linux/lib/string.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  linux/lib/string.c
   4 *
   5 *  Copyright (C) 1991, 1992  Linus Torvalds
   6 */
   7
   8/*
   9 * stupid library routines.. The optimized versions should generally be found
  10 * as inline code in <asm-xx/string.h>
  11 *
  12 * These are buggy as well..
  13 *
  14 * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
  15 * -  Added strsep() which will replace strtok() soon (because strsep() is
  16 *    reentrant and should be faster). Use only strsep() in new code, please.
  17 *
  18 * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
  19 *                    Matthew Hawkins <matt@mh.dropbear.id.au>
  20 * -  Kissed strtok() goodbye
  21 */
  22
  23#include <linux/types.h>
  24#include <linux/string.h>
  25#include <linux/ctype.h>
  26#include <linux/kernel.h>
  27#include <linux/export.h>
  28#include <linux/bug.h>
  29#include <linux/errno.h>
  30#include <linux/slab.h>
  31
  32#include <asm/unaligned.h>
  33#include <asm/byteorder.h>
  34#include <asm/word-at-a-time.h>
  35#include <asm/page.h>
  36
  37#ifndef __HAVE_ARCH_STRNCASECMP
  38/**
  39 * strncasecmp - Case insensitive, length-limited string comparison
  40 * @s1: One string
  41 * @s2: The other string
  42 * @len: the maximum number of characters to compare
  43 */
  44int strncasecmp(const char *s1, const char *s2, size_t len)
  45{
  46        /* Yes, Virginia, it had better be unsigned */
  47        unsigned char c1, c2;
  48
  49        if (!len)
  50                return 0;
  51
  52        do {
  53                c1 = *s1++;
  54                c2 = *s2++;
  55                if (!c1 || !c2)
  56                        break;
  57                if (c1 == c2)
  58                        continue;
  59                c1 = tolower(c1);
  60                c2 = tolower(c2);
  61                if (c1 != c2)
  62                        break;
  63        } while (--len);
  64        return (int)c1 - (int)c2;
  65}
  66EXPORT_SYMBOL(strncasecmp);
  67#endif
  68
  69#ifndef __HAVE_ARCH_STRCASECMP
  70int strcasecmp(const char *s1, const char *s2)
  71{
  72        int c1, c2;
  73
  74        do {
  75                c1 = tolower(*s1++);
  76                c2 = tolower(*s2++);
  77        } while (c1 == c2 && c1 != 0);
  78        return c1 - c2;
  79}
  80EXPORT_SYMBOL(strcasecmp);
  81#endif
  82
  83#ifndef __HAVE_ARCH_STRCPY
  84/**
  85 * strcpy - Copy a %NUL terminated string
  86 * @dest: Where to copy the string to
  87 * @src: Where to copy the string from
  88 */
  89char *strcpy(char *dest, const char *src)
  90{
  91        char *tmp = dest;
  92
  93        while ((*dest++ = *src++) != '\0')
  94                /* nothing */;
  95        return tmp;
  96}
  97EXPORT_SYMBOL(strcpy);
  98#endif
  99
 100#ifndef __HAVE_ARCH_STRNCPY
 101/**
 102 * strncpy - Copy a length-limited, C-string
 103 * @dest: Where to copy the string to
 104 * @src: Where to copy the string from
 105 * @count: The maximum number of bytes to copy
 106 *
 107 * The result is not %NUL-terminated if the source exceeds
 108 * @count bytes.
 109 *
 110 * In the case where the length of @src is less than  that  of
 111 * count, the remainder of @dest will be padded with %NUL.
 112 *
 113 */
 114char *strncpy(char *dest, const char *src, size_t count)
 115{
 116        char *tmp = dest;
 117
 118        while (count) {
 119                if ((*tmp = *src) != 0)
 120                        src++;
 121                tmp++;
 122                count--;
 123        }
 124        return dest;
 125}
 126EXPORT_SYMBOL(strncpy);
 127#endif
 128
 129#ifndef __HAVE_ARCH_STRLCPY
 130/**
 131 * strlcpy - Copy a C-string into a sized buffer
 132 * @dest: Where to copy the string to
 133 * @src: Where to copy the string from
 134 * @size: size of destination buffer
 135 *
 136 * Compatible with ``*BSD``: the result is always a valid
 137 * NUL-terminated string that fits in the buffer (unless,
 138 * of course, the buffer size is zero). It does not pad
 139 * out the result like strncpy() does.
