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  * Returns:
 177  * * The number of characters copied (not including the trailing %NUL)
 178  * * -E2BIG if count is 0 or @src was truncated.
 179  */
 180 ssize_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 }
 238 EXPORT_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  */
 261 ssize_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 }
 273 EXPORT_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  */
 290 char *stpcpy(char *__restrict__ dest, const char *__restrict__ src);
 291 char *stpcpy(char *__restrict__ dest, const char *__restrict__ src)
 292 {
 293         while ((*dest++ = *src++) != '\0')
 294                 /* nothing */;
 295         return --dest;
 296 }
 297 EXPORT_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  */
 305 #undef strcat
 306 char *strcat(char *dest, const char *src)
 307 {
 308         char *tmp = dest;
 309
 310         while (*dest)
 311                 dest++;
 312         while ((*dest++ = *src++) != '\0')
 313                 ;
 314         return tmp;
 315 }
 316 EXPORT_SYMBOL(strcat);
 317 #endif
 318
 319 #ifndef __HAVE_ARCH_STRNCAT
 320 /**
 321  * strncat - Append a length-limited, C-string to another
 322  * @dest: The string to be appended to
 323  * @src: The string to append to it
 324  * @count: The maximum numbers of bytes to copy
 325  *
 326  * Note that in contrast to strncpy(), strncat() ensures the result is
 327  * terminated.
 328  */
 329 char *strncat(char *dest, const char *src, size_t count)
 330 {
 331         char *tmp = dest;
 332
 333         if (count) {
 334                 while (*dest)
 335                         dest++;
 336                 while ((*dest++ = *src++) != 0) {
 337                         if (--count == 0) {
 338                                 *dest = '\0';
 339                                 break;
 340                         }
 341                 }
 342         }
 343         return tmp;
 344 }
 345 EXPORT_SYMBOL(strncat);
 346 #endif
 347
 348 #ifndef __HAVE_ARCH_STRLCAT
 349 /**
 350  * strlcat - Append a length-limited, C-string to another
 351  * @dest: The string to be appended to
 352  * @src: The string to append to it
 353  * @count: The size of the destination buffer.
 354  */
 355 size_t strlcat(char *dest, const char *src, size_t count)
 356 {
 357         size_t dsize = strlen(dest);
 358         size_t len = strlen(src);
 359         size_t res = dsize + len;
 360
 361         /* This would be a bug */
 362         BUG_ON(dsize >= count);
 363
 364         dest += dsize;
 365         count -= dsize;
 366         if (len >= count)
 367                 len = count-1;
 368         memcpy(dest, src, len);
 369         dest[len] = 0;
 370         return res;
 371 }
 372 EXPORT_SYMBOL(strlcat);
 373 #endif
 374
 375 #ifndef __HAVE_ARCH_STRCMP
 376 /**
 377  * strcmp - Compare two strings
 378  * @cs: One string
 379  * @ct: Another string
 380  */
 381 #undef strcmp
 382 int strcmp(const char *cs, const char *ct)
 383 {
 384         unsigned char c1, c2;
 385
 386         while (1) {
 387                 c1 = *cs++;
 388                 c2 = *ct++;
 389                 if (c1 != c2)
 390                         return c1 < c2 ? -1 : 1;
 391                 if (!c1)
 392                         break;
 393         }
 394         return 0;
 395 }
 396 EXPORT_SYMBOL(strcmp);
 397 #endif
 398
 399 #ifndef __HAVE_ARCH_STRNCMP
 400 /**
 401  * strncmp - Compare two length-limited strings
 402  * @cs: One string
 403  * @ct: Another string
 404  * @count: The maximum number of bytes to compare
 405  */
 406 int strncmp(const char *cs, const char *ct, size_t count)
 407 {
 408         unsigned char c1, c2;
 409
 410         while (count) {
 411                 c1 = *cs++;
 412                 c2 = *ct++;
 413                 if (c1 != c2)
 414                         return c1 < c2 ? -1 : 1;
 415                 if (!c1)
 416                         break;
 417                 count--;
 418         }
 419         return 0;
 420 }
 421 EXPORT_SYMBOL(strncmp);
 422 #endif
 423
 424 #ifndef __HAVE_ARCH_STRCHR
 425 /**
 426  * strchr - Find the first occurrence of a character in a string
 427  * @s: The string to be searched
 428  * @c: The character to search for
 429  *
 430  * Note that the %NUL-terminator is considered part of the string, and can
 431  * be searched for.
