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 #endif
  59
  60 #ifndef __HAVE_ARCH_STRCPY
  61 /**
  62  * strcpy - Copy a %NUL terminated string
  63  * @dest: Where to copy the string to
  64  * @src: Where to copy the string from
  65  */
  66 char * strcpy(char * dest,const char *src)
  67 {
  68         char *tmp = dest;
  69
  70         while ((*dest++ = *src++) != '\0')
  71                 /* nothing */;
  72         return tmp;
  73 }
  74 #endif
  75
  76 #ifndef __HAVE_ARCH_STRNCPY
  77 /**
  78  * strncpy - Copy a length-limited, %NUL-terminated string
  79  * @dest: Where to copy the string to
  80  * @src: Where to copy the string from
  81  * @count: The maximum number of bytes to copy
  82  *
  83  * Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
  84  * However, the result is not %NUL-terminated if the source exceeds
  85  * @count bytes.
  86  */
  87 char * strncpy(char * dest,const char *src,size_t count)
  88 {
  89         char *tmp = dest;
  90
  91         while (count-- && (*dest++ = *src++) != '\0')
  92                 /* nothing */;
  93
  94         return tmp;
  95 }
  96 #endif
  97
  98 #ifndef __HAVE_ARCH_STRLCPY
  99 /**
 100  * strlcpy - Copy a %NUL terminated string into a sized buffer
 101  * @dest: Where to copy the string to
 102  * @src: Where to copy the string from
 103  * @size: size of destination buffer
 104  *
 105  * Compatible with *BSD: the result is always a valid
 106  * NUL-terminated string that fits in the buffer (unless,
 107  * of course, the buffer size is zero). It does not pad
 108  * out the result like strncpy() does.
 109  */
 110 size_t strlcpy(char *dest, const char *src, size_t size)
 111 {
 112         size_t ret = strlen(src);
 113
 114         if (size) {
 115                 size_t len = (ret >= size) ? size-1 : ret;
 116                 memcpy(dest, src, len);
 117                 dest[len] = '\0';
 118         }
 119         return ret;
 120 }
 121 EXPORT_SYMBOL(strlcpy);
 122 #endif
 123
 124 #ifndef __HAVE_ARCH_STRCAT
 125 /**
 126  * strcat - Append one %NUL-terminated string to another
 127  * @dest: The string to be appended to
 128  * @src: The string to append to it
 129  */
 130 char * strcat(char * dest, const char * src)
 131 {
 132         char *tmp = dest;
 133
 134         while (*dest)
 135                 dest++;
 136         while ((*dest++ = *src++) != '\0')
 137                 ;
 138
 139         return tmp;
 140 }
 141 #endif
 142
 143 #ifndef __HAVE_ARCH_STRNCAT
 144 /**
 145  * strncat - Append a length-limited, %NUL-terminated string to another
 146  * @dest: The string to be appended to
 147  * @src: The string to append to it
 148  * @count: The maximum numbers of bytes to copy
 149  *
 150  * Note that in contrast to strncpy, strncat ensures the result is
 151  * terminated.
 152  */
 153 char * strncat(char *dest, const char *src, size_t count)
 154 {
 155         char *tmp = dest;
 156
 157         if (count) {
 158                 while (*dest)
 159                         dest++;
 160                 while ((*dest++ = *src++)) {
 161                         if (--count == 0) {
 162                                 *dest = '\0';
 163                                 break;
 164                         }
 165                 }
 166         }
 167
 168         return tmp;
 169 }
 170 #endif
 171
 172 #ifndef __HAVE_ARCH_STRLCAT
 173 /**
 174  * strlcat - Append a length-limited, %NUL-terminated string to another
 175  * @dest: The string to be appended to
 176  * @src: The string to append to it
 177  * @count: The size of the destination buffer.
