linux/lib/string.c
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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 * * 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/**
 539 * strtobool - convert common user inputs into boolean values
 540 * @s: input string
 541 * @res: result
 542 *
 543 * This routine returns 0 iff the first character is one of 'Yy1Nn0'.
 544 * Otherwise it will return -EINVAL.  Value pointed to by res is
 545 * updated upon finding a match.
 546 */
 547int strtobool(const char *s, bool *res)
 548{
 549        switch (s[0]) {
 550        case 'y':
 551        case 'Y':
 552        case '1':
 553                *res = true;
 554                break;
 555        case 'n':
 556        case 'N':
 557        case '0':
 558                *res = false;
 559                break;
 560        default:
 561                return -EINVAL;
 562        }
 563        return 0;
 564}
 565EXPORT_SYMBOL(strtobool);
 566
 567#ifndef __HAVE_ARCH_MEMSET
 568/**
 569 * memset - Fill a region of memory with the given value
 570 * @s: Pointer to the start of the area.
 571 * @c: The byte to fill the area with
 572 * @count: The size of the area.
 573 *
 574 * Do not use memset() to access IO space, use memset_io() instead.
 575 */
 576void *memset(void *s, int c, size_t count)
 577{
 578        char *xs = s;
 579
 580        while (count--)
 581                *xs++ = c;
 582        return s;
 583}
 584EXPORT_SYMBOL(memset);
 585#endif
 586
 587#ifndef __HAVE_ARCH_MEMCPY
 588/**
 589 * memcpy - Copy one area of memory to another
 590 * @dest: Where to copy to
 591 * @src: Where to copy from
 592 * @count: The size of the area.
 593 *
 594 * You should not use this function to access IO space, use memcpy_toio()
 595 * or memcpy_fromio() instead.
 596 */
 597void *memcpy(void *dest, const void *src, size_t count)
 598{
 599        char *tmp = dest;
 600        const char *s = src;
 601
 602        while (count--)
 603                *tmp++ = *s++;
 604        return dest;
 605}
 606EXPORT_SYMBOL(memcpy);
 607#endif
 608
 609#ifndef __HAVE_ARCH_MEMMOVE
 610/**
 611 * memmove - Copy one area of memory to another
 612 * @dest: Where to copy to
 613 * @src: Where to copy from
 614 * @count: The size of the area.
 615 *
 616 * Unlike memcpy(), memmove() copes with overlapping areas.
 617 */
 618void *memmove(void *dest, const void *src, size_t count)
 619{
 620        char *tmp;
 621        const char *s;
 622
 623        if (dest <= src) {
 624                tmp = dest;
 625                s = src;
 626                while (count--)
 627                        *tmp++ = *s++;
 628        } else {
 629                tmp = dest;
 630                tmp += count;
 631                s = src;
 632                s += count;
 633                while (count--)
 634                        *--tmp = *--s;
 635        }
 636        return dest;
 637}
 638EXPORT_SYMBOL(memmove);
 639#endif
 640
 641#ifndef __HAVE_ARCH_MEMCMP
 642/**
 643 * memcmp - Compare two areas of memory
 644 * @cs: One area of memory
 645 * @ct: Another area of memory
 646 * @count: The size of the area.
 647 */
 648#undef memcmp
 649int memcmp(const void *cs, const void *ct, size_t count)
 650{
 651        const unsigned char *su1, *su2;
 652        int res = 0;
 653
 654        for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 655                if ((res = *su1 - *su2) != 0)
 656                        break;
 657        return res;
 658}
 659EXPORT_SYMBOL(memcmp);
 660#endif
 661
 662#ifndef __HAVE_ARCH_MEMSCAN
 663/**
 664 * memscan - Find a character in an area of memory.
 665 * @addr: The memory area
 666 * @c: The byte to search for
 667 * @size: The size of the area.
 668 *
 669 * returns the address of the first occurrence of @c, or 1 byte past
 670 * the area if @c is not found
 671 */
 672void *memscan(void *addr, int c, size_t size)
 673{
 674        unsigned char *p = addr;
 675
 676        while (size) {
 677                if (*p == c)
 678                        return (void *)p;
 679                p++;
 680                size--;
 681        }
 682        return (void *)p;
 683}
 684EXPORT_SYMBOL(memscan);
 685#endif
 686
 687#ifndef __HAVE_ARCH_STRSTR
 688/**
 689 * strstr - Find the first substring in a %NUL terminated string
 690 * @s1: The string to be searched
 691 * @s2: The string to search for
 692 */
 693char *strstr(const char *s1, const char *s2)
 694{
 695        size_t l1, l2;
 696
 697        l2 = strlen(s2);
 698        if (!l2)
 699                return (char *)s1;
 700        l1 = strlen(s1);
 701        while (l1 >= l2) {
 702                l1--;
 703                if (!memcmp(s1, s2, l2))
 704                        return (char *)s1;
 705                s1++;
 706        }
 707        return NULL;
 708}
 709EXPORT_SYMBOL(strstr);
 710#endif
 711
 712#ifndef __HAVE_ARCH_STRNSTR
 713/**
 714 * strnstr - Find the first substring in a length-limited string
 715 * @s1: The string to be searched
 716 * @s2: The string to search for
 717 * @len: the maximum number of characters to search
 718 */
 719char *strnstr(const char *s1, const char *s2, size_t len)
 720{
 721        size_t l2;
 722
 723        l2 = strlen(s2);
 724        if (!l2)
 725                return (char *)s1;
 726        while (len >= l2) {
 727                len--;
 728                if (!memcmp(s1, s2, l2))
 729                        return (char *)s1;
 730                s1++;
 731        }
 732        return NULL;
 733}
 734EXPORT_SYMBOL(strnstr);
 735#endif
 736
 737#ifndef __HAVE_ARCH_MEMCHR
 738/**
 739 * memchr - Find a character in an area of memory.
 740 * @s: The memory area
 741 * @c: The byte to search for
 742 * @n: The size of the area.
 743 *
 744 * returns the address of the first occurrence of @c, or %NULL
 745 * if @c is not found
 746 */
 747void *memchr(const void *s, int c, size_t n)
 748{
 749        const unsigned char *p = s;
 750        while (n-- != 0) {
 751                if ((unsigned char)c == *p++) {
 752                        return (void *)(p - 1);
 753                }
 754        }
 755        return NULL;
 756}
 757EXPORT_SYMBOL(memchr);
 758#endif
 759
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