lib/string.c

   1 /*
   2  *  linux/lib/string.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 /*
   8  * stupid library routines.. The optimized versions should generally be found
   9  * as inline code in <asm-xx/string.h>
  10  *
  11  * These are buggy as well..
  12  *
  13  * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
  14  * -  Added strsep() which will replace strtok() soon (because strsep() is
  15  *    reentrant and should be faster). Use only strsep() in new code, please.
  16  *
  17  * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
  18  *                    Matthew Hawkins <matt@mh.dropbear.id.au>
  19  * -  Kissed strtok() goodbye
  20  */
  21
  22 #include <linux/types.h>
  23 #include <linux/string.h>
  24 #include <linux/ctype.h>
  25 #include <linux/module.h>
  26
  27 #ifndef __HAVE_ARCH_STRNICMP
  28 /**
  29  * strnicmp - Case insensitive, length-limited string comparison
  30  * @s1: One string
  31  * @s2: The other string
  32  * @len: the maximum number of characters to compare
  33  */
  34 int strnicmp(const char *s1, const char *s2, size_t len)
  35 {
  36         /* Yes, Virginia, it had better be unsigned */
  37         unsigned char c1, c2;
  38
  39         if (!len)
  40                 return 0;
  41
  42         do {
  43                 c1 = *s1++;
  44                 c2 = *s2++;
  45                 if (!c1 || !c2)
  46                         break;
  47                 if (c1 == c2)
  48                         continue;
  49                 c1 = tolower(c1);
  50                 c2 = tolower(c2);
  51                 if (c1 != c2)
  52                         break;
  53         } while (--len);
  54         return (int)c1 - (int)c2;
  55 }
  56 EXPORT_SYMBOL(strnicmp);
  57 #endif
  58
  59 #ifndef __HAVE_ARCH_STRCASECMP
  60 int strcasecmp(const char *s1, const char *s2)
  61 {
  62         int c1, c2;
  63
  64         do {
  65                 c1 = tolower(*s1++);
  66                 c2 = tolower(*s2++);
  67         } while (c1 == c2 && c1 != 0);
  68         return c1 - c2;
  69 }
  70 EXPORT_SYMBOL(strcasecmp);
  71 #endif
  72
  73 #ifndef __HAVE_ARCH_STRNCASECMP
  74 int strncasecmp(const char *s1, const char *s2, size_t n)
  75 {
  76         int c1, c2;
  77
  78         do {
  79                 c1 = tolower(*s1++);
  80                 c2 = tolower(*s2++);
  81         } while ((--n > 0) && c1 == c2 && c1 != 0);
  82         return c1 - c2;
  83 }
  84 EXPORT_SYMBOL(strncasecmp);
  85 #endif
  86
  87 #ifndef __HAVE_ARCH_STRCPY
  88 /**
  89  * strcpy - Copy a %NUL terminated string
  90  * @dest: Where to copy the string to
  91  * @src: Where to copy the string from
  92  */
  93 #undef strcpy
  94 char *strcpy(char *dest, const char *src)
  95 {
  96         char *tmp = dest;
  97
  98         while ((*dest++ = *src++) != '\0')
  99                 /* nothing */;
 100         return tmp;
 101 }
 102 EXPORT_SYMBOL(strcpy);
 103 #endif
 104
 105 #ifndef __HAVE_ARCH_STRNCPY
 106 /**
 107  * strncpy - Copy a length-limited, %NUL-terminated string
 108  * @dest: Where to copy the string to
 109  * @src: Where to copy the string from
 110  * @count: The maximum number of bytes to copy
 111  *
 112  * The result is not %NUL-terminated if the source exceeds
 113  * @count bytes.
 114  *
 115  * In the case where the length of @src is less than  that  of
 116  * count, the remainder of @dest will be padded with %NUL.