 432  */
 433 char *strchr(const char *s, int c)
 434 {
 435         for (; *s != (char)c; ++s)
 436                 if (*s == '\0')
 437                         return NULL;
 438         return (char *)s;
 439 }
 440 EXPORT_SYMBOL(strchr);
 441 #endif
 442
 443 #ifndef __HAVE_ARCH_STRCHRNUL
 444 /**
 445  * strchrnul - Find and return a character in a string, or end of string
 446  * @s: The string to be searched
 447  * @c: The character to search for
 448  *
 449  * Returns pointer to first occurrence of 'c' in s. If c is not found, then
 450  * return a pointer to the null byte at the end of s.
 451  */
 452 char *strchrnul(const char *s, int c)
 453 {
 454         while (*s && *s != (char)c)
 455                 s++;
 456         return (char *)s;
 457 }
 458 EXPORT_SYMBOL(strchrnul);
 459 #endif
 460
 461 /**
 462  * strnchrnul - Find and return a character in a length limited string,
 463  * or end of string
 464  * @s: The string to be searched
 465  * @count: The number of characters to be searched
 466  * @c: The character to search for
 467  *
 468  * Returns pointer to the first occurrence of 'c' in s. If c is not found,
 469  * then return a pointer to the last character of the string.
 470  */
 471 char *strnchrnul(const char *s, size_t count, int c)
 472 {
 473         while (count-- && *s && *s != (char)c)
 474                 s++;
 475         return (char *)s;
 476 }
 477
 478 #ifndef __HAVE_ARCH_STRRCHR
 479 /**
 480  * strrchr - Find the last occurrence of a character in a string
 481  * @s: The string to be searched
 482  * @c: The character to search for
 483  */
 484 char *strrchr(const char *s, int c)
 485 {
 486         const char *last = NULL;
 487         do {
 488                 if (*s == (char)c)
 489                         last = s;
 490         } while (*s++);
 491         return (char *)last;
 492 }
 493 EXPORT_SYMBOL(strrchr);
 494 #endif
 495
 496 #ifndef __HAVE_ARCH_STRNCHR
 497 /**
 498  * strnchr - Find a character in a length limited string
 499  * @s: The string to be searched
 500  * @count: The number of characters to be searched
 501  * @c: The character to search for
 502  *
 503  * Note that the %NUL-terminator is considered part of the string, and can
 504  * be searched for.
 505  */
 506 char *strnchr(const char *s, size_t count, int c)
 507 {
 508         while (count--) {
 509                 if (*s == (char)c)
 510                         return (char *)s;
 511                 if (*s++ == '\0')
 512                         break;
 513         }
 514         return NULL;
 515 }
 516 EXPORT_SYMBOL(strnchr);
 517 #endif
 518
 519 /**
 520  * skip_spaces - Removes leading whitespace from @str.
 521  * @str: The string to be stripped.
 522  *
 523  * Returns a pointer to the first non-whitespace character in @str.
 524  */
 525 char *skip_spaces(const char *str)
 526 {
 527         while (isspace(*str))
 528                 ++str;
 529         return (char *)str;
 530 }
 531 EXPORT_SYMBOL(skip_spaces);
 532
 533 /**
 534  * strim - Removes leading and trailing whitespace from @s.
 535  * @s: The string to be stripped.
