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
  24 #if 0 /* not used - was: #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
 218 /**
 219  * skip_spaces - Removes leading whitespace from @str.
 220  * @str: The string to be stripped.
 221  *
 222  * Returns a pointer to the first non-whitespace character in @str.
 223  */
 224 char *skip_spaces(const char *str)
 225 {
 226         while (isspace(*str))
 227                 ++str;
 228         return (char *)str;
 229 }
 230
 231 /**
 232  * strim - Removes leading and trailing whitespace from @s.
 233  * @s: The string to be stripped.
 234  *
 235  * Note that the first trailing whitespace is replaced with a %NUL-terminator
 236  * in the given string @s. Returns a pointer to the first non-whitespace
 237  * character in @s.
 238  */
 239 char *strim(char *s)
 240 {
 241         size_t size;
 242         char *end;
 243
 244         s = skip_spaces(s);
 245         size = strlen(s);
 246         if (!size)
 247                 return s;
 248
 249         end = s + size - 1;
 250         while (end >= s && isspace(*end))
 251                 end--;
 252         *(end + 1) = '\0';
 253
 254         return s;
 255 }
 256 #ifndef __HAVE_ARCH_STRLEN
 257 /**
 258  * strlen - Find the length of a string
 259  * @s: The string to be sized
 260  */
 261 size_t strlen(const char * s)
 262 {
 263         const char *sc;
 264
 265         for (sc = s; *sc != '\0'; ++sc)
 266                 /* nothing */;
 267         return sc - s;
 268 }
 269 #endif
 270
 271 #ifndef __HAVE_ARCH_STRNLEN
 272 /**
 273  * strnlen - Find the length of a length-limited string
 274  * @s: The string to be sized
 275  * @count: The maximum number of bytes to search
 276  */
 277 size_t strnlen(const char * s, size_t count)
 278 {
 279         const char *sc;
 280
 281         for (sc = s; count-- && *sc != '\0'; ++sc)
 282                 /* nothing */;
 283         return sc - s;
 284 }
 285 #endif
 286
 287 #ifndef __HAVE_ARCH_STRDUP
 288 char * strdup(const char *s)
 289 {
 290         char *new;
 291
 292         if ((s == NULL) ||
 293             ((new = malloc (strlen(s) + 1)) == NULL) ) {
 294                 return NULL;
 295         }
 296
 297         strcpy (new, s);
 298         return new;
 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 #ifndef __HAVE_ARCH_STRPBRK
 330 /**
 331  * strpbrk - Find the first occurrence of a set of characters
 332  * @cs: The string to be searched
 333  * @ct: The characters to search for
 334  */
 335 char * strpbrk(const char * cs,const char * ct)
 336 {
 337         const char *sc1,*sc2;
 338
 339         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 340                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 341                         if (*sc1 == *sc2)
 342                                 return (char *) sc1;
 343                 }
 344         }
 345         return NULL;
 346 }
 347 #endif
 348
 349 #ifndef __HAVE_ARCH_STRTOK
 350 /**
 351  * strtok - Split a string into tokens
 352  * @s: The string to be searched
 353  * @ct: The characters to search for
 354  *
 355  * WARNING: strtok is deprecated, use strsep instead.
 356  */
 357 char * strtok(char * s,const char * ct)
 358 {
 359         char *sbegin, *send;
 360
 361         sbegin  = s ? s : ___strtok;
 362         if (!sbegin) {
 363                 return NULL;
 364         }
 365         sbegin += strspn(sbegin,ct);
 366         if (*sbegin == '\0') {
 367                 ___strtok = NULL;
 368                 return( NULL );
 369         }
 370         send = strpbrk( sbegin, ct);
 371         if (send && *send != '\0')
 372                 *send++ = '\0';
 373         ___strtok = send;
 374         return (sbegin);
 375 }
 376 #endif
 377
 378 #ifndef __HAVE_ARCH_STRSEP
 379 /**
 380  * strsep - Split a string into tokens
 381  * @s: The string to be searched
 382  * @ct: The characters to search for
 383  *
 384  * strsep() updates @s to point after the token, ready for the next call.
