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 /**
  25  * strncasecmp - Case insensitive, length-limited string comparison
  26  * @s1: One string
  27  * @s2: The other string
  28  * @len: the maximum number of characters to compare
  29  */
  30 int strncasecmp(const char *s1, const char *s2, size_t len)
  31 {
  32         /* Yes, Virginia, it had better be unsigned */
  33         unsigned char c1, c2;
  34
  35         c1 = 0; c2 = 0;
  36         if (len) {
  37                 do {
  38                         c1 = *s1; c2 = *s2;
  39                         s1++; s2++;
  40                         if (!c1)
  41                                 break;
  42                         if (!c2)
  43                                 break;
  44                         if (c1 == c2)
  45                                 continue;
  46                         c1 = tolower(c1);
  47                         c2 = tolower(c2);
  48                         if (c1 != c2)
  49                                 break;
  50                 } while (--len);
  51         }
  52         return (int)c1 - (int)c2;
  53 }
  54
  55 /**
  56  * strcasecmp - Case insensitive string comparison
  57  * @s1: One string
  58  * @s2: The other string
  59  */
  60 int strcasecmp(const char *s1, const char *s2)
  61 {
  62         return strncasecmp(s1, s2, -1U);
  63 }
  64
  65 char * ___strtok;
  66
  67 #ifndef __HAVE_ARCH_STRCPY
  68 /**
  69  * strcpy - Copy a %NUL terminated string
  70  * @dest: Where to copy the string to
  71  * @src: Where to copy the string from
  72  */
  73 char * strcpy(char * dest,const char *src)
  74 {
  75         char *tmp = dest;
  76
  77         while ((*dest++ = *src++) != '\0')
  78                 /* nothing */;
  79         return tmp;
  80 }
  81 #endif
  82
  83 #ifndef __HAVE_ARCH_STRNCPY
  84 /**
  85  * strncpy - Copy a length-limited, %NUL-terminated string
  86  * @dest: Where to copy the string to
  87  * @src: Where to copy the string from
  88  * @count: The maximum number of bytes to copy
  89  *
  90  * Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
  91  * However, the result is not %NUL-terminated if the source exceeds
  92  * @count bytes.
  93  */
  94 char * strncpy(char * dest,const char *src,size_t count)
  95 {
  96         char *tmp = dest;
  97
  98         while (count-- && (*dest++ = *src++) != '\0')
  99                 /* nothing */;
 100
 101         return tmp;
 102 }
 103 #endif
 104
 105 #ifndef __HAVE_ARCH_STRLCPY
 106 /**
 107  * strlcpy - Copy a C-string into a sized buffer
 108  * @dest: Where to copy the string to
 109  * @src: Where to copy the string from
 110  * @size: size of destination buffer
 111  *
 112  * Compatible with *BSD: the result is always a valid
 113  * NUL-terminated string that fits in the buffer (unless,
 114  * of course, the buffer size is zero). It does not pad
 115  * out the result like strncpy() does.