 178  */
 179 size_t strlcat(char *dest, const char *src, size_t count)
 180 {
 181         size_t dsize = strlen(dest);
 182         size_t len = strlen(src);
 183         size_t res = dsize + len;
 184
 185         /* This would be a bug */
 186         BUG_ON(dsize >= count);
 187
 188         dest += dsize;
 189         count -= dsize;
 190         if (len >= count)
 191                 len = count-1;
 192         memcpy(dest, src, len);
 193         dest[len] = 0;
 194         return res;
 195 }
 196 EXPORT_SYMBOL(strlcat);
 197 #endif
 198
 199 #ifndef __HAVE_ARCH_STRCMP
 200 /**
 201  * strcmp - Compare two strings
 202  * @cs: One string
 203  * @ct: Another string
 204  */
 205 int strcmp(const char * cs,const char * ct)
 206 {
 207         register signed char __res;
 208
 209         while (1) {
 210                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 211                         break;
 212         }
 213
 214         return __res;
 215 }
 216 #endif
 217
 218 #ifndef __HAVE_ARCH_STRNCMP
 219 /**
 220  * strncmp - Compare two length-limited strings
 221  * @cs: One string
 222  * @ct: Another string
 223  * @count: The maximum number of bytes to compare
 224  */
 225 int strncmp(const char * cs,const char * ct,size_t count)
 226 {
 227         register signed char __res = 0;
 228
 229         while (count) {
 230                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 231                         break;
 232                 count--;
 233         }
 234
 235         return __res;
 236 }
 237 #endif
 238
 239 #ifndef __HAVE_ARCH_STRCHR
 240 /**
 241  * strchr - Find the first occurrence of a character in a string
 242  * @s: The string to be searched
 243  * @c: The character to search for
 244  */
 245 char * strchr(const char * s, int c)
 246 {
 247         for(; *s != (char) c; ++s)
 248                 if (*s == '\0')
 249                         return NULL;
 250         return (char *) s;
 251 }
 252 #endif
 253
 254 #ifndef __HAVE_ARCH_STRRCHR
 255 /**
 256  * strrchr - Find the last occurrence of a character in a string
 257  * @s: The string to be searched
 258  * @c: The character to search for
 259  */
 260 char * strrchr(const char * s, int c)
 261 {
 262        const char *p = s + strlen(s);
 263        do {
 264            if (*p == (char)c)
 265                return (char *)p;
 266        } while (--p >= s);
 267        return NULL;
 268 }
 269 #endif
 270
 271 #ifndef __HAVE_ARCH_STRLEN
 272 /**
 273  * strlen - Find the length of a string
 274  * @s: The string to be sized
 275  */
 276 size_t strlen(const char * s)
 277 {
 278         const char *sc;
 279
 280         for (sc = s; *sc != '\0'; ++sc)
 281                 /* nothing */;
 282         return sc - s;
 283 }
 284 #endif
 285
 286 #ifndef __HAVE_ARCH_STRNLEN
 287 /**
 288  * strnlen - Find the length of a length-limited string
 289  * @s: The string to be sized
 290  * @count: The maximum number of bytes to search
 291  */
 292 size_t strnlen(const char * s, size_t count)
 293 {
 294         const char *sc;
 295
 296         for (sc = s; count-- && *sc != '\0'; ++sc)
 297                 /* nothing */;
 298         return sc - s;
 299 }
 300 #endif
 301
 302 #ifndef __HAVE_ARCH_STRSPN
 303 /**
 304  * strspn - Calculate the length of the initial substring of @s which only
 305  *      contain letters in @accept
 306  * @s: The string to be searched
 307  * @accept: The string to search for
 308  */
 309 size_t strspn(const char *s, const char *accept)
 310 {
 311         const char *p;
 312         const char *a;
 313         size_t count = 0;
 314
 315         for (p = s; *p != '\0'; ++p) {
 316                 for (a = accept; *a != '\0'; ++a) {
 317                         if (*p == *a)
 318                                 break;
 319                 }
