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  * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
  18  *                    Matthew Hawkins <matt@mh.dropbear.id.au>
  19  * -  Kissed strtok() goodbye
  20  */
  21
  22 #include <linux/types.h>
  23 #include <linux/string.h>
  24 #include <linux/ctype.h>
  25 #include <linux/module.h>
  26
  27 #ifndef __HAVE_ARCH_STRNICMP
  28 /**
  29  * strnicmp - Case insensitive, length-limited string comparison
  30  * @s1: One string
  31  * @s2: The other string
  32  * @len: the maximum number of characters to compare
  33  */
  34 int strnicmp(const char *s1, const char *s2, size_t len)
  35 {
  36         /* Yes, Virginia, it had better be unsigned */
  37         unsigned char c1, c2;
  38
  39         c1 = c2 = 0;
  40         if (len) {
  41                 do {
  42                         c1 = *s1;
  43                         c2 = *s2;
  44                         s1++;
  45                         s2++;
  46                         if (!c1)
  47                                 break;
  48                         if (!c2)
  49                                 break;
  50                         if (c1 == c2)
  51                                 continue;
  52                         c1 = tolower(c1);
  53                         c2 = tolower(c2);
  54                         if (c1 != c2)
  55                                 break;
  56                 } while (--len);
  57         }
  58         return (int)c1 - (int)c2;
  59 }
  60 EXPORT_SYMBOL(strnicmp);
  61 #endif
  62
  63 #ifndef __HAVE_ARCH_STRCASECMP
  64 int strcasecmp(const char *s1, const char *s2)
  65 {
  66         int c1, c2;
  67
  68         do {
  69                 c1 = tolower(*s1++);
  70                 c2 = tolower(*s2++);
  71         } while (c1 == c2 && c1 != 0);
  72         return c1 - c2;
  73 }
  74 EXPORT_SYMBOL(strcasecmp);
  75 #endif
  76
  77 #ifndef __HAVE_ARCH_STRNCASECMP
  78 int strncasecmp(const char *s1, const char *s2, size_t n)
  79 {
  80         int c1, c2;
  81
  82         do {
  83                 c1 = tolower(*s1++);
  84                 c2 = tolower(*s2++);
  85         } while ((--n > 0) && c1 == c2 && c1 != 0);
  86         return c1 - c2;
  87 }
  88 EXPORT_SYMBOL(strncasecmp);
  89 #endif
  90
  91 #ifndef __HAVE_ARCH_STRCPY
  92 /**
  93  * strcpy - Copy a %NUL terminated string
  94  * @dest: Where to copy the string to
  95  * @src: Where to copy the string from
  96  */
  97 #undef strcpy
  98 char *strcpy(char *dest, const char *src)
  99 {
 100         char *tmp = dest;
 101
 102         while ((*dest++ = *src++) != '\0')
 103                 /* nothing */;
 104         return tmp;
 105 }
 106 EXPORT_SYMBOL(strcpy);
 107 #endif
 108
 109 #ifndef __HAVE_ARCH_STRNCPY
 110 /**
 111  * strncpy - Copy a length-limited, %NUL-terminated string
 112  * @dest: Where to copy the string to
 113  * @src: Where to copy the string from
 114  * @count: The maximum number of bytes to copy
 115  *
 116  * The result is not %NUL-terminated if the source exceeds
 117  * @count bytes.
 118  *
 119  * In the case where the length of @src is less than  that  of
 120  * count, the remainder of @dest will be padded with %NUL.
 121  *
 122  */
 123 char *strncpy(char *dest, const char *src, size_t count)
 124 {
 125         char *tmp = dest;
 126
 127         while (count) {
 128                 if ((*tmp = *src) != 0)
 129                         src++;
 130                 tmp++;
 131                 count--;
 132         }
 133         return dest;
 134 }
 135 EXPORT_SYMBOL(strncpy);
 136 #endif
 137
 138 #ifndef __HAVE_ARCH_STRLCPY
 139 /**
 140  * strlcpy - Copy a %NUL terminated string into a sized buffer
 141  * @dest: Where to copy the string to
 142  * @src: Where to copy the string from
 143  * @size: size of destination buffer
 144  *
 145  * Compatible with *BSD: the result is always a valid
 146  * NUL-terminated string that fits in the buffer (unless,
 147  * of course, the buffer size is zero). It does not pad
 148  * out the result like strncpy() does.