 117  *
 118  */
 119 char *strncpy(char *dest, const char *src, size_t count)
 120 {
 121         char *tmp = dest;
 122
 123         while (count) {
 124                 if ((*tmp = *src) != 0)
 125                         src++;
 126                 tmp++;
 127                 count--;
 128         }
 129         return dest;
 130 }
 131 EXPORT_SYMBOL(strncpy);
 132 #endif
 133
 134 #ifndef __HAVE_ARCH_STRLCPY
 135 /**
 136  * strlcpy - Copy a %NUL terminated string into a sized buffer
 137  * @dest: Where to copy the string to
 138  * @src: Where to copy the string from
 139  * @size: size of destination buffer
 140  *
 141  * Compatible with *BSD: the result is always a valid
 142  * NUL-terminated string that fits in the buffer (unless,
 143  * of course, the buffer size is zero). It does not pad
 144  * out the result like strncpy() does.
 145  */
 146 size_t strlcpy(char *dest, const char *src, size_t size)
 147 {
 148         size_t ret = strlen(src);
 149
 150         if (size) {
 151                 size_t len = (ret >= size) ? size - 1 : ret;
 152                 memcpy(dest, src, len);
 153                 dest[len] = '\0';
 154         }
 155         return ret;
 156 }
 157 EXPORT_SYMBOL(strlcpy);
 158 #endif
 159
 160 #ifndef __HAVE_ARCH_STRCAT
 161 /**
 162  * strcat - Append one %NUL-terminated string to another
 163  * @dest: The string to be appended to
 164  * @src: The string to append to it
 165  */
 166 #undef strcat
 167 char *strcat(char *dest, const char *src)
 168 {
 169         char *tmp = dest;
 170
 171         while (*dest)
 172                 dest++;
 173         while ((*dest++ = *src++) != '\0')
 174                 ;
 175         return tmp;
 176 }
 177 EXPORT_SYMBOL(strcat);
 178 #endif
 179
 180 #ifndef __HAVE_ARCH_STRNCAT
 181 /**
 182  * strncat - Append a length-limited, %NUL-terminated string to another
 183  * @dest: The string to be appended to
 184  * @src: The string to append to it
 185  * @count: The maximum numbers of bytes to copy
 186  *
 187  * Note that in contrast to strncpy(), strncat() ensures the result is
 188  * terminated.
 189  */
 190 char *strncat(char *dest, const char *src, size_t count)
 191 {
 192         char *tmp = dest;
 193
 194         if (count) {
 195                 while (*dest)
 196                         dest++;
 197                 while ((*dest++ = *src++) != 0) {
 198                         if (--count == 0) {
 199                                 *dest = '\0';
 200                                 break;
 201                         }
 202                 }
 203         }
 204         return tmp;
 205 }
 206 EXPORT_SYMBOL(strncat);
 207 #endif
 208
 209 #ifndef __HAVE_ARCH_STRLCAT
 210 /**
 211  * strlcat - Append a length-limited, %NUL-terminated string to another
 212  * @dest: The string to be appended to
 213  * @src: The string to append to it
 214  * @count: The size of the destination buffer.
