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 #ifndef __HAVE_ARCH_STRRCHR
 234 /**
 235  * strrchr - Find the last occurrence of a character in a string
 236  * @s: The string to be searched
 237  * @c: The character to search for
 238  */
 239 char * strrchr(const char * s, int c)
 240 {
 241        const char *p = s + strlen(s);
 242        do {
 243            if (*p == (char)c)
 244                return (char *)p;
 245        } while (--p >= s);
 246        return NULL;
 247 }
 248 #endif
 249
 250 #ifndef __HAVE_ARCH_STRLEN
 251 /**
 252  * strlen - Find the length of a string
 253  * @s: The string to be sized
 254  */
 255 size_t strlen(const char * s)
 256 {
 257         const char *sc;
 258
 259         for (sc = s; *sc != '\0'; ++sc)
 260                 /* nothing */;
 261         return sc - s;
 262 }
 263 #endif
 264
 265 #ifndef __HAVE_ARCH_STRNLEN
 266 /**
 267  * strnlen - Find the length of a length-limited string
 268  * @s: The string to be sized
 269  * @count: The maximum number of bytes to search
 270  */
 271 size_t strnlen(const char * s, size_t count)
 272 {
 273         const char *sc;
 274
 275         for (sc = s; count-- && *sc != '\0'; ++sc)
 276                 /* nothing */;
 277         return sc - s;
 278 }
 279 #endif
 280
 281 #ifndef __HAVE_ARCH_STRDUP
 282 char * strdup(const char *s)
 283 {
 284         char *new;
 285
 286         if ((s == NULL) ||
 287             ((new = malloc (strlen(s) + 1)) == NULL) ) {
 288                 return NULL;
 289         }
 290
 291         strcpy (new, s);
 292         return new;
 293 }
 294 #endif
 295
 296 #ifndef __HAVE_ARCH_STRSPN
 297 /**
 298  * strspn - Calculate the length of the initial substring of @s which only
 299  *      contain letters in @accept
 300  * @s: The string to be searched
 301  * @accept: The string to search for
 302  */
 303 size_t strspn(const char *s, const char *accept)
 304 {
 305         const char *p;
 306         const char *a;
 307         size_t count = 0;
 308
 309         for (p = s; *p != '\0'; ++p) {
 310                 for (a = accept; *a != '\0'; ++a) {
 311                         if (*p == *a)
 312                                 break;
 313                 }
 314                 if (*a == '\0')
 315                         return count;
 316                 ++count;
 317         }
 318
 319         return count;
 320 }
 321 #endif
 322
 323 #ifndef __HAVE_ARCH_STRPBRK
 324 /**
 325  * strpbrk - Find the first occurrence of a set of characters
 326  * @cs: The string to be searched
 327  * @ct: The characters to search for
 328  */
 329 char * strpbrk(const char * cs,const char * ct)
 330 {
 331         const char *sc1,*sc2;
 332
 333         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 334                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 335                         if (*sc1 == *sc2)
 336                                 return (char *) sc1;
 337                 }
 338         }
 339         return NULL;
 340 }
 341 #endif
 342
 343 #ifndef __HAVE_ARCH_STRTOK
 344 /**
 345  * strtok - Split a string into tokens
 346  * @s: The string to be searched
 347  * @ct: The characters to search for
 348  *
 349  * WARNING: strtok is deprecated, use strsep instead.
 350  */
 351 char * strtok(char * s,const char * ct)
 352 {
 353         char *sbegin, *send;
 354
 355         sbegin  = s ? s : ___strtok;
 356         if (!sbegin) {
 357                 return NULL;
 358         }
 359         sbegin += strspn(sbegin,ct);
 360         if (*sbegin == '\0') {
 361                 ___strtok = NULL;
 362                 return( NULL );
 363         }
 364         send = strpbrk( sbegin, ct);
 365         if (send && *send != '\0')
 366                 *send++ = '\0';
 367         ___strtok = send;
 368         return (sbegin);
 369 }
 370 #endif
 371
 372 #ifndef __HAVE_ARCH_STRSEP
 373 /**
 374  * strsep - Split a string into tokens
 375  * @s: The string to be searched
 376  * @ct: The characters to search for
 377  *
 378  * strsep() updates @s to point after the token, ready for the next call.
