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         signed char __res;
 250
 251         while (1) {
 252                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 253                         break;
 254         }
 255         return __res;
 256 }
 257 EXPORT_SYMBOL(strcmp);
 258 #endif
 259
 260 #ifndef __HAVE_ARCH_STRNCMP
 261 /**
 262  * strncmp - Compare two length-limited strings
 263  * @cs: One string
 264  * @ct: Another string
 265  * @count: The maximum number of bytes to compare
 266  */
 267 int strncmp(const char *cs, const char *ct, size_t count)
 268 {
 269         signed char __res = 0;
 270
 271         while (count) {
 272                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 273                         break;
 274                 count--;
 275         }
 276         return __res;
 277 }
 278 EXPORT_SYMBOL(strncmp);
 279 #endif
 280
 281 #ifndef __HAVE_ARCH_STRCHR
 282 /**
 283  * strchr - Find the first occurrence of a character in a string
 284  * @s: The string to be searched
 285  * @c: The character to search for
 286  */
 287 char *strchr(const char *s, int c)
 288 {
 289         for (; *s != (char)c; ++s)
 290                 if (*s == '\0')
 291                         return NULL;
 292         return (char *)s;
 293 }
 294 EXPORT_SYMBOL(strchr);
 295 #endif
 296
 297 #ifndef __HAVE_ARCH_STRRCHR
 298 /**
 299  * strrchr - Find the last occurrence of a character in a string
 300  * @s: The string to be searched
 301  * @c: The character to search for
 302  */
 303 char *strrchr(const char *s, int c)
 304 {
 305        const char *p = s + strlen(s);
 306        do {
 307            if (*p == (char)c)
 308                return (char *)p;
 309        } while (--p >= s);
 310        return NULL;
 311 }
 312 EXPORT_SYMBOL(strrchr);
 313 #endif
 314
 315 #ifndef __HAVE_ARCH_STRNCHR
 316 /**
 317  * strnchr - Find a character in a length limited string
 318  * @s: The string to be searched
 319  * @count: The number of characters to be searched
 320  * @c: The character to search for
 321  */
 322 char *strnchr(const char *s, size_t count, int c)
 323 {
 324         for (; count-- && *s != '\0'; ++s)
 325                 if (*s == (char)c)
 326                         return (char *)s;
 327         return NULL;
 328 }
 329 EXPORT_SYMBOL(strnchr);
 330 #endif
 331
 332 /**
 333  * strstrip - Removes leading and trailing whitespace from @s.
 334  * @s: The string to be stripped.
 335  *
 336  * Note that the first trailing whitespace is replaced with a %NUL-terminator
 337  * in the given string @s. Returns a pointer to the first non-whitespace
 338  * character in @s.
 339  */
 340 char *strstrip(char *s)
 341 {
 342         size_t size;
 343         char *end;
 344
 345         size = strlen(s);
 346
 347         if (!size)
 348                 return s;
 349
 350         end = s + size - 1;
 351         while (end >= s && isspace(*end))
 352                 end--;
 353         *(end + 1) = '\0';
 354
 355         while (*s && isspace(*s))
 356                 s++;
 357
 358         return s;
 359 }
 360 EXPORT_SYMBOL(strstrip);
 361
 362 #ifndef __HAVE_ARCH_STRLEN
 363 /**
 364  * strlen - Find the length of a string
 365  * @s: The string to be sized
 366  */
 367 size_t strlen(const char *s)
 368 {
 369         const char *sc;
 370
 371         for (sc = s; *sc != '\0'; ++sc)
 372                 /* nothing */;
 373         return sc - s;
 374 }
 375 EXPORT_SYMBOL(strlen);
 376 #endif
 377
 378 #ifndef __HAVE_ARCH_STRNLEN
 379 /**
 380  * strnlen - Find the length of a length-limited string
 381  * @s: The string to be sized
 382  * @count: The maximum number of bytes to search
 383  */
 384 size_t strnlen(const char *s, size_t count)
 385 {
 386         const char *sc;
 387
 388         for (sc = s; count-- && *sc != '\0'; ++sc)
 389                 /* nothing */;
 390         return sc - s;
 391 }
 392 EXPORT_SYMBOL(strnlen);
 393 #endif
 394
 395 #ifndef __HAVE_ARCH_STRSPN
 396 /**
 397  * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept
 398  * @s: The string to be searched
 399  * @accept: The string to search for
 400  */
 401 size_t strspn(const char *s, const char *accept)
 402 {
 403         const char *p;
 404         const char *a;
