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 #undef strcpy
  89 char *strcpy(char *dest, const char *src)
  90 {
  91         char *tmp = dest;
  92
  93         while ((*dest++ = *src++) != '\0')
  94                 /* nothing */;
  95         return tmp;
  96 }
  97 EXPORT_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  */
 114 char *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 }
 126 EXPORT_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  */
 141 size_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 }
 152 EXPORT_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  * Return: The number of characters copied (not including the trailing
 177  *         %NUL) or -E2BIG if the destination buffer wasn't big enough.
 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)
 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  * Return: The number of characters copied (not including the trailing
 257  *         %NUL) or -E2BIG if the destination buffer wasn't big enough.
 258  */
 259 ssize_t strscpy_pad(char *dest, const char *src, size_t count)
 260 {
 261         ssize_t written;
 262
 263         written = strscpy(dest, src, count);
 264         if (written < 0 || written == count - 1)
 265                 return written;
 266
 267         memset(dest + written + 1, 0, count - written - 1);
 268
 269         return written;
 270 }
 271 EXPORT_SYMBOL(strscpy_pad);
 272
 273 #ifndef __HAVE_ARCH_STRCAT
 274 /**
 275  * strcat - Append one %NUL-terminated string to another
 276  * @dest: The string to be appended to
 277  * @src: The string to append to it
 278  */
 279 #undef strcat
 280 char *strcat(char *dest, const char *src)
 281 {
 282         char *tmp = dest;
 283
 284         while (*dest)
 285                 dest++;
 286         while ((*dest++ = *src++) != '\0')
 287                 ;
 288         return tmp;
 289 }
 290 EXPORT_SYMBOL(strcat);
 291 #endif
 292
 293 #ifndef __HAVE_ARCH_STRNCAT
 294 /**
 295  * strncat - Append a length-limited, C-string to another
 296  * @dest: The string to be appended to
 297  * @src: The string to append to it
 298  * @count: The maximum numbers of bytes to copy
 299  *
 300  * Note that in contrast to strncpy(), strncat() ensures the result is
 301  * terminated.
 302  */
 303 char *strncat(char *dest, const char *src, size_t count)
 304 {
 305         char *tmp = dest;
 306
 307         if (count) {
 308                 while (*dest)
 309                         dest++;
 310                 while ((*dest++ = *src++) != 0) {
 311                         if (--count == 0) {
 312                                 *dest = '\0';
 313                                 break;
 314                         }
 315                 }
 316         }
 317         return tmp;
 318 }
 319 EXPORT_SYMBOL(strncat);
 320 #endif
 321
 322 #ifndef __HAVE_ARCH_STRLCAT
 323 /**
 324  * strlcat - Append a length-limited, C-string to another
 325  * @dest: The string to be appended to
 326  * @src: The string to append to it
 327  * @count: The size of the destination buffer.
 328  */
 329 size_t strlcat(char *dest, const char *src, size_t count)
 330 {
 331         size_t dsize = strlen(dest);
 332         size_t len = strlen(src);
 333         size_t res = dsize + len;
 334
 335         /* This would be a bug */
 336         BUG_ON(dsize >= count);
 337
 338         dest += dsize;
 339         count -= dsize;
 340         if (len >= count)
 341                 len = count-1;
 342         memcpy(dest, src, len);
 343         dest[len] = 0;
 344         return res;
 345 }
 346 EXPORT_SYMBOL(strlcat);
 347 #endif
 348
 349 #ifndef __HAVE_ARCH_STRCMP
 350 /**
 351  * strcmp - Compare two strings
 352  * @cs: One string
 353  * @ct: Another string
 354  */
 355 #undef strcmp
 356 int strcmp(const char *cs, const char *ct)
 357 {
 358         unsigned char c1, c2;
 359
 360         while (1) {
 361                 c1 = *cs++;
 362                 c2 = *ct++;
 363                 if (c1 != c2)
 364                         return c1 < c2 ? -1 : 1;
 365                 if (!c1)
 366                         break;
 367         }
 368         return 0;
 369 }
 370 EXPORT_SYMBOL(strcmp);
 371 #endif
 372
 373 #ifndef __HAVE_ARCH_STRNCMP
 374 /**
 375  * strncmp - Compare two length-limited strings
 376  * @cs: One string
 377  * @ct: Another string
 378  * @count: The maximum number of bytes to compare
 379  */
 380 int strncmp(const char *cs, const char *ct, size_t count)
 381 {
 382         unsigned char c1, c2;
 383
 384         while (count) {
 385                 c1 = *cs++;
 386                 c2 = *ct++;
 387                 if (c1 != c2)
 388                         return c1 < c2 ? -1 : 1;
 389                 if (!c1)
 390                         break;
 391                 count--;
 392         }
 393         return 0;
 394 }
 395 EXPORT_SYMBOL(strncmp);
 396 #endif
 397
 398 #ifndef __HAVE_ARCH_STRCHR
 399 /**
 400  * strchr - Find the first occurrence of a character in a string
 401  * @s: The string to be searched
 402  * @c: The character to search for
 403  */
 404 char *strchr(const char *s, int c)
 405 {
 406         for (; *s != (char)c; ++s)
 407                 if (*s == '\0')
 408                         return NULL;
 409         return (char *)s;
 410 }
 411 EXPORT_SYMBOL(strchr);
 412 #endif
 413
 414 #ifndef __HAVE_ARCH_STRCHRNUL
 415 /**
 416  * strchrnul - Find and return a character in a string, or end of string
 417  * @s: The string to be searched
 418  * @c: The character to search for
 419  *
 420  * Returns pointer to first occurrence of 'c' in s. If c is not found, then
 421  * return a pointer to the null byte at the end of s.