 536  *
 537  * Note that the first trailing whitespace is replaced with a %NUL-terminator
 538  * in the given string @s. Returns a pointer to the first non-whitespace
 539  * character in @s.
 540  */
 541 char *strim(char *s)
 542 {
 543         size_t size;
 544         char *end;
 545
 546         size = strlen(s);
 547         if (!size)
 548                 return s;
 549
 550         end = s + size - 1;
 551         while (end >= s && isspace(*end))
 552                 end--;
 553         *(end + 1) = '\0';
 554
 555         return skip_spaces(s);
 556 }
 557 EXPORT_SYMBOL(strim);
 558
 559 #ifndef __HAVE_ARCH_STRLEN
 560 /**
 561  * strlen - Find the length of a string
 562  * @s: The string to be sized
 563  */
 564 size_t strlen(const char *s)
 565 {
 566         const char *sc;
 567
 568         for (sc = s; *sc != '\0'; ++sc)
 569                 /* nothing */;
 570         return sc - s;
 571 }
 572 EXPORT_SYMBOL(strlen);
 573 #endif
 574
 575 #ifndef __HAVE_ARCH_STRNLEN
 576 /**
 577  * strnlen - Find the length of a length-limited string
 578  * @s: The string to be sized
 579  * @count: The maximum number of bytes to search
 580  */
 581 size_t strnlen(const char *s, size_t count)
 582 {
 583         const char *sc;
 584
 585         for (sc = s; count-- && *sc != '\0'; ++sc)
 586                 /* nothing */;
 587         return sc - s;
 588 }
 589 EXPORT_SYMBOL(strnlen);
 590 #endif
 591
 592 #ifndef __HAVE_ARCH_STRSPN
 593 /**
 594  * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
 595  * @s: The string to be searched
 596  * @accept: The string to search for
 597  */
 598 size_t strspn(const char *s, const char *accept)
 599 {
 600         const char *p;
 601         const char *a;
 602         size_t count = 0;
 603
 604         for (p = s; *p != '\0'; ++p) {
 605                 for (a = accept; *a != '\0'; ++a) {
 606                         if (*p == *a)
 607                                 break;
 608                 }
 609                 if (*a == '\0')
 610                         return count;
 611                 ++count;
 612         }
 613         return count;
 614 }
 615
 616 EXPORT_SYMBOL(strspn);
 617 #endif
 618
 619 #ifndef __HAVE_ARCH_STRCSPN
 620 /**
 621  * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
 622  * @s: The string to be searched
 623  * @reject: The string to avoid
 624  */
 625 size_t strcspn(const char *s, const char *reject)
 626 {
 627         const char *p;
 628         const char *r;
 629         size_t count = 0;
 630
 631         for (p = s; *p != '\0'; ++p) {
 632                 for (r = reject; *r != '\0'; ++r) {
 633                         if (*p == *r)
 634                                 return count;
 635                 }
 636                 ++count;
 637         }
 638         return count;
 639 }
 640 EXPORT_SYMBOL(strcspn);
 641 #endif
 642
 643 #ifndef __HAVE_ARCH_STRPBRK
 644 /**
 645  * strpbrk - Find the first occurrence of a set of characters
 646  * @cs: The string to be searched
 647  * @ct: The characters to search for
 648  */
 649 char *strpbrk(const char *cs, const char *ct)
 650 {
 651         const char *sc1, *sc2;
 652
 653         for (sc1 = cs; *sc1 != '\0'; ++sc1) {
 654                 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
 655                         if (*sc1 == *sc2)
 656                                 return (char *)sc1;
 657                 }
 658         }
 659         return NULL;
 660 }
 661 EXPORT_SYMBOL(strpbrk);
 662 #endif
 663
 664 #ifndef __HAVE_ARCH_STRSEP
 665 /**
 666  * strsep - Split a string into tokens
 667  * @s: The string to be searched
 668  * @ct: The characters to search for
 669  *
 670  * strsep() updates @s to point after the token, ready for the next call.
