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_STRLCPY
  66 /**
  67  * strlcpy - Copy a %NUL terminated string into a sized buffer
  68  * @dest: Where to copy the string to
  69  * @src: Where to copy the string from
  70  * @size: size of destination buffer
  71  *
  72  * Compatible with *BSD: the result is always a valid
  73  * NUL-terminated string that fits in the buffer (unless,
  74  * of course, the buffer size is zero). It does not pad
  75  * out the result like strncpy() does.
  76  */
  77 size_t strlcpy(char *dest, const char *src, size_t size)
  78 {
  79         size_t ret = strlen(src);
  80
  81         if (size) {
  82                 size_t len = (ret >= size) ? size - 1 : ret;
  83                 memcpy(dest, src, len);
  84                 dest[len] = '\0';
  85         }
  86         return ret;
  87 }
  88 EXPORT_SYMBOL(strlcpy);
  89 #endif
  90
  91 #ifndef __HAVE_ARCH_STRCAT
  92 /**
  93  * strcat - Append one %NUL-terminated string to another
  94  * @dest: The string to be appended to
  95  * @src: The string to append to it
  96  */
  97 char * strcat(char * dest, const char * src)
  98 {
  99         char *tmp = dest;
 100
 101         while (*dest)
 102                 dest++;
 103         while ((*dest++ = *src++) != '\0')
 104                 ;
 105
 106         return tmp;
 107 }
 108 #endif
 109 EXPORT_SYMBOL(strcat);
 110
 111 #ifndef __HAVE_ARCH_STRNCAT
 112 /**
 113  * strncat - Append a length-limited, %NUL-terminated string to another
 114  * @dest: The string to be appended to
 115  * @src: The string to append to it
 116  * @count: The maximum numbers of bytes to copy
 117  *
 118  * Note that in contrast to strncpy, strncat ensures the result is
 119  * terminated.
 120  */
 121 char * strncat(char *dest, const char *src, size_t count)
 122 {
 123         char *tmp = dest;
 124
 125         if (count) {
 126                 while (*dest)
 127                         dest++;
 128                 while ((*dest++ = *src++)) {
 129                         if (--count == 0) {
 130                                 *dest = '\0';
 131                                 break;
 132                         }
 133                 }
 134         }
 135
 136         return tmp;
 137 }
 138 #endif
 139 EXPORT_SYMBOL(strncat);
 140
 141 #ifndef __HAVE_ARCH_STRCMP
 142 /**
 143  * strcmp - Compare two strings
 144  * @cs: One string
 145  * @ct: Another string
 146  */
 147 int strcmp(const char * cs,const char * ct)
 148 {
 149         register signed char __res;
 150
 151         while (1) {
 152                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 153                         break;
 154         }
 155
 156         return __res;
 157 }
 158 #endif
 159 EXPORT_SYMBOL(strcmp);
 160
 161 #ifndef __HAVE_ARCH_STRNCMP
 162 /**
 163  * strncmp - Compare two length-limited strings
 164  * @cs: One string
 165  * @ct: Another string
 166  * @count: The maximum number of bytes to compare
 167  */
 168 int strncmp(const char * cs, const char * ct, size_t count)
 169 {
 170         register signed char __res = 0;
 171
 172         while (count) {
 173                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 174                         break;
 175                 count--;
 176         }
 177
 178         return __res;
 179 }
 180 #endif
 181 EXPORT_SYMBOL(strncmp);
 182
 183 #ifndef __HAVE_ARCH_STRCHR
 184 /**
 185  * strchr - Find the first occurrence of a character in a string
 186  * @s: The string to be searched
 187  * @c: The character to search for
 188  */
 189 char * _strchr(const char * s, int c)