 116  */
 117 size_t strlcpy(char *dest, const char *src, size_t size)
 118 {
 119         size_t ret = strlen(src);
 120
 121         if (size) {
 122                 size_t len = (ret >= size) ? size - 1 : ret;
 123                 memcpy(dest, src, len);
 124                 dest[len] = '\0';
 125         }
 126         return ret;
 127 }
 128 #endif
 129
 130 #ifndef __HAVE_ARCH_STRCAT
 131 /**
 132  * strcat - Append one %NUL-terminated string to another
 133  * @dest: The string to be appended to
 134  * @src: The string to append to it
 135  */
 136 char * strcat(char * dest, const char * src)
 137 {
 138         char *tmp = dest;
 139
 140         while (*dest)
 141                 dest++;
 142         while ((*dest++ = *src++) != '\0')
 143                 ;
 144
 145         return tmp;
 146 }
 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++)) {
 167                         if (--count == 0) {
 168                                 *dest = '\0';
 169                                 break;
 170                         }
 171                 }
 172         }
 173
 174         return tmp;
 175 }
 176 #endif
 177
 178 #ifndef __HAVE_ARCH_STRCMP
 179 /**
 180  * strcmp - Compare two strings
 181  * @cs: One string
 182  * @ct: Another string
 183  */
 184 int strcmp(const char * cs,const char * ct)
 185 {
 186         register signed char __res;
 187
 188         while (1) {
 189                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 190                         break;
 191         }
 192
 193         return __res;
 194 }
 195 #endif
 196
 197 #ifndef __HAVE_ARCH_STRNCMP
 198 /**
 199  * strncmp - Compare two length-limited strings
 200  * @cs: One string
 201  * @ct: Another string
 202  * @count: The maximum number of bytes to compare
 203  */
 204 int strncmp(const char * cs,const char * ct,size_t count)
 205 {
 206         register signed char __res = 0;
 207
 208         while (count) {
 209                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 210                         break;
 211                 count--;
 212         }
 213
 214         return __res;
 215 }
 216 #endif
 217
 218 #ifndef __HAVE_ARCH_STRCHR
 219 /**
 220  * strchr - Find the first occurrence of a character in a string
 221  * @s: The string to be searched
 222  * @c: The character to search for
 223  */
 224 char * strchr(const char * s, int c)
 225 {
 226         for(; *s != (char) c; ++s)
 227                 if (*s == '\0')
 228                         return NULL;
 229         return (char *) s;
 230 }
 231 #endif
 232
 233 const char *strchrnul(const char *s, int c)
 234 {
 235         for (; *s != (char)c; ++s)
 236                 if (*s == '\0')
 237                         break;
 238         return s;
 239 }
 240
 241 #ifndef __HAVE_ARCH_STRRCHR
 242 /**
 243  * strrchr - Find the last occurrence of a character in a string
 244  * @s: The string to be searched
 245  * @c: The character to search for
 246  */
 247 char * strrchr(const char * s, int c)
 248 {
 249        const char *p = s + strlen(s);
 250        do {
 251            if (*p == (char)c)
 252                return (char *)p;
 253        } while (--p >= s);
 254        return NULL;
 255 }
 256 #endif
 257
 258 #ifndef __HAVE_ARCH_STRLEN
 259 /**
 260  * strlen - Find the length of a string
 261  * @s: The string to be sized
 262  */
 263 size_t strlen(const char * s)
 264 {
 265         const char *sc;
 266
 267         for (sc = s; *sc != '\0'; ++sc)
 268                 /* nothing */;
 269         return sc - s;
 270 }
 271 #endif
 272
 273 #ifndef __HAVE_ARCH_STRNLEN
 274 /**
 275  * strnlen - Find the length of a length-limited string
 276  * @s: The string to be sized
 277  * @count: The maximum number of bytes to search
 278  */
 279 size_t strnlen(const char * s, size_t count)
 280 {
 281         const char *sc;
 282
 283         for (sc = s; count-- && *sc != '\0'; ++sc)
 284                 /* nothing */;
 285         return sc - s;
 286 }
 287 #endif
 288
 289 #ifndef __HAVE_ARCH_STRCSPN
 290 /**
 291  * strcspn - Calculate the length of the initial substring of @s which does
 292  * not contain letters in @reject
