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 <config.h>
  19 #include <linux/types.h>
  20 #include <linux/string.h>
  21 #include <linux/ctype.h>
  22 #include <malloc.h>
  23
  24
  25 /**
  26  * strncasecmp - 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 strncasecmp(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
  56 /**
  57  * strcasecmp - Case insensitive string comparison
  58  * @s1: One string
  59  * @s2: The other string
  60  */
  61 int strcasecmp(const char *s1, const char *s2)
  62 {
  63         return strncasecmp(s1, s2, -1U);
  64 }
  65
  66 char * ___strtok;
  67
  68 #ifndef __HAVE_ARCH_STRCPY
  69 /**
  70  * strcpy - Copy a %NUL terminated string
  71  * @dest: Where to copy the string to
  72  * @src: Where to copy the string from
  73  */
  74 char * strcpy(char * dest,const char *src)
  75 {
  76         char *tmp = dest;
  77
  78         while ((*dest++ = *src++) != '\0')
  79                 /* nothing */;
  80         return tmp;
  81 }
  82 #endif
  83
  84 #ifndef __HAVE_ARCH_STRNCPY
  85 /**
  86  * strncpy - Copy a length-limited, %NUL-terminated string
  87  * @dest: Where to copy the string to
  88  * @src: Where to copy the string from
  89  * @count: The maximum number of bytes to copy
  90  *
  91  * Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
  92  * However, the result is not %NUL-terminated if the source exceeds
  93  * @count bytes.
  94  */
  95 char * strncpy(char * dest,const char *src,size_t count)
  96 {
  97         char *tmp = dest;
  98
  99         while (count-- && (*dest++ = *src++) != '\0')
 100                 /* nothing */;
 101
 102         return tmp;
 103 }
 104 #endif
 105
 106 #ifndef __HAVE_ARCH_STRLCPY
 107 /**
 108  * strlcpy - Copy a C-string into a sized buffer
 109  * @dest: Where to copy the string to
 110  * @src: Where to copy the string from
 111  * @size: size of destination buffer
 112  *
 113  * Compatible with *BSD: the result is always a valid
 114  * NUL-terminated string that fits in the buffer (unless,
 115  * of course, the buffer size is zero). It does not pad
 116  * out the result like strncpy() does.
 117  */
 118 size_t strlcpy(char *dest, const char *src, size_t size)
 119 {
 120         size_t ret = strlen(src);
 121
 122         if (size) {
 123                 size_t len = (ret >= size) ? size - 1 : ret;
 124                 memcpy(dest, src, len);
 125                 dest[len] = '\0';
 126         }
 127         return ret;
 128 }
 129 #endif
 130
 131 #ifndef __HAVE_ARCH_STRCAT
 132 /**
 133  * strcat - Append one %NUL-terminated string to another
 134  * @dest: The string to be appended to
 135  * @src: The string to append to it
 136  */
 137 char * strcat(char * dest, const char * src)
 138 {
 139         char *tmp = dest;
 140
 141         while (*dest)
 142                 dest++;
 143         while ((*dest++ = *src++) != '\0')
 144                 ;
 145
 146         return tmp;
 147 }
 148 #endif
 149
 150 #ifndef __HAVE_ARCH_STRNCAT
 151 /**
 152  * strncat - Append a length-limited, %NUL-terminated string to another
 153  * @dest: The string to be appended to
 154  * @src: The string to append to it
 155  * @count: The maximum numbers of bytes to copy
 156  *
 157  * Note that in contrast to strncpy, strncat ensures the result is
 158  * terminated.
