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_STRCAT
 106 /**
 107  * strcat - Append one %NUL-terminated string to another
 108  * @dest: The string to be appended to
 109  * @src: The string to append to it
 110  */
 111 char * strcat(char * dest, const char * src)
 112 {
 113         char *tmp = dest;
 114
 115         while (*dest)
 116                 dest++;
 117         while ((*dest++ = *src++) != '\0')
 118                 ;
 119
 120         return tmp;
 121 }
 122 #endif
 123
 124 #ifndef __HAVE_ARCH_STRNCAT
 125 /**
 126  * strncat - Append a length-limited, %NUL-terminated string to another
 127  * @dest: The string to be appended to
 128  * @src: The string to append to it
 129  * @count: The maximum numbers of bytes to copy
 130  *
 131  * Note that in contrast to strncpy, strncat ensures the result is
 132  * terminated.
 133  */
 134 char * strncat(char *dest, const char *src, size_t count)
 135 {
 136         char *tmp = dest;
 137
 138         if (count) {
 139                 while (*dest)
 140                         dest++;
 141                 while ((*dest++ = *src++)) {
 142                         if (--count == 0) {
 143                                 *dest = '\0';
 144                                 break;
 145                         }
 146                 }
 147         }
 148
 149         return tmp;
 150 }
 151 #endif
 152
 153 #ifndef __HAVE_ARCH_STRCMP
 154 /**
 155  * strcmp - Compare two strings
 156  * @cs: One string
 157  * @ct: Another string
 158  */
 159 int strcmp(const char * cs,const char * ct)
 160 {
 161         register signed char __res;
 162
 163         while (1) {
 164                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 165                         break;
 166         }
 167
 168         return __res;
 169 }
 170 #endif
 171
 172 #ifndef __HAVE_ARCH_STRNCMP
 173 /**
 174  * strncmp - Compare two length-limited strings
 175  * @cs: One string
 176  * @ct: Another string
 177  * @count: The maximum number of bytes to compare
 178  */
 179 int strncmp(const char * cs,const char * ct,size_t count)
 180 {
 181         register signed char __res = 0;
 182
 183         while (count) {
 184                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 185                         break;
 186                 count--;
 187         }
 188
 189         return __res;
 190 }
 191 #endif
 192
 193 #ifndef __HAVE_ARCH_STRCHR
 194 /**
 195  * strchr - Find the first occurrence of a character in a string
 196  * @s: The string to be searched
 197  * @c: The character to search for
 198  */
 199 char * strchr(const char * s, int c)
 200 {
 201         for(; *s != (char) c; ++s)
 202                 if (*s == '\0')
 203                         return NULL;
 204         return (char *) s;
 205 }
 206 #endif
 207
 208 #ifndef __HAVE_ARCH_STRRCHR
 209 /**
 210  * strrchr - Find the last occurrence of a character in a string
 211  * @s: The string to be searched
 212  * @c: The character to search for
 213  */
 214 char * strrchr(const char * s, int c)
 215 {
 216        const char *p = s + strlen(s);
 217        do {
 218            if (*p == (char)c)
 219                return (char *)p;
 220        } while (--p >= s);
 221        return NULL;
 222 }
 223 #endif
 224
 225 #ifndef __HAVE_ARCH_STRLEN
 226 /**
 227  * strlen - Find the length of a string
 228  * @s: The string to be sized
 229  */
 230 size_t strlen(const char * s)
 231 {
 232         const char *sc;
 233
 234         for (sc = s; *sc != '\0'; ++sc)
 235                 /* nothing */;
 236         return sc - s;
 237 }
 238 #endif
 239
 240 #ifndef __HAVE_ARCH_STRNLEN
 241 /**
 242  * strnlen - Find the length of a length-limited string
 243  * @s: The string to be sized
 244  * @count: The maximum number of bytes to search
 245  */
 246 size_t strnlen(const char * s, size_t count)
 247 {
 248         const char *sc;
 249
 250         for (sc = s; count-- && *sc != '\0'; ++sc)
 251                 /* nothing */;
 252         return sc - s;
 253 }
 254 #endif
 255
 256 #ifndef __HAVE_ARCH_STRDUP
 257 char * strdup(const char *s)
 258 {
 259         char *new;
 260
