
69        c2 = tolower(*s2++);
70    } while (c1 == c2 && c1 != 0);
71    return c1 - c2;
72}
73EXPORT_SYMBOL(strcasecmp);
74#endif
75
76#ifndef __HAVE_ARCH_STRNCASECMP
77int strncasecmp(const char *s1, const char *s2, size_t n)
78{
79    int c1, c2;
80
81    do {
82        c1 = tolower(*s1++);
83        c2 = tolower(*s2++);
84    } while ((--n > 0) && c1 == c2 && c1 != 0);
85    return c1 - c2;
86}
87EXPORT_SYMBOL(strncasecmp);
88#endif
89
90#ifndef __HAVE_ARCH_STRCPY
91/**
92 * strcpy - Copy a %NUL terminated string
93 * @dest: Where to copy the string to
94 * @src: Where to copy the string from
95 */
96#undef strcpy
97char *strcpy(char *dest, const char *src)
98{
99    char *tmp = dest;
100
101    while ((*dest++ = *src++) != '\0')
102        /* nothing */;
103    return tmp;
104}
105EXPORT_SYMBOL(strcpy);
106#endif
107
108#ifndef __HAVE_ARCH_STRNCPY
109/**
110 * strncpy - Copy a length-limited, %NUL-terminated string
111 * @dest: Where to copy the string to
112 * @src: Where to copy the string from
113 * @count: The maximum number of bytes to copy
114 *
115 * The result is not %NUL-terminated if the source exceeds
116 * @count bytes.
117 *
118 * In the case where the length of @src is less than that of
119 * count, the remainder of @dest will be padded with %NUL.
120 *
121 */
122char *strncpy(char *dest, const char *src, size_t count)
123{
124    char *tmp = dest;
125
126    while (count) {
127        if ((*tmp = *src) != 0)
128            src++;
129        tmp++;
130        count--;
131    }
132    return dest;
133}
134EXPORT_SYMBOL(strncpy);
135#endif
136
137#ifndef __HAVE_ARCH_STRLCPY
138/**
139 * strlcpy - Copy a %NUL terminated string into a sized buffer
140 * @dest: Where to copy the string to
141 * @src: Where to copy the string from
142 * @size: size of destination buffer
143 *
144 * Compatible with *BSD: the result is always a valid
145 * NUL-terminated string that fits in the buffer (unless,
146 * of course, the buffer size is zero). It does not pad
147 * out the result like strncpy() does.
148 */
149size_t strlcpy(char *dest, const char *src, size_t size)
150{
151    size_t ret = strlen(src);
152
153    if (size) {
154        size_t len = (ret >= size) ? size - 1 : ret;
155        memcpy(dest, src, len);
156        dest[len] = '\0';
157    }
158    return ret;
159}
160EXPORT_SYMBOL(strlcpy);
161#endif
162
163#ifndef __HAVE_ARCH_STRCAT
164/**
165 * strcat - Append one %NUL-terminated string to another
166 * @dest: The string to be appended to
167 * @src: The string to append to it
168 */
169#undef strcat
170char *strcat(char *dest, const char *src)
171{
172    char *tmp = dest;
173
174    while (*dest)
175        dest++;
176    while ((*dest++ = *src++) != '\0')
177        ;
178    return tmp;
179}
180EXPORT_SYMBOL(strcat);
181#endif
182
183#ifndef __HAVE_ARCH_STRNCAT
184/**
185 * strncat - Append a length-limited, %NUL-terminated string to another
186 * @dest: The string to be appended to
187 * @src: The string to append to it
188 * @count: The maximum numbers of bytes to copy
189 *
190 * Note that in contrast to strncpy(), strncat() ensures the result is
191 * terminated.
192 */
193char *strncat(char *dest, const char *src, size_t count)
194{
195    char *tmp = dest;
196
197    if (count) {
198        while (*dest)
199            dest++;
200        while ((*dest++ = *src++) != 0) {
201            if (--count == 0) {
202                *dest = '\0';
203                break;
204            }
205        }
206    }
207    return tmp;
208}
209EXPORT_SYMBOL(strncat);
210#endif
211
212#ifndef __HAVE_ARCH_STRLCAT
213/**
214 * strlcat - Append a length-limited, %NUL-terminated string to another
215 * @dest: The string to be appended to
216 * @src: The string to append to it
217 * @count: The size of the destination buffer.