 140 */
 141size_t strlcpy(char *dest, const char *src, size_t size)
 142{
 143        size_t ret = strlen(src);
 144
 145        if (size) {
 146                size_t len = (ret >= size) ? size - 1 : ret;
 147                memcpy(dest, src, len);
 148                dest[len] = '\0';
 149        }
 150        return ret;
 151}
 152EXPORT_SYMBOL(strlcpy);
 153#endif
 154
 155#ifndef __HAVE_ARCH_STRSCPY
 156/**
 157 * strscpy - Copy a C-string into a sized buffer
 158 * @dest: Where to copy the string to
 159 * @src: Where to copy the string from
 160 * @count: Size of destination buffer
 161 *
 162 * Copy the string, or as much of it as fits, into the dest buffer.  The
 163 * behavior is undefined if the string buffers overlap.  The destination
 164 * buffer is always NUL terminated, unless it's zero-sized.
 165 *
 166 * Preferred to strlcpy() since the API doesn't require reading memory
 167 * from the src string beyond the specified "count" bytes, and since
 168 * the return value is easier to error-check than strlcpy()'s.
 169 * In addition, the implementation is robust to the string changing out
 170 * from underneath it, unlike the current strlcpy() implementation.
 171 *
 172 * Preferred to strncpy() since it always returns a valid string, and
 173 * doesn't unnecessarily force the tail of the destination buffer to be
 174 * zeroed.  If zeroing is desired please use strscpy_pad().
 175 *
 176 * Returns:
 177 * * The number of characters copied (not including the trailing %NUL)
 178 * * -E2BIG if count is 0 or @src was truncated.
 179 */
 180ssize_t strscpy(char *dest, const char *src, size_t count)
 181{
 182        const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
 183        size_t max = count;
 184        long res = 0;
 185
 186        if (count == 0 || WARN_ON_ONCE(count > INT_MAX))
 187                return -E2BIG;
 188
 189#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 190        /*
 191         * If src is unaligned, don't cross a page boundary,
 192         * since we don't know if the next page is mapped.
 193         */
 194        if ((long)src & (sizeof(long) - 1)) {
 195                size_t limit = PAGE_SIZE - ((long)src & (PAGE_SIZE - 1));
 196                if (limit < max)
 197                        max = limit;
 198        }
 199#else
 200        /* If src or dest is unaligned, don't do word-at-a-time. */
 201        if (((long) dest | (long) src) & (sizeof(long) - 1))
 202                max = 0;
 203#endif
 204
 205        while (max >= sizeof(unsigned long)) {
 206                unsigned long c, data;
 207
 208                c = read_word_at_a_time(src+res);
 209                if (has_zero(c, &data, &constants)) {
 210                        data = prep_zero_mask(c, data, &constants);
 211                        data = create_zero_mask(data);
 212                        *(unsigned long *)(dest+res) = c & zero_bytemask(data);
 213                        return res + find_zero(data);
 214                }
 215                *(unsigned long *)(dest+res) = c;
 216                res += sizeof(unsigned long);
 217                count -= sizeof(unsigned long);
 218                max -= sizeof(unsigned long);
 219        }
 220
 221        while (count) {
 222                char c;
 223
 224                c = src[res];
 225                dest[res] = c;
 226                if (!c)
 227                        return res;
 228                res++;
 229                count--;
 230        }
 231
 232        /* Hit buffer length without finding a NUL; force NUL-termination. */
 233        if (res)
 234                dest[res-1] = '\0';
 235
 236        return -E2BIG;
 237}
 238EXPORT_SYMBOL(strscpy);
 239#endif
 240
 241/**
 242 * strscpy_pad() - Copy a C-string into a sized buffer
 243 * @dest: Where to copy the string to
 244 * @src: Where to copy the string from
 245 * @count: Size of destination buffer
 246 *
 247 * Copy the string, or as much of it as fits, into the dest buffer.  The
 248 * behavior is undefined if the string buffers overlap.  The destination
 249 * buffer is always %NUL terminated, unless it's zero-sized.
 250 *
 251 * If the source string is shorter than the destination buffer, zeros
 252 * the tail of the destination buffer.
 253 *
 254 * For full explanation of why you may want to consider using the
 255 * 'strscpy' functions please see the function docstring for strscpy().
 256 *
 257 * Returns:
 258 * * The number of characters copied (not including the trailing %NUL)
 259 * * -E2BIG if count is 0 or @src was truncated.
 260 */
 261ssize_t strscpy_pad(char *dest, const char *src, size_t count)
 262{
 263        ssize_t written;
 264
 265        written = strscpy(dest, src, count);
 266        if (written < 0 || written == count - 1)
 267                return written;
 268
 269        memset(dest + written + 1, 0, count - written - 1);
 270
 271        return written;
 272}
 273EXPORT_SYMBOL(strscpy_pad);
 274
 275/**
 276 * stpcpy - copy a string from src to dest returning a pointer to the new end
 277 *          of dest, including src's %NUL-terminator. May overrun dest.
