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
  18 #include <linux/types.h>
  19 #include <linux/string.h>
  20 #include <linux/ctype.h>
  21 #include <malloc.h>
  22
  23 char * ___strtok;
  24
  25 #ifndef __HAVE_ARCH_STRCPY
  26 /**
  27  * strcpy - Copy a %NUL terminated string
  28  * @dest: Where to copy the string to
  29  * @src: Where to copy the string from
  30  */
  31 char * strcpy(char * dest,const char *src)
  32 {
  33         char *tmp = dest;
  34
  35         while ((*dest++ = *src++) != '\0')
  36                 /* nothing */;
  37         return tmp;
  38 }
  39 #endif
  40 EXPORT_SYMBOL(strcpy);
  41
  42 #ifndef __HAVE_ARCH_STRNCPY
  43 /**
  44  * strncpy - Copy a length-limited, %NUL-terminated string
  45  * @dest: Where to copy the string to
  46  * @src: Where to copy the string from
  47  * @count: The maximum number of bytes to copy
  48  *
  49  * Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
  50  * However, the result is not %NUL-terminated if the source exceeds
  51  * @count bytes.
  52  */
  53 char * strncpy(char * dest,const char *src,size_t count)
  54 {
  55         char *tmp = dest;
  56
  57         while (count-- && (*dest++ = *src++) != '\0')
  58                 /* nothing */;
  59
  60         return tmp;
  61 }
  62 #endif
  63 EXPORT_SYMBOL(strncpy);
  64
  65 #ifndef __HAVE_ARCH_STRCAT
  66 /**
  67  * strcat - Append one %NUL-terminated string to another
  68  * @dest: The string to be appended to
  69  * @src: The string to append to it
  70  */
  71 char * strcat(char * dest, const char * src)
  72 {
  73         char *tmp = dest;
  74
  75         while (*dest)
  76                 dest++;
  77         while ((*dest++ = *src++) != '\0')
  78                 ;
  79
  80         return tmp;
  81 }
  82 #endif
  83 EXPORT_SYMBOL(strcat);
  84
  85 #ifndef __HAVE_ARCH_STRNCAT
  86 /**
  87  * strncat - Append a length-limited, %NUL-terminated string to another
  88  * @dest: The string to be appended to
  89  * @src: The string to append to it
  90  * @count: The maximum numbers of bytes to copy
  91  *
  92  * Note that in contrast to strncpy, strncat ensures the result is
  93  * terminated.
  94  */
  95 char * strncat(char *dest, const char *src, size_t count)
  96 {
  97         char *tmp = dest;
  98
  99         if (count) {
 100                 while (*dest)
 101                         dest++;
 102                 while ((*dest++ = *src++)) {
 103                         if (--count == 0) {
 104                                 *dest = '\0';
 105                                 break;
 106                         }
 107                 }
 108         }
 109
 110         return tmp;
 111 }
 112 #endif
 113 EXPORT_SYMBOL(strncat);
 114
 115 #ifndef __HAVE_ARCH_STRCMP
 116 /**
 117  * strcmp - Compare two strings
 118  * @cs: One string
 119  * @ct: Another string
 120  */
 121 int strcmp(const char * cs,const char * ct)
 122 {
 123         register signed char __res;
 124
 125         while (1) {
 126                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 127                         break;
 128         }
 129
 130         return __res;
 131 }
 132 #endif
 133 EXPORT_SYMBOL(strcmp);
 134
 135 #ifndef __HAVE_ARCH_STRNCMP
 136 /**
 137  * strncmp - Compare two length-limited strings
 138  * @cs: One string
 139  * @ct: Another string
 140  * @count: The maximum number of bytes to compare
 141  */
 142 int strncmp(const char * cs, const char * ct, size_t count)
 143 {
 144         register signed char __res = 0;
 145
 146         while (count) {
 147                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 148                         break;
 149                 count--;
 150         }
 151
 152         return __res;
 153 }
 154 #endif
 155 EXPORT_SYMBOL(strncmp);
 156