 671  *
 672  * It returns empty tokens, too, behaving exactly like the libc function
 673  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 674  * Same semantics, slimmer shape. ;)
 675  */
 676 char *strsep(char **s, const char *ct)
 677 {
 678         char *sbegin = *s;
 679         char *end;
 680
 681         if (sbegin == NULL)
 682                 return NULL;
 683
 684         end = strpbrk(sbegin, ct);
 685         if (end)
 686                 *end++ = '\0';
 687         *s = end;
 688         return sbegin;
 689 }
 690 EXPORT_SYMBOL(strsep);
 691 #endif
 692
 693 /**
 694  * sysfs_streq - return true if strings are equal, modulo trailing newline
 695  * @s1: one string
 696  * @s2: another string
 697  *
 698  * This routine returns true iff two strings are equal, treating both
 699  * NUL and newline-then-NUL as equivalent string terminations.  It's
 700  * geared for use with sysfs input strings, which generally terminate
 701  * with newlines but are compared against values without newlines.
 702  */
 703 bool sysfs_streq(const char *s1, const char *s2)
 704 {
 705         while (*s1 && *s1 == *s2) {
 706                 s1++;
 707                 s2++;
 708         }
 709
 710         if (*s1 == *s2)
 711                 return true;
 712         if (!*s1 && *s2 == '\n' && !s2[1])
 713                 return true;
 714         if (*s1 == '\n' && !s1[1] && !*s2)
 715                 return true;
 716         return false;
 717 }
 718 EXPORT_SYMBOL(sysfs_streq);
 719
 720 /**
 721  * match_string - matches given string in an array
 722  * @array:      array of strings
 723  * @n:          number of strings in the array or -1 for NULL terminated arrays
 724  * @string:     string to match with
 725  *
 726  * This routine will look for a string in an array of strings up to the
 727  * n-th element in the array or until the first NULL element.
 728  *
 729  * Historically the value of -1 for @n, was used to search in arrays that
 730  * are NULL terminated. However, the function does not make a distinction
 731  * when finishing the search: either @n elements have been compared OR
 732  * the first NULL element was found.
 733  *
 734  * Return:
 735  * index of a @string in the @array if matches, or %-EINVAL otherwise.
 736  */
 737 int match_string(const char * const *array, size_t n, const char *string)
 738 {
 739         int index;
 740         const char *item;
 741
 742         for (index = 0; index < n; index++) {
 743                 item = array[index];
 744                 if (!item)
 745                         break;
 746                 if (!strcmp(item, string))
 747                         return index;
 748         }
 749
 750         return -EINVAL;
 751 }
 752 EXPORT_SYMBOL(match_string);
 753
 754 /**
 755  * __sysfs_match_string - matches given string in an array
 756  * @array: array of strings
 757  * @n: number of strings in the array or -1 for NULL terminated arrays
 758  * @str: string to match with
 759  *
 760  * Returns index of @str in the @array or -EINVAL, just like match_string().
 761  * Uses sysfs_streq instead of strcmp for matching.
 762  *
 763  * This routine will look for a string in an array of strings up to the
 764  * n-th element in the array or until the first NULL element.
 765  *
 766  * Historically the value of -1 for @n, was used to search in arrays that
 767  * are NULL terminated. However, the function does not make a distinction
 768  * when finishing the search: either @n elements have been compared OR
 769  * the first NULL element was found.
 770  */
 771 int __sysfs_match_string(const char * const *array, size_t n, const char *str)
 772 {
 773         const char *item;
 774         int index;
 775
 776         for (index = 0; index < n; index++) {
 777                 item = array[index];
 778                 if (!item)
 779                         break;
 780                 if (sysfs_streq(item, str))
 781                         return index;
 782         }
 783
 784         return -EINVAL;
 785 }
 786 EXPORT_SYMBOL(__sysfs_match_string);
 787
 788 #ifndef __HAVE_ARCH_MEMSET
 789 /**
 790  * memset - Fill a region of memory with the given value
 791  * @s: Pointer to the start of the area.