 422  */
 423 char *strchrnul(const char *s, int c)
 424 {
 425         while (*s && *s != (char)c)
 426                 s++;
 427         return (char *)s;
 428 }
 429 EXPORT_SYMBOL(strchrnul);
 430 #endif
 431
 432 #ifndef __HAVE_ARCH_STRRCHR
 433 /**
 434  * strrchr - Find the last occurrence of a character in a string
 435  * @s: The string to be searched
 436  * @c: The character to search for
 437  */
 438 char *strrchr(const char *s, int c)
 439 {
 440         const char *last = NULL;
 441         do {
 442                 if (*s == (char)c)
 443                         last = s;
 444         } while (*s++);
 445         return (char *)last;
 446 }
 447 EXPORT_SYMBOL(strrchr);
 448 #endif
 449
 450 #ifndef __HAVE_ARCH_STRNCHR
 451 /**
 452  * strnchr - Find a character in a length limited string
 453  * @s: The string to be searched
 454  * @count: The number of characters to be searched
 455  * @c: The character to search for
 456  */
 457 char *strnchr(const char *s, size_t count, int c)
 458 {
 459         for (; count-- && *s != '\0'; ++s)
 460                 if (*s == (char)c)
 461                         return (char *)s;
 462         return NULL;
 463 }
 464 EXPORT_SYMBOL(strnchr);
 465 #endif
 466
 467 /**
 468  * skip_spaces - Removes leading whitespace from @str.
 469  * @str: The string to be stripped.
 470  *
 471  * Returns a pointer to the first non-whitespace character in @str.
 472  */
 473 char *skip_spaces(const char *str)
 474 {
 475         while (isspace(*str))
 476                 ++str;
 477         return (char *)str;
 478 }
 479 EXPORT_SYMBOL(skip_spaces);
 480
 481 /**
 482  * strim - Removes leading and trailing whitespace from @s.
 483  * @s: The string to be stripped.
 484  *
 485  * Note that the first trailing whitespace is replaced with a %NUL-terminator
 486  * in the given string @s. Returns a pointer to the first non-whitespace
 487  * character in @s.