 157 #ifndef __HAVE_ARCH_STRCHR
 158 /**
 159  * strchr - Find the first occurrence of a character in a string
 160  * @s: The string to be searched
 161  * @c: The character to search for
 162  */
 163 char * _strchr(const char * s, int c)
 164 {
 165         for(; *s != (char) c; ++s)
 166                 if (*s == '\0')
 167                         return NULL;
 168         return (char *) s;
 169 }
 170 #endif
 171 EXPORT_SYMBOL(_strchr);
 172
 173 #ifndef __HAVE_ARCH_STRRCHR
 174 /**
 175  * strrchr - Find the last occurrence of a character in a string
 176  * @s: The string to be searched
 177  * @c: The character to search for
 178  */
 179 char * _strrchr(const char * s, int c)
 180 {
 181        const char *p = s + strlen(s);
 182        do {
 183            if (*p == (char)c)
 184                return (char *)p;
 185        } while (--p >= s);
 186        return NULL;
 187 }
 188 #endif
 189 EXPORT_SYMBOL(strrchr);
 190
 191 #ifndef __HAVE_ARCH_STRLEN
 192 /**
 193  * strlen - Find the length of a string
 194  * @s: The string to be sized
 195  */
 196 size_t strlen(const char * s)
 197 {
 198         const char *sc;
 199
 200         for (sc = s; *sc != '\0'; ++sc)
 201                 /* nothing */;
 202         return sc - s;
 203 }
 204 #endif
 205 EXPORT_SYMBOL(strlen);
 206
 207 #ifndef __HAVE_ARCH_STRNLEN
 208 /**
 209  * strnlen - Find the length of a length-limited string
 210  * @s: The string to be sized
 211  * @count: The maximum number of bytes to search
 212  */
 213 size_t strnlen(const char * s, size_t count)
 214 {
 215         const char *sc;
 216
 217         for (sc = s; count-- && *sc != '\0'; ++sc)
 218                 /* nothing */;
 219         return sc - s;
 220 }
 221 #endif
 222 EXPORT_SYMBOL(strnlen);
 223
 224 #ifndef __HAVE_ARCH_STRDUP
 225 char * strdup(const char *s)
 226 {
 227         char *new;
 228
 229         if ((s == NULL) ||
 230             ((new = malloc (strlen(s) + 1)) == NULL) ) {
 231                 return NULL;
 232         }
 233
 234         strcpy (new, s);
 235         return new;
 236 }
 237 #endif
 238 EXPORT_SYMBOL(strdup);
 239
 240 #ifndef __HAVE_ARCH_STRSPN
 241 /**
 242  * strspn - Calculate the length of the initial substring of @s which only
 243  *      contain letters in @accept
 244  * @s: The string to be searched
 245  * @accept: The string to search for
 246  */
 247 size_t strspn(const char *s, const char *accept)
 248 {
 249         const char *p;
 250         const char *a;
 251         size_t count = 0;
 252
 253         for (p = s; *p != '\0'; ++p) {
 254                 for (a = accept; *a != '\0'; ++a) {
 255                         if (*p == *a)
 256                                 break;
 257                 }
 258                 if (*a == '\0')
 259                         return count;
 260                 ++count;
 261         }
 262
 263         return count;
 264 }
 265 #endif
 266 EXPORT_SYMBOL(strspn);
 267
 268 #ifndef __HAVE_ARCH_STRPBRK
 269 /**
 270  * strpbrk - Find the first occurrence of a set of characters
 271  * @cs: The string to be searched
 272  * @ct: The characters to search for
 273  */
 274 char * strpbrk(const char * cs,const char * ct)
 275 {
 276         const char *sc1, *sc2;
 277
 278         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 279                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 280                         if (*sc1 == *sc2)
 281                                 return (char *) sc1;
 282                 }
 283         }
 284         return NULL;
 285 }
 286 #endif
 287 EXPORT_SYMBOL(strpbrk);
 288
 289 #ifndef __HAVE_ARCH_STRTOK
 290 /**
 291  * strtok - Split a string into tokens
 292  * @s: The string to be searched
 293  * @ct: The characters to search for
 294  *
 295  * WARNING: strtok is deprecated, use strsep instead.