 261         if ((s == NULL) ||
 262             ((new = malloc (strlen(s) + 1)) == NULL) ) {
 263                 return NULL;
 264         }
 265
 266         strcpy (new, s);
 267         return new;
 268 }
 269 #endif
 270
 271 #ifndef __HAVE_ARCH_STRSPN
 272 /**
 273  * strspn - Calculate the length of the initial substring of @s which only
 274  *      contain letters in @accept
 275  * @s: The string to be searched
 276  * @accept: The string to search for
 277  */
 278 size_t strspn(const char *s, const char *accept)
 279 {
 280         const char *p;
 281         const char *a;
 282         size_t count = 0;
 283
 284         for (p = s; *p != '\0'; ++p) {
 285                 for (a = accept; *a != '\0'; ++a) {
 286                         if (*p == *a)
 287                                 break;
 288                 }
 289                 if (*a == '\0')
 290                         return count;
 291                 ++count;
 292         }
 293
 294         return count;
 295 }
 296 #endif
 297
 298 #ifndef __HAVE_ARCH_STRPBRK
 299 /**
 300  * strpbrk - Find the first occurrence of a set of characters
 301  * @cs: The string to be searched
 302  * @ct: The characters to search for
 303  */
 304 char * strpbrk(const char * cs,const char * ct)
 305 {
 306         const char *sc1,*sc2;
 307
 308         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 309                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 310                         if (*sc1 == *sc2)
 311                                 return (char *) sc1;
 312                 }
 313         }
 314         return NULL;
 315 }
 316 #endif
 317
 318 #ifndef __HAVE_ARCH_STRTOK
 319 /**
 320  * strtok - Split a string into tokens
 321  * @s: The string to be searched
 322  * @ct: The characters to search for
 323  *
 324  * WARNING: strtok is deprecated, use strsep instead.
 325  */
 326 char * strtok(char * s,const char * ct)
 327 {
 328         char *sbegin, *send;
 329
 330         sbegin  = s ? s : ___strtok;
 331         if (!sbegin) {
 332                 return NULL;
 333         }
 334         sbegin += strspn(sbegin,ct);
 335         if (*sbegin == '\0') {
 336                 ___strtok = NULL;
 337                 return( NULL );
 338         }
 339         send = strpbrk( sbegin, ct);
 340         if (send && *send != '\0')
 341                 *send++ = '\0';
 342         ___strtok = send;
 343         return (sbegin);
 344 }
 345 #endif
 346
 347 #ifndef __HAVE_ARCH_STRSEP
 348 /**
 349  * strsep - Split a string into tokens
 350  * @s: The string to be searched
 351  * @ct: The characters to search for
 352  *
 353  * strsep() updates @s to point after the token, ready for the next call.
 354  *
 355  * It returns empty tokens, too, behaving exactly like the libc function
 356  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 357  * Same semantics, slimmer shape. ;)
 358  */
 359 char * strsep(char **s, const char *ct)
 360 {
 361         char *sbegin = *s, *end;
 362
 363         if (sbegin == NULL)
 364                 return NULL;
 365
 366         end = strpbrk(sbegin, ct);
 367         if (end)
 368                 *end++ = '\0';
 369         *s = end;
 370
 371         return sbegin;
 372 }
 373 #endif
 374
 375 #ifndef __HAVE_ARCH_STRSWAB
 376 /**
 377  * strswab - swap adjacent even and odd bytes in %NUL-terminated string
 378  * s: address of the string
 379  *
 380  * returns the address of the swapped string or NULL on error. If
 381  * string length is odd, last byte is untouched.
 382  */
 383 char *strswab(const char *s)
 384 {
 385         char *p, *q;
 386
 387         if ((NULL == s) || ('\0' == *s)) {
 388                 return (NULL);
 389         }
 390
 391         for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
 392                 char  tmp;
 393
 394                 tmp = *p;
 395                 *p  = *q;
 396                 *q  = tmp;
 397         }
 398
 399         return (char *) s;
 400 }
 401 #endif
 402
 403 #ifndef __HAVE_ARCH_MEMSET
 404 /**
 405  * memset - Fill a region of memory with the given value
 406  * @s: Pointer to the start of the area.