218 */
219size_t strlcat(char *dest, const char *src, size_t count)
220{
221    size_t dsize = strlen(dest);
222    size_t len = strlen(src);
223    size_t res = dsize + len;
224
225    /* This would be a bug */
226    BUG_ON(dsize >= count);
227
228    dest += dsize;
229    count -= dsize;
230    if (len >= count)
231        len = count-1;
232    memcpy(dest, src, len);
233    dest[len] = 0;
234    return res;
235}
236EXPORT_SYMBOL(strlcat);
237#endif
238
239#ifndef __HAVE_ARCH_STRCMP
240/**
241 * strcmp - Compare two strings
242 * @cs: One string
243 * @ct: Another string
244 */
245#undef strcmp
246int strcmp(const char *cs, const char *ct)
247{
248    unsigned char c1, c2;
249
250    while (1) {
251        c1 = *cs++;
252        c2 = *ct++;
253        if (c1 != c2)
254            return c1 < c2 ? -1 : 1;
255        if (!c1)
256            break;
257    }
258    return 0;
259}
260EXPORT_SYMBOL(strcmp);
261#endif
262
263#ifndef __HAVE_ARCH_STRNCMP
264/**
265 * strncmp - Compare two length-limited strings
266 * @cs: One string
267 * @ct: Another string
268 * @count: The maximum number of bytes to compare
269 */
270int strncmp(const char *cs, const char *ct, size_t count)
271{
272    unsigned char c1, c2;
273
274    while (count) {
275        c1 = *cs++;
276        c2 = *ct++;
277        if (c1 != c2)
278            return c1 < c2 ? -1 : 1;
279        if (!c1)
280            break;
281        count--;
282    }
283    return 0;
284}
285EXPORT_SYMBOL(strncmp);
286#endif
287
288#ifndef __HAVE_ARCH_STRCHR
289/**
290 * strchr - Find the first occurrence of a character in a string
291 * @s: The string to be searched
292 * @c: The character to search for
293 */
294char *strchr(const char *s, int c)
295{
296    for (; *s != (char)c; ++s)
297        if (*s == '\0')
298            return NULL;
299    return (char *)s;
300}
301EXPORT_SYMBOL(strchr);
302#endif
303
304#ifndef __HAVE_ARCH_STRRCHR
305/**
306 * strrchr - Find the last occurrence of a character in a string
307 * @s: The string to be searched
308 * @c: The character to search for
309 */
310char *strrchr(const char *s, int c)
311{
312       const char *p = s + strlen(s);
313       do {
314           if (*p == (char)c)
315               return (char *)p;
316       } while (--p >= s);
317       return NULL;
318}
319EXPORT_SYMBOL(strrchr);
320#endif
321
322#ifndef __HAVE_ARCH_STRNCHR
323/**
324 * strnchr - Find a character in a length limited string
325 * @s: The string to be searched
326 * @count: The number of characters to be searched
327 * @c: The character to search for
328 */
329char *strnchr(const char *s, size_t count, int c)
330{
331    for (; count-- && *s != '\0'; ++s)
332        if (*s == (char)c)
333            return (char *)s;
334    return NULL;
335}
336EXPORT_SYMBOL(strnchr);
337#endif
338
339/**
340 * skip_spaces - Removes leading whitespace from @str.
341 * @str: The string to be stripped.
342 *
343 * Returns a pointer to the first non-whitespace character in @str.
344 */
345char *skip_spaces(const char *str)
346{
347    while (isspace(*str))
348        ++str;
349    return (char *)str;
350}
351EXPORT_SYMBOL(skip_spaces);
352
353/**
354 * strim - Removes leading and trailing whitespace from @s.
355 * @s: The string to be stripped.
356 *
357 * Note that the first trailing whitespace is replaced with a %NUL-terminator
358 * in the given string @s. Returns a pointer to the first non-whitespace
359 * character in @s.