 320                 if (*a == '\0')
 321                         return count;
 322                 ++count;
 323         }
 324
 325         return count;
 326 }
 327 #endif
 328
 329 /**
 330  * strcspn - Calculate the length of the initial substring of @s which does
 331  *      not contain letters in @reject
 332  * @s: The string to be searched
 333  * @reject: The string to avoid
 334  */
 335 size_t strcspn(const char *s, const char *reject)
 336 {
 337         const char *p;
 338         const char *r;
 339         size_t count = 0;
 340
 341         for (p = s; *p != '\0'; ++p) {
 342                 for (r = reject; *r != '\0'; ++r) {
 343                         if (*p == *r)
 344                                 return count;
 345                 }
 346                 ++count;
 347         }
 348
 349         return count;
 350 }
 351
 352 #ifndef __HAVE_ARCH_STRPBRK
 353 /**
 354  * strpbrk - Find the first occurrence of a set of characters
 355  * @cs: The string to be searched
 356  * @ct: The characters to search for
 357  */
 358 char * strpbrk(const char * cs,const char * ct)
 359 {
 360         const char *sc1,*sc2;
 361
 362         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 363                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 364                         if (*sc1 == *sc2)
 365                                 return (char *) sc1;
 366                 }
 367         }
 368         return NULL;
 369 }
 370 #endif
 371
 372 #ifndef __HAVE_ARCH_STRSEP
 373 /**
 374  * strsep - Split a string into tokens
 375  * @s: The string to be searched
 376  * @ct: The characters to search for
 377  *
 378  * strsep() updates @s to point after the token, ready for the next call.
 379  *
 380  * It returns empty tokens, too, behaving exactly like the libc function
 381  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 382  * Same semantics, slimmer shape. ;)
 383  */
 384 char * strsep(char **s, const char *ct)
 385 {
 386         char *sbegin = *s, *end;
 387
 388         if (sbegin == NULL)
 389                 return NULL;
 390
 391         end = strpbrk(sbegin, ct);
 392         if (end)
 393                 *end++ = '\0';
 394         *s = end;
 395
 396         return sbegin;
 397 }
 398 #endif
 399
 400 #ifndef __HAVE_ARCH_MEMSET
 401 /**
 402  * memset - Fill a region of memory with the given value
 403  * @s: Pointer to the start of the area.
 404  * @c: The byte to fill the area with
 405  * @count: The size of the area.
 406  *
 407  * Do not use memset() to access IO space, use memset_io() instead.
 408  */
 409 void * memset(void * s,int c, size_t count)
 410 {
 411         char *xs = (char *) s;
 412
 413         while (count--)
 414                 *xs++ = c;
 415
 416         return s;
 417 }
 418 #endif
 419
 420 #ifndef __HAVE_ARCH_BCOPY
 421 /**
 422  * bcopy - Copy one area of memory to another
 423  * @src: Where to copy from
 424  * @dest: Where to copy to
 425  * @count: The size of the area.
 426  *
 427  * Note that this is the same as memcpy(), with the arguments reversed.
 428  * memcpy() is the standard, bcopy() is a legacy BSD function.
 429  *
 430  * You should not use this function to access IO space, use memcpy_toio()
 431  * or memcpy_fromio() instead.
 432  */
 433 char * bcopy(const char * src, char * dest, int count)
 434 {
 435         char *tmp = dest;
 436
 437         while (count--)
 438                 *tmp++ = *src++;
 439
 440         return dest;
 441 }
 442 #endif
 443
 444 #ifndef __HAVE_ARCH_MEMCPY
 445 /**
 446  * memcpy - Copy one area of memory to another
 447  * @dest: Where to copy to
 448  * @src: Where to copy from
 449  * @count: The size of the area.
 450  *
 451  * You should not use this function to access IO space, use memcpy_toio()
 452  * or memcpy_fromio() instead.