 296  */
 297 char * strtok(char * s, const char * ct)
 298 {
 299         char *sbegin, *send;
 300
 301         sbegin  = s ? s : ___strtok;
 302         if (!sbegin) {
 303                 return NULL;
 304         }
 305         sbegin += strspn(sbegin,ct);
 306         if (*sbegin == '\0') {
 307                 ___strtok = NULL;
 308                 return( NULL );
 309         }
 310         send = strpbrk( sbegin, ct);
 311         if (send && *send != '\0')
 312                 *send++ = '\0';
 313         ___strtok = send;
 314         return (sbegin);
 315 }
 316 #endif
 317 EXPORT_SYMBOL(strtok);
 318
 319 #ifndef __HAVE_ARCH_STRSEP
 320 /**
 321  * strsep - Split a string into tokens
 322  * @s: The string to be searched
 323  * @ct: The characters to search for
 324  *
 325  * strsep() updates @s to point after the token, ready for the next call.
 326  *
 327  * It returns empty tokens, too, behaving exactly like the libc function
 328  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 329  * Same semantics, slimmer shape. ;)
 330  */
 331 char * strsep(char **s, const char *ct)
 332 {
 333         char *sbegin = *s, *end;
 334
 335         if (sbegin == NULL)
 336                 return NULL;
 337
 338         end = strpbrk(sbegin, ct);
 339         if (end)
 340                 *end++ = '\0';
 341         *s = end;
 342
 343         return sbegin;
 344 }
 345 #endif
 346 EXPORT_SYMBOL(strsep);
 347
 348 #ifndef __HAVE_ARCH_STRSWAB
 349 /**
 350  * strswab - swap adjacent even and odd bytes in %NUL-terminated string
 351  * s: address of the string
 352  *
 353  * returns the address of the swapped string or NULL on error. If
 354  * string length is odd, last byte is untouched.
 355  */
 356 char *strswab(const char *s)
 357 {
 358         char *p, *q;
 359
 360         if ((NULL == s) || ('\0' == *s)) {
 361                 return (NULL);
 362         }
 363
 364         for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
 365                 char  tmp;
 366
 367                 tmp = *p;
 368                 *p  = *q;
 369                 *q  = tmp;
 370         }
 371
 372         return (char *) s;
 373 }
 374 #endif
 375
 376 #ifndef __HAVE_ARCH_MEMSET
 377 /**
 378  * memset - Fill a region of memory with the given value
 379  * @s: Pointer to the start of the area.
 380  * @c: The byte to fill the area with
 381  * @count: The size of the area.
 382  *
 383  * Do not use memset() to access IO space, use memset_io() instead.
 384  */
 385 void * memset(void * s,int c,size_t count)
 386 {
 387         char *xs = (char *) s;
 388
 389         while (count--)
 390                 *xs++ = c;
 391
 392         return s;
 393 }
 394 #endif
 395 EXPORT_SYMBOL(memset);
 396
 397 #ifndef __HAVE_ARCH_BCOPY
 398 /**
 399  * bcopy - Copy one area of memory to another
 400  * @src: Where to copy from
 401  * @dest: Where to copy to
 402  * @count: The size of the area.
 403  *
 404  * Note that this is the same as memcpy(), with the arguments reversed.
 405  * memcpy() is the standard, bcopy() is a legacy BSD function.
 406  *
 407  * You should not use this function to access IO space, use memcpy_toio()
 408  * or memcpy_fromio() instead.
 409  */
 410 char * bcopy(const char * src, char * dest, int count)
 411 {
 412         char *tmp = dest;
 413
 414         while (count--)
 415                 *tmp++ = *src++;
 416
 417         return dest;
 418 }
 419 #endif
 420
 421 #ifndef __HAVE_ARCH_MEMCPY
 422 /**
 423  * memcpy - Copy one area of memory to another
 424  * @dest: Where to copy to
 425  * @src: Where to copy from
 426  * @count: The size of the area.
 427  *
 428  * You should not use this function to access IO space, use memcpy_toio()
 429  * or memcpy_fromio() instead.