360 */
361char *strim(char *s)
362{
363    size_t size;
364    char *end;
365
366    size = strlen(s);
367    if (!size)
368        return s;
369
370    end = s + size - 1;
371    while (end >= s && isspace(*end))
372        end--;
373    *(end + 1) = '\0';
374
375    return skip_spaces(s);
376}
377EXPORT_SYMBOL(strim);
378
379#ifndef __HAVE_ARCH_STRLEN
380/**
381 * strlen - Find the length of a string
382 * @s: The string to be sized
383 */
384size_t strlen(const char *s)
385{
386    const char *sc;
387
388    for (sc = s; *sc != '\0'; ++sc)
389        /* nothing */;
390    return sc - s;
391}
392EXPORT_SYMBOL(strlen);
393#endif
394
395#ifndef __HAVE_ARCH_STRNLEN
396/**
397 * strnlen - Find the length of a length-limited string
398 * @s: The string to be sized
399 * @count: The maximum number of bytes to search
400 */
401size_t strnlen(const char *s, size_t count)
402{
403    const char *sc;
404
405    for (sc = s; count-- && *sc != '\0'; ++sc)
406        /* nothing */;
407    return sc - s;
408}
409EXPORT_SYMBOL(strnlen);
410#endif
411
412#ifndef __HAVE_ARCH_STRSPN
413/**
414 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
415 * @s: The string to be searched
416 * @accept: The string to search for
417 */
418size_t strspn(const char *s, const char *accept)
419{
420    const char *p;
421    const char *a;
422    size_t count = 0;
423
424    for (p = s; *p != '\0'; ++p) {
425        for (a = accept; *a != '\0'; ++a) {
426            if (*p == *a)
427                break;
428        }
429        if (*a == '\0')
430            return count;
431        ++count;
432    }
433    return count;
434}
435
436EXPORT_SYMBOL(strspn);
437#endif
438
439#ifndef __HAVE_ARCH_STRCSPN
440/**
441 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
442 * @s: The string to be searched
443 * @reject: The string to avoid
444 */
445size_t strcspn(const char *s, const char *reject)
446{
447    const char *p;
448    const char *r;
449    size_t count = 0;
450
451    for (p = s; *p != '\0'; ++p) {
452        for (r = reject; *r != '\0'; ++r) {
453            if (*p == *r)
454                return count;
455        }
456        ++count;
457    }
458    return count;
459}
460EXPORT_SYMBOL(strcspn);
461#endif
462
463#ifndef __HAVE_ARCH_STRPBRK
464/**
465 * strpbrk - Find the first occurrence of a set of characters
466 * @cs: The string to be searched
467 * @ct: The characters to search for
468 */
469char *strpbrk(const char *cs, const char *ct)
470{
471    const char *sc1, *sc2;
472
473    for (sc1 = cs; *sc1 != '\0'; ++sc1) {
474        for (sc2 = ct; *sc2 != '\0'; ++sc2) {
475            if (*sc1 == *sc2)
476                return (char *)sc1;
477        }
478    }
479    return NULL;
480}
481EXPORT_SYMBOL(strpbrk);
482#endif
483
484#ifndef __HAVE_ARCH_STRSEP
485/**
486 * strsep - Split a string into tokens
487 * @s: The string to be searched
488 * @ct: The characters to search for
489 *
490 * strsep() updates @s to point after the token, ready for the next call.
491 *
492 * It returns empty tokens, too, behaving exactly like the libc function
493 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
494 * Same semantics, slimmer shape. ;)
495 */
496char *strsep(char **s, const char *ct)
497{
498    char *sbegin = *s;
499    char *end;
500
501    if (sbegin == NULL)
502        return NULL;
503
504    end = strpbrk(sbegin, ct);
505    if (end)
506        *end++ = '\0';
507    *s = end;
508    return sbegin;
509}
510EXPORT_SYMBOL(strsep);
511#endif
512
513/**
514 * sysfs_streq - return true if strings are equal, modulo trailing newline
515 * @s1: one string
516 * @s2: another string
517 *
518 * This routine returns true iff two strings are equal, treating both
519 * NUL and newline-then-NUL as equivalent string terminations. It's
520 * geared for use with sysfs input strings, which generally terminate
521 * with newlines but are compared against values without newlines.
