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; c2 = *s2;
  43                         s1++; s2++;
  44                         if (!c1)
  45                                 break;
  46                         if (!c2)
  47                                 break;
  48                         if (c1 == c2)
  49                                 continue;
  50                         c1 = tolower(c1);
  51                         c2 = tolower(c2);
  52                         if (c1 != c2)
  53                                 break;
  54                 } while (--len);
  55         }
  56         return (int)c1 - (int)c2;
  57 }
  58
  59 EXPORT_SYMBOL(strnicmp);
  60 #endif
  61
  62 #ifndef __HAVE_ARCH_STRCPY
  63 /**
  64  * strcpy - Copy a %NUL terminated string
  65  * @dest: Where to copy the string to
  66  * @src: Where to copy the string from
  67  */
  68 #undef strcpy
  69 char * strcpy(char * dest,const char *src)
  70 {
  71         char *tmp = dest;
  72
  73         while ((*dest++ = *src++) != '\0')
  74                 /* nothing */;
  75         return tmp;
  76 }
  77 EXPORT_SYMBOL(strcpy);
  78 #endif
  79
  80 #ifndef __HAVE_ARCH_STRNCPY
  81 /**
  82  * strncpy - Copy a length-limited, %NUL-terminated string
  83  * @dest: Where to copy the string to
  84  * @src: Where to copy the string from
  85  * @count: The maximum number of bytes to copy
  86  *
  87  * The result is not %NUL-terminated if the source exceeds
  88  * @count bytes.
  89  *
  90  * In the case where the length of @src is less than  that  of
  91  * count, the remainder of @dest will be padded with %NUL.
  92  *
  93  */
  94 char * strncpy(char * dest,const char *src,size_t count)
  95 {
  96         char *tmp = dest;
  97
  98         while (count) {
  99                 if ((*tmp = *src) != 0) src++;
 100                 tmp++;
 101                 count--;
 102         }
 103         return dest;
 104 }
 105 EXPORT_SYMBOL(strncpy);
 106 #endif
 107
 108 #ifndef __HAVE_ARCH_STRLCPY
 109 /**
 110  * strlcpy - Copy a %NUL terminated string into a sized buffer
 111  * @dest: Where to copy the string to
 112  * @src: Where to copy the string from
 113  * @size: size of destination buffer
 114  *
 115  * Compatible with *BSD: the result is always a valid
 116  * NUL-terminated string that fits in the buffer (unless,
 117  * of course, the buffer size is zero). It does not pad
 118  * out the result like strncpy() does.
 119  */
 120 size_t strlcpy(char *dest, const char *src, size_t size)
 121 {
 122         size_t ret = strlen(src);
 123
 124         if (size) {
 125                 size_t len = (ret >= size) ? size-1 : ret;
 126                 memcpy(dest, src, len);
 127                 dest[len] = '\0';
 128         }
 129         return ret;
 130 }
 131 EXPORT_SYMBOL(strlcpy);
 132 #endif
 133
 134 #ifndef __HAVE_ARCH_STRCAT
 135 /**
 136  * strcat - Append one %NUL-terminated string to another
 137  * @dest: The string to be appended to
 138  * @src: The string to append to it
 139  */
 140 #undef strcat
 141 char * strcat(char * dest, const char * src)
 142 {
 143         char *tmp = dest;
 144
 145         while (*dest)
 146                 dest++;
 147         while ((*dest++ = *src++) != '\0')
 148                 ;
 149
 150         return tmp;
 151 }
 152 EXPORT_SYMBOL(strcat);
 153 #endif
 154
 155 #ifndef __HAVE_ARCH_STRNCAT
 156 /**
 157  * strncat - Append a length-limited, %NUL-terminated string to another
 158  * @dest: The string to be appended to
 159  * @src: The string to append to it
 160  * @count: The maximum numbers of bytes to copy
 161  *
 162  * Note that in contrast to strncpy, strncat ensures the result is
 163  * terminated.