 792  * @c: The byte to fill the area with
 793  * @count: The size of the area.
 794  *
 795  * Do not use memset() to access IO space, use memset_io() instead.
 796  */
 797 void *memset(void *s, int c, size_t count)
 798 {
 799         char *xs = s;
 800
 801         while (count--)
 802                 *xs++ = c;
 803         return s;
 804 }
 805 EXPORT_SYMBOL(memset);
 806 #endif
 807
 808 #ifndef __HAVE_ARCH_MEMSET16
 809 /**
 810  * memset16() - Fill a memory area with a uint16_t
 811  * @s: Pointer to the start of the area.
 812  * @v: The value to fill the area with
 813  * @count: The number of values to store
 814  *
 815  * Differs from memset() in that it fills with a uint16_t instead
 816  * of a byte.  Remember that @count is the number of uint16_ts to
 817  * store, not the number of bytes.
 818  */
 819 void *memset16(uint16_t *s, uint16_t v, size_t count)
 820 {
 821         uint16_t *xs = s;
 822
 823         while (count--)
 824                 *xs++ = v;
 825         return s;
 826 }
 827 EXPORT_SYMBOL(memset16);
 828 #endif
 829
 830 #ifndef __HAVE_ARCH_MEMSET32
 831 /**
 832  * memset32() - Fill a memory area with a uint32_t
 833  * @s: Pointer to the start of the area.
 834  * @v: The value to fill the area with
 835  * @count: The number of values to store
 836  *
 837  * Differs from memset() in that it fills with a uint32_t instead
 838  * of a byte.  Remember that @count is the number of uint32_ts to
 839  * store, not the number of bytes.
 840  */
 841 void *memset32(uint32_t *s, uint32_t v, size_t count)
 842 {
 843         uint32_t *xs = s;
 844
 845         while (count--)
 846                 *xs++ = v;
 847         return s;
 848 }
 849 EXPORT_SYMBOL(memset32);
 850 #endif
 851
 852 #ifndef __HAVE_ARCH_MEMSET64
 853 /**
 854  * memset64() - Fill a memory area with a uint64_t
 855  * @s: Pointer to the start of the area.
 856  * @v: The value to fill the area with
 857  * @count: The number of values to store
 858  *
 859  * Differs from memset() in that it fills with a uint64_t instead
 860  * of a byte.  Remember that @count is the number of uint64_ts to
 861  * store, not the number of bytes.
 862  */
 863 void *memset64(uint64_t *s, uint64_t v, size_t count)
 864 {
 865         uint64_t *xs = s;
 866
 867         while (count--)
 868                 *xs++ = v;
 869         return s;
 870 }
 871 EXPORT_SYMBOL(memset64);
 872 #endif
 873
 874 #ifndef __HAVE_ARCH_MEMCPY
 875 /**
 876  * memcpy - Copy one area of memory to another
 877  * @dest: Where to copy to
 878  * @src: Where to copy from
 879  * @count: The size of the area.
 880  *
 881  * You should not use this function to access IO space, use memcpy_toio()
 882  * or memcpy_fromio() instead.
 883  */
 884 void *memcpy(void *dest, const void *src, size_t count)
 885 {
 886         char *tmp = dest;
 887         const char *s = src;
 888
 889         while (count--)
 890                 *tmp++ = *s++;
 891         return dest;
 892 }
 893 EXPORT_SYMBOL(memcpy);
 894 #endif
 895
 896 #ifndef __HAVE_ARCH_MEMMOVE
 897 /**
 898  * memmove - Copy one area of memory to another
 899  * @dest: Where to copy to
 900  * @src: Where to copy from
 901  * @count: The size of the area.
 902  *
 903  * Unlike memcpy(), memmove() copes with overlapping areas.