 453  */
 454 void * memcpy(void * dest,const void *src,size_t count)
 455 {
 456         char *tmp = (char *) dest, *s = (char *) src;
 457
 458         while (count--)
 459                 *tmp++ = *s++;
 460
 461         return dest;
 462 }
 463 #endif
 464
 465 #ifndef __HAVE_ARCH_MEMMOVE
 466 /**
 467  * memmove - Copy one area of memory to another
 468  * @dest: Where to copy to
 469  * @src: Where to copy from
 470  * @count: The size of the area.
 471  *
 472  * Unlike memcpy(), memmove() copes with overlapping areas.
 473  */
 474 void * memmove(void * dest,const void *src,size_t count)
 475 {
 476         char *tmp, *s;
 477
 478         if (dest <= src) {
 479                 tmp = (char *) dest;
 480                 s = (char *) src;
 481                 while (count--)
 482                         *tmp++ = *s++;
 483                 }
 484         else {
 485                 tmp = (char *) dest + count;
 486                 s = (char *) src + count;
 487                 while (count--)
 488                         *--tmp = *--s;
 489                 }
 490
 491         return dest;
 492 }
 493 #endif
 494
 495 #ifndef __HAVE_ARCH_MEMCMP
 496 /**
 497  * memcmp - Compare two areas of memory
 498  * @cs: One area of memory
 499  * @ct: Another area of memory
 500  * @count: The size of the area.
 501  */
 502 int memcmp(const void * cs,const void * ct,size_t count)
 503 {
 504         const unsigned char *su1, *su2;
 505         int res = 0;
 506
 507         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 508                 if ((res = *su1 - *su2) != 0)
 509                         break;
 510         return res;
 511 }
 512 #endif
 513
 514 #ifndef __HAVE_ARCH_MEMSCAN
 515 /**
 516  * memscan - Find a character in an area of memory.
 517  * @addr: The memory area
 518  * @c: The byte to search for
 519  * @size: The size of the area.
 520  *
 521  * returns the address of the first occurrence of @c, or 1 byte past
 522  * the area if @c is not found
 523  */
 524 void * memscan(void * addr, int c, size_t size)
 525 {
 526         unsigned char * p = (unsigned char *) addr;
 527         unsigned char * e = p + size;
 528
 529         while (p != e) {
 530                 if (*p == (unsigned char)c)
 531                         return (void *) p;
 532                 p++;
 533         }
 534
 535         return (void *) p;
 536 }
 537 #endif
 538
 539 #ifndef __HAVE_ARCH_STRSTR
 540 /**
 541  * strstr - Find the first substring in a %NUL terminated string
 542  * @s1: The string to be searched
 543  * @s2: The string to search for
 544  */
 545 char * strstr(const char * s1,const char * s2)
 546 {
 547         int l1, l2;
 548
 549         l2 = strlen(s2);
 550         if (!l2)
 551                 return (char *) s1;
 552         l1 = strlen(s1);
 553         while (l1 >= l2) {
 554                 l1--;
 555                 if (!memcmp(s1,s2,l2))
 556                         return (char *) s1;
 557                 s1++;
 558         }
 559         return NULL;
 560 }
 561 #endif
 562
 563 #ifndef __HAVE_ARCH_MEMCHR
 564 /**
 565  * memchr - Find a character in an area of memory.
 566  * @s: The memory area
 567  * @c: The byte to search for
 568  * @n: The size of the area.
 569  *
 570  * returns the address of the first occurrence of @c, or %NULL
 571  * if @c is not found
 572  */
 573 void *memchr(const void *s, int c, size_t n)
 574 {
 575         const unsigned char *p = s;
 576         while (n-- != 0) {
 577                 if ((unsigned char)c == *p++) {
 578                         return (void *)(p-1);
 579                 }
 580         }
 581         return NULL;
 582 }
 583
 584 #endif