 190 {
 191         for(; *s != (char) c; ++s)
 192                 if (*s == '\0')
 193                         return NULL;
 194         return (char *) s;
 195 }
 196 #endif
 197 EXPORT_SYMBOL(_strchr);
 198
 199 #ifndef __HAVE_ARCH_STRRCHR
 200 /**
 201  * strrchr - Find the last occurrence of a character in a string
 202  * @s: The string to be searched
 203  * @c: The character to search for
 204  */
 205 char * _strrchr(const char * s, int c)
 206 {
 207        const char *p = s + strlen(s);
 208        do {
 209            if (*p == (char)c)
 210                return (char *)p;
 211        } while (--p >= s);
 212        return NULL;
 213 }
 214 #endif
 215 EXPORT_SYMBOL(_strrchr);
 216
 217 #ifndef __HAVE_ARCH_STRLEN
 218 /**
 219  * strlen - Find the length of a string
 220  * @s: The string to be sized
 221  */
 222 size_t strlen(const char * s)
 223 {
 224         const char *sc;
 225
 226         for (sc = s; *sc != '\0'; ++sc)
 227                 /* nothing */;
 228         return sc - s;
 229 }
 230 #endif
 231 EXPORT_SYMBOL(strlen);
 232
 233 #ifndef __HAVE_ARCH_STRNLEN
 234 /**
 235  * strnlen - Find the length of a length-limited string
 236  * @s: The string to be sized
 237  * @count: The maximum number of bytes to search
 238  */
 239 size_t strnlen(const char * s, size_t count)
 240 {
 241         const char *sc;
 242
 243         for (sc = s; count-- && *sc != '\0'; ++sc)
 244                 /* nothing */;
 245         return sc - s;
 246 }
 247 #endif
 248 EXPORT_SYMBOL(strnlen);
 249
 250 #ifndef __HAVE_ARCH_STRDUP
 251 char * strdup(const char *s)
 252 {
 253         char *new;
 254
 255         if ((s == NULL) ||
 256             ((new = malloc (strlen(s) + 1)) == NULL) ) {
 257                 return NULL;
 258         }
 259
 260         strcpy (new, s);
 261         return new;
 262 }
 263 #endif
 264 EXPORT_SYMBOL(strdup);
 265
 266 #ifndef __HAVE_ARCH_STRSPN
 267 /**
 268  * strspn - Calculate the length of the initial substring of @s which only
 269  *      contain letters in @accept
 270  * @s: The string to be searched
 271  * @accept: The string to search for
 272  */
 273 size_t strspn(const char *s, const char *accept)
 274 {
 275         const char *p;
 276         const char *a;
 277         size_t count = 0;
 278
 279         for (p = s; *p != '\0'; ++p) {
 280                 for (a = accept; *a != '\0'; ++a) {
 281                         if (*p == *a)
 282                                 break;
 283                 }
 284                 if (*a == '\0')
 285                         return count;
 286                 ++count;
 287         }
 288
 289         return count;
 290 }
 291 #endif
 292 EXPORT_SYMBOL(strspn);
 293
 294 #ifndef __HAVE_ARCH_STRPBRK
 295 /**
 296  * strpbrk - Find the first occurrence of a set of characters
 297  * @cs: The string to be searched
 298  * @ct: The characters to search for
 299  */
 300 char * strpbrk(const char * cs,const char * ct)
 301 {
 302         const char *sc1, *sc2;
 303
 304         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 305                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 306                         if (*sc1 == *sc2)
 307                                 return (char *) sc1;
 308                 }
 309         }
 310         return NULL;
 311 }
 312 #endif
 313 EXPORT_SYMBOL(strpbrk);
 314
 315 #ifndef __HAVE_ARCH_STRTOK
 316 /**
 317  * strtok - Split a string into tokens
 318  * @s: The string to be searched
 319  * @ct: The characters to search for
 320  *
 321  * WARNING: strtok is deprecated, use strsep instead.