 149  */
 150 size_t strlcpy(char *dest, const char *src, size_t size)
 151 {
 152         size_t ret = strlen(src);
 153
 154         if (size) {
 155                 size_t len = (ret >= size) ? size - 1 : ret;
 156                 memcpy(dest, src, len);
 157                 dest[len] = '\0';
 158         }
 159         return ret;
 160 }
 161 EXPORT_SYMBOL(strlcpy);
 162 #endif
 163
 164 #ifndef __HAVE_ARCH_STRCAT
 165 /**
 166  * strcat - Append one %NUL-terminated string to another
 167  * @dest: The string to be appended to
 168  * @src: The string to append to it
 169  */
 170 #undef strcat
 171 char *strcat(char *dest, const char *src)
 172 {
 173         char *tmp = dest;
 174
 175         while (*dest)
 176                 dest++;
 177         while ((*dest++ = *src++) != '\0')
 178                 ;
 179         return tmp;
 180 }
 181 EXPORT_SYMBOL(strcat);
 182 #endif
 183
 184 #ifndef __HAVE_ARCH_STRNCAT
 185 /**
 186  * strncat - Append a length-limited, %NUL-terminated string to another
 187  * @dest: The string to be appended to
 188  * @src: The string to append to it
 189  * @count: The maximum numbers of bytes to copy
 190  *
 191  * Note that in contrast to strncpy(), strncat() ensures the result is
 192  * terminated.
 193  */
 194 char *strncat(char *dest, const char *src, size_t count)
 195 {
 196         char *tmp = dest;
 197
 198         if (count) {
 199                 while (*dest)
 200                         dest++;
 201                 while ((*dest++ = *src++) != 0) {
 202                         if (--count == 0) {
 203                                 *dest = '\0';
 204                                 break;
 205                         }
 206                 }
 207         }
 208         return tmp;
 209 }
 210 EXPORT_SYMBOL(strncat);
 211 #endif
 212
 213 #ifndef __HAVE_ARCH_STRLCAT
 214 /**
 215  * strlcat - Append a length-limited, %NUL-terminated string to another
 216  * @dest: The string to be appended to
 217  * @src: The string to append to it
 218  * @count: The size of the destination buffer.
 219  */
 220 size_t strlcat(char *dest, const char *src, size_t count)
 221 {
 222         size_t dsize = strlen(dest);
 223         size_t len = strlen(src);
 224         size_t res = dsize + len;
 225
 226         /* This would be a bug */
 227         BUG_ON(dsize >= count);
 228
 229         dest += dsize;
 230         count -= dsize;
 231         if (len >= count)
 232                 len = count-1;
 233         memcpy(dest, src, len);
 234         dest[len] = 0;
 235         return res;
 236 }
 237 EXPORT_SYMBOL(strlcat);
 238 #endif
 239
 240 #ifndef __HAVE_ARCH_STRCMP
 241 /**
 242  * strcmp - Compare two strings
 243  * @cs: One string
 244  * @ct: Another string
 245  */
 246 #undef strcmp
 247 int strcmp(const char *cs, const char *ct)
 248 {
 249         unsigned char c1, c2;
 250
 251         while (1) {
 252                 c1 = *cs++;
 253                 c2 = *ct++;
 254                 if (c1 != c2)
 255                         return c1 < c2 ? -1 : 1;
 256                 if (!c1)
 257                         break;
 258         }
 259         return 0;
 260 }
 261 EXPORT_SYMBOL(strcmp);
 262 #endif
 263
 264 #ifndef __HAVE_ARCH_STRNCMP
 265 /**
 266  * strncmp - Compare two length-limited strings
 267  * @cs: One string
 268  * @ct: Another string
 269  * @count: The maximum number of bytes to compare
 270  */
 271 int strncmp(const char *cs, const char *ct, size_t count)
 272 {
 273         unsigned char c1, c2;
 274
 275         while (count) {
 276                 c1 = *cs++;
 277                 c2 = *ct++;
 278                 if (c1 != c2)
 279                         return c1 < c2 ? -1 : 1;
 280                 if (!c1)
 281                         break;
 282                 count--;
 283         }
 284         return 0;
 285 }