 215  */
 216 size_t strlcat(char *dest, const char *src, size_t count)
 217 {
 218         size_t dsize = strlen(dest);
 219         size_t len = strlen(src);
 220         size_t res = dsize + len;
 221
 222         /* This would be a bug */
 223         BUG_ON(dsize >= count);
 224
 225         dest += dsize;
 226         count -= dsize;
 227         if (len >= count)
 228                 len = count-1;
 229         memcpy(dest, src, len);
 230         dest[len] = 0;
 231         return res;
 232 }
 233 EXPORT_SYMBOL(strlcat);
 234 #endif
 235
 236 #ifndef __HAVE_ARCH_STRCMP
 237 /**
 238  * strcmp - Compare two strings
 239  * @cs: One string
 240  * @ct: Another string
 241  */
 242 #undef strcmp
 243 int strcmp(const char *cs, const char *ct)
 244 {
 245         unsigned char c1, c2;
 246
 247         while (1) {
 248                 c1 = *cs++;
 249                 c2 = *ct++;
 250                 if (c1 != c2)
 251                         return c1 < c2 ? -1 : 1;
 252                 if (!c1)
 253                         break;
 254         }
 255         return 0;
 256 }
 257 EXPORT_SYMBOL(strcmp);
 258 #endif
 259
 260 #ifndef __HAVE_ARCH_STRNCMP
 261 /**
 262  * strncmp - Compare two length-limited strings
 263  * @cs: One string
 264  * @ct: Another string
 265  * @count: The maximum number of bytes to compare
 266  */
 267 int strncmp(const char *cs, const char *ct, size_t count)
 268 {
 269         unsigned char c1, c2;
 270
 271         while (count) {
 272                 c1 = *cs++;
 273                 c2 = *ct++;
 274                 if (c1 != c2)
 275                         return c1 < c2 ? -1 : 1;
 276                 if (!c1)
 277                         break;
 278                 count--;
 279         }
 280         return 0;
 281 }
 282 EXPORT_SYMBOL(strncmp);
 283 #endif
 284
 285 #ifndef __HAVE_ARCH_STRCHR
 286 /**
 287  * strchr - Find the first occurrence of a character in a string
 288  * @s: The string to be searched
 289  * @c: The character to search for
 290  */
 291 char *strchr(const char *s, int c)
 292 {
 293         for (; *s != (char)c; ++s)
 294                 if (*s == '\0')
 295                         return NULL;
 296         return (char *)s;
 297 }
 298 EXPORT_SYMBOL(strchr);
 299 #endif
 300
 301 #ifndef __HAVE_ARCH_STRRCHR
 302 /**
 303  * strrchr - Find the last occurrence of a character in a string
 304  * @s: The string to be searched
 305  * @c: The character to search for
 306  */
 307 char *strrchr(const char *s, int c)
 308 {
 309        const char *p = s + strlen(s);
 310        do {
 311            if (*p == (char)c)
 312                return (char *)p;
 313        } while (--p >= s);
 314        return NULL;
 315 }
 316 EXPORT_SYMBOL(strrchr);
 317 #endif
 318
 319 #ifndef __HAVE_ARCH_STRNCHR
 320 /**
 321  * strnchr - Find a character in a length limited string
 322  * @s: The string to be searched
 323  * @count: The number of characters to be searched
 324  * @c: The character to search for
 325  */
 326 char *strnchr(const char *s, size_t count, int c)
 327 {
 328         for (; count-- && *s != '\0'; ++s)
 329                 if (*s == (char)c)
 330                         return (char *)s;
 331         return NULL;
 332 }
 333 EXPORT_SYMBOL(strnchr);
 334 #endif
 335
 336 /**
 337  * skip_spaces - Removes leading whitespace from @str.
 338  * @str: The string to be stripped.
 339  *
 340  * Returns a pointer to the first non-whitespace character in @str.
 341  */
 342 char *skip_spaces(const char *str)
 343 {
 344         while (isspace(*str))
 345                 ++str;
 346         return (char *)str;
 347 }
 348 EXPORT_SYMBOL(skip_spaces);
 349
 350 /**
 351  * strim - Removes leading and trailing whitespace from @s.
 352  * @s: The string to be stripped.
 353  *
 354  * Note that the first trailing whitespace is replaced with a %NUL-terminator
 355  * in the given string @s. Returns a pointer to the first non-whitespace
 356  * character in @s.