 488  */
 489 char *strim(char *s)
 490 {
 491         size_t size;
 492         char *end;
 493
 494         size = strlen(s);
 495         if (!size)
 496                 return s;
 497
 498         end = s + size - 1;
 499         while (end >= s && isspace(*end))
 500                 end--;
 501         *(end + 1) = '\0';
 502
 503         return skip_spaces(s);
 504 }
 505 EXPORT_SYMBOL(strim);
 506
 507 #ifndef __HAVE_ARCH_STRLEN
 508 /**
 509  * strlen - Find the length of a string
 510  * @s: The string to be sized
 511  */
 512 size_t strlen(const char *s)
 513 {
 514         const char *sc;
 515
 516         for (sc = s; *sc != '\0'; ++sc)
 517                 /* nothing */;
 518         return sc - s;
 519 }
 520 EXPORT_SYMBOL(strlen);
 521 #endif
 522
 523 #ifndef __HAVE_ARCH_STRNLEN
 524 /**
 525  * strnlen - Find the length of a length-limited string
 526  * @s: The string to be sized
 527  * @count: The maximum number of bytes to search
 528  */
 529 size_t strnlen(const char *s, size_t count)
 530 {
 531         const char *sc;
 532
 533         for (sc = s; count-- && *sc != '\0'; ++sc)
 534                 /* nothing */;
 535         return sc - s;
 536 }
 537 EXPORT_SYMBOL(strnlen);
 538 #endif
 539
 540 #ifndef __HAVE_ARCH_STRSPN
 541 /**
 542  * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
 543  * @s: The string to be searched
 544  * @accept: The string to search for
 545  */
 546 size_t strspn(const char *s, const char *accept)
 547 {
 548         const char *p;
 549         const char *a;
 550         size_t count = 0;
 551
 552         for (p = s; *p != '\0'; ++p) {
 553                 for (a = accept; *a != '\0'; ++a) {
 554                         if (*p == *a)
 555                                 break;
 556                 }
 557                 if (*a == '\0')
 558                         return count;
 559                 ++count;
 560         }
 561         return count;
 562 }
 563
 564 EXPORT_SYMBOL(strspn);
 565 #endif
 566
 567 #ifndef __HAVE_ARCH_STRCSPN
 568 /**
 569  * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
 570  * @s: The string to be searched
 571  * @reject: The string to avoid
 572  */
 573 size_t strcspn(const char *s, const char *reject)
 574 {
 575         const char *p;
 576         const char *r;
 577         size_t count = 0;
 578
 579         for (p = s; *p != '\0'; ++p) {
 580                 for (r = reject; *r != '\0'; ++r) {
 581                         if (*p == *r)
 582                                 return count;
 583                 }
 584                 ++count;
 585         }
 586         return count;
 587 }
 588 EXPORT_SYMBOL(strcspn);
 589 #endif
 590
 591 #ifndef __HAVE_ARCH_STRPBRK
 592 /**
 593  * strpbrk - Find the first occurrence of a set of characters
 594  * @cs: The string to be searched
 595  * @ct: The characters to search for
 596  */
 597 char *strpbrk(const char *cs, const char *ct)
 598 {
 599         const char *sc1, *sc2;
 600
 601         for (sc1 = cs; *sc1 != '\0'; ++sc1) {
 602                 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
 603                         if (*sc1 == *sc2)
 604                                 return (char *)sc1;
 605                 }
 606         }
 607         return NULL;
 608 }
 609 EXPORT_SYMBOL(strpbrk);
 610 #endif
 611
 612 #ifndef __HAVE_ARCH_STRSEP
 613 /**
 614  * strsep - Split a string into tokens
 615  * @s: The string to be searched
 616  * @ct: The characters to search for
 617  *
 618  * strsep() updates @s to point after the token, ready for the next call.
 619  *
 620  * It returns empty tokens, too, behaving exactly like the libc function
 621  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 622  * Same semantics, slimmer shape. ;)
 623  */
 624 char *strsep(char **s, const char *ct)
 625 {
 626         char *sbegin = *s;
 627         char *end;
 628
 629         if (sbegin == NULL)
 630                 return NULL;
 631
 632         end = strpbrk(sbegin, ct);
 633         if (end)
 634                 *end++ = '\0';
 635         *s = end;
 636         return sbegin;
 637 }
 638 EXPORT_SYMBOL(strsep);
 639 #endif
 640
 641 /**
 642  * sysfs_streq - return true if strings are equal, modulo trailing newline
 643  * @s1: one string
 644  * @s2: another string
 645  *
 646  * This routine returns true iff two strings are equal, treating both
 647  * NUL and newline-then-NUL as equivalent string terminations.  It's
 648  * geared for use with sysfs input strings, which generally terminate
 649  * with newlines but are compared against values without newlines.
 650  */
 651 bool sysfs_streq(const char *s1, const char *s2)
 652 {
 653         while (*s1 && *s1 == *s2) {
 654                 s1++;
 655                 s2++;
 656         }
 657
 658         if (*s1 == *s2)
 659                 return true;
 660         if (!*s1 && *s2 == '\n' && !s2[1])
 661                 return true;
 662         if (*s1 == '\n' && !s1[1] && !*s2)
 663                 return true;
 664         return false;
 665 }
 666 EXPORT_SYMBOL(sysfs_streq);
 667
 668 /**
 669  * match_string - matches given string in an array
 670  * @array:      array of strings
 671  * @n:          number of strings in the array or -1 for NULL terminated arrays
 672  * @string:     string to match with
 673  *
 674  * Return:
 675  * index of a @string in the @array if matches, or %-EINVAL otherwise.