 322  */
 323 char * strtok(char * s, const char * ct)
 324 {
 325         char *sbegin, *send;
 326
 327         sbegin  = s ? s : ___strtok;
 328         if (!sbegin) {
 329                 return NULL;
 330         }
 331         sbegin += strspn(sbegin,ct);
 332         if (*sbegin == '\0') {
 333                 ___strtok = NULL;
 334                 return( NULL );
 335         }
 336         send = strpbrk( sbegin, ct);
 337         if (send && *send != '\0')
 338                 *send++ = '\0';
 339         ___strtok = send;
 340         return (sbegin);
 341 }
 342 #endif
 343 EXPORT_SYMBOL(strtok);
 344
 345 #ifndef __HAVE_ARCH_STRSEP
 346 /**
 347  * strsep - Split a string into tokens
 348  * @s: The string to be searched
 349  * @ct: The characters to search for
 350  *
 351  * strsep() updates @s to point after the token, ready for the next call.
 352  *
 353  * It returns empty tokens, too, behaving exactly like the libc function
 354  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 355  * Same semantics, slimmer shape. ;)
 356  */
 357 char * strsep(char **s, const char *ct)
 358 {
 359         char *sbegin = *s, *end;
 360
 361         if (sbegin == NULL)
 362                 return NULL;
 363
 364         end = strpbrk(sbegin, ct);
 365         if (end)
 366                 *end++ = '\0';
 367         *s = end;
 368
 369         return sbegin;
 370 }
 371 #endif
 372 EXPORT_SYMBOL(strsep);
 373
 374 #ifndef __HAVE_ARCH_STRSWAB
 375 /**
 376  * strswab - swap adjacent even and odd bytes in %NUL-terminated string
 377  * s: address of the string
 378  *
 379  * returns the address of the swapped string or NULL on error. If
 380  * string length is odd, last byte is untouched.
 381  */
 382 char *strswab(const char *s)
 383 {
 384         char *p, *q;
 385
 386         if ((NULL == s) || ('\0' == *s)) {
 387                 return (NULL);
 388         }
 389
 390         for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
 391                 char  tmp;
 392
 393                 tmp = *p;
 394                 *p  = *q;
 395                 *q  = tmp;
 396         }
 397
 398         return (char *) s;
 399 }
 400 #endif
 401
 402 #ifndef __HAVE_ARCH_MEMSET
 403 /**
 404  * memset - Fill a region of memory with the given value
 405  * @s: Pointer to the start of the area.
 406  * @c: The byte to fill the area with
 407  * @count: The size of the area.
 408  *
 409  * Do not use memset() to access IO space, use memset_io() instead.
 410  */
 411 void * memset(void * s,int c,size_t count)
 412 {
 413         char *xs = (char *) s;
 414
 415         while (count--)
 416                 *xs++ = c;
 417
 418         return s;
 419 }
 420 #endif
 421 EXPORT_SYMBOL(memset);
 422
 423 #ifndef __HAVE_ARCH_BCOPY
 424 /**
 425  * bcopy - Copy one area of memory to another
 426  * @src: Where to copy from
 427  * @dest: Where to copy to
 428  * @count: The size of the area.
 429  *
 430  * Note that this is the same as memcpy(), with the arguments reversed.
 431  * memcpy() is the standard, bcopy() is a legacy BSD function.
 432  *
 433  * You should not use this function to access IO space, use memcpy_toio()
 434  * or memcpy_fromio() instead.
 435  */
 436 char * bcopy(const char * src, char * dest, int count)
 437 {
 438         char *tmp = dest;
 439
 440         while (count--)
 441                 *tmp++ = *src++;
 442
 443         return dest;
 444 }
 445 #endif
 446
 447 #ifndef __HAVE_ARCH_MEMCPY
 448 /**
 449  * memcpy - Copy one area of memory to another
 450  * @dest: Where to copy to
 451  * @src: Where to copy from
 452  * @count: The size of the area.
 453  *
 454  * You should not use this function to access IO space, use memcpy_toio()
 455  * or memcpy_fromio() instead.