 286 EXPORT_SYMBOL(strncmp);
 287 #endif
 288
 289 #ifndef __HAVE_ARCH_STRCHR
 290 /**
 291  * strchr - Find the first occurrence of a character in a string
 292  * @s: The string to be searched
 293  * @c: The character to search for
 294  */
 295 char *strchr(const char *s, int c)
 296 {
 297         for (; *s != (char)c; ++s)
 298                 if (*s == '\0')
 299                         return NULL;
 300         return (char *)s;
 301 }
 302 EXPORT_SYMBOL(strchr);
 303 #endif
 304
 305 #ifndef __HAVE_ARCH_STRRCHR
 306 /**
 307  * strrchr - Find the last occurrence of a character in a string
 308  * @s: The string to be searched
 309  * @c: The character to search for
 310  */
 311 char *strrchr(const char *s, int c)
 312 {
 313        const char *p = s + strlen(s);
 314        do {
 315            if (*p == (char)c)
 316                return (char *)p;
 317        } while (--p >= s);
 318        return NULL;
 319 }
 320 EXPORT_SYMBOL(strrchr);
 321 #endif
 322
 323 #ifndef __HAVE_ARCH_STRNCHR
 324 /**
 325  * strnchr - Find a character in a length limited string
 326  * @s: The string to be searched
 327  * @count: The number of characters to be searched
 328  * @c: The character to search for
 329  */
 330 char *strnchr(const char *s, size_t count, int c)
 331 {
 332         for (; count-- && *s != '\0'; ++s)
 333                 if (*s == (char)c)
 334                         return (char *)s;
 335         return NULL;
 336 }
 337 EXPORT_SYMBOL(strnchr);
 338 #endif
 339
 340 /**
 341  * strstrip - Removes leading and trailing whitespace from @s.
 342  * @s: The string to be stripped.
 343  *
 344  * Note that the first trailing whitespace is replaced with a %NUL-terminator
 345  * in the given string @s. Returns a pointer to the first non-whitespace
 346  * character in @s.
 347  */
 348 char *strstrip(char *s)
 349 {
 350         size_t size;
 351         char *end;
 352
 353         size = strlen(s);
 354
 355         if (!size)
 356                 return s;
 357
 358         end = s + size - 1;
 359         while (end >= s && isspace(*end))
 360                 end--;
 361         *(end + 1) = '\0';
 362
 363         while (*s && isspace(*s))
 364                 s++;
 365
 366         return s;
 367 }
 368 EXPORT_SYMBOL(strstrip);
 369
 370 #ifndef __HAVE_ARCH_STRLEN
 371 /**
 372  * strlen - Find the length of a string
 373  * @s: The string to be sized
 374  */
 375 size_t strlen(const char *s)
 376 {
 377         const char *sc;
 378
 379         for (sc = s; *sc != '\0'; ++sc)
 380                 /* nothing */;
 381         return sc - s;
 382 }
 383 EXPORT_SYMBOL(strlen);
 384 #endif
 385
 386 #ifndef __HAVE_ARCH_STRNLEN
 387 /**
 388  * strnlen - Find the length of a length-limited string
 389  * @s: The string to be sized
 390  * @count: The maximum number of bytes to search
 391  */
 392 size_t strnlen(const char *s, size_t count)
 393 {
 394         const char *sc;
 395
 396         for (sc = s; count-- && *sc != '\0'; ++sc)
 397                 /* nothing */;
 398         return sc - s;
 399 }
 400 EXPORT_SYMBOL(strnlen);
 401 #endif
 402
 403 #ifndef __HAVE_ARCH_STRSPN
 404 /**
 405  * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
 406  * @s: The string to be searched
 407  * @accept: The string to search for
 408  */
 409 size_t strspn(const char *s, const char *accept)
 410 {
 411         const char *p;
 412         const char *a;
 413         size_t count = 0;
 414
 415         for (p = s; *p != '\0'; ++p) {
 416                 for (a = accept; *a != '\0'; ++a) {
 417                         if (*p == *a)
 418                                 break;
 419                 }
 420                 if (*a == '\0')
 421                         return count;
 422                 ++count;
 423         }
 424         return count;
 425 }
 426
 427 EXPORT_SYMBOL(strspn);