 676  */
 677 int match_string(const char * const *array, size_t n, const char *string)
 678 {
 679         int index;
 680         const char *item;
 681
 682         for (index = 0; index < n; index++) {
 683                 item = array[index];
 684                 if (!item)
 685                         break;
 686                 if (!strcmp(item, string))
 687                         return index;
 688         }
 689
 690         return -EINVAL;
 691 }
 692 EXPORT_SYMBOL(match_string);
 693
 694 /**
 695  * __sysfs_match_string - matches given string in an array
 696  * @array: array of strings
 697  * @n: number of strings in the array or -1 for NULL terminated arrays
 698  * @str: string to match with
 699  *
 700  * Returns index of @str in the @array or -EINVAL, just like match_string().
 701  * Uses sysfs_streq instead of strcmp for matching.
 702  */
 703 int __sysfs_match_string(const char * const *array, size_t n, const char *str)
 704 {
 705         const char *item;
 706         int index;
 707
 708         for (index = 0; index < n; index++) {
 709                 item = array[index];
 710                 if (!item)
 711                         break;
 712                 if (sysfs_streq(item, str))
 713                         return index;
 714         }
 715
 716         return -EINVAL;
 717 }
 718 EXPORT_SYMBOL(__sysfs_match_string);
 719
 720 #ifndef __HAVE_ARCH_MEMSET
 721 /**
 722  * memset - Fill a region of memory with the given value
 723  * @s: Pointer to the start of the area.
 724  * @c: The byte to fill the area with
 725  * @count: The size of the area.
 726  *
 727  * Do not use memset() to access IO space, use memset_io() instead.
 728  */
 729 void *memset(void *s, int c, size_t count)
 730 {
 731         char *xs = s;
 732
 733         while (count--)
 734                 *xs++ = c;
 735         return s;
 736 }
 737 EXPORT_SYMBOL(memset);
 738 #endif
 739
 740 /**
 741  * memzero_explicit - Fill a region of memory (e.g. sensitive
 742  *                    keying data) with 0s.
 743  * @s: Pointer to the start of the area.
 744  * @count: The size of the area.
 745  *
 746  * Note: usually using memset() is just fine (!), but in cases
 747  * where clearing out _local_ data at the end of a scope is
 748  * necessary, memzero_explicit() should be used instead in
 749  * order to prevent the compiler from optimising away zeroing.
 750  *
 751  * memzero_explicit() doesn't need an arch-specific version as
 752  * it just invokes the one of memset() implicitly.
 753  */
 754 void memzero_explicit(void *s, size_t count)
 755 {
 756         memset(s, 0, count);
 757         barrier_data(s);
 758 }
 759 EXPORT_SYMBOL(memzero_explicit);
 760
 761 #ifndef __HAVE_ARCH_MEMSET16
 762 /**
 763  * memset16() - Fill a memory area with a uint16_t
 764  * @s: Pointer to the start of the area.
 765  * @v: The value to fill the area with
 766  * @count: The number of values to store
 767  *
 768  * Differs from memset() in that it fills with a uint16_t instead
 769  * of a byte.  Remember that @count is the number of uint16_ts to
 770  * store, not the number of bytes.
 771  */
 772 void *memset16(uint16_t *s, uint16_t v, size_t count)
 773 {
 774         uint16_t *xs = s;
 775
 776         while (count--)
 777                 *xs++ = v;
 778         return s;
 779 }
 780 EXPORT_SYMBOL(memset16);
 781 #endif
 782
 783 #ifndef __HAVE_ARCH_MEMSET32
 784 /**
 785  * memset32() - Fill a memory area with a uint32_t
 786  * @s: Pointer to the start of the area.
 787  * @v: The value to fill the area with
 788  * @count: The number of values to store
 789  *
 790  * Differs from memset() in that it fills with a uint32_t instead
 791  * of a byte.  Remember that @count is the number of uint32_ts to
 792  * store, not the number of bytes.
 793  */
 794 void *memset32(uint32_t *s, uint32_t v, size_t count)
 795 {
 796         uint32_t *xs = s;
 797
 798         while (count--)
 799                 *xs++ = v;
 800         return s;
 801 }
 802 EXPORT_SYMBOL(memset32);
 803 #endif
 804
 805 #ifndef __HAVE_ARCH_MEMSET64
 806 /**
 807  * memset64() - Fill a memory area with a uint64_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 uint64_t instead
 813  * of a byte.  Remember that @count is the number of uint64_ts to
 814  * store, not the number of bytes.