 904  */
 905 void *memmove(void *dest, const void *src, size_t count)
 906 {
 907         char *tmp;
 908         const char *s;
 909
 910         if (dest <= src) {
 911                 tmp = dest;
 912                 s = src;
 913                 while (count--)
 914                         *tmp++ = *s++;
 915         } else {
 916                 tmp = dest;
 917                 tmp += count;
 918                 s = src;
 919                 s += count;
 920                 while (count--)
 921                         *--tmp = *--s;
 922         }
 923         return dest;
 924 }
 925 EXPORT_SYMBOL(memmove);
 926 #endif
 927
 928 #ifndef __HAVE_ARCH_MEMCMP
 929 /**
 930  * memcmp - Compare two areas of memory
 931  * @cs: One area of memory
 932  * @ct: Another area of memory
 933  * @count: The size of the area.
 934  */
 935 #undef memcmp
 936 __visible int memcmp(const void *cs, const void *ct, size_t count)
 937 {
 938         const unsigned char *su1, *su2;
 939         int res = 0;
 940
 941         for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 942                 if ((res = *su1 - *su2) != 0)
 943                         break;
 944         return res;
 945 }
 946 EXPORT_SYMBOL(memcmp);
 947 #endif
 948
 949 #ifndef __HAVE_ARCH_BCMP
 950 /**
 951  * bcmp - returns 0 if and only if the buffers have identical contents.
 952  * @a: pointer to first buffer.
 953  * @b: pointer to second buffer.
 954  * @len: size of buffers.
 955  *
 956  * The sign or magnitude of a non-zero return value has no particular
 957  * meaning, and architectures may implement their own more efficient bcmp(). So
 958  * while this particular implementation is a simple (tail) call to memcmp, do
 959  * not rely on anything but whether the return value is zero or non-zero.
 960  */
 961 #undef bcmp
 962 int bcmp(const void *a, const void *b, size_t len)
 963 {
 964         return memcmp(a, b, len);
 965 }
 966 EXPORT_SYMBOL(bcmp);
 967 #endif
 968
 969 #ifndef __HAVE_ARCH_MEMSCAN
 970 /**
 971  * memscan - Find a character in an area of memory.
 972  * @addr: The memory area
 973  * @c: The byte to search for
 974  * @size: The size of the area.
 975  *
 976  * returns the address of the first occurrence of @c, or 1 byte past
 977  * the area if @c is not found
 978  */
 979 void *memscan(void *addr, int c, size_t size)
 980 {
 981         unsigned char *p = addr;
 982
 983         while (size) {
 984                 if (*p == c)
 985                         return (void *)p;
 986                 p++;
 987                 size--;
 988         }
 989         return (void *)p;
 990 }
 991 EXPORT_SYMBOL(memscan);
 992 #endif
 993
 994 #ifndef __HAVE_ARCH_STRSTR
 995 /**
 996  * strstr - Find the first substring in a %NUL terminated string
 997  * @s1: The string to be searched
 998  * @s2: The string to search for
 999  */
1000 char *strstr(const char *s1, const char *s2)
1001 {
1002         size_t l1, l2;
1003
1004         l2 = strlen(s2);
1005         if (!l2)
1006                 return (char *)s1;
1007         l1 = strlen(s1);
1008         while (l1 >= l2) {
1009                 l1--;
1010                 if (!memcmp(s1, s2, l2))
1011                         return (char *)s1;
1012                 s1++;
1013         }
1014         return NULL;
1015 }
1016 EXPORT_SYMBOL(strstr);
1017 #endif
1018
1019 #ifndef __HAVE_ARCH_STRNSTR
1020 /**
1021  * strnstr - Find the first substring in a length-limited string
1022  * @s1: The string to be searched
1023  * @s2: The string to search for
1024  * @len: the maximum number of characters to search
1025  */
1026 char *strnstr(const char *s1, const char *s2, size_t len)
1027 {
1028         size_t l2;
1029
1030         l2 = strlen(s2);
1031         if (!l2)
1032                 return (char *)s1;
1033         while (len >= l2) {
1034                 len--;
1035                 if (!memcmp(s1, s2, l2))
1036                         return (char *)s1;
1037                 s1++;
1038         }
1039         return NULL;
1040 }
1041 EXPORT_SYMBOL(strnstr);
1042 #endif
1043
1044 #ifndef __HAVE_ARCH_MEMCHR
1045 /**
1046  * memchr - Find a character in an area of memory.