 357  */
 358 char *strim(char *s)
 359 {
 360         size_t size;
 361         char *end;
 362
 363         s = skip_spaces(s);
 364         size = strlen(s);
 365         if (!size)
 366                 return s;
 367
 368         end = s + size - 1;
 369         while (end >= s && isspace(*end))
 370                 end--;
 371         *(end + 1) = '\0';
 372
 373         return s;
 374 }
 375 EXPORT_SYMBOL(strim);
 376
 377 #ifndef __HAVE_ARCH_STRLEN
 378 /**
 379  * strlen - Find the length of a string
 380  * @s: The string to be sized
 381  */
 382 size_t strlen(const char *s)
 383 {
 384         const char *sc;
 385
 386         for (sc = s; *sc != '\0'; ++sc)
 387                 /* nothing */;
 388         return sc - s;
 389 }
 390 EXPORT_SYMBOL(strlen);
 391 #endif
 392
 393 #ifndef __HAVE_ARCH_STRNLEN
 394 /**
 395  * strnlen - Find the length of a length-limited string
 396  * @s: The string to be sized
 397  * @count: The maximum number of bytes to search
 398  */
 399 size_t strnlen(const char *s, size_t count)
 400 {
 401         const char *sc;
 402
 403         for (sc = s; count-- && *sc != '\0'; ++sc)
 404                 /* nothing */;
 405         return sc - s;
 406 }
 407 EXPORT_SYMBOL(strnlen);
 408 #endif
 409
 410 #ifndef __HAVE_ARCH_STRSPN
 411 /**
 412  * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
 413  * @s: The string to be searched
 414  * @accept: The string to search for
 415  */
 416 size_t strspn(const char *s, const char *accept)
 417 {
 418         const char *p;
 419         const char *a;
 420         size_t count = 0;
 421
 422         for (p = s; *p != '\0'; ++p) {
 423                 for (a = accept; *a != '\0'; ++a) {
 424                         if (*p == *a)
 425                                 break;
 426                 }
 427                 if (*a == '\0')
 428                         return count;
 429                 ++count;
 430         }
 431         return count;
 432 }
 433
 434 EXPORT_SYMBOL(strspn);
 435 #endif
 436
 437 #ifndef __HAVE_ARCH_STRCSPN
 438 /**
 439  * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
 440  * @s: The string to be searched
 441  * @reject: The string to avoid
 442  */
 443 size_t strcspn(const char *s, const char *reject)
 444 {
 445         const char *p;
 446         const char *r;
 447         size_t count = 0;
 448
 449         for (p = s; *p != '\0'; ++p) {
 450                 for (r = reject; *r != '\0'; ++r) {
 451                         if (*p == *r)
 452                                 return count;
 453                 }
 454                 ++count;
 455         }
 456         return count;
 457 }
 458 EXPORT_SYMBOL(strcspn);
 459 #endif
 460
 461 #ifndef __HAVE_ARCH_STRPBRK
 462 /**
 463  * strpbrk - Find the first occurrence of a set of characters
 464  * @cs: The string to be searched
 465  * @ct: The characters to search for
 466  */
 467 char *strpbrk(const char *cs, const char *ct)
 468 {
 469         const char *sc1, *sc2;
 470
 471         for (sc1 = cs; *sc1 != '\0'; ++sc1) {
 472                 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
 473                         if (*sc1 == *sc2)
 474                                 return (char *)sc1;
 475                 }
 476         }
 477         return NULL;
 478 }
 479 EXPORT_SYMBOL(strpbrk);
 480 #endif
 481
 482 #ifndef __HAVE_ARCH_STRSEP
 483 /**
 484  * strsep - Split a string into tokens
 485  * @s: The string to be searched
 486  * @ct: The characters to search for
 487  *
 488  * strsep() updates @s to point after the token, ready for the next call.