 815  */
 816 void *memset64(uint64_t *s, uint64_t v, size_t count)
 817 {
 818         uint64_t *xs = s;
 819
 820         while (count--)
 821                 *xs++ = v;
 822         return s;
 823 }
 824 EXPORT_SYMBOL(memset64);
 825 #endif
 826
 827 #ifndef __HAVE_ARCH_MEMCPY
 828 /**
 829  * memcpy - Copy one area of memory to another
 830  * @dest: Where to copy to
 831  * @src: Where to copy from
 832  * @count: The size of the area.
 833  *
 834  * You should not use this function to access IO space, use memcpy_toio()
 835  * or memcpy_fromio() instead.
 836  */
 837 void *memcpy(void *dest, const void *src, size_t count)
 838 {
 839         char *tmp = dest;
 840         const char *s = src;
 841
 842         while (count--)
 843                 *tmp++ = *s++;
 844         return dest;
 845 }
 846 EXPORT_SYMBOL(memcpy);
 847 #endif
 848
 849 #ifndef __HAVE_ARCH_MEMMOVE
 850 /**
 851  * memmove - Copy one area of memory to another
 852  * @dest: Where to copy to
 853  * @src: Where to copy from
 854  * @count: The size of the area.
 855  *
 856  * Unlike memcpy(), memmove() copes with overlapping areas.
 857  */
 858 void *memmove(void *dest, const void *src, size_t count)
 859 {
 860         char *tmp;
 861         const char *s;
 862
 863         if (dest <= src) {
 864                 tmp = dest;
 865                 s = src;
 866                 while (count--)
 867                         *tmp++ = *s++;
 868         } else {
 869                 tmp = dest;
 870                 tmp += count;
 871                 s = src;
 872                 s += count;
 873                 while (count--)
 874                         *--tmp = *--s;
 875         }
 876         return dest;
 877 }
 878 EXPORT_SYMBOL(memmove);
 879 #endif
 880
 881 #ifndef __HAVE_ARCH_MEMCMP
 882 /**
 883  * memcmp - Compare two areas of memory
 884  * @cs: One area of memory
 885  * @ct: Another area of memory
 886  * @count: The size of the area.
 887  */
 888 #undef memcmp
 889 __visible int memcmp(const void *cs, const void *ct, size_t count)
 890 {
 891         const unsigned char *su1, *su2;
 892         int res = 0;
 893
 894         for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 895                 if ((res = *su1 - *su2) != 0)
 896                         break;
 897         return res;
 898 }
 899 EXPORT_SYMBOL(memcmp);
 900 #endif
 901
 902 #ifndef __HAVE_ARCH_BCMP
 903 /**
 904  * bcmp - returns 0 if and only if the buffers have identical contents.
 905  * @a: pointer to first buffer.
 906  * @b: pointer to second buffer.
 907  * @len: size of buffers.
 908  *
 909  * The sign or magnitude of a non-zero return value has no particular
 910  * meaning, and architectures may implement their own more efficient bcmp(). So
 911  * while this particular implementation is a simple (tail) call to memcmp, do
 912  * not rely on anything but whether the return value is zero or non-zero.
 913  */
 914 #undef bcmp
 915 int bcmp(const void *a, const void *b, size_t len)
 916 {
 917         return memcmp(a, b, len);
 918 }
 919 EXPORT_SYMBOL(bcmp);
 920 #endif
 921
 922 #ifndef __HAVE_ARCH_MEMSCAN
 923 /**
 924  * memscan - Find a character in an area of memory.
 925  * @addr: The memory area
 926  * @c: The byte to search for
 927  * @size: The size of the area.