 159  */
 160 char * strncat(char *dest, const char *src, size_t count)
 161 {
 162         char *tmp = dest;
 163
 164         if (count) {
 165                 while (*dest)
 166                         dest++;
 167                 while ((*dest++ = *src++)) {
 168                         if (--count == 0) {
 169                                 *dest = '\0';
 170                                 break;
 171                         }
 172                 }
 173         }
 174
 175         return tmp;
 176 }
 177 #endif
 178
 179 #ifndef __HAVE_ARCH_STRCMP
 180 /**
 181  * strcmp - Compare two strings
 182  * @cs: One string
 183  * @ct: Another string
 184  */
 185 int strcmp(const char * cs,const char * ct)
 186 {
 187         register signed char __res;
 188
 189         while (1) {
 190                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 191                         break;
 192         }
 193
 194         return __res;
 195 }
 196 #endif
 197
 198 #ifndef __HAVE_ARCH_STRNCMP
 199 /**
 200  * strncmp - Compare two length-limited strings
 201  * @cs: One string
 202  * @ct: Another string
 203  * @count: The maximum number of bytes to compare
 204  */
 205 int strncmp(const char * cs,const char * ct,size_t count)
 206 {
 207         register signed char __res = 0;
 208
 209         while (count) {
 210                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 211                         break;
 212                 count--;
 213         }
 214
 215         return __res;
 216 }
 217 #endif
 218
 219 #ifndef __HAVE_ARCH_STRCHR
 220 /**
 221  * strchr - Find the first occurrence of a character in a string
 222  * @s: The string to be searched
 223  * @c: The character to search for
 224  */
 225 char * strchr(const char * s, int c)
 226 {
 227         for(; *s != (char) c; ++s)
 228                 if (*s == '\0')
 229                         return NULL;
 230         return (char *) s;
 231 }
 232 #endif
 233
 234 const char *strchrnul(const char *s, int c)
 235 {
 236         for (; *s != (char)c; ++s)
 237                 if (*s == '\0')
 238                         break;
 239         return s;
 240 }
 241
 242 #ifndef __HAVE_ARCH_STRRCHR
 243 /**
 244  * strrchr - Find the last occurrence of a character in a string
 245  * @s: The string to be searched
 246  * @c: The character to search for
 247  */
 248 char * strrchr(const char * s, int c)
 249 {
 250        const char *p = s + strlen(s);
 251        do {
 252            if (*p == (char)c)
 253                return (char *)p;
 254        } while (--p >= s);
 255        return NULL;
 256 }
 257 #endif
 258
 259 #ifndef __HAVE_ARCH_STRLEN
 260 /**
 261  * strlen - Find the length of a string
 262  * @s: The string to be sized
 263  */
 264 size_t strlen(const char * s)
 265 {
 266         const char *sc;
 267
 268         for (sc = s; *sc != '\0'; ++sc)
 269                 /* nothing */;
 270         return sc - s;
 271 }
 272 #endif
 273
 274 #ifndef __HAVE_ARCH_STRNLEN
 275 /**
 276  * strnlen - Find the length of a length-limited string
 277  * @s: The string to be sized
 278  * @count: The maximum number of bytes to search
 279  */
 280 size_t strnlen(const char * s, size_t count)
 281 {
 282         const char *sc;
 283
 284         for (sc = s; count-- && *sc != '\0'; ++sc)
 285                 /* nothing */;
 286         return sc - s;
 287 }
 288 #endif
 289
 290 #ifndef __HAVE_ARCH_STRCSPN
 291 /**
 292  * strcspn - Calculate the length of the initial substring of @s which does
 293  * not contain letters in @reject
 294  * @s: The string to be searched
 295  * @reject: The string to avoid
 296  */
 297 size_t strcspn(const char *s, const char *reject)
 298 {
 299         const char *p;
 300         const char *r;
 301         size_t count = 0;
 302
 303         for (p = s; *p != '\0'; ++p) {
 304                 for (r = reject; *r != '\0'; ++r) {
 305                         if (*p == *r)
 306                                 return count;
 307                 }
 308                 ++count;
 309         }
 310         return count;
 311 }
 312 #endif
 313