 379  *
 380  * It returns empty tokens, too, behaving exactly like the libc function
 381  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 382  * Same semantics, slimmer shape. ;)
 383  */
 384 char * strsep(char **s, const char *ct)
 385 {
 386         char *sbegin = *s, *end;
 387
 388         if (sbegin == NULL)
 389                 return NULL;
 390
 391         end = strpbrk(sbegin, ct);
 392         if (end)
 393                 *end++ = '\0';
 394         *s = end;
 395
 396         return sbegin;
 397 }
 398 #endif
 399
 400 #ifndef __HAVE_ARCH_STRSWAB
 401 /**
 402  * strswab - swap adjacent even and odd bytes in %NUL-terminated string
 403  * s: address of the string
 404  *
 405  * returns the address of the swapped string or NULL on error. If
 406  * string length is odd, last byte is untouched.
 407  */
 408 char *strswab(const char *s)
 409 {
 410         char *p, *q;
 411
 412         if ((NULL == s) || ('\0' == *s)) {
 413                 return (NULL);
 414         }
 415
 416         for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
 417                 char  tmp;
 418
 419                 tmp = *p;
 420                 *p  = *q;
 421                 *q  = tmp;
 422         }
 423
 424         return (char *) s;
 425 }
 426 #endif
 427
 428 #ifndef __HAVE_ARCH_MEMSET
 429 /**
 430  * memset - Fill a region of memory with the given value
 431  * @s: Pointer to the start of the area.
 432  * @c: The byte to fill the area with
 433  * @count: The size of the area.
 434  *
 435  * Do not use memset() to access IO space, use memset_io() instead.
 436  */
 437 void * memset(void * s,int c,size_t count)
 438 {
 439         unsigned long *sl = (unsigned long *) s;
 440         char *s8;
 441
 442 #if !CONFIG_IS_ENABLED(TINY_MEMSET)
 443         unsigned long cl = 0;
 444         int i;
 445
 446         /* do it one word at a time (32 bits or 64 bits) while possible */
 447         if ( ((ulong)s & (sizeof(*sl) - 1)) == 0) {
 448                 for (i = 0; i < sizeof(*sl); i++) {
 449                         cl <<= 8;
 450                         cl |= c & 0xff;
 451                 }
 452                 while (count >= sizeof(*sl)) {
 453                         *sl++ = cl;
 454                         count -= sizeof(*sl);
 455                 }
 456         }
 457 #endif  /* fill 8 bits at a time */
 458         s8 = (char *)sl;
 459         while (count--)
 460                 *s8++ = c;
 461
 462         return s;
 463 }
 464 #endif
 465
 466 #ifndef __HAVE_ARCH_MEMCPY
 467 /**
 468  * memcpy - Copy one area of memory to another
 469  * @dest: Where to copy to
 470  * @src: Where to copy from
 471  * @count: The size of the area.
 472  *
 473  * You should not use this function to access IO space, use memcpy_toio()
 474  * or memcpy_fromio() instead.
 475  */
 476 void * memcpy(void *dest, const void *src, size_t count)
 477 {
 478         unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
 479         char *d8, *s8;
 480
 481         if (src == dest)
 482                 return dest;
 483
 484         /* while all data is aligned (common case), copy a word at a time */
 485         if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) {
 486                 while (count >= sizeof(*dl)) {
 487                         *dl++ = *sl++;
 488                         count -= sizeof(*dl);
 489                 }
 490         }
 491         /* copy the reset one byte at a time */
 492         d8 = (char *)dl;
 493         s8 = (char *)sl;
 494         while (count--)
 495                 *d8++ = *s8++;
 496
 497         return dest;
 498 }
 499 #endif
 500
 501 #ifndef __HAVE_ARCH_MEMMOVE
 502 /**
 503  * memmove - Copy one area of memory to another
 504  * @dest: Where to copy to
 505  * @src: Where to copy from
 506  * @count: The size of the area.
 507  *
 508  * Unlike memcpy(), memmove() copes with overlapping areas.
 509  */
 510 void * memmove(void * dest,const void *src,size_t count)
 511 {
 512         char *tmp, *s;
 513
 514         if (src == dest)
 515                 return dest;
 516
 517         if (dest <= src) {
 518                 tmp = (char *) dest;
 519                 s = (char *) src;
 520                 while (count--)
 521                         *tmp++ = *s++;
 522                 }
 523         else {
 524                 tmp = (char *) dest + count;
 525                 s = (char *) src + count;
 526                 while (count--)
 527                         *--tmp = *--s;
 528                 }
 529
 530         return dest;
 531 }
 532 #endif
 533
 534 #ifndef __HAVE_ARCH_MEMCMP
 535 /**
 536  * memcmp - Compare two areas of memory
 537  * @cs: One area of memory
 538  * @ct: Another area of memory
 539  * @count: The size of the area.