 928  *
 929  * returns the address of the first occurrence of @c, or 1 byte past
 930  * the area if @c is not found
 931  */
 932 void *memscan(void *addr, int c, size_t size)
 933 {
 934         unsigned char *p = addr;
 935
 936         while (size) {
 937                 if (*p == c)
 938                         return (void *)p;
 939                 p++;
 940                 size--;
 941         }
 942         return (void *)p;
 943 }
 944 EXPORT_SYMBOL(memscan);
 945 #endif
 946
 947 #ifndef __HAVE_ARCH_STRSTR
 948 /**
 949  * strstr - Find the first substring in a %NUL terminated string
 950  * @s1: The string to be searched
 951  * @s2: The string to search for
 952  */
 953 char *strstr(const char *s1, const char *s2)
 954 {
 955         size_t l1, l2;
 956
 957         l2 = strlen(s2);
 958         if (!l2)
 959                 return (char *)s1;
 960         l1 = strlen(s1);
 961         while (l1 >= l2) {
 962                 l1--;
 963                 if (!memcmp(s1, s2, l2))
 964                         return (char *)s1;
 965                 s1++;
 966         }
 967         return NULL;
 968 }
 969 EXPORT_SYMBOL(strstr);
 970 #endif
 971
 972 #ifndef __HAVE_ARCH_STRNSTR
 973 /**
 974  * strnstr - Find the first substring in a length-limited string
 975  * @s1: The string to be searched
 976  * @s2: The string to search for
 977  * @len: the maximum number of characters to search
 978  */
 979 char *strnstr(const char *s1, const char *s2, size_t len)
 980 {
 981         size_t l2;
 982
 983         l2 = strlen(s2);
 984         if (!l2)
 985                 return (char *)s1;
 986         while (len >= l2) {
 987                 len--;
 988                 if (!memcmp(s1, s2, l2))
 989                         return (char *)s1;
 990                 s1++;
 991         }
 992         return NULL;
 993 }
 994 EXPORT_SYMBOL(strnstr);
 995 #endif
 996
 997 #ifndef __HAVE_ARCH_MEMCHR
 998 /**
 999  * memchr - Find a character in an area of memory.
1000  * @s: The memory area
1001  * @c: The byte to search for
1002  * @n: The size of the area.
1003  *
1004  * returns the address of the first occurrence of @c, or %NULL
1005  * if @c is not found
1006  */
1007 void *memchr(const void *s, int c, size_t n)
1008 {
1009         const unsigned char *p = s;
1010         while (n-- != 0) {
1011                 if ((unsigned char)c == *p++) {
1012                         return (void *)(p - 1);
1013                 }
1014         }
1015         return NULL;
1016 }
1017 EXPORT_SYMBOL(memchr);
1018 #endif
1019
1020 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1021 {
1022         while (bytes) {
1023                 if (*start != value)
1024                         return (void *)start;
1025                 start++;
1026                 bytes--;
1027         }
1028         return NULL;
1029 }
1030
1031 /**
1032  * memchr_inv - Find an unmatching character in an area of memory.
1033  * @start: The memory area
1034  * @c: Find a character other than c
1035  * @bytes: The size of the area.
1036  *
1037  * returns the address of the first character other than @c, or %NULL
1038  * if the whole buffer contains just @c.
1039  */
1040 void *memchr_inv(const void *start, int c, size_t bytes)
1041 {
1042         u8 value = c;
1043         u64 value64;
1044         unsigned int words, prefix;
1045
1046         if (bytes <= 16)
1047                 return check_bytes8(start, value, bytes);
1048
1049         value64 = value;
1050 #if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1051         value64 *= 0x0101010101010101ULL;
1052 #elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1053         value64 *= 0x01010101;
1054         value64 |= value64 << 32;
1055 #else
1056         value64 |= value64 << 8;
1057         value64 |= value64 << 16;
1058         value64 |= value64 << 32;
1059 #endif
1060
1061         prefix = (unsigned long)start % 8;
1062         if (prefix) {
1063                 u8 *r;
1064
1065                 prefix = 8 - prefix;
1066                 r = check_bytes8(start, value, prefix);
1067                 if (r)
1068                         return r;
1069                 start += prefix;
1070                 bytes -= prefix;
1071         }
1072
1073         words = bytes / 8;
1074
1075         while (words) {
1076                 if (*(u64 *)start != value64)
1077                         return check_bytes8(start, value, 8);
1078                 start += 8;
1079                 words--;
1080         }
1081
1082         return check_bytes8(start, value, bytes % 8);
1083 }
1084 EXPORT_SYMBOL(memchr_inv);
1085
1086 /**
1087  * strreplace - Replace all occurrences of character in string.
1088  * @s: The string to operate on.
1089  * @old: The character being replaced.
1090  * @new: The character @old is replaced with.
1091  *
1092  * Returns pointer to the nul byte at the end of @s.
1093  */
1094 char *strreplace(char *s, char old, char new)
1095 {
1096         for (; *s; ++s)
1097                 if (*s == old)
1098                         *s = new;
1099         return s;
1100 }
1101 EXPORT_SYMBOL(strreplace);
1102
1103 void fortify_panic(const char *name)
1104 {
1105         pr_emerg("detected buffer overflow in %s\n", name);
1106         BUG();
1107 }
1108 EXPORT_SYMBOL(fortify_panic);