 164  */
 165 char * strncat(char *dest, const char *src, size_t count)
 166 {
 167         char *tmp = dest;
 168
 169         if (count) {
 170                 while (*dest)
 171                         dest++;
 172                 while ((*dest++ = *src++) != 0) {
 173                         if (--count == 0) {
 174                                 *dest = '\0';
 175                                 break;
 176                         }
 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         register signed char __res;
 222
 223         while (1) {
 224                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 225                         break;
 226         }
 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
 250         return __res;
 251 }
 252 EXPORT_SYMBOL(strncmp);
 253 #endif
 254
 255 #ifndef __HAVE_ARCH_STRCHR
 256 /**
 257  * strchr - Find the first occurrence of a character in a string
 258  * @s: The string to be searched
 259  * @c: The character to search for
 260  */
 261 char * strchr(const char * s, int c)
 262 {
 263         for(; *s != (char) c; ++s)
 264                 if (*s == '\0')
 265                         return NULL;
 266         return (char *) s;
 267 }
 268 EXPORT_SYMBOL(strchr);
 269 #endif
 270
 271 #ifndef __HAVE_ARCH_STRRCHR
 272 /**
 273  * strrchr - Find the last occurrence of a character in a string
 274  * @s: The string to be searched
 275  * @c: The character to search for
 276  */
 277 char * strrchr(const char * s, int c)
 278 {
 279        const char *p = s + strlen(s);
 280        do {
 281            if (*p == (char)c)
 282                return (char *)p;
 283        } while (--p >= s);
 284        return NULL;
 285 }
 286 EXPORT_SYMBOL(strrchr);
 287 #endif
 288
 289 #ifndef __HAVE_ARCH_STRNCHR
 290 /**
 291  * strnchr - Find a character in a length limited string
 292  * @s: The string to be searched
 293  * @count: The number of characters to be searched
 294  * @c: The character to search for
 295  */
 296 char *strnchr(const char *s, size_t count, int c)
 297 {
 298         for (; count-- && *s != '\0'; ++s)
 299                 if (*s == (char) c)
 300                         return (char *) s;
 301         return NULL;
 302 }
 303 EXPORT_SYMBOL(strnchr);
 304 #endif
 305
 306 #ifndef __HAVE_ARCH_STRLEN
 307 /**
 308  * strlen - Find the length of a string
 309  * @s: The string to be sized
 310  */
 311 size_t strlen(const char * s)
 312 {
 313         const char *sc;
 314
 315         for (sc = s; *sc != '\0'; ++sc)
 316                 /* nothing */;
 317         return sc - s;
 318 }
 319 EXPORT_SYMBOL(strlen);
 320 #endif
 321
 322 #ifndef __HAVE_ARCH_STRNLEN
 323 /**
 324  * strnlen - Find the length of a length-limited string
 325  * @s: The string to be sized
 326  * @count: The maximum number of bytes to search
 327  */
 328 size_t strnlen(const char * s, size_t count)
 329 {
 330         const char *sc;
 331
 332         for (sc = s; count-- && *sc != '\0'; ++sc)
 333                 /* nothing */;
 334         return sc - s;
 335 }
 336 EXPORT_SYMBOL(strnlen);
 337 #endif
 338
 339 #ifndef __HAVE_ARCH_STRSPN
 340 /**
 341  * strspn - Calculate the length of the initial substring of @s which only
 342  *      contain letters in @accept
 343  * @s: The string to be searched
 344  * @accept: The string to search for
 345  */
 346 size_t strspn(const char *s, const char *accept)
 347 {
 348         const char *p;
 349         const char *a;
 350         size_t count = 0;
 351
 352         for (p = s; *p != '\0'; ++p) {
 353                 for (a = accept; *a != '\0'; ++a) {
 354                         if (*p == *a)
 355                                 break;
 356                 }
 357                 if (*a == '\0')
 358                         return count;
 359                 ++count;
 360         }
 361
 362         return count;
 363 }
 364
 365 EXPORT_SYMBOL(strspn);
 366 #endif
 367
 368 /**
 369  * strcspn - Calculate the length of the initial substring of @s which does
 370  *      not contain letters in @reject
 371  * @s: The string to be searched
 372  * @reject: The string to avoid
 373  */
 374 size_t strcspn(const char *s, const char *reject)
 375 {
 376         const char *p;
 377         const char *r;
 378         size_t count = 0;
 379
 380         for (p = s; *p != '\0'; ++p) {
 381                 for (r = reject; *r != '\0'; ++r) {
 382                         if (*p == *r)
 383                                 return count;
 384                 }
 385                 ++count;
 386         }
 387
 388         return count;
 389 }
 390 EXPORT_SYMBOL(strcspn);
 391
 392 #ifndef __HAVE_ARCH_STRPBRK
 393 /**
 394  * strpbrk - Find the first occurrence of a set of characters
 395  * @cs: The string to be searched
 396  * @ct: The characters to search for
 397  */
 398 char * strpbrk(const char * cs,const char * ct)
 399 {
 400         const char *sc1,*sc2;
 401
 402         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 403                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 404                         if (*sc1 == *sc2)
 405                                 return (char *) sc1;
 406                 }
 407         }
 408         return NULL;
 409 }
 410 EXPORT_SYMBOL(strpbrk);
 411 #endif
 412
 413 #ifndef __HAVE_ARCH_STRSEP
 414 /**
 415  * strsep - Split a string into tokens
 416  * @s: The string to be searched
 417  * @ct: The characters to search for
 418  *
 419  * strsep() updates @s to point after the token, ready for the next call.
 420  *
 421  * It returns empty tokens, too, behaving exactly like the libc function
 422  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 423  * Same semantics, slimmer shape. ;)
 424  */
 425 char * strsep(char **s, const char *ct)
 426 {
 427         char *sbegin = *s, *end;
 428
 429         if (sbegin == NULL)
 430                 return NULL;
 431
 432         end = strpbrk(sbegin, ct);
 433         if (end)
 434                 *end++ = '\0';
 435         *s = end;
 436
 437         return sbegin;
 438 }
 439
 440 EXPORT_SYMBOL(strsep);
 441 #endif
 442
 443 #ifndef __HAVE_ARCH_MEMSET
 444 /**
 445  * memset - Fill a region of memory with the given value
 446  * @s: Pointer to the start of the area.
