lib_generic/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
  24 #ifndef __HAVE_ARCH_STRNICMP
  25 /**
  26  * strnicmp - Case insensitive, length-limited string comparison
  27  * @s1: One string
  28  * @s2: The other string
  29  * @len: the maximum number of characters to compare
  30  */
  31 int strnicmp(const char *s1, const char *s2, size_t len)
  32 {
  33         /* Yes, Virginia, it had better be unsigned */
  34         unsigned char c1, c2;
  35
  36         c1 = 0; c2 = 0;
  37         if (len) {
  38                 do {
  39                         c1 = *s1; c2 = *s2;
  40                         s1++; s2++;
  41                         if (!c1)
  42                                 break;
  43                         if (!c2)
  44                                 break;
  45                         if (c1 == c2)
  46                                 continue;
  47                         c1 = tolower(c1);
  48                         c2 = tolower(c2);
  49                         if (c1 != c2)
  50                                 break;
  51                 } while (--len);
  52         }
  53         return (int)c1 - (int)c2;
  54 }
  55 #endif
  56
  57 char * ___strtok;
  58
  59 #ifndef __HAVE_ARCH_STRCPY
  60 /**
  61  * strcpy - Copy a %NUL terminated string
  62  * @dest: Where to copy the string to
  63  * @src: Where to copy the string from
  64  */
  65 char * strcpy(char * dest,const char *src)
  66 {
  67         char *tmp = dest;
  68
  69         while ((*dest++ = *src++) != '\0')
  70                 /* nothing */;
  71         return tmp;
  72 }
  73 #endif
  74
  75 #ifndef __HAVE_ARCH_STRNCPY
  76 /**
  77  * strncpy - Copy a length-limited, %NUL-terminated string
  78  * @dest: Where to copy the string to
  79  * @src: Where to copy the string from
  80  * @count: The maximum number of bytes to copy
  81  *
  82  * Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
  83  * However, the result is not %NUL-terminated if the source exceeds
  84  * @count bytes.
  85  */
  86 char * strncpy(char * dest,const char *src,size_t count)
  87 {
  88         char *tmp = dest;
  89
  90         while (count-- && (*dest++ = *src++) != '\0')
  91                 /* nothing */;
  92
  93         return tmp;
  94 }
  95 #endif
  96
  97 #ifndef __HAVE_ARCH_STRCAT
  98 /**
  99  * strcat - Append one %NUL-terminated string to another
 100  * @dest: The string to be appended to
 101  * @src: The string to append to it
 102  */
 103 char * strcat(char * dest, const char * src)
 104 {
 105         char *tmp = dest;
 106
 107         while (*dest)
 108                 dest++;
 109         while ((*dest++ = *src++) != '\0')
 110                 ;
 111
 112         return tmp;
 113 }
 114 #endif
 115
 116 #ifndef __HAVE_ARCH_STRNCAT
 117 /**
 118  * strncat - Append a length-limited, %NUL-terminated string to another
 119  * @dest: The string to be appended to
 120  * @src: The string to append to it
 121  * @count: The maximum numbers of bytes to copy
 122  *
 123  * Note that in contrast to strncpy, strncat ensures the result is
 124  * terminated.