 430  */
 431 void * memcpy(void * dest,const void *src,size_t count)
 432 {
 433         char *tmp = (char *) dest, *s = (char *) src;
 434
 435         while (count--)
 436                 *tmp++ = *s++;
 437
 438         return dest;
 439 }
 440 #endif
 441 EXPORT_SYMBOL(memcpy);
 442
 443 #ifndef __HAVE_ARCH_MEMMOVE
 444 /**
 445  * memmove - Copy one area of memory to another
 446  * @dest: Where to copy to
 447  * @src: Where to copy from
 448  * @count: The size of the area.
 449  *
 450  * Unlike memcpy(), memmove() copes with overlapping areas.
 451  */
 452 void * memmove(void * dest,const void *src,size_t count)
 453 {
 454         char *tmp, *s;
 455
 456         if (dest <= src) {
 457                 tmp = (char *) dest;
 458                 s = (char *) src;
 459                 while (count--)
 460                         *tmp++ = *s++;
 461                 }
 462         else {
 463                 tmp = (char *) dest + count;
 464                 s = (char *) src + count;
 465                 while (count--)
 466                         *--tmp = *--s;
 467                 }
 468
 469         return dest;
 470 }
 471 #endif
 472 EXPORT_SYMBOL(memmove);
 473
 474 #ifndef __HAVE_ARCH_MEMCMP
 475 /**
 476  * memcmp - Compare two areas of memory
 477  * @cs: One area of memory
 478  * @ct: Another area of memory
 479  * @count: The size of the area.
 480  */
 481 int memcmp(const void * cs,const void * ct,size_t count)
 482 {
 483         const unsigned char *su1, *su2;
 484         int res = 0;
 485
 486         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 487                 if ((res = *su1 - *su2) != 0)
 488                         break;
 489         return res;
 490 }
 491 #endif
 492 EXPORT_SYMBOL(memcmp);
 493
 494 #ifndef __HAVE_ARCH_MEMSCAN
 495 /**
 496  * memscan - Find a character in an area of memory.
 497  * @addr: The memory area
 498  * @c: The byte to search for
 499  * @size: The size of the area.
 500  *
 501  * returns the address of the first occurrence of @c, or 1 byte past
 502  * the area if @c is not found
 503  */
 504 void * memscan(void * addr, int c, size_t size)
 505 {
 506         unsigned char * p = (unsigned char *) addr;
 507
 508         while (size) {
 509                 if (*p == c)
 510                         return (void *) p;
 511                 p++;
 512                 size--;
 513         }
 514         return (void *) p;
 515 }
 516 #endif
 517 EXPORT_SYMBOL(memscan);
 518
 519 #ifndef __HAVE_ARCH_STRSTR
 520 /**
 521  * strstr - Find the first substring in a %NUL terminated string
 522  * @s1: The string to be searched
 523  * @s2: The string to search for
 524  */
 525 char * _strstr(const char * s1,const char * s2)
 526 {
 527         int l1, l2;
 528
 529         l2 = strlen(s2);
 530         if (!l2)
 531                 return (char *) s1;
 532         l1 = strlen(s1);
 533         while (l1 >= l2) {
 534                 l1--;
 535                 if (!memcmp(s1,s2,l2))
 536                         return (char *) s1;
 537                 s1++;
 538         }
 539         return NULL;
 540 }
 541 #endif
 542 EXPORT_SYMBOL(strstr);
 543
 544 #ifndef __HAVE_ARCH_MEMCHR
 545 /**
 546  * memchr - Find a character in an area of memory.
 547  * @s: The memory area
 548  * @c: The byte to search for
 549  * @n: The size of the area.
 550  *
 551  * returns the address of the first occurrence of @c, or %NULL
 552  * if @c is not found
 553  */
 554 void *memchr(const void *s, int c, size_t n)
 555 {
 556         const unsigned char *p = s;
 557         while (n-- != 0) {
 558                 if ((unsigned char)c == *p++) {
 559                         return (void *)(p-1);
 560                 }
 561         }
 562         return NULL;
 563 }
 564
 565 #endif
 566 EXPORT_SYMBOL(memchr);
 567