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