 314 #ifndef __HAVE_ARCH_STRDUP
 315 char * strdup(const char *s)
 316 {
 317         char *new;
 318
 319         if ((s == NULL) ||
 320             ((new = malloc (strlen(s) + 1)) == NULL) ) {
 321                 return NULL;
 322         }
 323
 324         strcpy (new, s);
 325         return new;
 326 }
 327 #endif
 328
 329 char * strndup(const char *s, size_t n)
 330 {
 331         size_t len;
 332         char *new;
 333
 334         if (s == NULL)
 335                 return NULL;
 336
 337         len = strlen(s);
 338
 339         if (n < len)
 340                 len = n;
 341
 342         new = malloc(len + 1);
 343         if (new == NULL)
 344                 return NULL;
 345
 346         strncpy(new, s, len);
 347         new[len] = '\0';
 348
 349         return new;
 350 }
 351
 352 #ifndef __HAVE_ARCH_STRSPN
 353 /**
 354  * strspn - Calculate the length of the initial substring of @s which only
 355  *      contain letters in @accept
 356  * @s: The string to be searched
 357  * @accept: The string to search for
 358  */
 359 size_t strspn(const char *s, const char *accept)
 360 {
 361         const char *p;
 362         const char *a;
 363         size_t count = 0;
 364
 365         for (p = s; *p != '\0'; ++p) {
 366                 for (a = accept; *a != '\0'; ++a) {
 367                         if (*p == *a)
 368                                 break;
 369                 }
 370                 if (*a == '\0')
 371                         return count;
 372                 ++count;
 373         }
 374
 375         return count;
 376 }
 377 #endif
 378
 379 #ifndef __HAVE_ARCH_STRPBRK
 380 /**
 381  * strpbrk - Find the first occurrence of a set of characters
 382  * @cs: The string to be searched
 383  * @ct: The characters to search for
 384  */
 385 char * strpbrk(const char * cs,const char * ct)
 386 {
 387         const char *sc1,*sc2;
 388
 389         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 390                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 391                         if (*sc1 == *sc2)
 392                                 return (char *) sc1;
 393                 }
 394         }
 395         return NULL;
 396 }
 397 #endif
 398
 399 #ifndef __HAVE_ARCH_STRTOK
 400 /**
 401  * strtok - Split a string into tokens
 402  * @s: The string to be searched
 403  * @ct: The characters to search for
 404  *
 405  * WARNING: strtok is deprecated, use strsep instead.
 406  */
 407 char * strtok(char * s,const char * ct)
 408 {
 409         char *sbegin, *send;
 410
 411         sbegin  = s ? s : ___strtok;
 412         if (!sbegin) {
 413                 return NULL;
 414         }
 415         sbegin += strspn(sbegin,ct);
 416         if (*sbegin == '\0') {
 417                 ___strtok = NULL;
 418                 return( NULL );
 419         }
 420         send = strpbrk( sbegin, ct);
 421         if (send && *send != '\0')
 422                 *send++ = '\0';
 423         ___strtok = send;
 424         return (sbegin);
 425 }
 426 #endif
 427
 428 #ifndef __HAVE_ARCH_STRSEP
 429 /**
 430  * strsep - Split a string into tokens
 431  * @s: The string to be searched
 432  * @ct: The characters to search for
 433  *
 434  * strsep() updates @s to point after the token, ready for the next call.
 435  *
 436  * It returns empty tokens, too, behaving exactly like the libc function
 437  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 438  * Same semantics, slimmer shape. ;)
 439  */
 440 char * strsep(char **s, const char *ct)
 441 {
 442         char *sbegin = *s, *end;
 443
 444         if (sbegin == NULL)
 445                 return NULL;
 446
 447         end = strpbrk(sbegin, ct);
 448         if (end)
 449                 *end++ = '\0';
 450         *s = end;
 451
 452         return sbegin;
 453 }
 454 #endif
 455
 456 #ifndef __HAVE_ARCH_STRSWAB
 457 /**
 458  * strswab - swap adjacent even and odd bytes in %NUL-terminated string
 459  * s: address of the string
 460  *
 461  * returns the address of the swapped string or NULL on error. If
 462  * string length is odd, last byte is untouched.