 447  * @c: The byte to fill the area with
 448  * @count: The size of the area.
 449  *
 450  * Do not use memset() to access IO space, use memset_io() instead.
 451  */
 452 void * memset(void * s,int c,size_t count)
 453 {
 454         char *xs = (char *) s;
 455
 456         while (count--)
 457                 *xs++ = c;
 458
 459         return s;
 460 }
 461 EXPORT_SYMBOL(memset);
 462 #endif
 463
 464 #ifndef __HAVE_ARCH_MEMCPY
 465 /**
 466  * memcpy - Copy one area of memory to another
 467  * @dest: Where to copy to
 468  * @src: Where to copy from
 469  * @count: The size of the area.
 470  *
 471  * You should not use this function to access IO space, use memcpy_toio()
 472  * or memcpy_fromio() instead.
 473  */
 474 void * memcpy(void * dest,const void *src,size_t count)
 475 {
 476         char *tmp = (char *) dest, *s = (char *) src;
 477
 478         while (count--)
 479                 *tmp++ = *s++;
 480
 481         return dest;
 482 }
 483 EXPORT_SYMBOL(memcpy);
 484 #endif
 485
 486 #ifndef __HAVE_ARCH_MEMMOVE
 487 /**
 488  * memmove - Copy one area of memory to another
 489  * @dest: Where to copy to
 490  * @src: Where to copy from
 491  * @count: The size of the area.
 492  *
 493  * Unlike memcpy(), memmove() copes with overlapping areas.
 494  */
 495 void * memmove(void * dest,const void *src,size_t count)
 496 {
 497         char *tmp, *s;
 498
 499         if (dest <= src) {
 500                 tmp = (char *) dest;
 501                 s = (char *) src;
 502                 while (count--)
 503                         *tmp++ = *s++;
 504                 }
 505         else {
 506                 tmp = (char *) dest + count;
 507                 s = (char *) src + count;
 508                 while (count--)
 509                         *--tmp = *--s;
 510                 }
 511
 512         return dest;
 513 }
 514 EXPORT_SYMBOL(memmove);
 515 #endif
 516
 517 #ifndef __HAVE_ARCH_MEMCMP
 518 /**
 519  * memcmp - Compare two areas of memory
 520  * @cs: One area of memory
 521  * @ct: Another area of memory
 522  * @count: The size of the area.
 523  */
 524 #undef memcmp
 525 int memcmp(const void * cs,const void * ct,size_t count)
 526 {
 527         const unsigned char *su1, *su2;
 528         int res = 0;
 529
 530         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 531                 if ((res = *su1 - *su2) != 0)
 532                         break;
 533         return res;
 534 }
 535 EXPORT_SYMBOL(memcmp);
 536 #endif
 537
 538 #ifndef __HAVE_ARCH_MEMSCAN
 539 /**
 540  * memscan - Find a character in an area of memory.
 541  * @addr: The memory area
 542  * @c: The byte to search for
 543  * @size: The size of the area.
 544  *
 545  * returns the address of the first occurrence of @c, or 1 byte past
 546  * the area if @c is not found
 547  */
 548 void * memscan(void * addr, int c, size_t size)
 549 {
 550         unsigned char * p = (unsigned char *) addr;
 551
 552         while (size) {
 553                 if (*p == c)
 554                         return (void *) p;
 555                 p++;
 556                 size--;
 557         }
 558         return (void *) p;
 559 }
 560 EXPORT_SYMBOL(memscan);
 561 #endif
 562
 563 #ifndef __HAVE_ARCH_STRSTR
 564 /**
 565  * strstr - Find the first substring in a %NUL terminated string
 566  * @s1: The string to be searched
 567  * @s2: The string to search for
 568  */
 569 char * strstr(const char * s1,const char * s2)
 570 {
 571         int l1, l2;
 572
 573         l2 = strlen(s2);
 574         if (!l2)
 575                 return (char *) s1;
 576         l1 = strlen(s1);
 577         while (l1 >= l2) {
 578                 l1--;
 579                 if (!memcmp(s1,s2,l2))
 580                         return (char *) s1;
 581                 s1++;
 582         }
 583         return NULL;
 584 }
 585 EXPORT_SYMBOL(strstr);
 586 #endif
 587
 588 #ifndef __HAVE_ARCH_MEMCHR
 589 /**
 590  * memchr - Find a character in an area of memory.
 591  * @s: The memory area
 592  * @c: The byte to search for
 593  * @n: The size of the area.
 594  *
 595  * returns the address of the first occurrence of @c, or %NULL
 596  * if @c is not found
 597  */
 598 void *memchr(const void *s, int c, size_t n)
 599 {
 600         const unsigned char *p = s;
 601         while (n-- != 0) {
 602                 if ((unsigned char)c == *p++) {
 603                         return (void *)(p-1);
 604                 }
 605         }
 606         return NULL;
 607 }
 608 EXPORT_SYMBOL(memchr);
 609 #endif