 278 * @dest: pointer to end of string being copied into. Must be large enough
 279 *        to receive copy.
 280 * @src: pointer to the beginning of string being copied from. Must not overlap
 281 *       dest.
 282 *
 283 * stpcpy differs from strcpy in a key way: the return value is a pointer
 284 * to the new %NUL-terminating character in @dest. (For strcpy, the return
 285 * value is a pointer to the start of @dest). This interface is considered
 286 * unsafe as it doesn't perform bounds checking of the inputs. As such it's
 287 * not recommended for usage. Instead, its definition is provided in case
 288 * the compiler lowers other libcalls to stpcpy.
 289 */
 290char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
 291char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
 292{
 293        while ((*dest++ = *src++) != '\0')
 294                /* nothing */;
 295        return --dest;
 296}
 297EXPORT_SYMBOL(stpcpy);
 298
 299#ifndef __HAVE_ARCH_STRCAT
 300/**
 301 * strcat - Append one %NUL-terminated string to another
 302 * @dest: The string to be appended to
 303 * @src: The string to append to it
 304 */
 305char *strcat(char *dest, const char *src)
 306{
 307        char *tmp = dest;
 308
 309        while (*dest)
 310                dest++;
 311        while ((*dest++ = *src++) != '\0')
 312                ;
 313        return tmp;
 314}
 315EXPORT_SYMBOL(strcat);
 316#endif
 317
 318#ifndef __HAVE_ARCH_STRNCAT
 319/**
 320 * strncat - Append a length-limited, C-string to another
 321 * @dest: The string to be appended to
 322 * @src: The string to append to it
 323 * @count: The maximum numbers of bytes to copy
 324 *
 325 * Note that in contrast to strncpy(), strncat() ensures the result is
 326 * terminated.
 327 */
 328char *strncat(char *dest, const char *src, size_t count)
 329{
 330        char *tmp = dest;
 331
 332        if (count) {
 333                while (*dest)
 334                        dest++;
 335                while ((*dest++ = *src++) != 0) {
 336                        if (--count == 0) {
 337                                *dest = '\0';
 338                                break;
 339                        }
 340                }
 341        }
 342        return tmp;
 343}
 344EXPORT_SYMBOL(strncat);
 345#endif
 346
 347#ifndef __HAVE_ARCH_STRLCAT
 348/**
 349 * strlcat - Append a length-limited, C-string to another
 350 * @dest: The string to be appended to
 351 * @src: The string to append to it
 352 * @count: The size of the destination buffer.
 353 */
 354size_t strlcat(char *dest, const char *src, size_t count)
 355{
 356        size_t dsize = strlen(dest);
 357        size_t len = strlen(src);
 358        size_t res = dsize + len;
 359
 360        /* This would be a bug */
 361        BUG_ON(dsize >= count);
 362
 363        dest += dsize;
 364        count -= dsize;
 365        if (len >= count)
 366                len = count-1;
 367        memcpy(dest, src, len);
 368        dest[len] = 0;
 369        return res;
 370}
 371EXPORT_SYMBOL(strlcat);
 372#endif
 373
 374#ifndef __HAVE_ARCH_STRCMP
 375/**
 376 * strcmp - Compare two strings
 377 * @cs: One string
 378 * @ct: Another string
 379 */
 380int strcmp(const char *cs, const char *ct)
 381{
 382        unsigned char c1, c2;
 383
 384        while (1) {
 385                c1 = *cs++;
 386                c2 = *ct++;
 387                if (c1 != c2)
 388                        return c1 < c2 ? -1 : 1;
 389                if (!c1)
 390                        break;
 391        }
 392        return 0;
 393}
 394EXPORT_SYMBOL(strcmp);
 395#endif
 396
 397#ifndef __HAVE_ARCH_STRNCMP
 398/**
 399 * strncmp - Compare two length-limited strings
 400 * @cs: One string
 401 * @ct: Another string
 402 * @count: The maximum number of bytes to compare
 403 */
 404int strncmp(const char *cs, const char *ct, size_t count)
 405{
 406        unsigned char c1, c2;
 407
 408        while (count) {
 409                c1 = *cs++;
 410                c2 = *ct++;
 411                if (c1 != c2)
 412                        return c1 < c2 ? -1 : 1;
 413                if (!c1)
 414                        break;
 415                count--;
 416        }
 417        return 0;
 418}
 419EXPORT_SYMBOL(strncmp);
 420#endif
 421
 422#ifndef __HAVE_ARCH_STRCHR
 423/**
 424 * strchr - Find the first occurrence of a character in a string
 425 * @s: The string to be searched
 426 * @c: The character to search for
 427 *
 428 * Note that the %NUL-terminator is considered part of the string, and can
 429 * be searched for.