522 */
523bool sysfs_streq(const char *s1, const char *s2)
524{
525    while (*s1 && *s1 == *s2) {
526        s1++;
527        s2++;
528    }
529
530    if (*s1 == *s2)
531        return true;
532    if (!*s1 && *s2 == '\n' && !s2[1])
533        return true;
534    if (*s1 == '\n' && !s1[1] && !*s2)
535        return true;
536    return false;
537}
538EXPORT_SYMBOL(sysfs_streq);
539
540/**
541 * strtobool - convert common user inputs into boolean values
542 * @s: input string
543 * @res: result
544 *
545 * This routine returns 0 iff the first character is one of 'Yy1Nn0'.
546 * Otherwise it will return -EINVAL. Value pointed to by res is
547 * updated upon finding a match.
548 */
549int strtobool(const char *s, bool *res)
550{
551    switch (s[0]) {
552    case 'y':
553    case 'Y':
554    case '1':
555        *res = true;
556        break;
557    case 'n':
558    case 'N':
559    case '0':
560        *res = false;
561        break;
562    default:
563        return -EINVAL;
564    }
565    return 0;
566}
567EXPORT_SYMBOL(strtobool);
568
569#ifndef __HAVE_ARCH_MEMSET
570/**
571 * memset - Fill a region of memory with the given value
572 * @s: Pointer to the start of the area.
573 * @c: The byte to fill the area with
574 * @count: The size of the area.
575 *
576 * Do not use memset() to access IO space, use memset_io() instead.
577 */
578void *memset(void *s, int c, size_t count)
579{
580    char *xs = s;
581
582    while (count--)
583        *xs++ = c;
584    return s;
585}
586EXPORT_SYMBOL(memset);
587#endif
588
589#ifndef __HAVE_ARCH_MEMCPY
590/**
591 * memcpy - Copy one area of memory to another
592 * @dest: Where to copy to
593 * @src: Where to copy from
594 * @count: The size of the area.
595 *
596 * You should not use this function to access IO space, use memcpy_toio()
597 * or memcpy_fromio() instead.
598 */
599void *memcpy(void *dest, const void *src, size_t count)
600{
601    char *tmp = dest;
602    const char *s = src;
603
604    while (count--)
605        *tmp++ = *s++;
606    return dest;
607}
608EXPORT_SYMBOL(memcpy);
609#endif
610
611#ifndef __HAVE_ARCH_MEMMOVE
612/**
613 * memmove - Copy one area of memory to another
614 * @dest: Where to copy to
615 * @src: Where to copy from
616 * @count: The size of the area.
617 *
618 * Unlike memcpy(), memmove() copes with overlapping areas.
619 */
620void *memmove(void *dest, const void *src, size_t count)
621{
622    char *tmp;
623    const char *s;
624
625    if (dest <= src) {
626        tmp = dest;
627        s = src;
628        while (count--)
629            *tmp++ = *s++;
630    } else {
631        tmp = dest;
632        tmp += count;
633        s = src;
634        s += count;
635        while (count--)
636            *--tmp = *--s;
637    }
638    return dest;
639}
640EXPORT_SYMBOL(memmove);
641#endif
642
643#ifndef __HAVE_ARCH_MEMCMP
644/**
645 * memcmp - Compare two areas of memory
646 * @cs: One area of memory
647 * @ct: Another area of memory
648 * @count: The size of the area.
649 */
650#undef memcmp
651int memcmp(const void *cs, const void *ct, size_t count)
652{
653    const unsigned char *su1, *su2;
654    int res = 0;
655
656    for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
657        if ((res = *su1 - *su2) != 0)
658            break;
659    return res;
660}
661EXPORT_SYMBOL(memcmp);
662#endif
663
664#ifndef __HAVE_ARCH_MEMSCAN
665/**
666 * memscan - Find a character in an area of memory.
667 * @addr: The memory area
668 * @c: The byte to search for
669 * @size: The size of the area.