 405         size_t count = 0;
 406
 407         for (p = s; *p != '\0'; ++p) {
 408                 for (a = accept; *a != '\0'; ++a) {
 409                         if (*p == *a)
 410                                 break;
 411                 }
 412                 if (*a == '\0')
 413                         return count;
 414                 ++count;
 415         }
 416         return count;
 417 }
 418
 419 EXPORT_SYMBOL(strspn);
 420 #endif
 421
 422 #ifndef __HAVE_ARCH_STRCSPN
 423 /**
 424  * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject
 425  * @s: The string to be searched
 426  * @reject: The string to avoid
 427  */
 428 size_t strcspn(const char *s, const char *reject)
 429 {
 430         const char *p;
 431         const char *r;
 432         size_t count = 0;
 433
 434         for (p = s; *p != '\0'; ++p) {
 435                 for (r = reject; *r != '\0'; ++r) {
 436                         if (*p == *r)
 437                                 return count;
 438                 }
 439                 ++count;
 440         }
 441         return count;
 442 }
 443 EXPORT_SYMBOL(strcspn);
 444 #endif
 445
 446 #ifndef __HAVE_ARCH_STRPBRK
 447 /**
 448  * strpbrk - Find the first occurrence of a set of characters
 449  * @cs: The string to be searched
 450  * @ct: The characters to search for
 451  */
 452 char *strpbrk(const char *cs, const char *ct)
 453 {
 454         const char *sc1, *sc2;
 455
 456         for (sc1 = cs; *sc1 != '\0'; ++sc1) {
 457                 for (sc2 = ct; *sc2 != '\0'; ++sc2) {
 458                         if (*sc1 == *sc2)
 459                                 return (char *)sc1;
 460                 }
 461         }
 462         return NULL;
 463 }
 464 EXPORT_SYMBOL(strpbrk);
 465 #endif
 466
 467 #ifndef __HAVE_ARCH_STRSEP
 468 /**
 469  * strsep - Split a string into tokens
 470  * @s: The string to be searched
 471  * @ct: The characters to search for
 472  *
 473  * strsep() updates @s to point after the token, ready for the next call.
 474  *
 475  * It returns empty tokens, too, behaving exactly like the libc function
 476  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 477  * Same semantics, slimmer shape. ;)
 478  */
 479 char *strsep(char **s, const char *ct)
 480 {
 481         char *sbegin = *s;
 482         char *end;
 483
 484         if (sbegin == NULL)
 485                 return NULL;
 486
 487         end = strpbrk(sbegin, ct);
 488         if (end)
 489                 *end++ = '\0';
 490         *s = end;
 491         return sbegin;
 492 }
 493 EXPORT_SYMBOL(strsep);
 494 #endif
 495
 496 /**
 497  * sysfs_streq - return true if strings are equal, modulo trailing newline
 498  * @s1: one string
 499  * @s2: another string
 500  *
 501  * This routine returns true iff two strings are equal, treating both
 502  * NUL and newline-then-NUL as equivalent string terminations.  It's
 503  * geared for use with sysfs input strings, which generally terminate
 504  * with newlines but are compared against values without newlines.
 505  */
 506 bool sysfs_streq(const char *s1, const char *s2)
 507 {
 508         while (*s1 && *s1 == *s2) {
 509                 s1++;
 510                 s2++;
 511         }
 512
 513         if (*s1 == *s2)
 514                 return true;
 515         if (!*s1 && *s2 == '\n' && !s2[1])
 516                 return true;
 517         if (*s1 == '\n' && !s1[1] && !*s2)
 518                 return true;
 519         return false;
 520 }
 521 EXPORT_SYMBOL(sysfs_streq);
 522
 523 #ifndef __HAVE_ARCH_MEMSET
 524 /**
 525  * memset - Fill a region of memory with the given value
 526  * @s: Pointer to the start of the area.
 527  * @c: The byte to fill the area with
 528  * @count: The size of the area.
 529  *
 530  * Do not use memset() to access IO space, use memset_io() instead.
 531  */
 532 void *memset(void *s, int c, size_t count)
 533 {
 534         char *xs = s;
 535
 536         while (count--)
 537                 *xs++ = c;
 538         return s;
 539 }
 540 EXPORT_SYMBOL(memset);
 541 #endif
 542
 543 #ifndef __HAVE_ARCH_MEMCPY
 544 /**
 545  * memcpy - Copy one area of memory to another
 546  * @dest: Where to copy to
 547  * @src: Where to copy from
 548  * @count: The size of the area.