 385  *
 386  * It returns empty tokens, too, behaving exactly like the libc function
 387  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 388  * Same semantics, slimmer shape. ;)
 389  */
 390 char * strsep(char **s, const char *ct)
 391 {
 392         char *sbegin = *s, *end;
 393
 394         if (sbegin == NULL)
 395                 return NULL;
 396
 397         end = strpbrk(sbegin, ct);
 398         if (end)
 399                 *end++ = '\0';
 400         *s = end;
 401
 402         return sbegin;
 403 }
 404 #endif
 405
 406 #ifndef __HAVE_ARCH_STRSWAB
 407 /**
 408  * strswab - swap adjacent even and odd bytes in %NUL-terminated string
 409  * s: address of the string
 410  *
 411  * returns the address of the swapped string or NULL on error. If
 412  * string length is odd, last byte is untouched.
 413  */
 414 char *strswab(const char *s)
 415 {
 416         char *p, *q;
 417
 418         if ((NULL == s) || ('\0' == *s)) {
 419                 return (NULL);
 420         }
 421
 422         for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
 423                 char  tmp;
 424
 425                 tmp = *p;
 426                 *p  = *q;
 427                 *q  = tmp;
 428         }
 429
 430         return (char *) s;
 431 }
 432 #endif
 433
 434 #ifndef __HAVE_ARCH_MEMSET
 435 /**
 436  * memset - Fill a region of memory with the given value
 437  * @s: Pointer to the start of the area.
 438  * @c: The byte to fill the area with
 439  * @count: The size of the area.
 440  *
 441  * Do not use memset() to access IO space, use memset_io() instead.
 442  */
 443 void * memset(void * s,int c,size_t count)
 444 {
 445         unsigned long *sl = (unsigned long *) s;
 446         unsigned long cl = 0;
 447         char *s8;
 448         int i;
 449
 450         /* do it one word at a time (32 bits or 64 bits) while possible */
 451         if ( ((ulong)s & (sizeof(*sl) - 1)) == 0) {
 452                 for (i = 0; i < sizeof(*sl); i++) {
 453                         cl <<= 8;
 454                         cl |= c & 0xff;
 455                 }
 456                 while (count >= sizeof(*sl)) {
 457                         *sl++ = cl;
 458                         count -= sizeof(*sl);
 459                 }
 460         }
 461         /* fill 8 bits at a time */
 462         s8 = (char *)sl;
 463         while (count--)
 464                 *s8++ = c;
 465
 466         return s;
 467 }
 468 #endif
 469
 470 #ifndef __HAVE_ARCH_BCOPY
 471 /**
 472  * bcopy - Copy one area of memory to another
 473  * @src: Where to copy from
 474  * @dest: Where to copy to
 475  * @count: The size of the area.
 476  *
 477  * Note that this is the same as memcpy(), with the arguments reversed.
 478  * memcpy() is the standard, bcopy() is a legacy BSD function.
 479  *
 480  * You should not use this function to access IO space, use memcpy_toio()
 481  * or memcpy_fromio() instead.
 482  */
 483 char * bcopy(const char * src, char * dest, int count)
 484 {
 485         char *tmp = dest;
 486
 487         while (count--)
 488                 *tmp++ = *src++;
 489
 490         return dest;
 491 }
 492 #endif
 493
 494 #ifndef __HAVE_ARCH_MEMCPY
 495 /**
 496  * memcpy - Copy one area of memory to another
 497  * @dest: Where to copy to
 498  * @src: Where to copy from
 499  * @count: The size of the area.
 500  *
 501  * You should not use this function to access IO space, use memcpy_toio()
 502  * or memcpy_fromio() instead.