 456  */
 457 void * memcpy(void * dest,const void *src,size_t count)
 458 {
 459         char *tmp = (char *) dest, *s = (char *) src;
 460
 461         while (count--)
 462                 *tmp++ = *s++;
 463
 464         return dest;
 465 }
 466 #endif
 467 EXPORT_SYMBOL(memcpy);
 468
 469 #ifndef __HAVE_ARCH_MEMMOVE
 470 /**
 471  * memmove - Copy one area of memory to another
 472  * @dest: Where to copy to
 473  * @src: Where to copy from
 474  * @count: The size of the area.
 475  *
 476  * Unlike memcpy(), memmove() copes with overlapping areas.
 477  */
 478 void * memmove(void * dest,const void *src,size_t count)
 479 {
 480         char *tmp, *s;
 481
 482         if (dest <= src) {
 483                 tmp = (char *) dest;
 484                 s = (char *) src;
 485                 while (count--)
 486                         *tmp++ = *s++;
 487                 }
 488         else {
 489                 tmp = (char *) dest + count;
 490                 s = (char *) src + count;
 491                 while (count--)
 492                         *--tmp = *--s;
 493                 }
 494
 495         return dest;
 496 }
 497 #endif
 498 EXPORT_SYMBOL(memmove);
 499
 500 #ifndef __HAVE_ARCH_MEMCMP
 501 /**
 502  * memcmp - Compare two areas of memory
 503  * @cs: One area of memory
 504  * @ct: Another area of memory
 505  * @count: The size of the area.
 506  */
 507 int memcmp(const void * cs,const void * ct,size_t count)
 508 {
 509         const unsigned char *su1, *su2;
 510         int res = 0;
 511
 512         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 513                 if ((res = *su1 - *su2) != 0)
 514                         break;
 515         return res;
 516 }
 517 #endif
 518 EXPORT_SYMBOL(memcmp);
 519
 520 #ifndef __HAVE_ARCH_MEMSCAN
 521 /**
 522  * memscan - Find a character in an area of memory.
 523  * @addr: The memory area
 524  * @c: The byte to search for
 525  * @size: The size of the area.
 526  *
 527  * returns the address of the first occurrence of @c, or 1 byte past
 528  * the area if @c is not found
 529  */
 530 void * memscan(void * addr, int c, size_t size)
 531 {
 532         unsigned char * p = (unsigned char *) addr;
 533
 534         while (size) {
 535                 if (*p == c)
 536                         return (void *) p;
 537                 p++;
 538                 size--;
 539         }
 540         return (void *) p;
 541 }
 542 #endif
 543 EXPORT_SYMBOL(memscan);
 544
 545 #ifndef __HAVE_ARCH_STRSTR
 546 /**
 547  * strstr - Find the first substring in a %NUL terminated string
 548  * @s1: The string to be searched
 549  * @s2: The string to search for
 550  */
 551 char * _strstr(const char * s1,const char * s2)
 552 {
 553         int l1, l2;
 554
 555         l2 = strlen(s2);
 556         if (!l2)
 557                 return (char *) s1;
 558         l1 = strlen(s1);
 559         while (l1 >= l2) {
 560                 l1--;
 561                 if (!memcmp(s1,s2,l2))
 562                         return (char *) s1;
 563                 s1++;
 564         }
 565         return NULL;
 566 }
 567 #endif
 568 EXPORT_SYMBOL(_strstr);
 569
 570 #ifndef __HAVE_ARCH_MEMCHR
 571 /**
 572  * memchr - Find a character in an area of memory.
 573  * @s: The memory area
 574  * @c: The byte to search for
 575  * @n: The size of the area.
 576  *
 577  * returns the address of the first occurrence of @c, or %NULL
 578  * if @c is not found
 579  */
 580 void *memchr(const void *s, int c, size_t n)
 581 {
 582         const unsigned char *p = s;
 583         while (n-- != 0) {
 584                 if ((unsigned char)c == *p++) {
 585                         return (void *)(p-1);
 586                 }
 587         }
 588         return NULL;
 589 }
 590
 591 #endif
 592 EXPORT_SYMBOL(memchr);
 593