 540  */
 541 int memcmp(const void * cs,const void * ct,size_t count)
 542 {
 543         const unsigned char *su1, *su2;
 544         int res = 0;
 545
 546         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 547                 if ((res = *su1 - *su2) != 0)
 548                         break;
 549         return res;
 550 }
 551 #endif
 552
 553 #ifndef __HAVE_ARCH_MEMSCAN
 554 /**
 555  * memscan - Find a character in an area of memory.
 556  * @addr: The memory area
 557  * @c: The byte to search for
 558  * @size: The size of the area.
 559  *
 560  * returns the address of the first occurrence of @c, or 1 byte past
 561  * the area if @c is not found
 562  */
 563 void * memscan(void * addr, int c, size_t size)
 564 {
 565         unsigned char * p = (unsigned char *) addr;
 566
 567         while (size) {
 568                 if (*p == c)
 569                         return (void *) p;
 570                 p++;
 571                 size--;
 572         }
 573         return (void *) p;
 574 }
 575 #endif
 576
 577 #ifndef __HAVE_ARCH_STRSTR
 578 /**
 579  * strstr - Find the first substring in a %NUL terminated string
 580  * @s1: The string to be searched
 581  * @s2: The string to search for
 582  */
 583 char * strstr(const char * s1,const char * s2)
 584 {
 585         int l1, l2;
 586
 587         l2 = strlen(s2);
 588         if (!l2)
 589                 return (char *) s1;
 590         l1 = strlen(s1);
 591         while (l1 >= l2) {
 592                 l1--;
 593                 if (!memcmp(s1,s2,l2))
 594                         return (char *) s1;
 595                 s1++;
 596         }
 597         return NULL;
 598 }
 599 #endif
 600
 601 #ifndef __HAVE_ARCH_MEMCHR
 602 /**
 603  * memchr - Find a character in an area of memory.
 604  * @s: The memory area
 605  * @c: The byte to search for
 606  * @n: The size of the area.
 607  *
 608  * returns the address of the first occurrence of @c, or %NULL
 609  * if @c is not found
 610  */
 611 void *memchr(const void *s, int c, size_t n)
 612 {
 613         const unsigned char *p = s;
 614         while (n-- != 0) {
 615                 if ((unsigned char)c == *p++) {
 616                         return (void *)(p-1);
 617                 }
 618         }
 619         return NULL;
 620 }
 621
 622 #endif
 623 #ifndef __HAVE_ARCH_MEMCHR_INV
 624 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
 625 {
 626         while (bytes) {
 627                 if (*start != value)
 628                         return (void *)start;
 629                 start++;
 630                 bytes--;
 631         }
 632         return NULL;
 633 }
 634 /**
 635  * memchr_inv - Find an unmatching character in an area of memory.
 636  * @start: The memory area
 637  * @c: Find a character other than c
 638  * @bytes: The size of the area.
 639  *
 640  * returns the address of the first character other than @c, or %NULL
 641  * if the whole buffer contains just @c.
 642  */
 643 void *memchr_inv(const void *start, int c, size_t bytes)
 644 {
 645         u8 value = c;
 646         u64 value64;
 647         unsigned int words, prefix;
 648
 649         if (bytes <= 16)
 650                 return check_bytes8(start, value, bytes);
 651
 652         value64 = value;
 653         value64 |= value64 << 8;
 654         value64 |= value64 << 16;
 655         value64 |= value64 << 32;
 656
 657         prefix = (unsigned long)start % 8;
 658         if (prefix) {
 659                 u8 *r;
 660
 661                 prefix = 8 - prefix;
 662                 r = check_bytes8(start, value, prefix);
 663                 if (r)
 664                         return r;
 665                 start += prefix;
 666                 bytes -= prefix;
 667         }
 668
 669         words = bytes / 8;
 670
 671         while (words) {
 672                 if (*(u64 *)start != value64)
 673                         return check_bytes8(start, value, 8);
 674                 start += 8;
 675                 words--;
 676         }
 677
 678         return check_bytes8(start, value, bytes % 8);
 679 }
 680 #endif