 293  * @s: The string to be searched
 294  * @reject: The string to avoid
 295  */
 296 size_t strcspn(const char *s, const char *reject)
 297 {
 298         const char *p;
 299         const char *r;
 300         size_t count = 0;
 301
 302         for (p = s; *p != '\0'; ++p) {
 303                 for (r = reject; *r != '\0'; ++r) {
 304                         if (*p == *r)
 305                                 return count;
 306                 }
 307                 ++count;
 308         }
 309         return count;
 310 }
 311 #endif
 312
 313 #ifndef __HAVE_ARCH_STRDUP
 314 char * strdup(const char *s)
 315 {
 316         char *new;
 317
 318         if ((s == NULL) ||
 319             ((new = malloc (strlen(s) + 1)) == NULL) ) {
 320                 return NULL;
 321         }
 322
 323         strcpy (new, s);
 324         return new;
 325 }
 326 #endif
 327
 328 #ifndef __HAVE_ARCH_STRSPN
 329 /**
 330  * strspn - Calculate the length of the initial substring of @s which only
 331  *      contain letters in @accept
 332  * @s: The string to be searched
 333  * @accept: The string to search for
 334  */
 335 size_t strspn(const char *s, const char *accept)
 336 {
 337         const char *p;
 338         const char *a;
 339         size_t count = 0;
 340
 341         for (p = s; *p != '\0'; ++p) {
 342                 for (a = accept; *a != '\0'; ++a) {
 343                         if (*p == *a)
 344                                 break;
 345                 }
 346                 if (*a == '\0')
 347                         return count;
 348                 ++count;
 349         }
 350
 351         return count;
 352 }
 353 #endif
 354
 355 #ifndef __HAVE_ARCH_STRPBRK
 356 /**
 357  * strpbrk - Find the first occurrence of a set of characters
 358  * @cs: The string to be searched
 359  * @ct: The characters to search for
 360  */
 361 char * strpbrk(const char * cs,const char * ct)
 362 {
 363         const char *sc1,*sc2;
 364
 365         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 366                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 367                         if (*sc1 == *sc2)
 368                                 return (char *) sc1;
 369                 }
 370         }
 371         return NULL;
 372 }
 373 #endif
 374
 375 #ifndef __HAVE_ARCH_STRTOK
 376 /**
 377  * strtok - Split a string into tokens
 378  * @s: The string to be searched
 379  * @ct: The characters to search for
 380  *
 381  * WARNING: strtok is deprecated, use strsep instead.
 382  */
 383 char * strtok(char * s,const char * ct)
 384 {
 385         char *sbegin, *send;
 386
 387         sbegin  = s ? s : ___strtok;
 388         if (!sbegin) {
 389                 return NULL;
 390         }
 391         sbegin += strspn(sbegin,ct);
 392         if (*sbegin == '\0') {
 393                 ___strtok = NULL;
 394                 return( NULL );
 395         }
 396         send = strpbrk( sbegin, ct);
 397         if (send && *send != '\0')
 398                 *send++ = '\0';
 399         ___strtok = send;
 400         return (sbegin);
 401 }
 402 #endif
 403
 404 #ifndef __HAVE_ARCH_STRSEP
 405 /**
 406  * strsep - Split a string into tokens
 407  * @s: The string to be searched
 408  * @ct: The characters to search for
 409  *
 410  * strsep() updates @s to point after the token, ready for the next call.
 411  *
 412  * It returns empty tokens, too, behaving exactly like the libc function
 413  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 414  * Same semantics, slimmer shape. ;)
 415  */
 416 char * strsep(char **s, const char *ct)
 417 {
 418         char *sbegin = *s, *end;
 419
 420         if (sbegin == NULL)
 421                 return NULL;
 422
 423         end = strpbrk(sbegin, ct);
 424         if (end)
 425                 *end++ = '\0';
 426         *s = end;
 427
 428         return sbegin;
 429 }
 430 #endif
 431
 432 #ifndef __HAVE_ARCH_STRSWAB
 433 /**
 434  * strswab - swap adjacent even and odd bytes in %NUL-terminated string
 435  * s: address of the string
 436  *
 437  * returns the address of the swapped string or NULL on error. If
 438  * string length is odd, last byte is untouched.