1047  * @s: The memory area
1048  * @c: The byte to search for
1049  * @n: The size of the area.
1050  *
1051  * returns the address of the first occurrence of @c, or %NULL
1052  * if @c is not found
1053  */
1054 void *memchr(const void *s, int c, size_t n)
1055 {
1056         const unsigned char *p = s;
1057         while (n-- != 0) {
1058                 if ((unsigned char)c == *p++) {
1059                         return (void *)(p - 1);
1060                 }
1061         }
1062         return NULL;
1063 }
1064 EXPORT_SYMBOL(memchr);
1065 #endif
1066
1067 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
1068 {
1069         while (bytes) {
1070                 if (*start != value)
1071                         return (void *)start;
1072                 start++;
1073                 bytes--;
1074         }
1075         return NULL;
1076 }
1077
1078 /**
1079  * memchr_inv - Find an unmatching character in an area of memory.
1080  * @start: The memory area
1081  * @c: Find a character other than c
1082  * @bytes: The size of the area.
1083  *
1084  * returns the address of the first character other than @c, or %NULL
1085  * if the whole buffer contains just @c.
1086  */
1087 void *memchr_inv(const void *start, int c, size_t bytes)
1088 {
1089         u8 value = c;
1090         u64 value64;
1091         unsigned int words, prefix;
1092
1093         if (bytes <= 16)
1094                 return check_bytes8(start, value, bytes);
1095
1096         value64 = value;
1097 #if defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64
1098         value64 *= 0x0101010101010101ULL;
1099 #elif defined(CONFIG_ARCH_HAS_FAST_MULTIPLIER)
1100         value64 *= 0x01010101;
1101         value64 |= value64 << 32;
1102 #else
1103         value64 |= value64 << 8;
1104         value64 |= value64 << 16;
1105         value64 |= value64 << 32;
1106 #endif
1107
1108         prefix = (unsigned long)start % 8;
1109         if (prefix) {
1110                 u8 *r;
1111
1112                 prefix = 8 - prefix;
1113                 r = check_bytes8(start, value, prefix);
1114                 if (r)
1115                         return r;
1116                 start += prefix;
1117                 bytes -= prefix;
1118         }
1119
1120         words = bytes / 8;
1121
1122         while (words) {
1123                 if (*(u64 *)start != value64)
1124                         return check_bytes8(start, value, 8);
1125                 start += 8;
1126                 words--;
1127         }
1128
1129         return check_bytes8(start, value, bytes % 8);
1130 }
1131 EXPORT_SYMBOL(memchr_inv);
1132
1133 /**
1134  * strreplace - Replace all occurrences of character in string.
1135  * @s: The string to operate on.
1136  * @old: The character being replaced.
1137  * @new: The character @old is replaced with.
1138  *
1139  * Returns pointer to the nul byte at the end of @s.
1140  */
1141 char *strreplace(char *s, char old, char new)
1142 {
1143         for (; *s; ++s)
1144                 if (*s == old)
1145                         *s = new;
1146         return s;
1147 }
1148 EXPORT_SYMBOL(strreplace);
1149
1150 void fortify_panic(const char *name)
1151 {
1152         pr_emerg("detected buffer overflow in %s\n", name);
1153         BUG();
1154 }
1155 EXPORT_SYMBOL(fortify_panic);