lib/string.c

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