 439  */
 440 char *strswab(const char *s)
 441 {
 442         char *p, *q;
 443
 444         if ((NULL == s) || ('\0' == *s)) {
 445                 return (NULL);
 446         }
 447
 448         for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
 449                 char  tmp;
 450
 451                 tmp = *p;
 452                 *p  = *q;
 453                 *q  = tmp;
 454         }
 455
 456         return (char *) s;
 457 }
 458 #endif
 459
 460 #ifndef __HAVE_ARCH_MEMSET
 461 /**
 462  * memset - Fill a region of memory with the given value
 463  * @s: Pointer to the start of the area.
 464  * @c: The byte to fill the area with
 465  * @count: The size of the area.
 466  *
 467  * Do not use memset() to access IO space, use memset_io() instead.
 468  */
 469 void * memset(void * s,int c,size_t count)
 470 {
 471         unsigned long *sl = (unsigned long *) s;
 472         char *s8;
 473
 474 #if !CONFIG_IS_ENABLED(TINY_MEMSET)
 475         unsigned long cl = 0;
 476         int i;
 477
 478         /* do it one word at a time (32 bits or 64 bits) while possible */
 479         if ( ((ulong)s & (sizeof(*sl) - 1)) == 0) {
 480                 for (i = 0; i < sizeof(*sl); i++) {
 481                         cl <<= 8;
 482                         cl |= c & 0xff;
 483                 }
 484                 while (count >= sizeof(*sl)) {
 485                         *sl++ = cl;
 486                         count -= sizeof(*sl);
 487                 }
 488         }
 489 #endif  /* fill 8 bits at a time */
 490         s8 = (char *)sl;
 491         while (count--)
 492                 *s8++ = c;
 493
 494         return s;
 495 }
 496 #endif
 497
 498 #ifndef __HAVE_ARCH_MEMCPY
 499 /**
 500  * memcpy - Copy one area of memory to another
 501  * @dest: Where to copy to
 502  * @src: Where to copy from
 503  * @count: The size of the area.
 504  *
 505  * You should not use this function to access IO space, use memcpy_toio()
 506  * or memcpy_fromio() instead.
 507  */
 508 void * memcpy(void *dest, const void *src, size_t count)
 509 {
 510         unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
 511         char *d8, *s8;
 512
 513         if (src == dest)
 514                 return dest;
 515
 516         /* while all data is aligned (common case), copy a word at a time */
 517         if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) {
 518                 while (count >= sizeof(*dl)) {
 519                         *dl++ = *sl++;
 520                         count -= sizeof(*dl);
 521                 }
 522         }
 523         /* copy the reset one byte at a time */
 524         d8 = (char *)dl;
 525         s8 = (char *)sl;
 526         while (count--)
 527                 *d8++ = *s8++;
 528
 529         return dest;
 530 }
 531 #endif
 532
 533 #ifndef __HAVE_ARCH_MEMMOVE
 534 /**
 535  * memmove - Copy one area of memory to another
 536  * @dest: Where to copy to
 537  * @src: Where to copy from
 538  * @count: The size of the area.
 539  *
 540  * Unlike memcpy(), memmove() copes with overlapping areas.
 541  */
 542 void * memmove(void * dest,const void *src,size_t count)
 543 {
 544         char *tmp, *s;
 545
 546         if (dest <= src) {
 547                 memcpy(dest, src, count);
 548         } else {
 549                 tmp = (char *) dest + count;
 550                 s = (char *) src + count;
 551                 while (count--)
 552                         *--tmp = *--s;
 553                 }
 554
 555         return dest;
 556 }
 557 #endif
 558
 559 #ifndef __HAVE_ARCH_MEMCMP
 560 /**
 561  * memcmp - Compare two areas of memory
 562  * @cs: One area of memory
 563  * @ct: Another area of memory
 564  * @count: The size of the area.