 428 #endif
 429
 430 #ifndef __HAVE_ARCH_STRCSPN
 431 /**
 432  * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
 433  * @s: The string to be searched
 434  * @reject: The string to avoid
 435  */
 436 size_t strcspn(const char *s, const char *reject)
 437 {
 438         const char *p;
 439         const char *r;
 440         size_t count = 0;
 441
 442         for (p = s; *p != '\0'; ++p) {
 443                 for (r = reject; *r != '\0'; ++r) {
 444                         if (*p == *r)
 445                                 return count;
 446                 }
 447                 ++count;
 448         }
 449         return count;
 450 }
 451 EXPORT_SYMBOL(strcspn);
 452 #endif
 453
 454 #ifndef __HAVE_ARCH_STRPBRK
 455 /**
 456  * strpbrk - Find the first occurrence of a set of characters
 457  * @cs: The string to be searched
 458  * @ct: The characters to search for
 459  */
 460 char *strpbrk(const char *cs, const char *ct)
 461 {
 462         const char *sc1, *sc2;
 463
 464         for (sc1 = cs; *sc1 != '\0'; ++sc1) {
 465                 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
 466                         if (*sc1 == *sc2)
 467                                 return (char *)sc1;
 468                 }
 469         }
 470         return NULL;
 471 }
 472 EXPORT_SYMBOL(strpbrk);
 473 #endif
 474
 475 #ifndef __HAVE_ARCH_STRSEP
 476 /**
 477  * strsep - Split a string into tokens
 478  * @s: The string to be searched
 479  * @ct: The characters to search for
 480  *
 481  * strsep() updates @s to point after the token, ready for the next call.
 482  *
 483  * It returns empty tokens, too, behaving exactly like the libc function
 484  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 485  * Same semantics, slimmer shape. ;)
 486  */
 487 char *strsep(char **s, const char *ct)
 488 {
 489         char *sbegin = *s;
 490         char *end;
 491
 492         if (sbegin == NULL)
 493                 return NULL;
 494
 495         end = strpbrk(sbegin, ct);
 496         if (end)
 497                 *end++ = '\0';
 498         *s = end;
 499         return sbegin;
 500 }
 501 EXPORT_SYMBOL(strsep);
 502 #endif
 503
 504 /**
 505  * sysfs_streq - return true if strings are equal, modulo trailing newline
 506  * @s1: one string
 507  * @s2: another string
 508  *
 509  * This routine returns true iff two strings are equal, treating both
 510  * NUL and newline-then-NUL as equivalent string terminations.  It's
 511  * geared for use with sysfs input strings, which generally terminate
 512  * with newlines but are compared against values without newlines.
 513  */
 514 bool sysfs_streq(const char *s1, const char *s2)
 515 {
 516         while (*s1 && *s1 == *s2) {
 517                 s1++;
 518                 s2++;
 519         }
 520
 521         if (*s1 == *s2)
 522                 return true;
 523         if (!*s1 && *s2 == '\n' && !s2[1])
 524                 return true;
 525         if (*s1 == '\n' && !s1[1] && !*s2)
 526                 return true;
 527         return false;
 528 }
 529 EXPORT_SYMBOL(sysfs_streq);
 530
 531 #ifndef __HAVE_ARCH_MEMSET
 532 /**
 533  * memset - Fill a region of memory with the given value
 534  * @s: Pointer to the start of the area.
 535  * @c: The byte to fill the area with
 536  * @count: The size of the area.
 537  *
 538  * Do not use memset() to access IO space, use memset_io() instead.
 539  */
 540 void *memset(void *s, int c, size_t count)
 541 {
 542         char *xs = s;
 543
 544         while (count--)
 545                 *xs++ = c;
 546         return s;
 547 }
 548 EXPORT_SYMBOL(memset);
 549 #endif
 550
 551 #ifndef __HAVE_ARCH_MEMCPY
 552 /**
 553  * memcpy - Copy one area of memory to another
 554  * @dest: Where to copy to
 555  * @src: Where to copy from
 556  * @count: The size of the area.
