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