 565  */
 566 int memcmp(const void * cs,const void * ct,size_t count)
 567 {
 568         const unsigned char *su1, *su2;
 569         int res = 0;
 570
 571         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 572                 if ((res = *su1 - *su2) != 0)
 573                         break;
 574         return res;
 575 }
 576 #endif
 577
 578 #ifndef __HAVE_ARCH_MEMSCAN
 579 /**
 580  * memscan - Find a character in an area of memory.
 581  * @addr: The memory area
 582  * @c: The byte to search for
 583  * @size: The size of the area.
 584  *
 585  * returns the address of the first occurrence of @c, or 1 byte past
 586  * the area if @c is not found
 587  */
 588 void * memscan(void * addr, int c, size_t size)
 589 {
 590         unsigned char * p = (unsigned char *) addr;
 591
 592         while (size) {
 593                 if (*p == c)
 594                         return (void *) p;
 595                 p++;
 596                 size--;
 597         }
 598         return (void *) p;
 599 }
 600 #endif
 601
 602 #ifndef __HAVE_ARCH_STRSTR
 603 /**
 604  * strstr - Find the first substring in a %NUL terminated string
 605  * @s1: The string to be searched
 606  * @s2: The string to search for
 607  */
 608 char * strstr(const char * s1,const char * s2)
 609 {
 610         int l1, l2;
 611
 612         l2 = strlen(s2);
 613         if (!l2)
 614                 return (char *) s1;
 615         l1 = strlen(s1);
 616         while (l1 >= l2) {
 617                 l1--;
 618                 if (!memcmp(s1,s2,l2))
 619                         return (char *) s1;
 620                 s1++;
 621         }
 622         return NULL;
 623 }
 624 #endif
 625
 626 #ifndef __HAVE_ARCH_MEMCHR
 627 /**
 628  * memchr - Find a character in an area of memory.
 629  * @s: The memory area
 630  * @c: The byte to search for
 631  * @n: The size of the area.
 632  *
 633  * returns the address of the first occurrence of @c, or %NULL
 634  * if @c is not found
 635  */
 636 void *memchr(const void *s, int c, size_t n)
 637 {
 638         const unsigned char *p = s;
 639         while (n-- != 0) {
 640                 if ((unsigned char)c == *p++) {
 641                         return (void *)(p-1);
 642                 }
 643         }
 644         return NULL;
 645 }
 646
 647 #endif
 648 #ifndef __HAVE_ARCH_MEMCHR_INV
 649 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
 650 {
 651         while (bytes) {
 652                 if (*start != value)
 653                         return (void *)start;
 654                 start++;
 655                 bytes--;
 656         }
 657         return NULL;
 658 }
 659 /**
 660  * memchr_inv - Find an unmatching character in an area of memory.
 661  * @start: The memory area
 662  * @c: Find a character other than c
 663  * @bytes: The size of the area.
 664  *
 665  * returns the address of the first character other than @c, or %NULL
 666  * if the whole buffer contains just @c.
 667  */
 668 void *memchr_inv(const void *start, int c, size_t bytes)
 669 {
 670         u8 value = c;
 671         u64 value64;
 672         unsigned int words, prefix;
 673
 674         if (bytes <= 16)
 675                 return check_bytes8(start, value, bytes);
 676
 677         value64 = value;
 678         value64 |= value64 << 8;
 679         value64 |= value64 << 16;
 680         value64 |= value64 << 32;
 681
 682         prefix = (unsigned long)start % 8;
 683         if (prefix) {
 684                 u8 *r;
 685
 686                 prefix = 8 - prefix;
 687                 r = check_bytes8(start, value, prefix);
 688                 if (r)
 689                         return r;
 690                 start += prefix;
 691                 bytes -= prefix;
 692         }
 693
 694         words = bytes / 8;
 695
 696         while (words) {
 697                 if (*(u64 *)start != value64)
 698                         return check_bytes8(start, value, 8);
 699                 start += 8;
 700                 words--;
 701         }
 702
 703         return check_bytes8(start, value, bytes % 8);
 704 }
 705 #endif