 125  */
 126 char * strncat(char *dest, const char *src, size_t count)
 127 {
 128         char *tmp = dest;
 129
 130         if (count) {
 131                 while (*dest)
 132                         dest++;
 133                 while ((*dest++ = *src++)) {
 134                         if (--count == 0) {
 135                                 *dest = '\0';
 136                                 break;
 137                         }
 138                 }
 139         }
 140
 141         return tmp;
 142 }
 143 #endif
 144
 145 #ifndef __HAVE_ARCH_STRCMP
 146 /**
 147  * strcmp - Compare two strings
 148  * @cs: One string
 149  * @ct: Another string
 150  */
 151 int strcmp(const char * cs,const char * ct)
 152 {
 153         register signed char __res;
 154
 155         while (1) {
 156                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 157                         break;
 158         }
 159
 160         return __res;
 161 }
 162 #endif
 163
 164 #ifndef __HAVE_ARCH_STRNCMP
 165 /**
 166  * strncmp - Compare two length-limited strings
 167  * @cs: One string
 168  * @ct: Another string
 169  * @count: The maximum number of bytes to compare
 170  */
 171 int strncmp(const char * cs,const char * ct,size_t count)
 172 {
 173         register signed char __res = 0;
 174
 175         while (count) {
 176                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 177                         break;
 178                 count--;
 179         }
 180
 181         return __res;
 182 }
 183 #endif
 184
 185 #ifndef __HAVE_ARCH_STRCHR
 186 /**
 187  * strchr - Find the first occurrence of a character in a string
 188  * @s: The string to be searched
 189  * @c: The character to search for
 190  */
 191 char * strchr(const char * s, int c)
 192 {
 193         for(; *s != (char) c; ++s)
 194                 if (*s == '\0')
 195                         return NULL;
 196         return (char *) s;
 197 }
 198 #endif
 199
 200 #ifndef __HAVE_ARCH_STRRCHR
 201 /**
 202  * strrchr - Find the last occurrence of a character in a string
 203  * @s: The string to be searched
 204  * @c: The character to search for
 205  */
 206 char * strrchr(const char * s, int c)
 207 {
 208        const char *p = s + strlen(s);
 209        do {
 210            if (*p == (char)c)
 211                return (char *)p;
 212        } while (--p >= s);
 213        return NULL;
 214 }
 215 #endif
 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
 232 #ifndef __HAVE_ARCH_STRNLEN
 233 /**
 234  * strnlen - Find the length of a length-limited string
 235  * @s: The string to be sized
 236  * @count: The maximum number of bytes to search
 237  */
 238 size_t strnlen(const char * s, size_t count)
 239 {
 240         const char *sc;
 241
 242         for (sc = s; count-- && *sc != '\0'; ++sc)
 243                 /* nothing */;
 244         return sc - s;
 245 }
 246 #endif
 247
 248 #ifndef __HAVE_ARCH_STRDUP
 249 char * strdup(const char *s)
 250 {
 251         char *new;
 252
 253         if ((s == NULL) ||
 254             ((new = malloc (strlen(s) + 1)) == NULL) ) {
 255                 return NULL;
 256         }
 257
 258         strcpy (new, s);
 259         return new;
 260 }
 261 #endif
 262
 263 #ifndef __HAVE_ARCH_STRSPN
 264 /**
 265  * strspn - Calculate the length of the initial substring of @s which only
 266  *      contain letters in @accept
 267  * @s: The string to be searched
 268  * @accept: The string to search for
 269  */
 270 size_t strspn(const char *s, const char *accept)
 271 {
 272         const char *p;
 273         const char *a;
 274         size_t count = 0;
 275
 276         for (p = s; *p != '\0'; ++p) {
 277                 for (a = accept; *a != '\0'; ++a) {
 278                         if (*p == *a)
 279                                 break;
 280                 }
 281                 if (*a == '\0')
 282                         return count;
 283                 ++count;
 284         }
 285
 286         return count;
 287 }
 288 #endif
 289
 290 #ifndef __HAVE_ARCH_STRPBRK
 291 /**
 292  * strpbrk - Find the first occurrence of a set of characters
 293  * @cs: The string to be searched
 294  * @ct: The characters to search for
 295  */
 296 char * strpbrk(const char * cs,const char * ct)
 297 {
 298         const char *sc1,*sc2;
 299
 300         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 301                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 302                         if (*sc1 == *sc2)
 303                                 return (char *) sc1;
 304                 }
 305         }
 306         return NULL;
 307 }
 308 #endif
 309
 310 #ifndef __HAVE_ARCH_STRTOK
 311 /**
 312  * strtok - Split a string into tokens
 313  * @s: The string to be searched
 314  * @ct: The characters to search for
 315  *
 316  * WARNING: strtok is deprecated, use strsep instead.