 430 */
 431char *strchr(const char *s, int c)
 432{
 433        for (; *s != (char)c; ++s)
 434                if (*s == '\0')
 435                        return NULL;
 436        return (char *)s;
 437}
 438EXPORT_SYMBOL(strchr);
 439#endif
 440
 441#ifndef __HAVE_ARCH_STRCHRNUL
 442/**
 443 * strchrnul - Find and return a character in a string, or end of string
 444 * @s: The string to be searched
 445 * @c: The character to search for
 446 *
 447 * Returns pointer to first occurrence of 'c' in s. If c is not found, then
 448 * return a pointer to the null byte at the end of s.
 449 */
 450char *strchrnul(const char *s, int c)
 451{
 452        while (*s && *s != (char)c)
 453                s++;
 454        return (char *)s;
 455}
 456EXPORT_SYMBOL(strchrnul);
 457#endif
 458
 459/**
 460 * strnchrnul - Find and return a character in a length limited string,
 461 * or end of string
 462 * @s: The string to be searched
 463 * @count: The number of characters to be searched
 464 * @c: The character to search for
 465 *
 466 * Returns pointer to the first occurrence of 'c' in s. If c is not found,
 467 * then return a pointer to the last character of the string.
 468 */
 469char *strnchrnul(const char *s, size_t count, int c)
 470{
 471        while (count-- && *s && *s != (char)c)
 472                s++;
 473        return (char *)s;
 474}
 475
 476#ifndef __HAVE_ARCH_STRRCHR
 477/**
 478 * strrchr - Find the last occurrence of a character in a string
 479 * @s: The string to be searched
 480 * @c: The character to search for
 481 */
 482char *strrchr(const char *s, int c)
 483{
 484        const char *last = NULL;
 485        do {
 486                if (*s == (char)c)
 487                        last = s;
 488        } while (*s++);
 489        return (char *)last;
 490}
 491EXPORT_SYMBOL(strrchr);
 492#endif
 493
 494#ifndef __HAVE_ARCH_STRNCHR
 495/**
 496 * strnchr - Find a character in a length limited string
 497 * @s: The string to be searched
 498 * @count: The number of characters to be searched
 499 * @c: The character to search for
 500 *
 501 * Note that the %NUL-terminator is considered part of the string, and can
 502 * be searched for.
 503 */
 504char *strnchr(const char *s, size_t count, int c)
 505{
 506        while (count--) {
 507                if (*s == (char)c)
 508                        return (char *)s;
 509                if (*s++ == '\0')
 510                        break;
 511        }
 512        return NULL;
 513}
 514EXPORT_SYMBOL(strnchr);
 515#endif
 516
 517/**
 518 * skip_spaces - Removes leading whitespace from @str.
 519 * @str: The string to be stripped.
 520 *
 521 * Returns a pointer to the first non-whitespace character in @str.
 522 */
 523char *skip_spaces(const char *str)
 524{
 525        while (isspace(*str))
 526                ++str;
 527        return (char *)str;
 528}
 529EXPORT_SYMBOL(skip_spaces);
 530
 531/**
 532 * strim - Removes leading and trailing whitespace from @s.
 533 * @s: The string to be stripped.
 534 *
 535 * Note that the first trailing whitespace is replaced with a %NUL-terminator
 536 * in the given string @s. Returns a pointer to the first non-whitespace
 537 * character in @s.