 407  * @c: The byte to fill the area with
 408  * @count: The size of the area.
 409  *
 410  * Do not use memset() to access IO space, use memset_io() instead.
 411  */
 412 void * memset(void * s,int c,size_t count)
 413 {
 414         unsigned long *sl = (unsigned long *) s;
 415         unsigned long cl = 0;
 416         char *s8;
 417         int i;
 418
 419         /* do it one word at a time (32 bits or 64 bits) while possible */
 420         if ( ((ulong)s & (sizeof(*sl) - 1)) == 0) {
 421                 for (i = 0; i < sizeof(*sl); i++) {
 422                         cl <<= 8;
 423                         cl |= c & 0xff;
 424                 }
 425                 while (count >= sizeof(*sl)) {
 426                         *sl++ = cl;
 427                         count -= sizeof(*sl);
 428                 }
 429         }
 430         /* fill 8 bits at a time */
 431         s8 = (char *)sl;
 432         while (count--)
 433                 *s8++ = c;
 434
 435         return s;
 436 }
 437 #endif
 438
 439 #ifndef __HAVE_ARCH_BCOPY
 440 /**
 441  * bcopy - Copy one area of memory to another
 442  * @src: Where to copy from
 443  * @dest: Where to copy to
 444  * @count: The size of the area.
 445  *
 446  * Note that this is the same as memcpy(), with the arguments reversed.
 447  * memcpy() is the standard, bcopy() is a legacy BSD function.
 448  *
 449  * You should not use this function to access IO space, use memcpy_toio()
 450  * or memcpy_fromio() instead.
 451  */
 452 char * bcopy(const char * src, char * dest, int count)
 453 {
 454         char *tmp = dest;
 455
 456         while (count--)
 457                 *tmp++ = *src++;
 458
 459         return dest;
 460 }
 461 #endif
 462
 463 #ifndef __HAVE_ARCH_MEMCPY
 464 /**
 465  * memcpy - Copy one area of memory to another
 466  * @dest: Where to copy to
 467  * @src: Where to copy from
 468  * @count: The size of the area.
 469  *
 470  * You should not use this function to access IO space, use memcpy_toio()
 471  * or memcpy_fromio() instead.
 472  */
 473 void * memcpy(void *dest, const void *src, size_t count)
 474 {
 475         unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
 476         char *d8, *s8;
 477
 478         if (src == dest)
 479                 return dest;
 480
 481         /* while all data is aligned (common case), copy a word at a time */
 482         if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) {
 483                 while (count >= sizeof(*dl)) {
 484                         *dl++ = *sl++;
 485                         count -= sizeof(*dl);
 486                 }
 487         }
 488         /* copy the reset one byte at a time */
 489         d8 = (char *)dl;
 490         s8 = (char *)sl;
 491         while (count--)
 492                 *d8++ = *s8++;
 493
 494         return dest;
 495 }
 496 #endif
 497
 498 #ifndef __HAVE_ARCH_MEMMOVE
 499 /**
 500  * memmove - 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  * Unlike memcpy(), memmove() copes with overlapping areas.
 506  */
 507 void * memmove(void * dest,const void *src,size_t count)
 508 {
 509         char *tmp, *s;
 510
 511         if (src == dest)
 512                 return dest;
 513
 514         if (dest <= src) {
 515                 tmp = (char *) dest;
 516                 s = (char *) src;
 517                 while (count--)
 518                         *tmp++ = *s++;
 519                 }
 520         else {
 521                 tmp = (char *) dest + count;
 522                 s = (char *) src + count;
 523                 while (count--)
 524                         *--tmp = *--s;
 525                 }
 526
 527         return dest;
 528 }
 529 #endif
 530
 531 #ifndef __HAVE_ARCH_MEMCMP
 532 /**
 533  * memcmp - Compare two areas of memory
 534  * @cs: One area of memory
 535  * @ct: Another area of memory
 536  * @count: The size of the area.