 489  *
 490  * It returns empty tokens, too, behaving exactly like the libc function
 491  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 492  * Same semantics, slimmer shape. ;)
 493  */
 494 char *strsep(char **s, const char *ct)
 495 {
 496         char *sbegin = *s;
 497         char *end;
 498
 499         if (sbegin == NULL)
 500                 return NULL;
 501
 502         end = strpbrk(sbegin, ct);
 503         if (end)
 504                 *end++ = '\0';
 505         *s = end;
 506         return sbegin;
 507 }
 508 EXPORT_SYMBOL(strsep);
 509 #endif
 510
 511 /**
 512  * sysfs_streq - return true if strings are equal, modulo trailing newline
 513  * @s1: one string
 514  * @s2: another string
 515  *
 516  * This routine returns true iff two strings are equal, treating both
 517  * NUL and newline-then-NUL as equivalent string terminations.  It's
 518  * geared for use with sysfs input strings, which generally terminate
 519  * with newlines but are compared against values without newlines.
 520  */
 521 bool sysfs_streq(const char *s1, const char *s2)
 522 {
 523         while (*s1 && *s1 == *s2) {
 524                 s1++;
 525                 s2++;
 526         }
 527
 528         if (*s1 == *s2)
 529                 return true;
 530         if (!*s1 && *s2 == '\n' && !s2[1])
 531                 return true;
 532         if (*s1 == '\n' && !s1[1] && !*s2)
 533                 return true;
 534         return false;
 535 }
 536 EXPORT_SYMBOL(sysfs_streq);
 537
 538 /**
 539  * strtobool - convert common user inputs into boolean values
 540  * @s: input string
 541  * @res: result
 542  *
 543  * This routine returns 0 iff the first character is one of 'Yy1Nn0'.
 544  * Otherwise it will return -EINVAL.  Value pointed to by res is
 545  * updated upon finding a match.
 546  */
 547 int strtobool(const char *s, bool *res)
 548 {
 549         switch (s[0]) {
 550         case 'y':
 551         case 'Y':
 552         case '1':
 553                 *res = true;
 554                 break;
 555         case 'n':
 556         case 'N':
 557         case '0':
 558                 *res = false;
 559                 break;
 560         default:
 561                 return -EINVAL;
 562         }
 563         return 0;
 564 }
 565 EXPORT_SYMBOL(strtobool);
 566
 567 #ifndef __HAVE_ARCH_MEMSET
 568 /**
 569  * memset - Fill a region of memory with the given value
 570  * @s: Pointer to the start of the area.
 571  * @c: The byte to fill the area with
 572  * @count: The size of the area.
 573  *
 574  * Do not use memset() to access IO space, use memset_io() instead.
 575  */
 576 void *memset(void *s, int c, size_t count)
 577 {
 578         char *xs = s;
 579
 580         while (count--)
 581                 *xs++ = c;
 582         return s;
 583 }
 584 EXPORT_SYMBOL(memset);
 585 #endif
 586
 587 #ifndef __HAVE_ARCH_MEMCPY
 588 /**
 589  * memcpy - Copy one area of memory to another
 590  * @dest: Where to copy to
 591  * @src: Where to copy from
 592  * @count: The size of the area.
 593  *
 594  * You should not use this function to access IO space, use memcpy_toio()
 595  * or memcpy_fromio() instead.
 596  */
 597 void *memcpy(void *dest, const void *src, size_t count)
 598 {
 599         char *tmp = dest;
 600         const char *s = src;
 601
 602         while (count--)
 603                 *tmp++ = *s++;
 604         return dest;
 605 }
 606 EXPORT_SYMBOL(memcpy);
 607 #endif
 608
 609 #ifndef __HAVE_ARCH_MEMMOVE
 610 /**
 611  * memmove - Copy one area of memory to another
 612  * @dest: Where to copy to
 613  * @src: Where to copy from
 614  * @count: The size of the area.
 615  *
 616  * Unlike memcpy(), memmove() copes with overlapping areas.