 538 */
 539char *strim(char *s)
 540{
 541        size_t size;
 542        char *end;
 543
 544        size = strlen(s);
 545        if (!size)
 546                return s;
 547
 548        end = s + size - 1;
 549        while (end >= s && isspace(*end))
 550                end--;
 551        *(end + 1) = '\0';
 552
 553        return skip_spaces(s);
 554}
 555EXPORT_SYMBOL(strim);
 556
 557#ifndef __HAVE_ARCH_STRLEN
 558/**
 559 * strlen - Find the length of a string
 560 * @s: The string to be sized
 561 */
 562size_t strlen(const char *s)
 563{
 564        const char *sc;
 565
 566        for (sc = s; *sc != '\0'; ++sc)
 567                /* nothing */;
 568        return sc - s;
 569}
 570EXPORT_SYMBOL(strlen);
 571#endif
 572
 573#ifndef __HAVE_ARCH_STRNLEN
 574/**
 575 * strnlen - Find the length of a length-limited string
 576 * @s: The string to be sized
 577 * @count: The maximum number of bytes to search
 578 */
 579size_t strnlen(const char *s, size_t count)
 580{
 581        const char *sc;
 582
 583        for (sc = s; count-- && *sc != '\0'; ++sc)
 584                /* nothing */;
 585        return sc - s;
 586}
 587EXPORT_SYMBOL(strnlen);
 588#endif
 589
 590#ifndef __HAVE_ARCH_STRSPN
 591/**
 592 * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
 593 * @s: The string to be searched
 594 * @accept: The string to search for
 595 */
 596size_t strspn(const char *s, const char *accept)
 597{
 598        const char *p;
 599        const char *a;
 600        size_t count = 0;
 601
 602        for (p = s; *p != '\0'; ++p) {
 603                for (a = accept; *a != '\0'; ++a) {
 604                        if (*p == *a)
 605                                break;
 606                }
 607                if (*a == '\0')
 608                        return count;
 609                ++count;
 610        }
 611        return count;
 612}
 613
 614EXPORT_SYMBOL(strspn);
 615#endif
 616
 617#ifndef __HAVE_ARCH_STRCSPN
 618/**
 619 * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
 620 * @s: The string to be searched
 621 * @reject: The string to avoid
 622 */
 623size_t strcspn(const char *s, const char *reject)
 624{
 625        const char *p;
 626        const char *r;
 627        size_t count = 0;
 628
 629        for (p = s; *p != '\0'; ++p) {
 630                for (r = reject; *r != '\0'; ++r) {
 631                        if (*p == *r)
 632                                return count;
 633                }
 634                ++count;
 635        }
 636        return count;
 637}
 638EXPORT_SYMBOL(strcspn);
 639#endif
 640
 641#ifndef __HAVE_ARCH_STRPBRK
 642/**
 643 * strpbrk - Find the first occurrence of a set of characters
 644 * @cs: The string to be searched
 645 * @ct: The characters to search for
 646 */
 647char *strpbrk(const char *cs, const char *ct)
 648{
 649        const char *sc1, *sc2;
 650
 651        for (sc1 = cs; *sc1 != '\0'; ++sc1) {
 652                for (sc2 = ct; *sc2 != '\0'; ++sc2) {
 653                        if (*sc1 == *sc2)
 654                                return (char *)sc1;
 655                }
 656        }
 657        return NULL;
 658}
 659EXPORT_SYMBOL(strpbrk);
 660#endif
 661
 662#ifndef __HAVE_ARCH_STRSEP
 663/**
 664 * strsep - Split a string into tokens
 665 * @s: The string to be searched
 666 * @ct: The characters to search for
 667 *
 668 * strsep() updates @s to point after the token, ready for the next call.
 669 *
 670 * It returns empty tokens, too, behaving exactly like the libc function
 671 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 672 * Same semantics, slimmer shape. ;)
 673 */
 674char *strsep(char **s, const char *ct)
 675{
 676        char *sbegin = *s;
 677        char *end;
 678
 679        if (sbegin == NULL)
 680                return NULL;
 681
 682        end = strpbrk(sbegin, ct);
 683        if (end)
 684                *end++ = '\0';
 685        *s = end;
 686        return sbegin;
 687}
 688EXPORT_SYMBOL(strsep);
 689#endif
 690
 691/**
 692 * sysfs_streq - return true if strings are equal, modulo trailing newline
 693 * @s1: one string
 694 * @s2: another string
 695 *
 696 * This routine returns true iff two strings are equal, treating both
 697 * NUL and newline-then-NUL as equivalent string terminations.  It's
 698 * geared for use with sysfs input strings, which generally terminate
 699 * with newlines but are compared against values without newlines.
 700 */
 701bool sysfs_streq(const char *s1, const char *s2)
 702{
 703        while (*s1 && *s1 == *s2) {
 704                s1++;
 705                s2++;
 706        }
 707
 708        if (*s1 == *s2)
 709                return true;
 710        if (!*s1 && *s2 == '\n' && !s2[1])
 711                return true;
 712        if (*s1 == '\n' && !s1[1] && !*s2)
 713                return true;
 714        return false;
 715}
 716EXPORT_SYMBOL(sysfs_streq);
 717
 718/**
 719 * match_string - matches given string in an array
 720 * @array:      array of strings
 721 * @n:          number of strings in the array or -1 for NULL terminated arrays
 722 * @string:     string to match with
 723 *
 724 * This routine will look for a string in an array of strings up to the
 725 * n-th element in the array or until the first NULL element.