 463  */
 464 char *strswab(const char *s)
 465 {
 466         char *p, *q;
 467
 468         if ((NULL == s) || ('\0' == *s)) {
 469                 return (NULL);
 470         }
 471
 472         for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
 473                 char  tmp;
 474
 475                 tmp = *p;
 476                 *p  = *q;
 477                 *q  = tmp;
 478         }
 479
 480         return (char *) s;
 481 }
 482 #endif
 483
 484 #ifndef __HAVE_ARCH_MEMSET
 485 /**
 486  * memset - Fill a region of memory with the given value
 487  * @s: Pointer to the start of the area.
 488  * @c: The byte to fill the area with
 489  * @count: The size of the area.
 490  *
 491  * Do not use memset() to access IO space, use memset_io() instead.
 492  */
 493 void * memset(void * s,int c,size_t count)
 494 {
 495         unsigned long *sl = (unsigned long *) s;
 496         char *s8;
 497
 498 #if !CONFIG_IS_ENABLED(TINY_MEMSET)
 499         unsigned long cl = 0;
 500         int i;
 501
 502         /* do it one word at a time (32 bits or 64 bits) while possible */
 503         if ( ((ulong)s & (sizeof(*sl) - 1)) == 0) {
 504                 for (i = 0; i < sizeof(*sl); i++) {
 505                         cl <<= 8;
 506                         cl |= c & 0xff;
 507                 }
 508                 while (count >= sizeof(*sl)) {
 509                         *sl++ = cl;
 510                         count -= sizeof(*sl);
 511                 }
 512         }
 513 #endif  /* fill 8 bits at a time */
 514         s8 = (char *)sl;
 515         while (count--)
 516                 *s8++ = c;
 517
 518         return s;
 519 }
 520 #endif
 521
 522 #ifndef __HAVE_ARCH_MEMCPY
 523 /**
 524  * memcpy - Copy one area of memory to another
 525  * @dest: Where to copy to
 526  * @src: Where to copy from
 527  * @count: The size of the area.
 528  *
 529  * You should not use this function to access IO space, use memcpy_toio()
 530  * or memcpy_fromio() instead.
 531  */
 532 void * memcpy(void *dest, const void *src, size_t count)
 533 {
 534         unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
 535         char *d8, *s8;
 536
 537         if (src == dest)
 538                 return dest;
 539
 540         /* while all data is aligned (common case), copy a word at a time */
 541         if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) {
 542                 while (count >= sizeof(*dl)) {
 543                         *dl++ = *sl++;
 544                         count -= sizeof(*dl);
 545                 }
 546         }
 547         /* copy the reset one byte at a time */
 548         d8 = (char *)dl;
 549         s8 = (char *)sl;
 550         while (count--)
 551                 *d8++ = *s8++;
 552
 553         return dest;
 554 }
 555 #endif
 556
 557 #ifndef __HAVE_ARCH_MEMMOVE
 558 /**
 559  * memmove - Copy one area of memory to another
 560  * @dest: Where to copy to
 561  * @src: Where to copy from
 562  * @count: The size of the area.
 563  *
 564  * Unlike memcpy(), memmove() copes with overlapping areas.
 565  */
 566 void * memmove(void * dest,const void *src,size_t count)
 567 {
 568         char *tmp, *s;
 569
 570         if (dest <= src) {
 571                 memcpy(dest, src, count);
 572         } else {
 573                 tmp = (char *) dest + count;
 574                 s = (char *) src + count;
 575                 while (count--)
 576                         *--tmp = *--s;
 577                 }
 578
 579         return dest;
 580 }
 581 #endif
 582
 583 #ifndef __HAVE_ARCH_MEMCMP
 584 /**
 585  * memcmp - Compare two areas of memory
 586  * @cs: One area of memory
 587  * @ct: Another area of memory
 588  * @count: The size of the area.