 549  *
 550  * You should not use this function to access IO space, use memcpy_toio()
 551  * or memcpy_fromio() instead.
 552  */
 553 void *memcpy(void *dest, const void *src, size_t count)
 554 {
 555         char *tmp = dest;
 556         const char *s = src;
 557
 558         while (count--)
 559                 *tmp++ = *s++;
 560         return dest;
 561 }
 562 EXPORT_SYMBOL(memcpy);
 563 #endif
 564
 565 #ifndef __HAVE_ARCH_MEMMOVE
 566 /**
 567  * memmove - Copy one area of memory to another
 568  * @dest: Where to copy to
 569  * @src: Where to copy from
 570  * @count: The size of the area.
 571  *
 572  * Unlike memcpy(), memmove() copes with overlapping areas.
 573  */
 574 void *memmove(void *dest, const void *src, size_t count)
 575 {
 576         char *tmp;
 577         const char *s;
 578
 579         if (dest <= src) {
 580                 tmp = dest;
 581                 s = src;
 582                 while (count--)
 583                         *tmp++ = *s++;
 584         } else {
 585                 tmp = dest;
 586                 tmp += count;
 587                 s = src;
 588                 s += count;
 589                 while (count--)
 590                         *--tmp = *--s;
 591         }
 592         return dest;
 593 }
 594 EXPORT_SYMBOL(memmove);
 595 #endif
 596
 597 #ifndef __HAVE_ARCH_MEMCMP
 598 /**
 599  * memcmp - Compare two areas of memory
 600  * @cs: One area of memory
 601  * @ct: Another area of memory
 602  * @count: The size of the area.
 603  */
 604 #undef memcmp
 605 int memcmp(const void *cs, const void *ct, size_t count)
 606 {
 607         const unsigned char *su1, *su2;
 608         int res = 0;
 609
 610         for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 611                 if ((res = *su1 - *su2) != 0)
 612                         break;
 613         return res;
 614 }
 615 EXPORT_SYMBOL(memcmp);
 616 #endif
 617
 618 #ifndef __HAVE_ARCH_MEMSCAN
 619 /**
 620  * memscan - Find a character in an area of memory.
 621  * @addr: The memory area
 622  * @c: The byte to search for
 623  * @size: The size of the area.
 624  *
 625  * returns the address of the first occurrence of @c, or 1 byte past
 626  * the area if @c is not found
 627  */
 628 void *memscan(void *addr, int c, size_t size)
 629 {
 630         unsigned char *p = addr;
 631
 632         while (size) {
 633                 if (*p == c)
 634                         return (void *)p;
 635                 p++;
 636                 size--;
 637         }
 638         return (void *)p;
 639 }
 640 EXPORT_SYMBOL(memscan);
 641 #endif
 642
 643 #ifndef __HAVE_ARCH_STRSTR
 644 /**
 645  * strstr - Find the first substring in a %NUL terminated string
 646  * @s1: The string to be searched
 647  * @s2: The string to search for
 648  */
 649 char *strstr(const char *s1, const char *s2)
 650 {
 651         int l1, l2;
 652
 653         l2 = strlen(s2);
 654         if (!l2)
 655                 return (char *)s1;
 656         l1 = strlen(s1);
 657         while (l1 >= l2) {
 658                 l1--;
 659                 if (!memcmp(s1, s2, l2))
 660                         return (char *)s1;
 661                 s1++;
 662         }
 663         return NULL;
 664 }
 665 EXPORT_SYMBOL(strstr);
 666 #endif
 667
 668 #ifndef __HAVE_ARCH_MEMCHR
 669 /**
 670  * memchr - Find a character in an area of memory.
 671  * @s: The memory area
 672  * @c: The byte to search for
 673  * @n: The size of the area.
 674  *
 675  * returns the address of the first occurrence of @c, or %NULL
 676  * if @c is not found
 677  */
 678 void *memchr(const void *s, int c, size_t n)
 679 {
 680         const unsigned char *p = s;
 681         while (n-- != 0) {
 682                 if ((unsigned char)c == *p++) {
 683                         return (void *)(p - 1);
 684                 }
 685         }
 686         return NULL;
 687 }
 688 EXPORT_SYMBOL(memchr);
 689 #endif