 537  */
 538 int memcmp(const void * cs,const void * ct,size_t count)
 539 {
 540         const unsigned char *su1, *su2;
 541         int res = 0;
 542
 543         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 544                 if ((res = *su1 - *su2) != 0)
 545                         break;
 546         return res;
 547 }
 548 #endif
 549
 550 #ifndef __HAVE_ARCH_MEMSCAN
 551 /**
 552  * memscan - Find a character in an area of memory.
 553  * @addr: The memory area
 554  * @c: The byte to search for
 555  * @size: The size of the area.
 556  *
 557  * returns the address of the first occurrence of @c, or 1 byte past
 558  * the area if @c is not found
 559  */
 560 void * memscan(void * addr, int c, size_t size)
 561 {
 562         unsigned char * p = (unsigned char *) addr;
 563
 564         while (size) {
 565                 if (*p == c)
 566                         return (void *) p;
 567                 p++;
 568                 size--;
 569         }
 570         return (void *) p;
 571 }
 572 #endif
 573
 574 #ifndef __HAVE_ARCH_STRSTR
 575 /**
 576  * strstr - Find the first substring in a %NUL terminated string
 577  * @s1: The string to be searched
 578  * @s2: The string to search for
 579  */
 580 char * strstr(const char * s1,const char * s2)
 581 {
 582         int l1, l2;
 583
 584         l2 = strlen(s2);
 585         if (!l2)
 586                 return (char *) s1;
 587         l1 = strlen(s1);
 588         while (l1 >= l2) {
 589                 l1--;
 590                 if (!memcmp(s1,s2,l2))
 591                         return (char *) s1;
 592                 s1++;
 593         }
 594         return NULL;
 595 }
 596 #endif
 597
 598 #ifndef __HAVE_ARCH_MEMCHR
 599 /**
 600  * memchr - Find a character in an area of memory.
 601  * @s: The memory area
 602  * @c: The byte to search for
 603  * @n: The size of the area.
 604  *
 605  * returns the address of the first occurrence of @c, or %NULL
 606  * if @c is not found
 607  */
 608 void *memchr(const void *s, int c, size_t n)
 609 {
 610         const unsigned char *p = s;
 611         while (n-- != 0) {
 612                 if ((unsigned char)c == *p++) {
 613                         return (void *)(p-1);
 614                 }
 615         }
 616         return NULL;
 617 }
 618
 619 #endif
 620 #ifndef __HAVE_ARCH_MEMCHR_INV
 621 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
 622 {
 623         while (bytes) {
 624                 if (*start != value)
 625                         return (void *)start;
 626                 start++;
 627                 bytes--;
 628         }
 629         return NULL;
 630 }
 631 /**
 632  * memchr_inv - Find an unmatching character in an area of memory.
 633  * @start: The memory area
 634  * @c: Find a character other than c
 635  * @bytes: The size of the area.
 636  *
 637  * returns the address of the first character other than @c, or %NULL
 638  * if the whole buffer contains just @c.
 639  */
 640 void *memchr_inv(const void *start, int c, size_t bytes)
 641 {
 642         u8 value = c;
 643         u64 value64;
 644         unsigned int words, prefix;
 645
 646         if (bytes <= 16)
 647                 return check_bytes8(start, value, bytes);
 648
 649         value64 = value;
 650         value64 |= value64 << 8;
 651         value64 |= value64 << 16;
 652         value64 |= value64 << 32;
 653
 654         prefix = (unsigned long)start % 8;
 655         if (prefix) {
 656                 u8 *r;
 657
 658                 prefix = 8 - prefix;
 659                 r = check_bytes8(start, value, prefix);
 660                 if (r)
 661                         return r;
 662                 start += prefix;
 663                 bytes -= prefix;
 664         }
 665
 666         words = bytes / 8;
 667
 668         while (words) {
 669                 if (*(u64 *)start != value64)
 670                         return check_bytes8(start, value, 8);
 671                 start += 8;
 672                 words--;
 673         }
 674
 675         return check_bytes8(start, value, bytes % 8);
 676 }
 677 #endif
 678