 317  */
 318 char * strtok(char * s,const char * ct)
 319 {
 320         char *sbegin, *send;
 321
 322         sbegin  = s ? s : ___strtok;
 323         if (!sbegin) {
 324                 return NULL;
 325         }
 326         sbegin += strspn(sbegin,ct);
 327         if (*sbegin == '\0') {
 328                 ___strtok = NULL;
 329                 return( NULL );
 330         }
 331         send = strpbrk( sbegin, ct);
 332         if (send && *send != '\0')
 333                 *send++ = '\0';
 334         ___strtok = send;
 335         return (sbegin);
 336 }
 337 #endif
 338
 339 #ifndef __HAVE_ARCH_STRSEP
 340 /**
 341  * strsep - Split a string into tokens
 342  * @s: The string to be searched
 343  * @ct: The characters to search for
 344  *
 345  * strsep() updates @s to point after the token, ready for the next call.
 346  *
 347  * It returns empty tokens, too, behaving exactly like the libc function
 348  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 349  * Same semantics, slimmer shape. ;)
 350  */
 351 char * strsep(char **s, const char *ct)
 352 {
 353         char *sbegin = *s, *end;
 354
 355         if (sbegin == NULL)
 356                 return NULL;
 357
 358         end = strpbrk(sbegin, ct);
 359         if (end)
 360                 *end++ = '\0';
 361         *s = end;
 362
 363         return sbegin;
 364 }
 365 #endif
 366
 367 #ifndef __HAVE_ARCH_STRSWAB
 368 /**
 369  * strswab - swap adjacent even and odd bytes in %NUL-terminated string
 370  * s: address of the string
 371  *
 372  * returns the address of the swapped string or NULL on error. If
 373  * string length is odd, last byte is untouched.
 374  */
 375 char *strswab(const char *s)
 376 {
 377         char *p, *q;
 378
 379         if ((NULL == s) || ('\0' == *s)) {
 380                 return (NULL);
 381         }
 382
 383         for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
 384                 char  tmp;
 385
 386                 tmp = *p;
 387                 *p  = *q;
 388                 *q  = tmp;
 389         }
 390
 391         return (char *) s;
 392 }
 393 #endif
 394
 395 #ifndef __HAVE_ARCH_MEMSET
 396 /**
 397  * memset - Fill a region of memory with the given value
 398  * @s: Pointer to the start of the area.
 399  * @c: The byte to fill the area with
 400  * @count: The size of the area.
 401  *
 402  * Do not use memset() to access IO space, use memset_io() instead.
 403  */
 404 void * memset(void * s,int c,size_t count)
 405 {
 406         char *xs = (char *) s;
 407
 408         while (count--)
 409                 *xs++ = c;
 410
 411         return s;
 412 }
 413 #endif
 414
 415 #ifndef __HAVE_ARCH_BCOPY
 416 /**
 417  * bcopy - Copy one area of memory to another
 418  * @src: Where to copy from
 419  * @dest: Where to copy to
 420  * @count: The size of the area.
 421  *
 422  * Note that this is the same as memcpy(), with the arguments reversed.
 423  * memcpy() is the standard, bcopy() is a legacy BSD function.
 424  *
 425  * You should not use this function to access IO space, use memcpy_toio()
 426  * or memcpy_fromio() instead.
 427  */
 428 char * bcopy(const char * src, char * dest, int count)
 429 {
 430         char *tmp = dest;
 431
 432         while (count--)
 433                 *tmp++ = *src++;
 434
 435         return dest;
 436 }
 437 #endif
 438
 439 #ifndef __HAVE_ARCH_MEMCPY
 440 /**
 441  * memcpy - Copy one area of memory to another
 442  * @dest: Where to copy to
 443  * @src: Where to copy from
 444  * @count: The size of the area.