 589  */
 590 int memcmp(const void * cs,const void * ct,size_t count)
 591 {
 592         const unsigned char *su1, *su2;
 593         int res = 0;
 594
 595         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 596                 if ((res = *su1 - *su2) != 0)
 597                         break;
 598         return res;
 599 }
 600 #endif
 601
 602 #ifndef __HAVE_ARCH_MEMSCAN
 603 /**
 604  * memscan - Find a character in an area of memory.
 605  * @addr: The memory area
 606  * @c: The byte to search for
 607  * @size: The size of the area.
 608  *
 609  * returns the address of the first occurrence of @c, or 1 byte past
 610  * the area if @c is not found
 611  */
 612 void * memscan(void * addr, int c, size_t size)
 613 {
 614         unsigned char * p = (unsigned char *) addr;
 615
 616         while (size) {
 617                 if (*p == c)
 618                         return (void *) p;
 619                 p++;
 620                 size--;
 621         }
 622         return (void *) p;
 623 }
 624 #endif
 625
 626 #ifndef __HAVE_ARCH_STRSTR
 627 /**
 628  * strstr - Find the first substring in a %NUL terminated string
 629  * @s1: The string to be searched
 630  * @s2: The string to search for
 631  */
 632 char * strstr(const char * s1,const char * s2)
 633 {
 634         int l1, l2;
 635
 636         l2 = strlen(s2);
 637         if (!l2)
 638                 return (char *) s1;
 639         l1 = strlen(s1);
 640         while (l1 >= l2) {
 641                 l1--;
 642                 if (!memcmp(s1,s2,l2))
 643                         return (char *) s1;
 644                 s1++;
 645         }
 646         return NULL;
 647 }
 648 #endif
 649
 650 #ifndef __HAVE_ARCH_MEMCHR
 651 /**
 652  * memchr - Find a character in an area of memory.
 653  * @s: The memory area
 654  * @c: The byte to search for
 655  * @n: The size of the area.
 656  *
 657  * returns the address of the first occurrence of @c, or %NULL
 658  * if @c is not found
 659  */
 660 void *memchr(const void *s, int c, size_t n)
 661 {
 662         const unsigned char *p = s;
 663         while (n-- != 0) {
 664                 if ((unsigned char)c == *p++) {
 665                         return (void *)(p-1);
 666                 }
 667         }
 668         return NULL;
 669 }
 670
 671 #endif
 672 #ifndef __HAVE_ARCH_MEMCHR_INV
 673 static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
 674 {
 675         while (bytes) {
 676                 if (*start != value)
 677                         return (void *)start;
 678                 start++;
 679                 bytes--;
 680         }
 681         return NULL;
 682 }
 683 /**
 684  * memchr_inv - Find an unmatching character in an area of memory.
 685  * @start: The memory area
 686  * @c: Find a character other than c
 687  * @bytes: The size of the area.
 688  *
 689  * returns the address of the first character other than @c, or %NULL
 690  * if the whole buffer contains just @c.
 691  */
 692 void *memchr_inv(const void *start, int c, size_t bytes)
 693 {
 694         u8 value = c;
 695         u64 value64;
 696         unsigned int words, prefix;
 697
 698         if (bytes <= 16)
 699                 return check_bytes8(start, value, bytes);
 700
 701         value64 = value;
 702         value64 |= value64 << 8;
 703         value64 |= value64 << 16;
 704         value64 |= value64 << 32;
 705
 706         prefix = (unsigned long)start % 8;
 707         if (prefix) {
 708                 u8 *r;
 709
 710                 prefix = 8 - prefix;
 711                 r = check_bytes8(start, value, prefix);
 712                 if (r)
 713                         return r;
 714                 start += prefix;
 715                 bytes -= prefix;
 716         }
 717
 718         words = bytes / 8;
 719
 720         while (words) {
 721                 if (*(u64 *)start != value64)
 722                         return check_bytes8(start, value, 8);
 723                 start += 8;
 724                 words--;
 725         }
 726
 727         return check_bytes8(start, value, bytes % 8);
 728 }
 729 #endif