 726 *
 727 * Historically the value of -1 for @n, was used to search in arrays that
 728 * are NULL terminated. However, the function does not make a distinction
 729 * when finishing the search: either @n elements have been compared OR
 730 * the first NULL element was found.
 731 *
 732 * Return:
 733 * index of a @string in the @array if matches, or %-EINVAL otherwise.
 734 */
 735int match_string(const char * const *array, size_t n, const char *string)
 736{
 737        int index;
 738        const char *item;
 739
 740        for (index = 0; index < n; index++) {
 741                item = array[index];
 742                if (!item)
 743                        break;
 744                if (!strcmp(item, string))
 745                        return index;
 746        }
 747
 748        return -EINVAL;
 749}
 750EXPORT_SYMBOL(match_string);
 751
 752/**
 753 * __sysfs_match_string - matches given string in an array
 754 * @array: array of strings
 755 * @n: number of strings in the array or -1 for NULL terminated arrays
 756 * @str: string to match with
 757 *
 758 * Returns index of @str in the @array or -EINVAL, just like match_string().
 759 * Uses sysfs_streq instead of strcmp for matching.
 760 *
 761 * This routine will look for a string in an array of strings up to the
 762 * n-th element in the array or until the first NULL element.
 763 *
 764 * Historically the value of -1 for @n, was used to search in arrays that
 765 * are NULL terminated. However, the function does not make a distinction
 766 * when finishing the search: either @n elements have been compared OR
 767 * the first NULL element was found.
 768 */
 769int __sysfs_match_string(const char * const *array, size_t n, const char *str)
 770{
 771        const char *item;
 772        int index;
 773
 774        for (index = 0; index < n; index++) {
 775                item = array[index];
 776                if (!item)
 777                        break;
 778                if (sysfs_streq(item, str))
 779                        return index;
 780        }
 781
 782        return -EINVAL;
 783}
 784EXPORT_SYMBOL(__sysfs_match_string);
 785
 786#ifndef __HAVE_ARCH_MEMSET
 787/**
 788 * memset - Fill a region of memory with the given value
 789 * @s: Pointer to the start of the area.
 790 * @c: The byte to fill the area with
 791 * @count: The size of the area.
 792 *
 793 * Do not use memset() to access IO space, use memset_io() instead.
 794 */
 795void *memset(void *s, int c, size_t count)
 796{
 797        char *xs = s;
 798
 799        while (count--)
 800                *xs++ = c;
 801        return s;
 802}
 803EXPORT_SYMBOL(memset);
 804#endif
 805
 806#ifndef __HAVE_ARCH_MEMSET16
 807/**
 808 * memset16() - Fill a memory area with a uint16_t
 809 * @s: Pointer to the start of the area.
 810 * @v: The value to fill the area with
 811 * @count: The number of values to store
 812 *
 813 * Differs from memset() in that it fills with a uint16_t instead
 814 * of a byte.  Remember that @count is the number of uint16_ts to
 815 * store, not the number of bytes.
 816 */
 817void *memset16(uint16_t *s, uint16_t v, size_t count)
 818{
 819        uint16_t *xs = s;
 820
 821        while (count--)
 822                *xs++ = v;
 823        return s;
 824}
 825EXPORT_SYMBOL(memset16);
 826#endif
 827
 828#ifndef __HAVE_ARCH_MEMSET32
 829/**
 830 * memset32() - Fill a memory area with a uint32_t
 831 * @s: Pointer to the start of the area.
 832 * @v: The value to fill the area with
 833 * @count: The number of values to store
 834 *
 835 * Differs from memset() in that it fills with a uint32_t instead
 836 * of a byte.  Remember that @count is the number of uint32_ts to
 837 * store, not the number of bytes.
 838 */
 839void *memset32(uint32_t *s, uint32_t v, size_t count)
 840{
 841        uint32_t *xs = s;
 842
 843        while (count--)
 844                *xs++ = v;
 845        return s;
 846}
 847EXPORT_SYMBOL(memset32);
 848#endif
 849
 850#ifndef __HAVE_ARCH_MEMSET64
 851/**
 852 * memset64() - Fill a memory area with a uint64_t
 853 * @s: Pointer to the start of the area.
 854 * @v: The value to fill the area with
 855 * @count: The number of values to store
 856 *
 857 * Differs from memset() in that it fills with a uint64_t instead
 858 * of a byte.  Remember that @count is the number of uint64_ts to
 859 * store, not the number of bytes.