 445  *
 446  * You should not use this function to access IO space, use memcpy_toio()
 447  * or memcpy_fromio() instead.
 448  */
 449 void * memcpy(void * dest,const void *src,size_t count)
 450 {
 451         char *tmp = (char *) dest, *s = (char *) src;
 452
 453         while (count--)
 454                 *tmp++ = *s++;
 455
 456         return dest;
 457 }
 458 #endif
 459
 460 #ifndef __HAVE_ARCH_MEMMOVE
 461 /**
 462  * memmove - Copy one area of memory to another
 463  * @dest: Where to copy to
 464  * @src: Where to copy from
 465  * @count: The size of the area.
 466  *
 467  * Unlike memcpy(), memmove() copes with overlapping areas.
 468  */
 469 void * memmove(void * dest,const void *src,size_t count)
 470 {
 471         char *tmp, *s;
 472
 473         if (dest <= src) {
 474                 tmp = (char *) dest;
 475                 s = (char *) src;
 476                 while (count--)
 477                         *tmp++ = *s++;
 478                 }
 479         else {
 480                 tmp = (char *) dest + count;
 481                 s = (char *) src + count;
 482                 while (count--)
 483                         *--tmp = *--s;
 484                 }
 485
 486         return dest;
 487 }
 488 #endif
 489
 490 #ifndef __HAVE_ARCH_MEMCMP
 491 /**
 492  * memcmp - Compare two areas of memory
 493  * @cs: One area of memory
 494  * @ct: Another area of memory
 495  * @count: The size of the area.
 496  */
 497 int memcmp(const void * cs,const void * ct,size_t count)
 498 {
 499         const unsigned char *su1, *su2;
 500         int res = 0;
 501
 502         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 503                 if ((res = *su1 - *su2) != 0)
 504                         break;
 505         return res;
 506 }
 507 #endif
 508
 509 #ifndef __HAVE_ARCH_MEMSCAN
 510 /**
 511  * memscan - Find a character in an area of memory.
 512  * @addr: The memory area
 513  * @c: The byte to search for
 514  * @size: The size of the area.
 515  *
 516  * returns the address of the first occurrence of @c, or 1 byte past
 517  * the area if @c is not found
 518  */
 519 void * memscan(void * addr, int c, size_t size)
 520 {
 521         unsigned char * p = (unsigned char *) addr;
 522
 523         while (size) {
 524                 if (*p == c)
 525                         return (void *) p;
 526                 p++;
 527                 size--;
 528         }
 529         return (void *) p;
 530 }
 531 #endif
 532
 533 #ifndef __HAVE_ARCH_STRSTR
 534 /**
 535  * strstr - Find the first substring in a %NUL terminated string
 536  * @s1: The string to be searched
 537  * @s2: The string to search for
 538  */
 539 char * strstr(const char * s1,const char * s2)
 540 {
 541         int l1, l2;
 542
 543         l2 = strlen(s2);
 544         if (!l2)
 545                 return (char *) s1;
 546         l1 = strlen(s1);
 547         while (l1 >= l2) {
 548                 l1--;
 549                 if (!memcmp(s1,s2,l2))
 550                         return (char *) s1;
 551                 s1++;
 552         }
 553         return NULL;
 554 }
 555 #endif
 556
 557 #ifndef __HAVE_ARCH_MEMCHR
 558 /**
 559  * memchr - Find a character in an area of memory.
 560  * @s: The memory area
 561  * @c: The byte to search for
 562  * @n: The size of the area.
 563  *
 564  * returns the address of the first occurrence of @c, or %NULL
 565  * if @c is not found
 566  */
 567 void *memchr(const void *s, int c, size_t n)
 568 {
 569         const unsigned char *p = s;
 570         while (n-- != 0) {
 571                 if ((unsigned char)c == *p++) {
 572                         return (void *)(p-1);
 573                 }
 574         }
 575         return NULL;
 576 }
 577
 578 #endif