 503  */
 504 void * memcpy(void *dest, const void *src, size_t count)
 505 {
 506         unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
 507         char *d8, *s8;
 508
 509         if (src == dest)
 510                 return dest;
 511
 512         /* while all data is aligned (common case), copy a word at a time */
 513         if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) {
 514                 while (count >= sizeof(*dl)) {
 515                         *dl++ = *sl++;
 516                         count -= sizeof(*dl);
 517                 }
 518         }
 519         /* copy the reset one byte at a time */
 520         d8 = (char *)dl;
 521         s8 = (char *)sl;
 522         while (count--)
 523                 *d8++ = *s8++;
 524
 525         return dest;
 526 }
 527 #endif
 528
 529 #ifndef __HAVE_ARCH_MEMMOVE
 530 /**
 531  * memmove - Copy one area of memory to another
 532  * @dest: Where to copy to
 533  * @src: Where to copy from
 534  * @count: The size of the area.
 535  *
 536  * Unlike memcpy(), memmove() copes with overlapping areas.
 537  */
 538 void * memmove(void * dest,const void *src,size_t count)
 539 {
 540         char *tmp, *s;
 541
 542         if (src == dest)
 543                 return dest;
 544
 545         if (dest <= src) {
 546                 tmp = (char *) dest;
 547                 s = (char *) src;
 548                 while (count--)
 549                         *tmp++ = *s++;
 550                 }
 551         else {
 552                 tmp = (char *) dest + count;
 553                 s = (char *) src + count;
 554                 while (count--)
 555                         *--tmp = *--s;
 556                 }
 557
 558         return dest;
 559 }
 560 #endif
 561
 562 #ifndef __HAVE_ARCH_MEMCMP
 563 /**
 564  * memcmp - Compare two areas of memory
 565  * @cs: One area of memory
 566  * @ct: Another area of memory
 567  * @count: The size of the area.
 568  */
 569 int memcmp(const void * cs,const void * ct,size_t count)
 570 {
 571         const unsigned char *su1, *su2;
 572         int res = 0;
 573
 574         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 575                 if ((res = *su1 - *su2) != 0)
 576                         break;
 577         return res;
 578 }
 579 #endif
 580
 581 #ifndef __HAVE_ARCH_MEMSCAN
 582 /**
 583  * memscan - Find a character in an area of memory.
 584  * @addr: The memory area
 585  * @c: The byte to search for
 586  * @size: The size of the area.
 587  *
 588  * returns the address of the first occurrence of @c, or 1 byte past
 589  * the area if @c is not found
 590  */
 591 void * memscan(void * addr, int c, size_t size)
 592 {
 593         unsigned char * p = (unsigned char *) addr;
 594
 595         while (size) {
 596                 if (*p == c)
 597                         return (void *) p;
 598                 p++;
 599                 size--;
 600         }
 601         return (void *) p;
 602 }
 603 #endif
 604
 605 #ifndef __HAVE_ARCH_STRSTR
 606 /**
 607  * strstr - Find the first substring in a %NUL terminated string
 608  * @s1: The string to be searched
 609  * @s2: The string to search for
 610  */
 611 char * strstr(const char * s1,const char * s2)
 612 {
 613         int l1, l2;
 614
 615         l2 = strlen(s2);
 616         if (!l2)
 617                 return (char *) s1;
 618         l1 = strlen(s1);
 619         while (l1 >= l2) {
 620                 l1--;
 621                 if (!memcmp(s1,s2,l2))
 622                         return (char *) s1;
 623                 s1++;
 624         }
 625         return NULL;
 626 }
 627 #endif
 628
 629 #ifndef __HAVE_ARCH_MEMCHR
 630 /**
 631  * memchr - Find a character in an area of memory.
 632  * @s: The memory area
 633  * @c: The byte to search for
 634  * @n: The size of the area.
 635  *
 636  * returns the address of the first occurrence of @c, or %NULL
 637  * if @c is not found
 638  */
 639 void *memchr(const void *s, int c, size_t n)
 640 {
 641         const unsigned char *p = s;
 642         while (n-- != 0) {
 643                 if ((unsigned char)c == *p++) {
 644                         return (void *)(p-1);
 645                 }
 646         }
 647         return NULL;
 648 }
 649
 650 #endif