 557  *
 558  * You should not use this function to access IO space, use memcpy_toio()
 559  * or memcpy_fromio() instead.
 560  */
 561 void *memcpy(void *dest, const void *src, size_t count)
 562 {
 563         char *tmp = dest;
 564         const char *s = src;
 565
 566         while (count--)
 567                 *tmp++ = *s++;
 568         return dest;
 569 }
 570 EXPORT_SYMBOL(memcpy);
 571 #endif
 572
 573 #ifndef __HAVE_ARCH_MEMMOVE
 574 /**
 575  * memmove - Copy one area of memory to another
 576  * @dest: Where to copy to
 577  * @src: Where to copy from
 578  * @count: The size of the area.
 579  *
 580  * Unlike memcpy(), memmove() copes with overlapping areas.
 581  */
 582 void *memmove(void *dest, const void *src, size_t count)
 583 {
 584         char *tmp;
 585         const char *s;
 586
 587         if (dest <= src) {
 588                 tmp = dest;
 589                 s = src;
 590                 while (count--)
 591                         *tmp++ = *s++;
 592         } else {
 593                 tmp = dest;
 594                 tmp += count;
 595                 s = src;
 596                 s += count;
 597                 while (count--)
 598                         *--tmp = *--s;
 599         }
 600         return dest;
 601 }
 602 EXPORT_SYMBOL(memmove);
 603 #endif
 604
 605 #ifndef __HAVE_ARCH_MEMCMP
 606 /**
 607  * memcmp - Compare two areas of memory
 608  * @cs: One area of memory
 609  * @ct: Another area of memory
 610  * @count: The size of the area.
 611  */
 612 #undef memcmp
 613 int memcmp(const void *cs, const void *ct, size_t count)
 614 {
 615         const unsigned char *su1, *su2;
 616         int res = 0;
 617
 618         for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 619                 if ((res = *su1 - *su2) != 0)
 620                         break;
 621         return res;
 622 }
 623 EXPORT_SYMBOL(memcmp);
 624 #endif
 625
 626 #ifndef __HAVE_ARCH_MEMSCAN
 627 /**
 628  * memscan - Find a character in an area of memory.
 629  * @addr: The memory area
 630  * @c: The byte to search for
 631  * @size: The size of the area.
 632  *
 633  * returns the address of the first occurrence of @c, or 1 byte past
 634  * the area if @c is not found
 635  */
 636 void *memscan(void *addr, int c, size_t size)
 637 {
 638         unsigned char *p = addr;
 639
 640         while (size) {
 641                 if (*p == c)
 642                         return (void *)p;
 643                 p++;
 644                 size--;
 645         }
 646         return (void *)p;
 647 }
 648 EXPORT_SYMBOL(memscan);
 649 #endif
 650
 651 #ifndef __HAVE_ARCH_STRSTR
 652 /**
 653  * strstr - Find the first substring in a %NUL terminated string
 654  * @s1: The string to be searched
 655  * @s2: The string to search for
 656  */
 657 char *strstr(const char *s1, const char *s2)
 658 {
 659         int l1, l2;
 660
 661         l2 = strlen(s2);
 662         if (!l2)
 663                 return (char *)s1;
 664         l1 = strlen(s1);
 665         while (l1 >= l2) {
 666                 l1--;
 667                 if (!memcmp(s1, s2, l2))
 668                         return (char *)s1;
 669                 s1++;
 670         }
 671         return NULL;
 672 }
 673 EXPORT_SYMBOL(strstr);
 674 #endif
 675
 676 #ifndef __HAVE_ARCH_MEMCHR
 677 /**
 678  * memchr - Find a character in an area of memory.
 679  * @s: The memory area
 680  * @c: The byte to search for
 681  * @n: The size of the area.
 682  *
 683  * returns the address of the first occurrence of @c, or %NULL
 684  * if @c is not found
 685  */
 686 void *memchr(const void *s, int c, size_t n)
 687 {
 688         const unsigned char *p = s;
 689         while (n-- != 0) {
 690                 if ((unsigned char)c == *p++) {
 691                         return (void *)(p - 1);
 692                 }
 693         }
 694         return NULL;
 695 }
 696 EXPORT_SYMBOL(memchr);
 697 #endif