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