 617  */
 618 void *memmove(void *dest, const void *src, size_t count)
 619 {
 620         char *tmp;
 621         const char *s;
 622
 623         if (dest <= src) {
 624                 tmp = dest;
 625                 s = src;
 626                 while (count--)
 627                         *tmp++ = *s++;
 628         } else {
 629                 tmp = dest;
 630                 tmp += count;
 631                 s = src;
 632                 s += count;
 633                 while (count--)
 634                         *--tmp = *--s;
 635         }
 636         return dest;
 637 }
 638 EXPORT_SYMBOL(memmove);
 639 #endif
 640
 641 #ifndef __HAVE_ARCH_MEMCMP
 642 /**
 643  * memcmp - Compare two areas of memory
 644  * @cs: One area of memory
 645  * @ct: Another area of memory
 646  * @count: The size of the area.
 647  */
 648 #undef memcmp
 649 int memcmp(const void *cs, const void *ct, size_t count)
 650 {
 651         const unsigned char *su1, *su2;
 652         int res = 0;
 653
 654         for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 655                 if ((res = *su1 - *su2) != 0)
 656                         break;
 657         return res;
 658 }
 659 EXPORT_SYMBOL(memcmp);
 660 #endif
 661
 662 #ifndef __HAVE_ARCH_MEMSCAN
 663 /**
 664  * memscan - Find a character in an area of memory.
 665  * @addr: The memory area
 666  * @c: The byte to search for
 667  * @size: The size of the area.
 668  *
 669  * returns the address of the first occurrence of @c, or 1 byte past
 670  * the area if @c is not found
 671  */
 672 void *memscan(void *addr, int c, size_t size)
 673 {
 674         unsigned char *p = addr;
 675
 676         while (size) {
 677                 if (*p == c)
 678                         return (void *)p;
 679                 p++;
 680                 size--;
 681         }
 682         return (void *)p;
 683 }
 684 EXPORT_SYMBOL(memscan);
 685 #endif
 686
 687 #ifndef __HAVE_ARCH_STRSTR
 688 /**
 689  * strstr - Find the first substring in a %NUL terminated string
 690  * @s1: The string to be searched
 691  * @s2: The string to search for
 692  */
 693 char *strstr(const char *s1, const char *s2)
 694 {
 695         size_t l1, l2;
 696
 697         l2 = strlen(s2);
 698         if (!l2)
 699                 return (char *)s1;
 700         l1 = strlen(s1);
 701         while (l1 >= l2) {
 702                 l1--;
 703                 if (!memcmp(s1, s2, l2))
 704                         return (char *)s1;
 705                 s1++;
 706         }
 707         return NULL;
 708 }
 709 EXPORT_SYMBOL(strstr);
 710 #endif
 711
 712 #ifndef __HAVE_ARCH_STRNSTR
 713 /**
 714  * strnstr - Find the first substring in a length-limited string
 715  * @s1: The string to be searched
 716  * @s2: The string to search for
 717  * @len: the maximum number of characters to search
 718  */
 719 char *strnstr(const char *s1, const char *s2, size_t len)
 720 {
 721         size_t l2;
 722
 723         l2 = strlen(s2);
 724         if (!l2)
 725                 return (char *)s1;
 726         while (len >= l2) {
 727                 len--;
 728                 if (!memcmp(s1, s2, l2))
 729                         return (char *)s1;
 730                 s1++;
 731         }
 732         return NULL;
 733 }
 734 EXPORT_SYMBOL(strnstr);
 735 #endif
 736
 737 #ifndef __HAVE_ARCH_MEMCHR
 738 /**
 739  * memchr - Find a character in an area of memory.
 740  * @s: The memory area
 741  * @c: The byte to search for
 742  * @n: The size of the area.
 743  *
 744  * returns the address of the first occurrence of @c, or %NULL
 745  * if @c is not found
 746  */
 747 void *memchr(const void *s, int c, size_t n)
 748 {
 749         const unsigned char *p = s;
 750         while (n-- != 0) {
 751                 if ((unsigned char)c == *p++) {
 752                         return (void *)(p - 1);
 753                 }
 754         }
 755         return NULL;
 756 }
 757 EXPORT_SYMBOL(memchr);
 758 #endif