670 *
671 * returns the address of the first occurrence of @c, or 1 byte past
672 * the area if @c is not found
673 */
674void *memscan(void *addr, int c, size_t size)
675{
676    unsigned char *p = addr;
677
678    while (size) {
679        if (*p == c)
680            return (void *)p;
681        p++;
682        size--;
683    }
684      return (void *)p;
685}
686EXPORT_SYMBOL(memscan);
687#endif
688
689#ifndef __HAVE_ARCH_STRSTR
690/**
691 * strstr - Find the first substring in a %NUL terminated string
692 * @s1: The string to be searched
693 * @s2: The string to search for
694 */
695char *strstr(const char *s1, const char *s2)
696{
697    size_t l1, l2;
698
699    l2 = strlen(s2);
700    if (!l2)
701        return (char *)s1;
702    l1 = strlen(s1);
703    while (l1 >= l2) {
704        l1--;
705        if (!memcmp(s1, s2, l2))
706            return (char *)s1;
707        s1++;
708    }
709    return NULL;
710}
711EXPORT_SYMBOL(strstr);
712#endif
713
714#ifndef __HAVE_ARCH_STRNSTR
715/**
716 * strnstr - Find the first substring in a length-limited string
717 * @s1: The string to be searched
718 * @s2: The string to search for
719 * @len: the maximum number of characters to search
720 */
721char *strnstr(const char *s1, const char *s2, size_t len)
722{
723    size_t l2;
724
725    l2 = strlen(s2);
726    if (!l2)
727        return (char *)s1;
728    while (len >= l2) {
729        len--;
730        if (!memcmp(s1, s2, l2))
731            return (char *)s1;
732        s1++;
733    }
734    return NULL;
735}
736EXPORT_SYMBOL(strnstr);
737#endif
738
739#ifndef __HAVE_ARCH_MEMCHR
740/**
741 * memchr - Find a character in an area of memory.
742 * @s: The memory area
743 * @c: The byte to search for
744 * @n: The size of the area.
745 *
746 * returns the address of the first occurrence of @c, or %NULL
747 * if @c is not found
748 */
749void *memchr(const void *s, int c, size_t n)
750{
751    const unsigned char *p = s;
752    while (n-- != 0) {
753            if ((unsigned char)c == *p++) {
754            return (void *)(p - 1);
755        }
756    }
757    return NULL;
758}
759EXPORT_SYMBOL(memchr);
760#endif
761
762static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
763{
764    while (bytes) {
765        if (*start != value)
766            return (void *)start;
767        start++;
768        bytes--;
769    }
770    return NULL;
771}
772
773/**
774 * memchr_inv - Find an unmatching character in an area of memory.
775 * @start: The memory area
776 * @c: Find a character other than c
777 * @bytes: The size of the area.
778 *
779 * returns the address of the first character other than @c, or %NULL
780 * if the whole buffer contains just @c.
781 */
782void *memchr_inv(const void *start, int c, size_t bytes)
783{
784    u8 value = c;
785    u64 value64;
786    unsigned int words, prefix;
787
788    if (bytes <= 16)
789        return check_bytes8(start, value, bytes);
790
791    value64 = value;
792#if defined(ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
793    value64 *= 0x0101010101010101;
794#elif defined(ARCH_HAS_FAST_MULTIPLIER)
795    value64 *= 0x01010101;
796    value64 |= value64 << 32;
797#else
798    value64 |= value64 << 8;
799    value64 |= value64 << 16;
800    value64 |= value64 << 32;
801#endif
802
803    prefix = (unsigned long)start % 8;
804    if (prefix) {
805        u8 *r;
806
807        prefix = 8 - prefix;
808        r = check_bytes8(start, value, prefix);
809        if (r)
810            return r;
811        start += prefix;
812        bytes -= prefix;
813    }
814
815    words = bytes / 8;
816
817    while (words) {
818        if (*(u64 *)start != value64)
819            return check_bytes8(start, value, 8);
820        start += 8;
821        words--;
822    }
823
824    return check_bytes8(start, value, bytes % 8);
825}
826EXPORT_SYMBOL(memchr_inv);
827

Archive Download this file



interactive