 860 */
 861void *memset64(uint64_t *s, uint64_t v, size_t count)
 862{
 863        uint64_t *xs = s;
 864
 865        while (count--)
 866                *xs++ = v;
 867        return s;
 868}
 869EXPORT_SYMBOL(memset64);
 870#endif
 871
 872#ifndef __HAVE_ARCH_MEMCPY
 873/**
 874 * memcpy - Copy one area of memory to another
 875 * @dest: Where to copy to
 876 * @src: Where to copy from
 877 * @count: The size of the area.
 878 *
 879 * You should not use this function to access IO space, use memcpy_toio()
 880 * or memcpy_fromio() instead.
 881 */
 882void *memcpy(void *dest, const void *src, size_t count)
 883{
 884        char *tmp = dest;
 885        const char *s = src;
 886
 887        while (count--)
 888                *tmp++ = *s++;
 889        return dest;
 890}
 891EXPORT_SYMBOL(memcpy);
 892#endif
 893
 894#ifndef __HAVE_ARCH_MEMMOVE
 895/**
 896 * memmove - Copy one area of memory to another
 897 * @dest: Where to copy to
 898 * @src: Where to copy from
 899 * @count: The size of the area.
 900 *
 901 * Unlike memcpy(), memmove() copes with overlapping areas.
 902 */
 903void *memmove(void *dest, const void *src, size_t count)
 904{
 905        char *tmp;
 906        const char *s;
 907
 908        if (dest <= src) {
 909                tmp = dest;
 910                s = src;
 911                while (count--)
 912                        *tmp++ = *s++;
 913        } else {
 914                tmp = dest;
 915                tmp += count;
 916                s = src;
 917                s += count;
 918                while (count--)
 919                        *--tmp = *--s;
 920        }
 921        return dest;
 922}
 923EXPORT_SYMBOL(memmove);
 924#endif
 925
 926#ifndef __HAVE_ARCH_MEMCMP
 927/**
 928 * memcmp - Compare two areas of memory
 929 * @cs: One area of memory
 930 * @ct: Another area of memory
 931 * @count: The size of the area.
 932 */
 933#undef memcmp
 934__visible int memcmp(const void *cs, const void *ct, size_t count)
 935{
 936        const unsigned char *su1, *su2;
 937        int res = 0;
 938
 939#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 940        if (count >= sizeof(unsigned long)) {
 941                const unsigned long *u1 = cs;
 942                const unsigned long *u2 = ct;
 943                do {
 944                        if (get_unaligned(u1) != get_unaligned(u2))
 945                                break;
 946                        u1++;
 947                        u2++;
 948                        count -= sizeof(unsigned long);
 949                } while (count >= sizeof(unsigned long));
 950                cs = u1;
 951                ct = u2;
 952        }
 953#endif
 954        for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 955                if ((res = *su1 - *su2) != 0)
 956                        break;
 957        return res;
 958}
 959EXPORT_SYMBOL(memcmp);
 960#endif
 961
 962#ifndef __HAVE_ARCH_BCMP
 963/**
 964 * bcmp - returns 0 if and only if the buffers have identical contents.
 965 * @a: pointer to first buffer.
 966 * @b: pointer to second buffer.
 967 * @len: size of buffers.
 968 *
 969 * The sign or magnitude of a non-zero return value has no particular
 970 * meaning, and architectures may implement their own more efficient bcmp(). So
 971 * while this particular implementation is a simple (tail) call to memcmp, do
 972 * not rely on anything but whether the return value is zero or non-zero.
 973 */
 974int bcmp(const void *a, const void *b, size_t len)
 975{
 976        return memcmp(a, b, len);
 977}
 978EXPORT_SYMBOL(bcmp);
 979#endif
 980
 981#ifndef __HAVE_ARCH_MEMSCAN
 982/**
 983 * memscan - Find a character in an area of memory.
 984 * @addr: The memory area
 985 * @c: The byte to search for
 986 * @size: The size of the area.
