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