 987 *
 988 * returns the address of the first occurrence of @c, or 1 byte past
 989 * the area if @c is not found
 990 */
 991void *memscan(void *addr, int c, size_t size)
 992{
 993        unsigned char *p = addr;
 994
 995        while (size) {
 996                if (*p == (unsigned char)c)
 997                        return (void *)p;
 998                p++;
 999                size--;
1000        }
1001        return (void *)p;
1002}
1003EXPORT_SYMBOL(memscan);
1004#endif
1005
1006#ifndef __HAVE_ARCH_STRSTR
1007/**
1008 * strstr - Find the first substring in a %NUL terminated string
1009 * @s1: The string to be searched
1010 * @s2: The string to search for
1011 */
1012char *strstr(const char *s1, const char *s2)
1013{
1014        size_t l1, l2;
1015
1016        l2 = strlen(s2);
1017        if (!l2)
1018                return (char *)s1;
1019        l1 = strlen(s1);
1020        while (l1 >= l2) {
1021                l1--;
1022                if (!memcmp(s1, s2, l2))
1023                        return (char *)s1;
1024                s1++;
1025        }
1026        return NULL;
1027}
1028EXPORT_SYMBOL(strstr);
1029#endif
1030
1031#ifndef __HAVE_ARCH_STRNSTR
1032/**
1033 * strnstr - Find the first substring in a length-limited string
1034 * @s1: The string to be searched
1035 * @s2: The string to search for
1036 * @len: the maximum number of characters to search
1037 */
1038char *strnstr(const char *s1, const char *s2, size_t len)
1039{
1040        size_t l2;
1041
1042        l2 = strlen(s2);
1043        if (!l2)
1044                return (char *)s1;
1045        while (len >= l2) {
1046                len--;
1047                if (!memcmp(s1, s2, l2))
1048                        return (char *)s1;
1049                s1++;
1050        }
1051        return NULL;
1052}
1053EXPORT_SYMBOL(strnstr);
1054#endif
1055
1056#ifndef __HAVE_ARCH_MEMCHR
1057/**
1058 * memchr - Find a character in an area of memory.
1059 * @s: The memory area
1060 * @c: The byte to search for
1061 * @n: The size of the area.
1062 *
1063 * returns the address of the first occurrence of @c, or %NULL
1064 * if @c is not found
1065 */
1066void *memchr(const void *s, int c, size_t n)
1067{
1068        const unsigned char *p = s;
1069        while (n-- != 0) {
1070                if ((unsigned char)c == *p++) {
1071                        return (void *)(p - 1);
1072                }
1073        }
1074        return NULL;
1075}
1076EXPORT_SYMBOL(memchr);
1077#endif
1078
1079static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1080{
1081        while (bytes) {
1082                if (*start != value)
1083                        return (void *)start;
1084                start++;
1085                bytes--;
1086        }
1087        return NULL;
1088}
1089
1090/**
1091 * memchr_inv - Find an unmatching character in an area of memory.
1092 * @start: The memory area
1093 * @c: Find a character other than c
1094 * @bytes: The size of the area.
1095 *
1096 * returns the address of the first character other than @c, or %NULL
1097 * if the whole buffer contains just @c.
1098 */
1099void *memchr_inv(const void *start, int c, size_t bytes)
1100{
1101        u8 value = c;
1102        u64 value64;
1103        unsigned int words, prefix;
1104
1105        if (bytes <= 16)
1106                return check_bytes8(start, value, bytes);
1107
1108        value64 = value;
1109#if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1110        value64 *= 0x0101010101010101ULL;
1111#elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1112        value64 *= 0x01010101;
1113        value64 |= value64 << 32;
1114#else
1115        value64 |= value64 << 8;
1116        value64 |= value64 << 16;
1117        value64 |= value64 << 32;
1118#endif
1119
1120        prefix = (unsigned long)start % 8;
1121        if (prefix) {
1122                u8 *r;
1123
1124                prefix = 8 - prefix;
1125                r = check_bytes8(start, value, prefix);
1126                if (r)
1127                        return r;
1128                start += prefix;
1129                bytes -= prefix;
1130        }
1131
1132        words = bytes / 8;
1133
1134        while (words) {
1135                if (*(u64 *)start != value64)
1136                        return check_bytes8(start, value, 8);
1137                start += 8;
1138                words--;
1139        }
1140
1141        return check_bytes8(start, value, bytes % 8);
1142}
1143EXPORT_SYMBOL(memchr_inv);
1144
1145/**
1146 * strreplace - Replace all occurrences of character in string.
1147 * @s: The string to operate on.
1148 * @old: The character being replaced.
1149 * @new: The character @old is replaced with.
1150 *
1151 * Returns pointer to the nul byte at the end of @s.
1152 */
1153char *strreplace(char *s, char old, char new)
1154{
1155        for (; *s; ++s)
1156                if (*s == old)
1157                        *s = new;
1158        return s;
1159}
1160EXPORT_SYMBOL(strreplace);
1161
1162void fortify_panic(const char *name)
1163{
1164        pr_emerg("detected buffer overflow in %s\n", name);
1165        BUG();
1166}
1167EXPORT_SYMBOL(fortify_panic);
1168